Language：Japanese   Publisher：(一社)日本脳循環代謝学会  

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Language：Japanese   Publisher：(一社)日本脳循環代謝学会  

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PURPOSE: To clarify the type of spin compartment in arterial spin labeling (ASL) that is eliminated by delays alternating with nutation for tailored excitation (DANTE) pulse using T2 -relaxometry, and to demonstrate the feasibility of arterial cerebral blood volume (CBVa ) imaging using DANTE-ASL in combination with a simplified two-compartment model. METHOD: The DANTE and T2 -preparation modules were combined into a single ASL sequence. T2 values under the application of DANTE were determined to evaluate changes in T2 , along with the post-labeling delay (PLD) and the relationship between transit time without DANTE (TTnoVS ) and T2 . The reference tissue T2 (T2_ref ) was also obtained. Subsequently, the DANTE module was embedded into the Hadamard-encoded ASL. Cerebral blood flow (CBF) and CBVa were computed using two Hadamard-encoding datasets (with and without DANTE) in a rest and breath-holding (BH) task. RESULTS: While T2 without DANTE (T2_noVS ) decreased as the PLD increased, T2 with DANTE (T2_DANTE ) was equivalent to T2_ref and did not change with the PLD. Although there was a significant positive correlation between TTnoVS and T2_noVS with short PLD, T2_DANTE was not correlated with TTnoVS nor PLD. Baseline CBVa values obtained at rest were 0.64 ± 0.12, 0.64 ± 0.11, and 0.58 ± 0.15 mL/100 g for anterior, middle, and posterior cerebral arteries, respectively. Significant CBF and CBVa elevations were observed in the BH task. CONCLUSION: Microvascular compartment signals were eliminated from the total ASL signals by DANTE. CBVa can be measured using Hadamard-encoded DANTE-ASL in combination with a simplified two-compartment model.

DOI： 10.1002/mrm.29052

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Publishing type：Research paper (scientific journal)   Publisher：American Society of Neuroradiology ({ASNR})  

DOI： 10.3174/ajnr.A7167

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Language：English   Publishing type：Research paper (scientific journal)  

We investigated the spatial and temporal variations of flip-angle (FA) distributions in the human brain from multiple scans, using an eight-channel parallel transmission (pTx) system at 7T. Nine healthy volunteers were scanned in five sessions using three radiofrequency excitation techniques each time: circular polarization (CP), static pTx, and dynamic pTx. We calculated the coefficients of variation of the FA values within the brain area to evaluate the variations, and the maximum intersession differences in the FA values (Dmax), comparing them between the three methods. The coefficients of variation decreased in the following order: CP, static pTx, and dynamic pTx (median: 20.1%, 13.6%, and 5.7%, respectively; p < 0.001). The average Dmax values were significantly higher for the static pTx (5.4°) than for the dynamic pTx (2.8°) and CP (1.7°) methods (p = 0.004 and 0.001, respectively). Compared to the CP method, the dynamic pTx method at 7T can efficiently minimize spatial variations in the FA distribution with a mild increase in temporal variations. The static pTx method exhibited a remarkably wide temporal variation.

DOI： 10.1007/s12194-021-00612-8

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Cerebrovascular reactivity (CVR) to acetazolamide (ACZ) on single-photon emission computed tomography (SPECT) can be used to assess the severity of chronic cerebral ischemia; however, this is an invasive method. We examined whether whole-brain magnetic resonance angiography (MRA) at 7T could non-invasively detect impaired CVR in patients with chronic cerebral ischemia by demonstrating the leptomeningeal collaterals (LMCs). METHODS: Fifty-seven patients with symptomatic unilateral cervical stenosis underwent whole-brain time-of-flight MRA at 7T and cerebral perfusion SPECT before/after the ACZ challenge. MRA images were visually assessed based on 6-point grading systems to evaluate the development of LMCs toward the middle cerebral artery (MCA) and antegrade flow of MCA. CVR of the affected side was calculated from the SPECT data. Subsequently, we compared the LMC grades on MRA with CVR on SPECT. RESULTS: CVR was significantly lower in grades ≥ 2 of LMCs than in grades 0-1 (P < 0.05) when applying LMCs from the anterior cerebral artery (ACA) and/or posterior cerebral artery (PCA). These differences were more evident than those in the grading of the antegrade MCA flow. The LMC grades from ACA/PCA readily detected reduced CVR (< 18.4%) with a sensitivity/specificity of 0.79/0.82. CONCLUSION: The development of LMCs on whole-brain MRA at 7T can non-invasively detect reduced CVR with a high sensitivity/specificity in patients with unilateral cervical stenosis.

DOI： 10.1016/j.jstrokecerebrovasdis.2020.105081

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/nbm.4319

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/nbm.4319

Language：English   Publishing type：Research paper (scientific journal)  

RATIONALE AND OBJECTIVE: Differentiation between multiple system atrophy (MSA) and other spinocerebellar degenerations showing cerebellar ataxia is often difficult. Hence, we investigated whether magnetic resonance diffusion kurtosis imaging (DKI) could detect pathological changes that occur in these patients and be used for differential diagnosis. METHODS: Thirty-six subjects (12 patients with MSA accompanied by predominant cerebellar ataxia [MSA-C], 10 patients with spinocerebellar ataxias [SCAs] or sporadic adult-onset ataxia of unknown etiology [SAOA], and 14 healthy controls) were examined using 1.5- or 3-T magnetic resonance scanners. From the DKI data, the mean kurtosis, fractional anisotropy, and mean diffusivity values of the pontine crossing tract (PCT), middle cerebellar peduncle, and cerebellum were automatically measured, and the ratios against the values of the corpus callosum were calculated. RESULTS: We found significant decreases in mean kurtosis and fractional anisotropy ratios in the PCT and middle cerebellar peduncle, and a significant increase in the mean diffusivity ratio in the PCT in the MSA-C group, as compared with the SCA/SAOA and control groups (p < 0.027-0.001). Among these metrics, there were no significant differences in the diagnostic performance. By contrast, the ratios in the cerebellum showed no significant differences between the MSA-C and SCA/SAOA groups but were significantly altered when compared with the controls (p < 0.001). CONCLUSION: Quantitative DKI analyses can be used to differentiate between patients with MSA-C and those with SCA/SAOA.

DOI： 10.1016/j.acra.2018.12.015

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OBJECTIVE: To optimize the delays alternating with nutation for tailored excitation (DANTE) pulse as a vascular crushing gradient to eliminate macro-and micro-vascular signals and to generate a macrovascular space-related map by applying DANTE with multiple conditions. MATERIALS AND METHODS: Numerical simulation was performed to estimate the optimal flip angle (FA) of the DANTE. A phantom study was conducted to evaluate the impact of the FA and gradient area (GA) of the DANTE with three flow velocities and various parameters of the DANTE. Finally, an in vivo study was performed to assess the optimal DANTE parameters and to map the estimated macrovascular signal of the arterial spin labeling (ASL) signal. RESULTS: Numerical simulation revealed that the decrease of magnetization plateaued at 12.5° of FA. The phantom study showed that the setting of larger FA or GA decreased the ASL signals. The decrease of the ASL signal depended on the flow velocity, and the dependence increased with decreasing GA. The in vivo study revealed that larger FA and GA decreased the perfusion signal. DISCUSSION: An optimized DANTE makes it possible to efficiently suppress the macro-and-micro vascular signals depending on the flow velocity. Moreover, macrovascular signal mapping may be useful to assess altered hemodynamic states.

DOI： 10.1007/s10334-019-00785-9

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Language：English  

The purpose of our study was to clarify the dependence of quantitative susceptibility mapping (QSM) on echo time (TE). We constructed a phantom consisting of six tubes; three tubes were filled with different concentrations (0.5, 1.0, and 2.5 mM) of gadopentetate dimeglumine (Gd-DTPA), and three were filled with different concentrations (100, 200, and 350 mg/mL) of calcium hydroxyapatite. Real and imaginary images from multi-echo spoiled gradient-echo data (12 echoes) were acquired. We then used four datasets with three serial echoes. The QSM procedure consists of four steps: field map estimation, phase unwrapping, background removal, and dipole inversion. For each sample, we compared the measured mean susceptibility value with the theoretical susceptibility value and conducted a linear regression analysis. Accordingly, the relationship between the measured susceptibility and concentration of Gd-DTPA was shown to agree well with the theoretical values (TEs = 16.4, 20.8, and 25.2 ms; slope = 0.24, R2 = 1.00). Furthermore, the relationship between the measured susceptibility and concentration of hydroxyapatite also showed good linearity (TEs = 16.4, 20.8, and 25.2 ms; slope = - 0.00121, R2 = 1.00). In conclusion, the optimization of the TE in QSM makes it possible to obtain more detailed information regarding the susceptibility of biomaterials.

DOI： 10.1007/s12194-019-00513-x

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BACKGROUND: Respiration-induced phase shift affects B0 /B1+ mapping repeatability in parallel transmission (pTx) calibration for 7T brain MRI, but is improved by breath-holding (BH). However, BH cannot be applied during long scans. PURPOSE: To examine whether interleaved acquisition during calibration scanning could improve pTx repeatability and image homogeneity. STUDY TYPE: Prospective. SUBJECTS: Nine healthy subjects. FIELD STRENGTH/SEQUENCE: 7T MRI with a two-channel RF transmission system was used. ASSESSMENT: Calibration scanning for B0 /B1+ mapping was performed under sequential acquisition/free-breathing (Seq-FB), Seq-BH, and interleaved acquisition/FB (Int-FB) conditions. The B0 map was calculated with two echo times, and the B1+ map was obtained using the Bloch-Siegert method. Actual flip-angle imaging (AFI) and gradient echo (GRE) imaging were performed using pTx and quadrature-Tx (qTx). All scans were acquired in five sessions. Repeatability was evaluated using intersession standard deviation (SD) or coefficient of variance (CV), and in-plane homogeneity was evaluated using in-plane CV. STATISTICAL TESTS: A paired t-test with Bonferroni correction for multiple comparisons was used. RESULTS: The intersession CV/SDs for the B0 /B1+ maps were significantly smaller in Int-FB than in Seq-FB (Bonferroni-corrected P < 0.05 for all). The intersession CVs for the AFI and GRE images were also significantly smaller in Int-FB, Seq-BH, and qTx than in Seq-FB (Bonferroni-corrected P < 0.05 for all). The in-plane CVs for the AFI and GRE images in Seq-FB, Int-FB, and Seq-BH were significantly smaller than in qTx (Bonferroni-corrected P < 0.01 for all). DATA CONCLUSION: Using interleaved acquisition during calibration scans of pTx for 7T brain MRI improved the repeatability of B0 /B1+ mapping, AFI, and GRE images, without BH. LEVEL OF EVIDENCE: 1 Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2017.

DOI： 10.1002/jmri.25903

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Inc.  

On arterial spin-labeled (ASL) images, areas of bright intravascular signal will appear when the post labeling delay time is shorter than arterial transit time. Vascular suppression (VS) schemes reduce artefactual bright signal by dephasing intravascular labeled spins. However, existing VS methods, such as Motion-Sensitized Driven-Equilibrium (MSDE), decrease the uniformity of the signal intensity distribution and extend the echo time. The purpose of this study is to compare VS using a Delays Alternating with Nutation for Tailored Excitation (DANTE) preparation pulse, with MSDE for ASL imaging on a flow phantom and volunteer data. In the phantom study, the signal decay pattern of moving water was similar for both methods. In the volunteer study, the bright intravascular signal artifact was decreased by both methods. However right–left differences in signal intensity were smaller using DANTE-prepared ASL. The proposed DANTE-prepared ASL sequence has a vessel suppression effect while maintaining a uniform signal intensity distribution. This study indicates that DANTE is a potentially useful method for vessel suppression in ASL imaging.

DOI： 10.1016/j.mri.2018.02.001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Verlag  

Objectives: We evaluated the vascularity of retained products of conception (RPOC) using arterial spin-labeling magnetic resonance imaging (ASL-MRI) to clarify the clinical feasibility of this approach. Materials and methods: A pulsed-continuous ASL sequence with echo-planar imaging (EPI) acquisitions was used. Ten consecutive patients with RPOC were enrolled. All ASL images were evaluated visually and semiquantitatively and compared with the findings of Doppler ultrasound (US) and dynamic contrast-enhanced MRI (DCE-MRI). Results: The technical success rate was 93.7% (15/16 scans). One failed case was excluded from the analysis. Six patients showed quite high signals over RPOC, while three patients showed no abnormal signals. Doppler US alone failed to detect the hypervascular area in two cases, and ASL-MRI alone failed in three. A significant linear correlation was found between semiquantitative values of ASL-MRI and DCE-MRI. All six patients showing high signals on ASL-MRI underwent follow-up MRI after therapy. High signals in five patients decreased visually and semiquantitatively, while one patient showed signal increases. Conclusion: Evaluation of RPOC using ASL-MRI was clinically feasible and response to therapy could be evaluated. However, the clinical advantages over conventional imaging remain unclear and need to be evaluated.

DOI： 10.1007/s10334-018-0681-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Tokyo  

The purpose of this study was to evaluate the magnetization and demagnetization of magnetic dental attachments in a 3.0-T magnetic resonance imaging (MRI) scanner. A high-field-strength (3.0 T) MRI scanner (Achieva 3.0 T, Philips, Amsterdam, Netherlands) was used. Magnetic flux leakage was measured using a gaussmeter. To evaluate the magnetization and demagnetization of the magnetic assemblies and keepers caused by the moving in and out of the MRI scanner, the magnetic force of the attachments was measured before and after the table was moved in and out. Two settings were used wherein the magnetic assemblies and keepers were positioned on the table at angles of 0° or 90° with respect to the magnetic flux of the static magnetic field. The movement of the table was repeated 15 times. In addition, the retentive force of the magnetic dental attachments was measured after magnetic field exposure. The magnetic force of the magnetic attachments positioned at 0° decreased significantly after moving in and out of the MRI scanner (p &lt
 0.05). In contrast, the magnetic force of the magnetic attachments positioned at 90° was stable after the movement of the table. The magnetic force of the keepers placed at both 0° and 90° was slightly increased after the movement of the table. At 0°, the retentive force of the magnet-keeper combinations decreased when the magnetic assembly was exposed to the strong magnetic flux of the MRI scanner. Therefore, the removal of all removable magnetic dentures is recommended before an MRI examination.

DOI： 10.1007/s12194-017-0399-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Purpose: To evaluate the feasibility, reproducibility, and variation of renal perfusion and arterial transit time (ATT) using pseudocontinuous arterial spin labeling magnetic resonance imaging (PCASL MRI) in healthy volunteers.
Materials and Methods: PCASL MRI at 3T was performed in 25 healthy volunteers on two different occasions. The ATT and ATT-corrected renal blood flow (ATT-cRBF) were calculated at four different post-labeling delay points (0.5, 1.0, 1.5, and 2.0 s) and evaluated for each kidney and subject. The intraclass correlation (ICC) and Bland-Altman plot were used to assess the reproducibility of the PCASL MRI technique. The within-subject coefficient of variance was determined.
Results: Results were obtained for 46 kidneys of 23 subjects with a mean age of 38.6 +/- 9.8 years and estimated glomerular filtration rate (eGFR) of 89.1 +/- 21.2 ml/min/1.73m(2). Two subjects failed in the ASL MRI examination. The mean cortical and medullary ATT-cRBF for the subjects were 215 +/- 65 and 81 +/- 21 ml/min/100 g, respectively, and the mean cortical and medullary ATT were 1141 +/- 262 and 1123 +/- 245 msec, correspondingly. The ICC for the cortical ATT-cRBF was 0.927 and the within-subject coefficient of variance was 14.4%. The ICCs for the medullary ATT-cRBF and the cortical and medullary ATT were poor. The Bland-Altman plot for cortical RBF showed good agreement between the two measurements.
Conclusion: PCASL MRI is a feasible and reproducible method for measuring renal cortical perfusion. In contrast, ATT for the renal cortex and medulla has poor reproducibility and high variation.

DOI： 10.1002/jmri.25634

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OBJECTIVE: Preterm infants are at high risk for developmental delay, epilepsy, and autism spectrum disorders. Some reports have described associations between these conditions and gamma-aminobutyric acid (GABA) dysfunction; however, no study has evaluated temporal changes in GABA in preterm infants. Therefore, we assessed temporal changes in brain metabolites including GABA using single-voxel 3-Tesla (T) proton magnetic resonance spectroscopy (1H-MRS) in preterm infants with normal development. METHODS: We performed 3T 1H-MRS at 37-46 postmenstrual weeks (PMWs, period A) and 64-73PMWs (period B). GABA was assessed with the MEGA-PRESS method. N-acetyl aspartate (NAA), glutamate-glutamine complex (Glx), creatine (Cr), choline (Cho), and myo-inositol (Ins) were assessed with the PRESS method. Metabolite concentrations were automatically calculated using LCModel. RESULTS: Data were collected from 20 preterm infants for periods A and B (medians [ranges], 30 [24-34] gestational weeks, 1281 [486-2030]g birth weight). GABA/Cr ratio decreased significantly in period B (p=0.03), but there was no significant difference in GABA/Cho ratios (p=0.58) between the two periods. In period B, NAA/Cr, Glx/Cr, NAA/Cho, and Glx/Cho ratios were significantly increased (p<0.01), whereas Cho/Cr, Ins/Cr, and Ins/Cho ratios were significantly decreased (p<0.01). There was no significant difference for GABA or Cho concentrations (p=0.52, p=0.22, respectively). NAA, Glx, and Cr concentrations were significantly increased (p<0.01), whereas Ins was significantly decreased (p<0.01). CONCLUSIONS: Our results provide new information on normative values of brain metabolites in preterm infants.

DOI： 10.1016/j.braindev.2016.10.006

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SAGE PUBLICATIONS LTD  

Background The signal intensity obtained by arterial spin labeling (ASL) depends not only on perfusion signal, but also on arterial transit time (ATT). Although ATT has a more significant effect on accurate regional cerebral blood flow (CBF) calculations, the multiple post-labeling delay (PLD) approach is difficult to use in routine examinations.
Purpose To optimize imaging parameters for labeling duration (LD) and PLD and to confirm their validity in long-labeled pseudo-continuous ASL.
Material and Methods The perfusion signal was simulated in four LDs and theoretical signal-to-noise ratio efficiency (SNReff) was calculated. Invivo studies were performed on a 3.0T magnetic resonance imaging (MRI) scanner and 15 volunteers were categorized into either the young or elderly adult groups. We compared the differences in CBF values with or without ATT correction.
Results Regarding signal simulation, perfusion signal increased with the length of LD. SNReff also improved with LD, but SNReff plateaued at an LD of 3.0s. As for the invivo study, SNR linearly increased along with the LD. The CBF differences with the correction of ATT were larger in the elderly adult group. This trend was most prominent in the longer ATT area in the occipital cortical region.
Conclusion A combination of imaging settings of LD=3.5s and PLD=2.0s were suggested as optimal imaging parameters for allowing acceptable CBF quantification and sufficient SNR in both young and elderly individuals.

DOI： 10.1177/0284185116632387

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JPN SOC MAGNETIC RESONANCE MEDICINE  

Purpose: Hereditary diffuse leukoencephalopathy with spheroids (HDLS) is a rare neurodegenerative disorder with various clinical presentations. Mutation of the colony-stimulating factor 1 receptor (CSF1R) gene is considered to be a cause of this autosomal dominant disorder. The purpose of this study was to report magnetic resonance spectroscopy (MRS) findings in patients with HDLS and asymptomatic carriers and to clarify the use of MRS in this disease.
Materials and Methods: In this retrospective, institutional review board-approved study, we included four consecutive patients, genetically diagnosed with HDLS, and two asymptomatic carriers after acquiring informed consent. We performed single-voxel MRS of the left centrum semiovale on a 3T clinical scanner. We also included a sex-matched normal dataset. We quantified N-acetylaspartate (NAA), creatine, choline-containing compounds (Cho), glutamine, glutamate (Glu), myo-inositol (Ins), glutathione, lactate (Lac), and gamma-amino butyric acid using LCModel. We performed statistical analysis, and P value &lt; 0.05 was considered significant.
Results: In HDLS cases, MRS revealed decreased NAA and Glu concentrations, which probably reflected neuronal damage and/or loss, and a subsequent reduction of neurotransmitters. A patient with HDLS also had increased Cho and Ins concentrations, indicating gliosis, and increased Cho concentration was also observed in an asymptomatic carrier. This suggests that metabolic changes had already occurred in an asymptomatic state.
Conclusion: We demonstrated changes in metabolite concentrations not only in patients with HDLS but also in asymptomatic CSF1R mutation carriers. Our study indicates that MRS is a potentially useful tool for the analysis of metabolic and pathophysiological findings of HDLS, even during the early stages of disease.

DOI： 10.2463/mrms.mp.2016-0016

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JPN SOC MAGNETIC RESONANCE IN MEDICINE  

Purpose: The B0 and B1+ maps required for calculation of the radiofrequency (RF) pulse of parallel transmission (pTx) are obtained in calibration scans; however, they may be affected by respiratory motion. We aimed to compare the reproducibility of B0 and B1+ maps and gradient echo (GRE) images of the brain scanned with pTx at 7T between free-breathing (FB) and breath-holding (BH) conditions during the calibration scan.
Methods: Nine healthy volunteers were scanned by 7T MRI using a two-channel quadrature head coil. In the pTx calibration scans performed with FB and BH, the B0 map was obtained from two different TE images and the B1+ map was calculated by the Bloch-Siegert method. A GRE image (gradient-recalled acquisition in steady state) was also obtained with RF shimming and RF design of pTx with spoke method, as well as quadrature transmission (qTx). All the scans were repeated over five sessions. The reproducibility of the B0 and B1+ maps and GRE image was evaluated with region-of-interest measurements using inter-session standard deviation (SD) and coefficient of variation (CV) values. Intensity homogeneity of GRE images was also assessed with in-plane CV.
Results: Inter-session SDs of B0 and B1+ maps were significantly smaller in BH (P &lt; 0.01). Inter-session CVs of GRE images were significantly smaller in qTx than BH and FB (P &lt; 0.01, both); however, the CVs of BH were significantly smaller (P &lt; 0.01). In-plane CVs of FB and BH with RF shimming were not significantly different with qTx; however, CVs of FB and BH with RF design were significantly smaller than those of qTx (P &lt; 0.05 and P &lt; 0.01, respectively).
Conclusion: BH could improve the reproducibility of B0 and B1+ maps in pTx calibration scans and GRE images. These results might facilitate the development of pTx in human brain at 7T.

DOI： 10.2463/mrms.mp.2015-0137

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JPN SOC MAGNETIC RESONANCE IN MEDICINE  

Purpose: The importance of arterial transit time (ATT) correction for arterial spin labeling MRI has been well debated in neuroimaging, but it has not been well evaluated in renal imaging. The purpose of this study was to evaluate the feasibility of pulsed continuous arterial spin labeling (pcASL) MRI with multiple post-labeling delay (PLD) acquisition for measuring ATT-corrected renal blood flow (ATC-RBF).
Materials and Methods: A total of 14 volunteers were categorized into younger (n = 8; mean age, 27.0 years) and older groups (n = 6; 64.8 years). Images of pcASL were obtained at three different PLDs (0.5, 1.0, and 1.5 s), and ATC-RBF and ATT were calculated using a single-compartment model. To validate ATC-RBF, a comparative study of effective renal plasma flow (ERPF) measured by 55mTc-MAG3 scintigraphy was performed. ATC-RBF was corrected by kidney volume (ATC-cRBF) for comparison with ERPF.
Results: The younger group showed significantly higher ATC-RBF (157.68 +/- 38.37 mL/min/100 g) and shorter ATT (961.33 +/- 260.87 ms) than the older group (117.42 +/- 24.03 mL/min/100 g and 1227.94 +/- 226.51 ms, respectively; P &lt; 0.05). A significant correlation was evident between ATC-cRBF and ERPF (P &lt; 0.05, r = 0.47). With suboptimal single PLD (1.5 s) settings, there was no significant correlation between ERPF and kidney volume-corrected RBF calculated from single PLD data.
Conclusion: Calculation of ATT and ATC-RBF by pcASL with multiple PLD was feasible in healthy volunteers, and differences in ATT and ATC-RBF were seen between the younger and older groups. Although ATT correction by multiple PLD acquisitions may not always be necessary for RBF quantification in the healthy subjects, the effect of ATT should be taken into account in renal ASL-MRI as debated in brain imaging.

DOI： 10.2463/mrms.mp.2015-0117

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society for Magnetic Resonance in Medicine  

Purpose: Hereditary diffuse leukoencephalopathy with spheroids (HDLS) is a rare neurodegenerative disorder with various clinical presentations. Mutation of the colony-stimulating factor 1 receptor (CSF1R) gene is considered to be a cause of this autosomal dominant disorder. The purpose of this study was to report magnetic resonance spectroscopy (MRS) findings in patients with HDLS and asymptomatic carriers and to clarify the use of MRS in this disease. Materials and Methods: In this retrospective, institutional review board-approved study, we included four consecutive patients, genetically diagnosed with HDLS, and two asymptomatic carriers after acquiring informed consent. We performed single-voxel MRS of the left centrum semiovale on a 3T clinical scanner. We also included a sex-matched normal dataset. We quantified N-acetylaspartate (NAA), creatine, choline-containing compounds (Cho), glutamine, glutamate (Glu), myo-inositol (Ins), glutathione, lactate (Lac), and gamma-amino butyric acid using LCModel. We performed statistical analysis, and P value &lt
0.05 was considered significant. Results: In HDLS cases, MRS revealed decreased NAA and Glu concentrations, which probably reflected neuronal damage and/or loss, and a subsequent reduction of neurotransmitters. A patient with HDLS also had increased Cho and Ins concentrations, indicating gliosis, and increased Cho concentration was also observed in an asymptomatic carrier. This suggests that metabolic changes had already occurred in an asymptomatic state. Conclusion: We demonstrated changes in metabolite concentrations not only in patients with HDLS but also in asymptomatic CSF1R mutation carriers. Our study indicates that MRS is a potentially useful tool for the analysis of metabolic and pathophysiological findings of HDLS, even during the early stages of disease.

DOI： 10.2463/mrms.mp.2016-0016

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In the previous studies, carbon monoxide (CO) poisoning showed an imbalance between cerebral perfusion and metabolism in the acute phase and the brain temperature (BT) in these patients remained abnormally high from the acute to the subacute phase. As observed in chronic ischemic patients, BT can continuously remain high depending on impairments of cerebral blood flow and metabolism; this is because heat removal and production system in the brain may mainly be maintained by the balance of these two factors; thus, cerebral white matter damage (WMD) affecting normal metabolism may affect the BT in patients with CO poisoning. Here, we investigated whether the BT correlates with the degree of WMD in patients with subacute CO-poisoning. In 16 patients with subacute CO-poisoning, the BT and degree of WMD were quantitatively measured by using magnetic resonance spectroscopy and the fractional anisotropy (FA) value from diffusion tensor imaging dataset. Consequently, the BT significantly correlated with the degree of WMD. In particular, BT observed in patients with delayed neuropsychiatric sequelae, a crucial symptom with sudden-onset in the chronic phase after CO exposure, might indicate cerebral hypo-metabolism and abnormal hemodynamics like "matched perfusion," in which the reduced perfusion matches the reduced metabolism.

DOI： 10.1038/srep36523

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DOI： 10.6009/jjrt.2016_JSRT_72.8.674

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Tokyo  

Our purpose in this study was to reduce the noise in order to improve the SNR of Dw images with high b-value by using two correction schemes. This study was performed with use of phantoms made from water and sucrose at different concentrations, which were 10, 30, and 50 weight percent (wt%). In noise reduction for Dw imaging of the phantoms, we compared two correction schemes that are based on the Rician distribution and the Gaussian distribution. The highest error values for each concentration with use of the Rician distribution scheme were 7.3 % for 10 wt%, 2.4 % for 30 wt%, and 0.1 % for 50 wt%. The highest error values for each concentration with use of the Gaussian distribution scheme were 20.3 % for 10 wt%, 11.6 % for 30 wt%, and 3.4 % for 50 wt%. In Dw imaging, the noise reduction makes it possible to apply the correction scheme of Rician distribution.

DOI： 10.1007/s12194-016-0350-9

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Language：English   Publisher：PUBLIC LIBRARY SCIENCE  

DOI： 10.1371/journal.pone.0159894

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Arterial transit time (ATT) is most crucial for measuring absolute cerebral blood flow (CBF) by arterial spin labeling (ASL), a noninvasive magnetic resonance (MR) perfusion assessment technique, in patients with chronic occlusive cerebrovascular disease. We validated ASL-CBF and ASL-ATT maps calculated by pulsed continuous ASL (pCASL) with multiple post-label delay acquisitions in patients with occlusive cerebrovascular disease. Fifteen patients underwent MR scans, including pCASL, and positron emission tomography (PET) scans with O-15-water to obtain PET-CBF. MR acquisitions with different post-label delays (1.0, 1.5, 2.0, 2.5 and 3.0 sec) were also obtained for ATT correction. The theoretical framework of 2-compartmental model (2CM) was also used for the delay compensation. ASL-CBF and ASL-ATT were calculated based on the proposed 2CM, and the effect on the CBF values and the ATT correction characteristics were discussed. Linear regression analyses were performed both on pixel-by-pixel and region-of-interest bases in the middle cerebral artery (MCA) territory. There were significant correlations between ASL-CBF and PET-CBF both for voxel values (r = 0.74 +/- 0.08, slope: 0.87 +/- 0.22, intercept: 6.1 +/- 4.9) and for the MCA territorial comparison in both affected (R-2 = 0.67, y = 0.83x + 6.3) and contralateral sides (R-2 = 0.66, y = 0.74x + 6.3). ASL-ATTs in the affected side were significantly longer than those in the contralateral side (1.51 +/- 0.41 sec and 1.12 +/- 0.30 sec, respectively, p &lt; 0.0005). CBF measurement using pCASL with delay compensation was feasible and fairly accurate even in altered hemodynamic states.

DOI： 10.1371/journal.pone.0156005

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INTRODUCTION: Brain temperature (BT) is associated with the balance between cerebral blood flow and metabolism according to the "heat-removal" theory. The present study investigated whether BT is abnormally altered in acute and subacute CO-poisoned patients by using (1)H-magnetic resonance spectroscopy (MRS). METHODS: Eight adult CO-poisoned patients underwent 3-T magnetic resonance imaging in the acute and subacute phases after CO exposure. MRS was performed on deep cerebral white matter in the centrum semiovale, and MRS-based BT was estimated by the chemical shift difference between water and the N-acetyl aspartate signal. We defined the mean BT + 1.96 standard deviations of the BT in 15 healthy controls as the cutoff value for abnormal BT increases (p < 0.05) in CO-poisoned patients. RESULTS: BT of CO-poisoned patients in both the acute and subacute phases was significantly higher than that of the healthy control group. However, BT in the subacute phase was significantly lower than in the acute phase. On the other hand, no significant difference in body temperature was observed between acute and subacute CO-poisoned patients. BT weakly correlated with body temperature, but this correlation was not statistically significant (rho = 0.304, p = 0.2909). CONCLUSIONS: The present results suggest that BT in CO-poisoned patients is abnormally high in the acute phase and remains abnormal in the subacute phase. BT alteration in these patients may be associated with brain perfusion and metabolism rather than other factors such as systemic inflammation and body temperature.

DOI： 10.1007/s00234-015-1600-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JPN SOC MAGNETIC RESONANCE IN MEDICINE  

Purpose: We compared the regional cerebral blood flow (rCBF) obtained by pulsed continuous arterial spin labeling (pCASL) and iodine-123-N-isopropyl-p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) using 3-dimensional stereotactic region-of-interest (ROT) software for automated definition of ROIs in anatomic regions of the brain.
Methods: Thirteen patients with cerebrovascular occlusive disease and three with transient ischemic attacks underwent pCASL and IMP SPECT imaging. We compared rCBF values of each anatomic region and calculated the correlation coefficients between pCASL and IMP SPECT. We also calculated the asymmetry index (AI) using ROIs in contralateral regions of the hemispheres.
Results: The rCBF values calculated from pCASL and IMP SPECT were comparable in most segments, but rCBF in the thalamus (P &lt; 0.0001) and hippocampus (P = 0.0006) was significantly higher measured by pCASL than IMP SPECT. The correlation of rCBF between pCASL and IMP SPECT in the affected hemisphere (r = 0.50) tended to be lower than that in the normal hemisphere (r = 0.59), but not significantly different (P = 0.25). Moreover, there was a fixed bias for underestimation of rCBF by pCASL (P = 0.0047) in the affected hemisphere. The calculated AT showed a significant relationship between methods (r = 0.79, P &lt; 0.0001).
Conclusion: The rCBF obtained by pCASL had positive relationships with IMP SPECT. However, it should be considered that pCASL tends to have a weak relationship with IMP SPECT in some normal regions and regions affected by cerebrovascular occlusive disease.

DOI： 10.2463/mrms.2013-0117

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Object: The brain temperature at rest is determined by the balance between heat produced by cerebral energy turnover, which is identical to cerebral metabolism, and heat that is removed, primarily by cerebral blood flow. The present study investigated whether brain temperature measured by proton magnetic resonance (MR) spectroscopy can detect cerebral hemodynamic impairment in patients with arteriovenous malformations (AVMs) as shown by single photon emission computed tomography (SPECT).
Methods: Brain temperature, cerebral blood flow, and cerebrovascular reactivity were measured using proton MR spectroscopy and SPECT in five healthy volunteers and six patients with AVMs. Regions of interest were selected adjacent to the AVMs and in the corresponding contralateral region.
Results: Brain temperature around AVMs was calculated in all subjects using MR spectroscopy. The mean brain temperature in volunteers was 37.1 +/- 0.41 degrees C. A significant correlation was observed between brain temperature ratio (affected side/contralateral side) and cerebrovascular reactivity ratio (affected side/contralateral side) (r = -0.82, p = 0.0480).
Conclusion: Brain temperature measured by proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with AVMs. Further investigations regarding the relationships between brain temperature and clinical feature in patients with AVMs are needed. (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.clineuro.2012.06.022

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The aim of this study was to determine to what extent we could identify the metabolism product peak using 3-T proton magnetic resonance spectroscopic imaging (MRSI) of the prostate gland in healthy volunteers by combining an external array coil with Malcolm Levitt composite-pulse decoupling sequence (MLEV)-point-resolved spatially localized spectroscopy (PRESS).
MRSI data were obtained from the entire prostate gland in six healthy volunteers. The heights of the choline, citrate peaks and the standard deviation (SD) of the noise in each voxel were calculated. When the choline and/or citrate peak in a voxel exceeded 3 SD, the peak was clearly identified.
The clear citrate peak rate in the peripheral zone (PZ) and the central gland (CG) were 78.8 and 70.3 %, respectively. The clear choline peak rate in the PZ and the CG were 55.4 and 44.9 %, respectively. In addition, the clear peak rates for both citrate and choline in the PZ and the CG were 51.8 and 38.6 %. Therefore, in the entire prostate gland, 75.2 % had a clear citrate peak, 51.1 % had a clear choline peak, and 46.3 % had both citrate and choline peaks.
The citrate peak was clearly detected in 75.2 % of the voxels by this technique.

DOI： 10.1007/s11604-012-0165-5

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The focus of this study was on the investigation of the accuracy of the fat fraction of the liver by use of single-breath-holding magnetic resonance spectroscopy (MRS) with T 2 correction. Single-voxel proton MRS was performed with several TE values, and the fat fraction was determined with and without T 2 correction. MRS was also performed with use of the point-resolved spectroscopy sequence in single breath holding. The T 2 values of both water and fat were determined separately at the same time, and the effect of T 2 on the fat fraction was corrected. In addition, MRS-based fat fractions were compared with the degree of hepatic steatosis (HS) by liver biopsy in human subjects. With T 2 correction, the MRI-derived fat fractions were in good agreement with the fat fractions in all phantoms, but the fat fractions were overestimated without T 2 correction. R 2 values were in good agreement with the preset iron concentrations in the phantoms. The MRI-derived fat fraction was well correlated with the degree of HS. Iron deposited in the liver affects the signal strength when proton MRS is used for detection of the fat signal in the liver. However, the fat signal can be evaluated more accurately when the T 2 correction is applied. Breath-holding MRS minimizes the respiratory motion, and it can be more accurate in the quantification of the hepatic fat fraction. © 2012 Japanese Society of Radiological Technology and Japan Society of Medical Physics.

DOI： 10.1007/s12194-012-0191-0

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Purpose: Our purposes were to establish suitable conditions for proton magnetic resonance spectroscopy (MRS) to measure dynamic changes in alcohol concentration in the human brain, to evaluate these changes, and to compare the findings with data from analysis of breath vapor and blood samples.
Materials and Methods: We evaluated 4 healthy volunteers (mean age 26.5 years; 3 males, one female) with no neurological findings. All studies were performed with 3-tesla clinical equipment using an 8-channel head coil. We applied our modified single-voxel point-resolved spectroscopy (PRESS) sequence. Continuous measurements of MRS, breath vapor, and blood samples were conducted before and after the subjects drank alcohol with a light meal. The obtained spectra were quantified by LCModel Ver. 6.1, and the accuracy of the MRS measurements was estimated using the estimated standard deviation expressed in percentage (%SD) as a criterion.
Results: Alcohol peaks after drinking were clearly detected at 1.2 ppm for all durations of measurement. Good correlations between breath vapor or blood sample and MRS were found by sub-minute MRS measurement. The continuous measurement showed time-dependent changes in alcohol in the brain and various patterns that differed among subjects.
Conclusions: The clinical 3T equipment enables direct evaluation of sub-minute changes in alcohol metabolism in the human brain.

DOI： 10.2463/mrms.2012-0056

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The introduction of ultrahigh-field MRI at 7 tesla (7T) has increased the interest in the use of neuroimaging techniques in clinical research. The high signal-to-noise ratio and profound susceptibility effect at 7T can remarkably improve the spatial resolution and image contrast of structural imaging, susceptibility imaging, and functional imaging techniques, whereas the heating effects of the radio frequency and the inhomogeneities of the local magnetic field can have substantial negative effects on parameter setting, acquisition time, and image quality. T1 prolongation at 7T can improve the enhancement effects of gadolinium agents and the inflow effects on MR angiography and arterial spin labeling. Ultrahigh-field MRI is expected to have a high clinical impact in the near future; however, further technological advances tailored to ultrahigh-field systems as well as the accumulation of scientific evidence will be needed to establish its clinical significance.

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To propose a new arterial spin labeling (ASL) perfusion-imaging method (alternate slab width inversion recovery ASL: AIRASL) that takes advantage of the qualities of 3.0 T.
AIRASL utilizes alternate slab width IR pulses for labeling blood to obtain a higher signal-to-noise ratio (SNR). Numerical simulations were used to evaluate perfusion signals. In vivo studies were performed to show the feasibility of AIRASL on five healthy subjects. We performed a statistical analysis of the differences in perfusion SNR measurements between flow-sensitive alternating inversion recovery (FAIR) and AIRASL.
In signal simulation, the signal obtained by AIRASL at 3.0 and 1.5 T was 1.14 and 0.85%, respectively, whereas the signal obtained by FAIR at 3.0 and 1.5 T was 0.57 and 0.47%, respectively. In an in vivo study, the SNR of FAIR (3.0 T) and FAIR (1.5 T) were 1.73 +/- A 0.49 and 1.02 +/- A 0.20, respectively, whereas the SNRs of AIRASL (3.0 T) and AIRASL (1.5 T) were 3.93 +/- A 1.65 and 1.34 +/- A 0.31, respectively. SNR in AIRASL at 3.0 T was significantly greater than that in FAIR at 3.0 T.
The most significant potential advantage of AIRASL is its high SNR, which takes advantage of the qualities of 3.0 T. This sequence can be easily applied in the clinical setting and will enable ASL to become more relevant for clinical application.

DOI： 10.1007/s10334-011-0301-8

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In order to improve the fat suppression performance of in vivo C-13-MRS operating at 3.0 Tesla, a phantom model study was conducted using a combination of two fat suppression techniques; a. set of pulses for frequency (chemical shift) selective suppression (CHESS), and spatial saturation (SAT). By optimizing the slab thickness for SAT and the irradiation bandwidth for CHESS, the signals of the CH: peak at 49 ppm and the -(CH2)-C-13- peak at 26 ppm simulating fat components were suppressed to 5% and 19%, respectively. Combination of these two fat suppression pulses achieved a 53% increase of the height ratio of the glucose C1 beta peak compared with the sum of all other peaks, indicating better sensitivity for glucose signal detection. This method will be applicable for in vivo C-13-MRS by additional adjustment with the in vivo relaxation times of the metabolites.

DOI： 10.2183/pjab.87.425

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The objectives of this study were to examine the reproducibility of the MEGA-editing J-difference technique and to determine the normal variation in the gamma-aminobutyric acid (GABA) level depending on the cerebral region and its fluctuation according to the menstrual cycle as baseline data for clinical application. The participants consisted of 15 normal adult volunteers (eight men and seven women), and all measurements were repeated twice in all participants. The MEGA-editing pulses were incorporated into point-resolved spectroscopy on a 3 T instrument to obtain the J-difference editing spectra from a voxel located in the lentiform nuclei (LN), left frontal lobe (FL), and anterior cingulate cortex (AC). The GABA levels in the gray matter (GM) were compensated by the fraction ratios of the gray and white matters and cerebrospinal fluid in the measurement volume. The extent of the variation in GABA was almost the same as that observed in the major metabolites, and its reproducibility was also maintained (intraclass correlation coefficient &gt; 0.7). GABA level was highest in LN and lowest in AC. A difference in the GABA level between the follicular and luteal phases of the menstrual cycle was found in both LN and FL, but not in AC. This technique showed the differences in the GABA levels in the GM and the region-specific decrease in the GABA levels during the women&apos;s luteal phase. Hum Brain Mapp 32: 828-833, 2011. (C) 2010 Wiley-Liss, Inc.

DOI： 10.1002/hbm.21086

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Working conditions such as shift work constitute a well-known risk factor for insomnia and excessive daytime sleepiness complaints. We compared brain gamma-aminobutyric acid (GABA), glutamic acid (Glu), glutamine (Gln), and Glx (Glu+Gln) levels in day-shift versus alternate-shift workers with proton magnetic resonance spectroscopy (1H-MRS) at 3T. The study population consisted of 32 healthy adult volunteers (16day-shift and 16 alternate-shift workers). Each subject underwent MRS conducted using a MEGA-PRESS sequence in the early morning and early evening on the same day. Spectroscopy voxels (3.0cm×3.0cm×3.0cm) were placed in the frontal lobe and parieto-occipital lobe. The GABA/Cr ratio in the frontal lobe was significantly lower for the alternate-shift group than for the day-shift group in the early evening (1.885 vs. 0.875). For the other metabolite ratios (Gln/Cr and Glx/Cr), there were no significant differences between the two groups regardless of morning or evening schedule. Our preliminary finding represents a possible alteration of GABA content in the brain related to an irregular work schedule. © 2010 Elsevier Ireland Ltd.

DOI： 10.1016/j.pscychresns.2010.10.011

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Amino acids related to neurotransmitters and the GABAergic/glutamatergic system were measured using a 3 T-MRI instrument in 12 patients with autism and 10 normal controls. All measurements were performed in the frontal lobe (FL) and lenticular nuclei (LN) using a conventional sequence for n-acetyl aspartate (NAA) and glutamate (Glu), and the MEGA-editing method for GABA. The GABA level and [GABA]/[NAA] ratio were significantly lower (p &lt; 0.01) in the FL, but not the LN, in patients with autism compared to normal controls. The [GABA]/[Glu] ratio in the FL was also significantly lower (p &lt; 0.05) in the patients than in the normal controls, thus suggesting a possible abnormality in the regulation between GABA and Glu.

DOI： 10.1007/s10803-010-1065-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

The purpose of this Study was to estimate the gamma-aminobutyric acid (GABA) and glutamate plus glutamine (Glx) concentrations in the cortical tubers of patients with tuberous sclerosis complex (TSC) using the MEGA-editing J-difference method and a stimulated echo-acquisition mode with a short echo time, and to determine which abnormality Was more dominant between GABA and Glx in patients with TSC with epilepsy. This study included six patients with TSC (mean age, 4.3 years) and seven control subjects (mean age, 4.8 years). Measurements were obtained with a three-Tesla apparatus and postprocessing was conducted with an LCModel. The GABA level in the cortical gray matter (cgGABA) was calculated as a result of segmentation in voxels and from the literature values for gray and white matter ratios for GABA. Increased GABA and myo-inositol (ml) concentrations and a decreased N-acetyl aspartate (NAA) concentration were observed in the cortical tubers. The cgGABA level,and cgGABA/NAA and cgGABA/GlX ratios were also higher inpatients with TSC than in Control subjects. No significant difference was found in Glx concentration between patients with TSC and control subjects. Although the number of patients with TSC in this study was small, the increase in GABA and no significant change in Glx were consistent with previous neurochemical studies and support the hypothesis that brain GABA plays a key role in the pathophysiology of epilepsy during the process of neuronal development. (C) 2009 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.neuroimage.2009.05.060

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Background: Glutathione (GSH), a major intracellular antioxidant, plays a role in NMDA receptor-mediated neurotransmission, which is involved in the pathophysiology of schizophrenia. In the present study, we aimed to investigate whether GSH levels are altered in the posterior medial frontal cortex of schizophrenic patients. Furthermore, we examined correlations between GSH levels and clinical variables in patients.
Methods and Findings: Twenty schizophrenia patients and 16 age-and gender-matched normal controls were enrolled to examine the levels of GSH in the posterior medial frontal cortex by using 3T SIGNA EXCITE H-1-MRS with the spectral editing technique, MEGA-PRESS. Clinical variables of patients were assessed by the Global Assessment of Functioning (GAF), Scale for the Assessment of Negative Symptoms (SANS), Brief Psychiatric Rating Scale (BPRS), Drug-Induced Extra-Pyramidal Symptoms Scale (DIEPSS), and five cognitive performance tests (Word Fluency Test, Stroop Test, Trail Making Test, Wisconsin Card Sorting Test and Digit Span Distractibility Test). Levels of GSH in the posterior medial frontal cortex of schizophrenic patients were not different from those of normal controls. However, we found a significant negative correlation between GSH levels and the severity of negative symptoms (SANS total score and negative symptom subscore on BPRS) in patients. There were no correlations between brain GSH levels and scores on any cognitive performance test except Trail Making Test part A.
Conclusion: These results suggest that GSH levels in the posterior medial frontal cortex may be related to negative symptoms in schizophrenic patients. Therefore, agents that increase GSH levels in the brain could be potential therapeutic drugs for negative symptoms in schizophrenia.

DOI： 10.1371/journal.pone.0001944

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KARGER  

Background: We compared ischemic findings on gradient echo-type T-2*-weighted images at 3-tesla MRI (T-2* WI) in patients with acute ischemia and major vessel occlusion, and stroke patients with lacunar infarction or branch atheromatous disease. Methods: Our study population consisted of 45 patients with acute stroke. They underwent 3-tesla MRI within 12 h of stroke onset. Included were 24 patients (13 men and 11 women, mean age 68 years) with major vessel occlusion and 21 patients (11 men and 10 women, mean age 69 years) with minor infarction such as lacunar infarcts or branch atheromatous disease. We classified vascular ischemic findings of T-2* WI into 3 sign categories, i.e. artery susceptibility sign, cortical vessel sign (hypointensity and enlargement of the cortical vessels) and brush sign (hypointensity of vessels in the deep white matter). Decreased intensity in the ischemic parenchyma was designated ischemic tissue sign. We compared regions of interest in the hypoperfused area on flow-sensitive alternating inversion recovery (FAIR) images with our vascular ischemic findings. Results: None of the vascular ischemic signs nor the ischemic tissue sign were found in patients with minor vessel disease. All 24 patients with major vessel occlusion manifested the cortical vessel sign, 23 the brush sign. The area with ischemic vessel signs on T-2* WI was almost as large or somewhat smaller than the hypoperfused area on FAIR images. Compared to the contralateral side, 14 of 24 patients (58.3%) with major vessel occlusion showed decreased intensity in the ischemic parenchyma (ischemic tissue sign). Region of interest measurements on FAIR images demonstrated greater hypoperfusion in the area classified as ischemic tissue sign on T-2* WI. Conclusions: Ischemic vessel signs and the ischemic tissue sign on T-2* WI at 3 T would be useful to evaluate the extensive ischemia due to major vessel occlusion and may be correlated with the blood-oxygen-level-dependent effect due to increased deoxyhemoglobin. The ischemic tissue sign may be reflective of severe ischemia. Copyright (C) 2008 S. Karger AG, Basel.

DOI： 10.1159/000151640

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Objectives: To retrospectively evaluate the feasibility of perfusion-weighted MRI (PWI) in uterine leiomyomas.
Materials and Methods: Eighteen uterine leiomyomas in 15 patients were evaluated. PWI was performed using a double-echo T2*-weighted spoiled gradient-recalled acquisition sequence, and the first-pass pharmacokinetic model was applied to calculate relative blood volume (rBV). Histopathologic analysis was performed to measure vascular area (VA).
Results: PWI was successful in 13 of 15 patients. On quantitative analysis, mean (+/- SD) rBV calculated from PWI was 0.17 +/- 0.13 (range, 0.06-0.55), whereas mean VA was 3.3% +/- 1.6% (range, 1.7-8.5%). A significant correlation was identified between rBV and VA (r = 0.87, P &lt; 0.001).
Conclusions: The rBV determined at PWI correlates with histologic vascular area in uterine leiomyomas.

DOI： 10.1097/RLI.0b013e318059ae69

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We devised a method of analyzing a regional fat fraction using a modulus and real multiple gradient-echo (MRM-GRE) 4-7 echo Dixon sequence. The regional fat fraction was calculated with a theoretically fitted signal-intensity curve for multiple GRE images at each echo time (i.e., 4-7 echoes.) on a 1.5 Tesla MRI to correct T2* decay and phase cycling. Then the real image of the first echo was used to differentiate between the areas above and below the 50 percent fat fraction. To eliminate the T1-effect, the flip angle was set at 12 degrees. Fat fractions of the phantom with MRM-GRE were compared with those using conventional double-GRE and other MRI techniques. Fat fractions of liver and spinal bone marrow in healthy volunteers were determined during a breath-hold. The fat fraction of the phantom obtained by the MRM-GRE method tended to agree with the actual fat fraction. On the other hand, in both the phantom and in healthy volunteers, the double-GRE was underestimated owing to T2* decay. The MRM-GRE method enables simple, accurate analysis of the regional fat fraction.

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DOI： 10.1002/jmri.20829

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The patient was a 25-year-old Japanese woman with postpartum eclampsia, in whom magnetic resonance imaging (MRI) was performed ten hours after convulsion. The patient improved within three days. Diffusion-weighted images showed a high apparent diffusion coefficient (ADC), and perfusion-weighted images obtained by the multi-slice flow-sensitive alternating inversion recovery (FAIR) method showed hyperperfusion, which was suggestive of vasogenic edema, on the parietal and occipital subcortical white matter, corresponding with transient hyperintensities on T2-weighted images. MR angiography (MRA) revealed no signs of vasospasm. These findings suggested hyperperfusion-induced vasogenic edema without cerebrovascular spastic change in the early stage of eclampsia. The FAIR method is considered a useful technique for perfusion-weighted MRI, especially useful to evaluate the cerebral perfusion of emergency patients such as those with eclampsia.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

A strategy for proton decoupled carbon-13 MR spectroscopy ({H-1}-C-13 MRS) with a strong static magnetic field (3.0T) in vivo was investigated. The proton decoupling improves the signal-to-noise ratio, however, the effect of the decoupling power on the human body, especially in strong magnetic fields, should be considered. In order to establish a technique for monitoring the metabolism of glucose in the liver using {H-1}-C-13 MRS at 3.0T, two phantom experiments were performed. To assess whether the decoupling energy conformed to SAR limits defined by the IEC, temperature rises inside an agar gel phantom were monitored during a {H-1}-C-13 MRS experiment. Then, the decoupling conditions of a glucose solution phantom were systematically optimized with combinations of decoupling bandwidth and power. The reliability of this procedure was discussed in conjunction with IEC guidelines. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.ejrad.2004.11.011

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The purpose of this study was to evaluate the effect of different inversion times (TIs) on flow-sensitive alternating inversion recovery (FAIR) perfusion imaging and compare them with the cerebral blood flow reserve evaluated by acetazolamide challenge using single-photon-emission computed tomography (SPECT). The subjects were nine patients with unilateral obstruction of the internal carotid artery. The signal ratio (SR16/8) of two images with different TIs (1,600 ms and 800 ms) was calculated, and the cerebral blood flow reserve (CFR) was evaluated by the increase in the ratio of cerebral perfusion after administration of acetazolamide in the SPECT study. A reversed linear correlation ( r =0.75) was found between SR and CFR, indicating that differences of FAIR images with changes of TI will be affected by cerebral flow reserve.

DOI： 10.1007/s00234-004-1228-9

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Purpose: To assess the usefulness of centrally fat-saturated three-dimensional magnetic resonance (MR) angiography of the abdomen using an elliptical centric view order and selective placement of fat-saturation pulses in the central 30% portion of the k-space in terms of fat signal reduction, image contrast of post-contrast images, and breath-holding time.
Methods: Fat signal in abdomen and breath-holding time were compared between centrally fat-saturated three-dimensional sequence and partially fat-saturated three-dimensional sequence or conventional fat-saturated three-dimensional sequence. Abdominal contrast-enhanced centrally fat-saturated three-dimensional MR angiography was obtained at arterial and equilibrium phases, and image quality was quantitatively and visually evaluated.
Results: Centrally fat-saturated three-dimensional sequence suppressed fat signal, as did the conventional fat-saturated three-dimensional sequence, and the breath-hold was prolonged only by 1.5 seconds compared to the partially fat-saturated three-dimensional sequence. Contrast-enhanced centrally fat-saturated three-dimensional MR angiography provided abdominal MR arteriography with large signal difference between vessels and fat, while venous signal was insufficient at equilibrium phase.
Conclusion: : Abdominal contrast-enhanced centrally fat-saturated three-dimensional MR angiography using an elliptical centric view order and selective central fat-saturation of k-space reduced fat signal comparable to conventional fat-saturated three-dimensional sequence, and provided contrast-enhanced MR arteriography with high vascular contrast and minimum prolongation of breath-hold.

DOI： 10.1002/jmri.10385

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

The purpose of this study was to examine the signal change occurring with different inversion times (TIs) of the flow-sensitive alternating inversion recovery (FAIR) technique and to compare with the perfusion image obtained with Gd-DTPA injection. The subjects were 11 patients with unilateral occlusive cerebrovascular disease. Two FAIR images with different TIs (800 ms and 1600 ms) were measured for each patient and dynamic perfusion MRI was performed to produce four kinds of parameter maps: mean transit time (MTT), time to peak (TTP), relative cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV) maps. Asymmetry ratios (ARs) between the affected and contra-lateral vascular sides were measured in both FAIR images and the four dynamic parameter maps. The AR of the MTT map of the four parameters showed the highest correlation with that of the FAIR images, especially with that of TI = 1600 ms (r = 0.829), and the AR of the rCBV map revealed the worst correlation with the FAIR images. The AR of the FAIR image with TI = 800 ms was less correlated with that of MTT than that with TI = 1600 ms. These results suggested that the signal intensity of the FAIR image was influenced by flow transition time and the change in TI could be used to select the flow with a different transition time. Our study suggested that a longer TI in the FAIR technique might be more useful than a shorter TI for evaluating chronic occlusive cerebrovascular disease in the clinical setting. (C) 2003 Elsevier Inc. All rights reserved.

DOI： 10.1016/S0730-725X(03)00104-8

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Purpose: To assess the clinical utility of a new method for real-time estimation of T1 during the first pass of contrast agent by using this method to examine brain tumors.
Materials and Methods: The multi-phase spoiled gradient-echo pulse sequence using the double-echo magnetic resonance (MR) technique was modified. In the first half of the pulse sequence, the flip angle was varied systematically. Then, static T1 values were calculated using differences in MR signal intensities between different flip angles. In the latter half of this sequence, changes in absolute T1 were calculated using differences in signal intensities before and after injection of contrast agent. The double-echo MR data were used to minimize the T2* effect. Five cases of neurinoma and seven cases of meningioma were examined. Changes in T1 during the first pass of contrast agent were compared between neurinoma and meningioma.
Results: Changes in absolute T1 were clearly demonstrated on the parametric map. Although the changes in absolute T1 during the first pass of contrast agent did not allow differentiation between the two types of tumors, the mean gradient after the first pass was statistically higher for neurinoma than for meningioma (P &lt; 0.05; meningioma, 0.011 +/- 0.012 second(-1)/second; neurinoma, 0.034 +/- 0.020 second(-1)/second).
Conclusion: The present method appears to be useful for estimation of dynamic T1 changes in brain tumors in clinical settings.

DOI： 10.1002/jmri.10331

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Purpose: To determine the appropriate rate of fat suppression pulses (using spec IR-spectral selective inversion recovery) for fat-suppressed 3D magnetic resonance angiography (MRA) with an elliptical centric view order.
Materials and Methods: In abdominal 3D fast spoiled gradient echo (fast SPGR) with an elliptical centric view order the spec IR pulse rate was changed from zero to one every 15 repetitions (in nine steps) in eight volunteers. In the equilibrium phase, abdominal contrast enhanced 3D MRA was obtained by 3D fast SPGR using an elliptical centric view order without fat-suppression and with two spec IR, and by fat-suppressed 3D fast SPGR with a sequential centric view order (efgre 3D) in 18 cases. Fat and vascular signals were estimated.
Results: Although 3D fast SPGR using in elliptical centric view order with spec IR placed every 15 TR and efgre3D effectively decreased fat signals, these sequences lengthened the breath-hold by 4-6 seconds compared with nonfat suppressed sequence. 3D fast SPGR using in elliptical centric view order and two spec IR reduced the fat signal by 30% and provided good 3D MR angiography without substantial prolongation of breath-hold.
Conclusion: Two spec IR can be used for generation of partially fat-suppressed abdominal 3D MRA without prolongation of the breath hold when performing 3D fast SPGR using an elliptical centric view order.

DOI： 10.1002/jmri.10200

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RATIONALE AND OBJECTIVE. To evaluate the vascularity and vascular leakage of well-enhanced gliomas by double-echo dynamic magnetic resonance (MR) imaging.
MATERIALS AND METHODS. Eight patients with glioblastoma multiforme (GBM) and two patients with juvenile pilocytic astrocytoma (JPA) were studied. Double-echo dynamic MR imaging was utilized to separate the T2* shortening effect and the T1 shortening effect. The former was represented by the vascularity index, and the latter was represented by the leakage index. These indexes were compared with histopathologic data.
RESULTS. The mean vascularity index of the GBM was higher than that of the JPA (mean +/- SD, 3.48 +/- 1.57 [GBM] versus 0.51 +/- 0.29 [JPA]), and the mean leakage index of the JPA was higher than that of the GBM (1.35 +/- 0.87 [JPA] versus 0.27 +/- 0.15 [GBM]). Abundant vascularity was noted in the tight interstitial space in the pathologic specimen of GBM. Conversely, sparse vasculature was observed in the wide interstitial space in the pathologic specimen of JPA.
CONCLUSION. This method may enable better characterization of grade in well-enhanced glioma by providing the information on the vascularity and leakage indexes.

DOI： 10.1097/01.RLI.0000028483.51109.29

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Objective: To investigate the usefulness of dynamic contrast magnetic resonance (MR) imaging in the differentiation of prostate cancer (PC) from benign prostate hypertrophy (BPH). Materials and methods: Eleven PC patients and 13 BPH patients were entered into the analysis. The mean gradient (MG) was calculated from the T2* term-eliminated time-signal intensity curve obtained from dynamic contrast MR data, and the MG of PC and that of BPH were compared. Results: The MG of PC was significantly higher than that of BPH. When the threshold value was set to per s for discriminating PC from BPH, the sensitivity, specificity, and accuracy were 100, 85, and 92%, respectively. Conclusions: The MG, which is derived from the T2* term-eliminated time-signal intensity curve, may be a useful index for differentiating PC from BPK (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

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Purpose: Information regarding prostate blood flow as determined by positron emission tomography (PET) with (H2O)-O-15 may provide useful information about tumor diagnosis; however, PET requires a cyclotron for the production of an extremely short half-life (2 minutes) tracer. Therefore, the aim of this study was to propose a complementary index for blood flow as determined by MRI to validate the results and compare them with PET, especially for prostate tissue.
Methods: Six consecutive patients with prostate disease were studied. The two semiquantitative indices for tumor blood flow were calculated from the time-concentration curve measured from double-echo MR images. The theory of nondiffusible tracers by means of indicator dilution theory was applied to MR data. The relative regional blood flow (rrBF) was calculated as the ratio of the relative regional blood volume to relative regional mean transit time. Another proposed index was the maximum height of the time-concentration curve. PET studies Were also performed. and absolute blood flow values were calculated for each subject. These indices calculated from different modalities were then compared.
Results: A significant correlation was found between the rrBF and the absolute blood flow as determined by PET (r(2) = 0.69, p &lt; 0.005). A significant correlation was also found between the maximum height of the time-concentration curve and the absolute blood flow (r(2) = 0.85, p &lt; 0.0001).
Conclusions: The semiquantitative tumor blood flow indices measured with MRI have a good correlation with the corresponding measurements by PET therefore, these indices may provide useful information about tumor diagnosis in clinical settings.

DOI： 10.1097/01.RCT.0000028234.30636.26

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The apparent diffusion coefficients (ADCs) of water and brain metabolites were determined by proton MR spectroscopy on a clinical MR scanner for healthy volunteers and for pathological changes in cases of acute cerebral infarction and brain tumor. The ADCs of N-acetyl aspartate (NAA) and creatines in tissue involved in acute infarction were decreased compared to normal control values, while in tumors they showed increased values. Since NAA is a neuronal marker, these findings suggest that neuronal cell viscosity changes according to the pathological status of the tissue. The lactate ADC was significantly larger than the values for other major metabolites in cases of ischemia and tumor, suggesting that lactate is present in a different compartment. These results indicate that metabolite diffusion data can be used to reveal changes in the intracellular environment depending on the pathological status. Copyright (C) 2001 John Wiley Sons, Ltd.

DOI： 10.1002/nbm.759

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Purpose: To evaluate the efficacy of a fully automatic, single-voxel, proton MR spectroscopy algorithm on a 3.0T MR system. Methods: The PROBE/SVQ algorithm (GE Medical Systems) was evaluated on a General Electric (GE) Signa LX-3T system. Ten normal volunteers (female, 21.1±2.0 years old) participated in the study. Nine representative regions of interest were examined, namely, right and left frontal white matter
right and left parietal white matter
right and left basal ganglia
right and left dentate nucleus
and pons. Results: The mean coefficients of variation in all regions for the N-acetyl-aspartate to creatine ratio (NAA/Cr), choline to creatine ratio (Cho/Cr), and choline to N-acetyl-aspartate ratio (Cho/NAA) were 10.2±2.4%, 11.4±3.2% and 12.6±1.4%, respectively. Conclusion: A fully automated spectroscopic examination under clinical setting utilizing the PROBE/SVQ algorithm appears to be a reliable method, extending the window of routine clinical assessment of brain metabolism. © 2002 by Japanese Society for Magnetic Resonance in Medicine.

DOI： 10.2463/mrms.1.121

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BACKGROUND AND PURPOSE: After bolus injection, gadopentetate dimeglumine causes a T2* rate change in permeable tissue that is contaminated by the T1 shortening effect due to the leakage of contrast agent. Therefore, tumor vascularity as reported in previous single-echo perfusion-weighted MR imaging studies has been underestimated. Our aim was to quantitatively and qualitatively evaluate the degree of blood volume of glioblastoma multiformes (GBMs) underestimated by this T1 shortening effect.
METHODS: We used double-echo dynamic MR imaging after a bolus injection of gadopentetate dimeglumine (double-echo perfusion-weighted MR imaging) to simultaneously determine tumor blood volume without (V-T1U) and with (V-T1C) T1 shortening correction. MR imaging was performed in five consecutive patients with GBMs. The ratios Of V-T1U and V-T1C were calculated and compared by means of quantitative analysis. The degree of tumor blood volume as determined by VT1U and V-T1C maps were qualitatively compared using a three-point scale.
RESULTS: All GBMs showed contrast enhancement on postcontrast T1-weighted images. In all subjects, the values Of V-T1U were significantly lower than those Of V-T1C (mean +/- SD, 2.05 +/- 1.01 vs. 3.62 +/- 1.40, respectively [P &lt; .05]), indicating that tumor blood volume obtained by double-echo perfusion-weighted MR imaging was significantly higher than that by single-echo imaging. In the qualitative analysis, tumor blood volume on the VT1U map was less conspicuous than that on the V-T1C map.
CONCLUSION. Careful attention should be paid to the underestimation of tumor blood volume resulting from T1 shortening effects when using single-echo perfusion-weighted MR imaging. Double-echo imaging may be more suitable for the analysis of blood volume in GBMs.

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Double-echo dynamic magnetic resonance (MR) imaging was used to evaluate both vascularity and permeability of tissues simultaneously. Vascularity was evaluated on the basis of the T2*-shortening effect due to the intravascular fraction of the contrast agent and permeability on the basis of the T1- shortening effect due to the extravascular fraction. Meningioma was characterized on the basis of higher vascularity and neurinoma on the basis of higher permeability. The proposed method enables better tissue characterization.

DOI： 10.1148/radiology.214.3.r00mr15912

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We evaluated hemodynamic change of acute cerebral infarction using FAIR sequence and found that MRI offers almost the same information as perfusion SPECT. However semi-quantitative result showed underestimation on low perfusion by FAIR compared with SPECT.
The metabolite change of acute cerebral infarction was estimated using CSI and the peripheral area of infarction showed lactate peak without NAA decrease, We considered that metabolic ratios as NAA/Cr and Lactate/Cr can be used as a threshold for discriminating ischemic penumbra.

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The purpose of this study is to determine the tissue characterization of meningiomas and neurinomas using a "permeability index" obtained from double echo dynamic MRI. The permeability index is the index of the vascular permeability. For the present study, the permeability index was obtained by dynamic MRI using a double echo technique after a bolus injection of Gd-DTPA. Eleven patients with acoustic neurinomas and 11 patients with meningiomas were studied. Although, in some cases, the permeability index overlapped, the mean permeability index of neurinomas was much higher than that of meningiomas. The permeability index proposed here provided useful information for characterizing the tissue; this index may prove helpful in differentiating between meningiomas and neurinomas in the clinical setting.

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In this study, we report on the influence of trace elements (TE) on signal intensities of nuclear magnetic resonance images (MRI), both in vivo and in vitro. Optimal parameters for the assessment of Mn concentration in the brain of rats on total parenteral nutrition were established. For the in vitro study, Mn and trace element solutions, one containing Zn, Cu, Fe, and I (TE-4) and another containing the above elements plus Mn (TE-5), were diluted with physiological saline or with rat brain homogenate and used to measure signal intensities in MRI. Concentration-dependent signal hyperintensity was observed in both cases in the Mn and the TE-5 solutions, but no effect was observed with the TE-4 solution. The signal increase was greater for brain tissue homogenates. In the in vivo study, the experimental animals were maintained under total parenteral nutrition (TPN) with a standard clinical dose of TE-5 and/or with 10-fold the clinical dose of TE-4 and TE-5 for 1 wk. Only rats that were receiving the increased TE-5 dose showed signal hyperintensity on MRI. Positive correlations were observed among the signal hyperintensity, the blood Mn concentrations, and that of the rat brain. Our results suggest that Mn in TE preparations may be the cause of signal hyperintensity on MRI in a concentration-dependent fashion, and that MRI and measurement of blood Mn may be used to estimate Mn accumulation in brain tissue.

DOI： 10.1007/BF02785276

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The purpose of this study was to evaluate cerebral perfusion with T2*-weighted dynamic MRI in the area around the infarcted core, We examined seven patients with subacute cerebral infarction. After bolus injection of gadopentetate dimeglumine, a series of gradient-echo images were recorded in a selected slice, From these images, concentration-time curves were created on a region-of-interest [ROI] basis around infarction for calculating relative regional cerebral blood volume (rrCBV), Brain perfusion single photon emission computed tomography (SPECT) study also was performed with intravenous injection of I-123-labeled N-isopropyl-p-iodoamphetamine (I-123-IMP). All patients showed prolonged signal decrease in the area around the infarcted core. ROI analysis showed significantly increased rrCBV compared to the normal side (P &lt;.01, paired t test). The I-123-IMP SPECT study showed that these areas had decreased cerebral blood flow, These findings suggest compensatory vascular dilatation due to decreased perfusion pressure. T2*-weighted dynamic MRI is a useful method for detecting compensatory vasodilatation of ischemic insult in the periinfarcted area.

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DOI： 10.1097/00004728-199507000-00033

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PURPOSE: To evaluate the usefulness of hydrogen-1 magnetic resonance (MR) spectroscopy in the evaluation of the developing brain. MATERIALS AND METHODS: Localized MR spectra were obtained with an echo time of 272 msec from the brain of 78 neonates and infants aged 1 week to 100 months. All patients were retrospectively classified into three groups on the basis of neurologic development: abnormal (group 2, n = 21), normal despite minor neurologic signs (group 1, n = 23), and normal (group 0, n = 34). RESULTS: Seventeen patients in group 2 and eight patients in group 1 revealed abnormally low N-acetylaspartate (NAA)/choline or NAA/creatine ratios compared with those obtained in group 0. MR spectroscopy was slightly more useful in the differentiation of patients in groups 2 and 1 (x2 test, P &lt
.005) than MR imaging (P &lt
.01). CONCLUSION: H-1 MR spectroscopy provides prognostic information about the brain in healthy and neurologically damaged infants and augments the value of MR imaging.

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We studied the frequency and clinical value of cerebrospinal fluid flow void in 49 normal children who underwent MRI on a 0.35 T unit. T2-weighted axial SE images were retrospectively analysed to determine relative signal intensities of the fourth, third and lateral ventricles and the cerebral aqueduct, rated as high intensity, low intensity, and no signal (flow void). Flow void was seen in the fourth ventricle in 20% of children up to 3 months of age, 67% from 4 to 6 months of age, in all children aged between 7 months and 2 years and in about half of those aged more than 3 years. In cerebral aqueduct the figures were 40% up to 1 month, age, 80% at 2-3 months and 100% above 4-6 months of age, and in the third ventricle 0% up to 1 month, 60% at 2-3 months, 67% at 4-6 months, and almost 100% in above 7 months. Flow void was much more frequent at 1-6 years of age than in adults and less frequent in neonates, which may reflect the different compliance of the growing brain. © 1993 Springer-Verlag.

DOI： 10.1007/BF00602825

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PURPOSE: To evaluate the hemodynamics of acute stroke in cats by means of dynamic susceptibility-contrast magnetic resonance (MR) imaging compared with standard T2- and diffusion-weighted MR imaging. MATERIALS AND METHODS: Unilateral permanent occlusion of the middle cerebral artery was performed in 18 cats. MR imaging was performed with each method 2 hours (n = 2), 6 hours (n = 10), and 24 hours (n = 11) after occlusion. RESULTS: At every time point, dynamic MR images clearly showed ischemic regions of steady-state signal hyperintensity and areas of less dynamic decrease in signal intensity that corresponded closely to those seen on diffusion-weighted MR images. T2- weighted MR images did not reveal regions of high signal intensity 2 hours after occlusion. The measurements of relative blood volume obtained with the dynamic method were significantly lower in steady-state hyperintense ischemic areas of the affected side than those in the contralateral normal areas at 6 and 24 hours (P &lt
.001). CONCLUSION: This dynamic method can advance the time of detection of early ischemia in comparison with T2-weighted MR imaging and provides functional information about hemodynamics not provided by other methods of MR imaging.

DOI： 10.1148/radiology.189.1.8372198

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Intravoxel incoherent motion MRI was used to assess six intracranial, extraaxial cysts and tumors including two epidermoids, two cystic acoustic schwannomas, and two arachnoid cysts. A maximum gradient strength of 0.7 g/cm was used simultaneously along all axes (maximum gradient b value: 445 s/mm2) and comparisons were made with an external water phantom. In epidermoid tumors the apparent diffusion coefficient (ADC) was similar to that of normal brain, thus indicating their solid nature. In acoustic schwannomas an ADC similar to the external water phantom indicated cystic components, whereas an ADC similar to brain was found in the solid portions of the tumor. The ADC of arachnoid cysts was similar to that of the water phantom, indicating their fluid nature. Due to macroscopic CSF flow, cisternal CSF showed high ADC, which enabled epidermoid tumors to be highlighted.

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Ten temporomandibular joints (TMJs) of 5 healthy volunteers and 19 TMJs of internal derangements in 16 patients with splint therapy were examined with MR imaging. T1-weighted images were obtained only in the closed mouth position, and gradient recalled acquisition in steady state (GRASS) images were obtained in active opening and closing phases, allowing a pseudodynamic display of TMJ movement. All patients received protrusive splint treatment. the usefulness of MR imaging to assess the efficacy of splint therapy was evaluated. Corrected disk position with the splint in place was clearly demonstrated in 9 TMJs, corresponding with elimination of reciprocal clicking. Ten other TMJs of anterior disk displacement without reduction showed uncorrected disk position by the splint. This information could confirm the therapeutic efficacy, or suggest other treatment alternatives. GRASS MR imaging can provide accurate and physiologic information about disk function in initial and follow-up assessment of protrusive splint therapy © 1992 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.

DOI： 10.1080/02841859209172023

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The evaluation of Gd-DTPA contrast enhancement (CE) in high intensity tissues on Tl-weighted magnetic resonance images, such as fat and bone marrow, is quite difficult. In this study, we used subtraction and subtracted color images in an attempt to show more clearly the Gd-DTPA CE. In addition, we also carried out sequential post-Gd-DTPA imaging to assess the changes in enhancement of lesions with time. Twenty patients were studied with these methods and our results are illustrated. © 1989 Raven Press, Ltd., New York.

DOI： 10.1097/00004728-198909000-00038

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The development and aging of four brain midline structures - the pituitary gland, pons, cerebellar vermis, and corpus callosum - were studied. The dimensions and area of these structures were measured by means of midsagittal magnetic resonance imaging. The study group consisted of 94 patients newborn to 15 years old and 49 patients and seven volunteers 16-60 years old. Except for growth spurts in the 1st year and in the 10-15-year age range, the pituitary gland showed linear growth. The pons, cerebellar vermis, and corpus callosum al showed exponential growth. The cerebellar vermis showed the sharpest 1st-year growth spurt, followed by the corpus callosum and the pons. The pituitary gland showed a decrease in size in the 51-60-year age range. The corpus callosum also showed a tendency to diminish in size but to a lesser degree. There were no statistically significant declines in the size of either the pons or the cerebellar vermis in the 51-60-year age range.

DOI： 10.1148/radiology.172.1.2740500

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Magnetic resonance imaging was performed in 8 patients with muscle disease and 6 normal controls. High intensity areas of varying dimensions were found in thigh muscles of the patients with progressive muscular dystrophy (PMD) and congenital myopathy. Shortened T, and prolonged T2 values with disease progression were characteristic. The T, values were variable and prolonged, T2 values were more characteristic of progressive muscular degeneration. The T, value may help to detect the early stage of PMD. Magnetic resonance imaging is useful in detecting the muscle lesions in PMD and essential for selection of a biopsy site. © 1989.

DOI： 10.1016/0895-6111(89)90210-3

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Language：Japanese   Publisher：日本脳循環代謝学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

MR装置はIngenia 1.5T Omegaを用い、人工内耳はPULSARおよびCONCERTOの2機種を用い、添付文書やパンフレットに具体的記載のない制約条件について、詳細な情報を得ることを目的として、1.5T MR装置における条件付きMRI対応人工内耳の力学的作用(吸引力およびトルク)およびインプラント磁石の減磁現象について検証した。最大磁場勾配位置における2機種の平均偏向角はそれぞれ37.3°、45.8°と機種により異なり、並進吸引力は最大でも0.26Nであった。同機種間の変動誤差は0.001〜0.003Nと結果に影響を与えないほど小さかった。最大静磁場強度位置における2機種のトルクはそれぞれ4.30N、4.66Nであった。同機種間の変動誤差は0.01〜0.03Nで、吸引力試験と同様に小さかった。インプラント磁石の磁界方向が静磁場方向に対して80°および90°の場合、磁束密度の有意な低下は認められなかった。一方、100°以上では往復運動1〜3回目から磁束密度の低下が認められ、110°および180°の場合は有意に磁束密度が低下した。低下の割合はそれぞれ100°で約5〜10%、110°で12〜20%、180ドで8〜30%であった。

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7T MRI装置は、臨床研究に使用可能な汎用の商用装置としては現在最も高い静磁場強度を持った装置である。国際電気標準会議(International Electrotechnical Commision:IEC)ならびに米国食品医薬品局(Food and Drug Administration:FDA)によると、研究機として使用可能な静磁場強度の上限は1歳児以上では8Tであり、1歳児未満では4Tまでが利用可能と規定されている。日本では、ヒト用MRI装置に関しては薬事承認の基準のみが規定されており、通常操作モードでは3T以下、第一次水準管理操作モードでは4T以下のため、7T MRI装置は薬事承認対象外であり、Investigational Device Exemption(IDE)として各施設の倫理委員会による規制の下で、ヒトでの使用が可能な装置ということになる。このように、ヒト用7T MRI装置は保険請求では維持管理することのできない研究用装置であるにもかかわらず、世界では50台以上、日本においては2015年にはその約1割が稼働しようとしている。本稿では、現在7T MRI装置がどのように使われており、またどのような問題点と直面しているかを述べ、それに対するアプローチとしてどのような研究などが行われているかを簡単に述べることで、7T MRI装置における現状と研究動向、将来性について触れる。(著者抄録)

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To improve magnetic resonance (MR) safety, we surveyed the accidents caused by large ferromagnetic materials brought into MR systems accidentally. We sent a questionnaire to 700 Japanese medical institutions and received 405 valid responses (58%). A total of 97 accidents in 77 institutions were observed and we analyzed them regarding incidental rate, the detail situation and environmental factors. The mean accident rate of each institute was 0.7/100,000 examinations, which was widely distributed (0–25.6/100,000) depending on the institute. In this survey, relatively small institutes with less than 500 beds tend to have these accidents more frequently (p<0.01). The institutes in which daily MR examination counts are more than 10 patients have fewer accidents than those with less than 10 daily examinations. The institutes with 6–10 MR examinations daily have significantly more accidents than that with more than 10 daily MR examinations (p<0.01). The main mental factors of the accidents were considered to be “prejudice” and “carelessness” but some advocate “ignorance.” Though we could not find significant reduction in the institutes that have lectures and training for MR safety, we should continue lectures and training for MR safety to reduce accidents due to “ignorance.”

DOI： 10.6009/jjrt.2013_JSRT_69.1.99

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MR専門技術者の認定取得前後で安全に関する意識の変化、認定者が在籍していない施設との吸着事故の件数の違いを調べるためにアンケートを実施した。MR専門技術者が在籍している施設は、在籍していない施設に比べ1日あたり約2倍の検査をこなしているが、吸引事故の発生率は在籍していない施設に比べ低かった。スタッフの充実度や体外金属の確認の実施に関しては認定者の在籍と因果関係はなく、各施設において適切な手順が設けられていたが、事故の多くは思い込みや確認不足であり、その背景には業務多忙やスタッフ間の連携ミスなど、普段よく耳にする医療ミスの発生原因と大きく変わらなかった。知識不足・認識不足は教育によって改善されると考えられるが、確認不足は施設毎に労働条件や施設環境が異なりさまざまな要因を抱えていた。

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Language：Japanese   Publisher：(株)医学書院  

7TMRIは高い信号雑音比を活かして脳神経領域の超高精細形態画像を得ることができる他、強い磁化率効果を利用して、T2強調画像、磁化率強調画像の大幅なコントラスト向上や、functional MRIの精度向上が可能となる。また、T1の延長はMRAやarterial spin labelingの大幅な画質向上や造影効果の向上に寄与し、化学シフトの増加はMR spectroscopyの分離能向上をもたらす。7TMRIの特徴・画像・将来について述べた。

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.59.0_64

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

Using a questionnaire, we surveyed 2,500 facilities in Japan to clarify medical accidents concerning the magnetic resonance device and its environment. Data derived from 1,319 valid responses (52.8%), allowed us to analyze the situation of (or the reason for) the occurrence of the accidents and their environmental factors. Five hundred and nine facilities (39% of all facilities) had the experience of magnetically induced displacement of the large ferromagnetic material. Intravenous (I.V.) drip stands were involved the largest number of them: 31% (228 cases). Oxygen bottles had the second largest number of incidents: 20%. There were also many incidents involving various materials brought in by non-medical staff (e.g. stepladder for construction). About 20% of the accidents occurred outside of working hours. Patients in 12% of the facilities (154 facilities) experienced burns. In 39 of the cases, burns were received to the inside of the thighs. In 38 of the cases, patients received burns from an electrical cable touching the skin. There were also frequent incidents of burning regarding the boa. We received reports of burns and pain from the halo vest even though it’s required to be worn for MR safety. Regarding incidents of contraindications, 280 patients with pacemakers were brought into the magnetic resonance (MR) inspection room. Twelve percent of the facilities experienced natural quench. Lack of training for the staff who introduce and operate high magnetic field devices are considered involving frequently occurring accidents of attractions and burns at hospitals with over 500 beds caused by carrying in materials.

DOI： 10.6009/jjrt.67.895

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Language：Japanese   Publisher：(株)インナービジョン  

前立腺がんは、罹患率が上昇している疾患であり、その予後はさまざまである。また、現在、いろいろな治療法が存在しているため、治療前に正確に前立腺がんの存在部位、進行度を把握し、予後を推測し、治療法を選ぶことが重要となっている。しかし、前立腺がんのMRIは、施設、機種、読影医の差により、検査情報が異なるものになってしまうことがあるので、その有用性はいまだに一定していない。そこで、MRIの欠点を補い、非侵襲的、客観的に生体内の代謝産物情報を提供できるMRスペクトロスコピー(MRS)に期待が寄せられている。だが、国内ではソフトやコイルの問題があり、前立腺MRSの普及はいまだ不十分と思われる。本稿では、現在の前立腺MRSの基本的有効性を概説し、3T装置によるMRSへの期待について述べる。(著者抄録)

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.57.0_2

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.56.0_44

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Language：Japanese   Publisher：日本安定同位体・生体ガス医学応用学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(株)響文社  

超音波で診断された非アルコール性脂肪性肝疾患(NAFLD)34例(男18例、女性16例、平均55.6歳)を対象に、1H-Magnetic Resonance Spectroscopy(1H-MRS)を用い、肝脂肪量を測定し、皮下・内臓脂肪量およびアディポサイトカインと比較検討した。NAFLD全症例におけるBMIは26.4±3.8のうち25以下は29.4%と肥満症を呈さない症例が認められた。肝臓脂肪/水比は14.6±13.6%で0.04〜49.11%と幅広く分散し、内臓脂肪136.4±56.9cm2、皮下脂肪200.6±86.8cm2であった。肝臓脂肪/水比との相関は年齢r=-0.47、BMIr=0.31、内臓脂肪r=0.33、皮下脂肪r=0.21、ASTr=0.55、ALTr=0.71であった。アディポネクチン10.8±9.0(20例)、高分子アディポネクチン6.1±6.7、レプチン11.8±13.2で肝臓脂肪/水比と相関傾向は認められなかった。内臓脂肪と皮下脂肪の全脂肪面積に対する面積比の検討を行い、性別による検討では男性においてBMIr=0.191、内臓脂肪r=0.423、皮下脂肪r=0.507と内臓・皮下脂肪量と肝臓脂肪量に有意な関係を認めた。一方、女性ではBMIr=0.328、内臓脂肪r=0.060、皮下脂肪r=0.261と明らかな相関は示さなかった。

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：産業開発機構(株)  

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2009&ichushi_jid=J00116&link_issn=&doc_id=20100106160004&doc_link_id=%2Fan7eizoc%2F2009%2F004114%2F010%2F0062-0067%26dl%3D0&url=https%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fan7eizoc%2F2009%2F004114%2F010%2F0062-0067%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

Language：Japanese   Publisher：日本脳循環代謝学会  

J-GLOBAL

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.52.0_67

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Language：Japanese   Publisher：Japanese Society of Radiological Technology (JSRT)  

DOI： 10.6009/jjrt.64.1491

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Language：Japanese   Publisher：Japanese Society of Radiological Technology (JSRT)  

DOI： 10.6009/jjrt.64.1575

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Language：Japanese   Publisher：Japanese Society of Radiological Technology (JSRT)  

The purpose of this study was to suppress CSF flow artifacts in the fast FLAIR sequence at 3.0T MRI. We investigated the influence of thickness of the inversion pulse in the sequence on the high-intensity CSF flow artifacts based on the flow phantom and in-vivo studies at 1.5T and 3.0T. Results demonstrated that CSF flow artifacts at 3.0T were clearly stronger than at as 1.5T. Moreover, 3.0T was influenced by the crosstalk between each inversion pulse compared with 1.5T. The optimal setting of inversion pulse for two interleaving acquisitions for fast FLAIR imaging at 3.0T was approximately 1.5 fold on the basis of sum of slice thickness and slice gap. The appropriate setting of thickness of inversion pulse in fast FLAIR imaging reduces the incidence of CSF flow artifacts at 3.0T.

DOI： 10.6009/jjrt.64.1513

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Language：Japanese   Publisher：(一社)日本脳神経外科学会  

J-GLOBAL

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Language：Japanese   Publisher：公益社団法人日本放射線技術学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(一社)日本脳卒中学会  

J-GLOBAL

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：Japanese Society of Radiological Technology (JSRT)  

The purpose of this study was to decrease vascular artifacts caused by the in-flow effect in three-dimensional inversion recovery prepared fast spoiled gradient recalled acquisition in the steady state (3D IR FSPGR) at 3.0 Tesla. We developed 3D double IR FSPGR and investigated the signal characteristics of the new sequence. The 3D double IR FSPGR sequence uses two inversion pulses, the first for obtaining tissue contrast and the second for nulling vascular signal, which is applied at the time of the first IR period at the neck region. We have optimized scan parameters based on both phantom and <i>in-vivo</i> study. As a result, optimized parameters (1st TI=700 ms, 2nd TI=400 ms) successfully have produced much less vessel signal at reduction than conventional 3D IR FSPGR over a wide imaging range, while preserving the signal-to-noise ratio (SNR) and gray/white matter contrast. Moreover, the decreased artifact was also confirmed by visual inspection of the images obtained <i>in vivo</i> using those parameters. Thus, 3D double IR FSPGR was a useful sequence for the acquisition of T1-weighted images at 3.0 Tesla. (Article in Japanese)

DOI： 10.6009/jjrt.63.1239

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Language：Japanese   Publisher：日本脳循環代謝学会  

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Language：Japanese   Publisher：日本脳循環代謝学会  

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Language：Japanese   Publisher：日本脳循環代謝学会  

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Language：Japanese   Publisher：Japanese Society of Radiological Technology (JSRT)  

We devised a method of analyzing a regional fat fraction using a modulus and real multiple gradient-echo (MRM-GRE) 4-7 echo Dixon sequence. The regional fat fraction was calculated with a theoretically fitted signal-intensity curve for multiple GRE images at each echo time (i.e., 4-7 echoes.) on a 1.5 Tesla MRI to correct T2* decay and phase cycling. Then the real image of the first echo was used to differentiate between the areas above and below the 50 percent fat fraction. To eliminate the T1-effect, the flip angle was set at 12 degrees. Fat fractions of the phantom with MRM-GRE were compared with those using conventional double-GRE and other MRI techniques. Fat fractions of liver and spinal bone marrow in healthy volunteers were determined during a breath-hold. The fat fraction of the phantom obtained by the MRM-GRE method tended to agree with the actual fat fraction. On the other hand, in both the phantom and in healthy volunteers, the double-GRE was underestimated owing to T2* decay. The MRM-GRE method enables simple, accurate analysis of the regional fat fraction.

DOI： 10.6009/jjrt.63.312

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.48.0_37

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.49.0_64

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.48.0_54

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Language：Japanese   Publisher：Japanese Society of Radiological Technology (JSRT)  

The purpose of this study was to decrease vascular artifacts caused by the in-flow effect in three-dimensional inversion recovery prepared fast spoiled gradient recalled acquisition in the steady state (3D IR FSPGR) at 3.0 Tesla. We developed 3D triple IR (3IR) FSPGR and examined the signal characteristics of the new sequence. We have optimized scan parameters based on simulation, phantom, and <i>in-vivo</i> studies. As a result, optimized parameters (1st TI=600 ms, 3rd TI=500 ms) successfully have produced the vessel signal at more than 40% reduction, while gray-white matter contrast was preserved. Moreover, the reduced artifact was also confirmed by visual inspection of the <i>in-vivo</i> images for which this condition was used. Thus, 3D 3IR FSPGR was a useful sequence for the acquisition of T1-weighted images at 3.0 Tesla.

DOI： 10.6009/jjrt.62.1560

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Language：Japanese   Publisher：(一社)日本磁気共鳴医学会  

位相マスク処理におけるHamming窓サイズの影響について検討し,磁化率強調画像の画質改善を試みた.健常ボランティア11例,脳血管障害患者2例を対象とした.位相マスク処理画像では,処理をしない画像に比べ,生理的鉄沈着部位,髄質静脈,深部静脈における位相変化に基づく信号低下が強調された.小さなHamming窓では,基底核,皮質の信号低下がとらえられた.中程度のHamming窓では髄質静脈,深部静脈の信号低下が強調され,MinIP画壕における静脈の描出能が向上した.大きなHamming窓では,比較的太い深部静脈の信号低下は不明瞭となり,髄質静脈の低信号のみが強調された.静脈奇形では,中程度のHamming窓で位相マスク処理をすることで,拡張した髄質静脈や幹静脈のコントラストが改善した.微小出血においては,病変の視認性はむしろ低下した

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Language：Japanese   Publisher：(一社)日本磁気共鳴医学会  

3TMRIによる磁化率強調画像(SWI)を用いて,多発性硬化症における磁化率効果に起因する画像所見について検討した.多発性硬化症患者8例を対象とした.位相マスク処理によって深部静脈,髄質静脈の描出能が大幅に向上した.3TMRIでは従来描出できなかった局所位相シフトに基づく小病変を検出できた.8例中7例で髄質静脈が脱髄斑の中央を貫いている様子が良好に観察した.8例中6例では一部の脱髄斑内における髄質静脈の拡張を認め,病変の活動性を反映している可能性が示唆された.T2WIで高信号を呈する脱髄斑は,SWIでは多彩な所見を呈し,4パターンに分類できた.T2WIで異常信号を呈さない白質,灰白質においてSWIで低信号を呈する病変をそれぞれ8例中4例,8例中5例で認めた.多発性硬化症における脱髄病変の検出や病態解析に有望であることが示唆された

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.47.0_5

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.46.0_39

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.47.0_50

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Language：Japanese   Publisher：(株)医薬ジャーナル社  

最近のMRI(magnetic resonance imaging)機器進歩の最たるものは,高磁場化である.高磁場化に伴い得られたS/Nが改善し,多断面化,高分解能化が得られる.機能検査への応用として,fundctional MRI,perfusion MR,DTI and Fiber tracking,MR spectroscopyのそれぞれについて,高磁場の利点をいかした最近の展開を紹介した(著者抄録)

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Language：Japanese   Publisher：産業開発機構(株)  

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Other Link： https://search-tp.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2005&ichushi_jid=J00116&link_issn=&doc_id=20050909190006&doc_link_id=%2Fan7eizoc%2F2005%2F003710%2F009%2F0993-0999%26dl%3D0&url=https%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fan7eizoc%2F2005%2F003710%2F009%2F0993-0999%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

The method to measure the neurotransimtter agent was developed for clinical 3Tesla MRI.

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Language：Japanese   Publisher：(公社)日本獣医学会  

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00004028526

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Language：Japanese  

J-GLOBAL

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Language：Japanese  

J-GLOBAL

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(一社)日本小児神経外科学会  

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Language：Japanese   Publisher：(一社)日本磁気共鳴医学会  

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.43.0_1

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00003174562

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

Magnetization transfer contrast (MTC) was evaluated by changing the off-set frequency and pulse intensity of MTC with the spoiled gradient echo (SPGR) sequence (T2^*-weighted image) using an experimental phantom that included olive oil, protein, fiber, collagen, and pure water. The intensity of pure water reached a constant level just above the off-set frequency (1200 Hz)regardless of MT pulse power. The contrast-to-noise ratio(CNR)in each of the phantom materials was maximal at the MT pulse power of 2500 degrees (equivalent flip angle). The CNR and image noise obtained by body coil were inferior to those obtained with an extremity coil. In clinical application, the MTC effect on chondrosarcoma was higher(MT ratio, ROI-1:0.448, ROI-2:0.382)than those of other cases in this study. Since the image contrast was improved between the malignant fibrous histiocytoma(MFH, MT ratio, ROI-1:0.282, ROI-2:0.289)and peripheral tissues, extraskeletal extension could be observed more easily than without MTC imaging. In conclusion, the effects of MTC might be in providing useful information, in presuming composed tissues, differential diagnoses, and extent to the surrounding structures because of changing the image contrast to surrounding tissues corresponding to the rate of included bound water.

DOI： 10.6009/jjrt.KJ00003326546

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00003326540

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

造影ダイナミックMRIにおいてリアルタイムにT1値計測が可能な手法を開発し臨床応用を試みた.SPGRシーケンスを改良し,一画像ごとにflip angleを変化することを可能にすることによって,異なるflip angleで得られた画像より静的な状態での組織のT1値を計測することを可能にし,引き続き一定のflip angleのもとで得られた画像の信号強度変化から造影効果によるT1値変化の換算を実現した.臨床例は聴神経腫瘍で,一般に神経鞘腫は血流量はあまり豊富ではなく,血管外への造影剤浸出は多い.又,造影遅延相ではよく似た像を呈する髄膜腫とはダイナミックスタディでは異なる信号変化を呈することがよく知られている.1/T1値ダイナミックカーブでも神経鞘腫の特徴である徐々に造影効果が上がる現象を捉えられている.測定対象に応じた最適なスキャンパラメータを選ぶことにより,10%前後の精度で造影ダイナミックT1値計測MRIが実現できた

DOI： 10.6009/jjrt.kj00000921684

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Other Link： https://search-tp.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2003&ichushi_jid=J01192&link_issn=&doc_id=20030930320178&doc_link_id=10.6009%2Fjjrt.KJ00000922051&url=https%3A%2F%2Fdoi.org%2F10.6009%2Fjjrt.KJ00000922051&type=J-STAGE&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00007_3.gif

Language：Japanese   Publisher：(株)インナービジョン  

MRIのみでは組織や細胞のコンパートメントを分離し評価することは困難であると考えられ,代謝物の局在を利用したコンパートメント評価は有用性が高いと考えられた.代謝物濃度に加えて代謝物ごとの拡散能を測定することにより,代謝物の局在ごとのコンパートメントの環境変化の違いを評価した.臨床用MRI装置による代謝物拡散能の測定は,技術的な改善の余地と,臨床応用のための再現性やばらつきの検討を加える必要があるが,十分実用であり,これ迄の方法では得られない細胞や組織の局在化が可能であり,これらに起因する環境変化を反映する情報が非侵襲的に得られる点で,臨床的にも非常に有用な方法であると考えられた

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Language：Japanese   Publisher：(公社)日本医学放射線学会  

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Language：Japanese   Publisher：社団法人日本放射線技術学会  

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

Among several techniques for contrast-enhanced MRA, the elliptical centric view ordering method, originally developed at the Mayo Clinic, is a promising one. It has been difficult to apply a fat-suppression prepulse, mainly because the conventional fat suppression method requires a longer acquisition time during sampling of the lowfrequency domain in k-space, and it causes severe image distortion due to the great change in longitudinal magnetization derived from fat tissue. We developed a novel method to append fat saturation to the elliptical centric view ordering technique, and assessed the feasibility of its use. Our method is to apply fat-saturation pulses only at selected sampling points when any gradient is applied in the slice-encoding direction. In this way, we achieved efficient suppression of fat-derived signal within a relatively short time, comparable to that of the conventional fat-saturation method, and succeeded in minimizing artifacts.

DOI： 10.6009/jjrt.KJ00000921769

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.18973/photographingjsrt.40.0_65

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00000922051

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DOI： 10.6009/jjrt.KJ00000921915

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We modified the multi-phase spoiled gradient recalled echo (SPGR.) pulse sequence using the double-echo MR technique for estimation of T_1 during the first pass of contrast agent, and examined its precision. In the first half of the pulse sequence, the flip angle was varied systematically to calculate static T_1 values. It was necessary to choose optimal flip angles to minimize the calculation error of static T_1 values. In the latter half of this sequence, changes in absolute T_1 were calculated using differences in signal intensities before and after the injection of contrast agent. The optimal flip angle was 20 degrees for precise conversion to T_1 values under the short TR(33.3 ms)condition. Double echo MR data were used to minimize the T_2 effect. The present method appears to be useful for quantitative estimation of dynamic contrast-enhanced MRI.

DOI： 10.6009/jjrt.KJ00000921684

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初期の頃のMRの撮影はSE (spin echo)法が中心であり,1枚の画像を得るために数分から,十数分の時間が必要であった.これを改善するためにさまざまな工夫が続けられ,現在に至っている.これには主にパルスシーケンスの工夫と,画像再構成の工夫があり,それらを組み合わせて高速化を行っている.今回は高速撮影がどのような方法で達成されているかまとめることで(Fig. 1)日常業務に役立てていただくことを目的とした.

DOI： 10.6009/jjrt.KJ00000921628

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00000921584

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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DOI： 10.18973/photographingjsrt.39.0_46

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00001364732

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DOI： 10.6009/jjrt.KJ00001364599

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DOI： 10.6009/jjrt.KJ00001364598

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DOI： 10.6009/jjrt.KJ00001364328

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DOI： 10.18973/photographingjsrt.38.0_20

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DOI： 10.6009/jjrt.KJ00001357594

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DOI： 10.6009/jjrt.KJ00003111239

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DOI： 10.6009/jjrt.KJ00003111078

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DOI： 10.6009/jjrt.KJ00003111252

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DOI： 10.6009/jjrt.KJ00001357037

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Language：Japanese   Publisher：(株)インナービジョン  

prototypeの3T-MR装置を用いて,ヒト脳における1H-MRSを測定することができた.磁場強度上昇に伴うS/Nの上昇により測定時間が短縮され,再現性の良いGlxピークを検出することが可能であった

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We improved the fat suppression technique based on chemical shift selective saturation (CHESS). To do this, we shortened the duration of the CHESS pulse to achieve a short repetition time (TR) for MR angiography (MRA). A short-duration CHESS pulse causes broad frequency band saturation, creating extensive offset from the resonance frequency of water. In our phantom experiment, the best parameters of the short-duration CHESS pulse were 3.84 ms in duration, -650 Hz in offset frequency from water resonance, and had a 130-degree flip angle. With this technique, MRA will be able to be carried out without a significant increase in TR. Thus, better vessel contrast will be maintained in time-of-flight (TOF) MRA or contrast-enhanced MRA when using the maximum intensity projection (MIP) method.

DOI： 10.6009/jjrt.KJ00001357001

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DOI： 10.18973/photographingjsrt.34.0_50

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DOI： 10.6009/jjrt.KJ00001357200

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DOI： 10.6009/jjrt.KJ00001357189

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DOI： 10.6009/jjrt.KJ00001357038

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DOI： 10.18973/photographingjsrt.32.0_84

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DOI： 10.6009/jjrt.KJ00003110838

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DOI： 10.6009/jjrt.KJ00003110697

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decreased groupは最終的に全例,中枢神経系日和見疾患が存在した.また,decreased groupは有意に髄液中HIV-RNAが高値であった.更に,decreased groupは6名中5名が死亡し,病理解剖の結果,中枢神経系日和見疾患が証明されている.non-decreased groupでは10名中2名が死亡したが,その2名とも死因は中枢神経疾患とは無関係であった

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DOI： 10.6009/jjrt.KJ00001351731

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DOI： 10.6009/jjrt.KJ00001354236

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Gradient echo法において認められる信号低下率1/T2*を利用して,非侵襲的な局所骨梁評価の試みを行った.ファントム実験では信号低下率1/T2*は磁化率の異なる物質間の界面積密度に相関することが明らかとなった.臨床応用では成長による骨塩量の増加に1/T2*が相関するが,骨塩量増加と共に1/T2*増加の程度は緩やかとなり,単なる骨塩量の変化に加えて骨梁の構成内容の変化も加味されることが示唆された.従って本法は骨梁変化の評価に有用であろうと考えた

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DOI： 10.6009/jjrt.KJ00003109334

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1)成猫に実験的に脳梗塞巣を作成し,拡散強調後,T2及び造影T1強調像によって捉えられた細胞内浮腫から細胞外浮腫への生理学的な変化を,1H-MRSによって追跡することで,生化学的変化との相応についての検討をした。2)拡散強調像では,発症後1時間から細胞内浮腫の状態が拡散係数の低下として示されたが,以後拡散係数は24時間後まで明らかな変化は認められなかった。3)造影T1及びT2強調像においては,BBB破綻にともなう細胞外浮腫の状況が,4時間後より捉え得るようになった。4)1H-MRSにおいては,発症後1時間において嫌気的解糖系の亢進を示す乳酸が認められた。乳酸は24時間後にいたるまで局所に蓄積される傾向にあった。5)生存神経細胞の指標であるNAAは,虚血作成後2時間から3時間後で減少し,以後24時間後に至るまでこの所見は持続した。6)CHOについては水信号の増加によると思われる所見が得られた

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各ピクセルにおける信号解析の結果、運動野領域外でも位相は異なるが運動負荷波形と同じ周波数ピークを示す信号が検出され、その原因として脳機能およびアーチファクトの可能性を検討する必要がある。Hajnalらの研究では指運動負荷による脳全体のモーションアーチファクトの存在を示しその補正の重要性が報告されている(2、3)。一方、信号解析手法の応用による脳賦活画像では、特に周波数処理において位相情報を積極的に用いることで高精度の賦活領域の検出が可能であった。

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

本班は2年間にわたって事業を継続し以下の問題について検討し結論を得た.1)撮影条件の最適化について1)MRIのスキャン・パラメータは多数あり, アンケートの結果によればそれらはかなり広範囲に分布している.スキャンタイムの短縮, スキャン方向の減少等がスループットに大きく寄与するので各施設の経営方針がバラツキを左右するものと考えられる.2)MRI装置の発展はまだ日進月歩の段階であり各メーカーが開発を競っており用語の統一もまだなされていない.3)MRIは従来のX線写真の評価で問題となるコントラスト, 鮮鋭度以外にT1, T2強調, フロー等の診断要素が加わるので画像診断医の意見も無視できない.4)症例, 撮影部位により撮影パラメータ, コイル, 付属品などハードも異なりこれらを決定することは不可能である.5)MRI装置, 磁場強度によりSN比, コントラスト比が異なるため各装置, 磁場強度ごとに撮影パラメータを設定しなければならず問題が多い.これら以外にも細かな問題点もあり撮影条件の最適化を決定することは困難である.2)性能評価について現状では標準ファントム, SN比, コントラスト比等の測定方法がNEMA, AAPM, EEC等で検討され一部は報告されているが以下の項目について検討した.1)SE法によるT1, T2強調の頭部イメージについてT1強調像の視覚評価では0.5Tの上下で差があった.1.5TではT1強調像の画質がT2強調像より撮影パラメータに影響される傾向にあった.SN比は磁場強度, TR, TEにより異なるが1.5Tの機種間で大きな差があった.コントラスト比は0.3Tで最大となり, TR, TEについては値がバラツイた.原因は画像再構成, パラメータの選択, 動き, フロー等が考えられる.2)班試作の統一ファントム・イメージについて磁場強度によるSN比の差はあった.しかし同一磁場(1.5T)装置間で大きな差がみられた.これはRFコイルの形状, タイプによる感度差, 生データでなく画像表示方法の相違などが主原因と考えられる.TR, TEによるSN比の変動はファントム溶液の緩和時間に依存したものであり装置間で同様な傾向であった.以上の検討よりパラメータの非統一化, ハードの差などによる臨床評価との差はあるが規定したTR, TEによるSN比を用いた性能評価は可能である.

DOI： 10.6009/jjrt.KJ00003577873

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00003577738

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00003577652

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会  

DOI： 10.6009/jjrt.KJ00003501294

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00003501248

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Language：Japanese   Publisher：(公社)日本放射線技術学会  

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00003533349

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Language：Japanese   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.KJ00003577070

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Language：Japanese   Publisher：公益社団法人 日本放射線技術学会