2021/10/25 更新

写真a

ヤマザキ モトヒコ
山崎 元彦
YAMAZAKI Motohiko
所属
医歯学総合病院 放射線診断科 講師
職名
講師
外部リンク

学位

  • 博士(医学) ( 2015年3月   新潟大学 )

経歴

  • 新潟大学   医歯学総合病院 放射線診断科   講師

    2021年4月 - 現在

  • 新潟大学   医歯学総合病院 放射線診断科   助教

    2016年4月 - 2021年3月

  • 新潟大学   医歯学総合病院 放射線診断科   特任助教

    2015年6月 - 2016年3月

 

論文

  • Low Tube Voltage Computed Tomography Venography for Patients With Deep Vein Thrombosis of the Lower Extremities - A Comparison With Venous Ultrasonography.

    Tatsuhiko Sato, Norihiko Yoshimura, Yosuke Horii, Motohiko Yamazaki, Ken Sato, Kazuki Kumagai, Hiroyuki Ishikawa

    Circulation journal : official journal of the Japanese Circulation Society   85 ( 4 )   369 - 376   2021年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Low tube voltage computed tomography venography (CTV) can be expected to increase imaging contrast and decrease radiation exposure by using iterative reconstruction (IR). This study evaluated the diagnostic ability of low tube voltage CTV with IR for deep vein thrombosis (DVT), compared to ultrasonography (US).Methods and Results:Two experienced radiologists retrospectively reevaluated the CTV data of 55 of 318 consecutive patients suspected of having DVT or pulmonary embolism between December 2015 and April 2017. The 55 patients had undergone both low tube voltage CTV and US (within 1 day before or after CTV). The lower extremity veins were divided into 10 segments. The DVT forms were categorized into 3 types: complete, concentric, and eccentric. We analyzed the 534 overall segments (16 segments excluded in US) measured using both CTV and US. The sensitivity-specificity was overall 73.3-90.0%, for femoropopliteal, it was 90.0-93.2%, and for the calf, it was 71.1-87.2%. The diagnostic accuracy between the 'eccentric only' and 'others' groups focusing on DVT forms was compared, and significant differences were revealed, especially in the muscular vein. CONCLUSIONS: The DVT diagnostic ability above the knee was comparable between low tube voltage CTV with IR and conventional CTV, and the radiation dose was reduced. It was suggested that eccentric DVT measured by CTV tend to be a false-positive, especially in the calf muscular vein.

    DOI: 10.1253/circj.CJ-20-0416

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  • Quantitative 3D Shape Analysis of CT Images of Thymoma: A Comparison With Histological Types. 国際誌

    Motohiko Yamazaki, Kanako Oyanagi, Hajime Umezu, Takuya Yagi, Hiroyuki Ishikawa, Norihiko Yoshimura, Hidefumi Aoyama

    AJR. American journal of roentgenology   214 ( 2 )   341 - 347   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    OBJECTIVE. The purpose of this study is to differentiate between low- and high-risk types of thymoma using quantitative 3D shape analysis of CT images. MATERIALS AND METHODS. This retrospective study included 44 patients with a pathologic diagnosis of thymoma. Two radiologists semiautomatically contoured CT images of the tumors and evaluated 3D shape parameters-namely, quantitative indicators of surface smoothness, including sphericity, ellipsoidality, and discrete compactness. The visual CT findings that were analyzed included longest diameter, shape (round-oval, lobulated, or irregular), calcification, cystic or necrotic changes, and enhancement pattern (homogeneous or heterogeneous). The difference and discriminating performance between low-risk (types A, AB, and B1) and high-risk (types B2 and B3) thymomas were statistically assessed. Interobserver agreement was determined using the concordance correlation coefficient. RESULTS. Twenty-three low-risk and 21 high-risk thymomas were identified on the basis of pathologic findings. The median values of sphericity and ellipsoidality were significantly higher for low-risk thymomas than for high-risk thymomas (for sphericity, 0.566 vs 0.517; for ellipsoidality, 0.941 vs 0.875; p < 0.05 for both). The AUC values of sphericity and ellipsoidality were 0.704 and 0.712, respectively. The best cutoff values were 0.528 and 0.919 for sphericity and ellipsoidality, respectively. Risk assessment combining these cutoff values and the mode of tumor detection (incidental detection or detection based on the presence of symptoms) improved the AUC value to 0.856 (sensitivity, 81.0% [17 of 21 patients]; specificity, 82.6% [19 of 23 patients]). All 3D shape parameters showed almost perfect interobserver agreement (concordance correlation coefficient, > 0.90). The visual CT findings were not significantly different between low- and high-risk thymomas (p > 0.05 for all). CONCLUSION. Quantitative 3D shape analysis has excellent reproducibility, and combining this technique with information on the detection mode helps differentiate low- from high-risk thymomas.

    DOI: 10.2214/AJR.19.21844

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  • Assessment of a simple method of heart weight estimation by postmortem computed tomography. 国際誌

    Rei Ogawa, Naoya Takahashi, Takeshi Higuchi, Hiroyuki Shibuya, Motohiko Yamazaki, Norihiko Yoshimura, Hisakazu Takatsuka, Hidefumi Aoyama

    Forensic science international   296   22 - 27   2019年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Measurement of heart weight is important when investigating cause of death, but there is presently no satisfactory method of heart weight estimation by postmortem computed tomography (PMCT). METHOD: We investigated 33 consecutive cases that underwent both PMCT and autopsy between February 2008 and June 2014. Heart and left ventricular (LV) weights were calculated by PMCT morphometry. We used a simple method to estimate LV weight: We assumed that LV was an ellipsoid and multiplied its volume on PMCT with myocardial specific gravity. We then compared the various heart and LV weights using linear regression. The calculated and estimated LV weights on PMCT were also compared. RESULTS: It was not possible to predict heart weight at autopsy from PMCT (R2 = 0.53). However, heart weight at autopsy could be accurately predicted from LV weight calculated by PMCT (R2 = 0.77). In addition, there was a strong correlation between the estimated and calculated LV weights by PMCT (R2 = 0.92). Heart weight at autopsy could also be accurately predicted using the PMCT-estimated LV weight (R2 = 0.72). CONCLUSION: Heart weight at autopsy could be accurately predicted using a simple method in which LV volume was assumed to be an ellipsoid on PMCT.

    DOI: 10.1016/j.forsciint.2018.12.019

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  • HRCT texture analysis for pure or part-solid ground-glass nodules: distinguishability of adenocarcinoma in situ or minimally invasive adenocarcinoma from invasive adenocarcinoma.

    Takuya Yagi, Motohiko Yamazaki, Riuko Ohashi, Rei Ogawa, Hiroyuki Ishikawa, Norihiko Yoshimura, Masanori Tsuchida, Yoichi Ajioka, Hidefumi Aoyama

    Japanese journal of radiology   36 ( 2 )   113 - 121   2018年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    PURPOSE: To distinguish between adenocarcinoma in situ (AIS)-minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma (IAC) showing pure or part-solid ground-glass nodules (GGNs) by high-resolution computed tomography (HRCT) texture analysis. MATERIALS AND METHODS: This retrospective study included 101 consecutive patients with 115 pure or part-solid GGNs ≤ 3 cm diameter, which were surgically resected and pathologically diagnosed with AIS, MIA, or IAC (48 AIS-MIA and 67 IAC) between April 2011 and March 2015. Each tumor was manually segmented on axial CT images, and the following texture features were calculated: volume, mass, mean CT value, variance, skewness, kurtosis, entropy, uniformity, and percentile CT numbers (10th, 25th, 50th, 75th, 90th, 95th percentiles). The differences between AIS-MIA and IAC were statistically evaluated using univariate, multivariate, and receiver operating characteristic analysis. RESULTS: Compared with IAC, AIS-MIA had significantly greater skewness, kurtosis, and uniformity, whereas in the other parameters, AIS-MIA demonstrated significantly lower values than those of IAC. Multivariate analysis revealed that independent differentiators were the 90th percentile CT numbers (P < 0.001) and entropy (P = 0.005) with an excellent accuracy (area under the curve, 0.90). CONCLUSIONS: The 90th percentile CT numbers and entropy can accurately distinguish AIS-MIA from IAC.

    DOI: 10.1007/s11604-017-0711-2

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  • Acute coronary syndrome: evaluation of detection capability using non-electrocardiogram-gated parenchymal phase CT imaging.

    Motohiko Yamazaki, Takeshi Higuchi, Toshikazu Shimokoshi, Takao Kiguchi, Yosuke Horii, Norihiko Yoshimura, Hidefumi Aoyama

    Japanese journal of radiology   34 ( 5 )   331 - 8   2016年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    PURPOSE: To evaluate the capability to detect acute coronary syndrome (ACS) by using non-electrocardiogram-gated parenchymal phase CT imaging. MATERIALS AND METHODS: Of 962 consecutive patients who underwent emergent coronary angiography for suspected ACS, 32 with ACS who underwent CT ≤24 h before angiography and 15 without ACS who underwent CT ≤24 h before or after angiography were included. Parenchymal phase was acquired at 100-s scan delay. The presence of a myocardial perfusion defect (MPD) on the left ventricle (a decrease of >20 HU) and its capability to detect ACS were evaluated. Results were compared with laboratory findings. RESULTS: MPD was detected in 29 of 32 ACSs. The sensitivity, specificity, and positive and negative predictive values were 91 % (29/32), 93 % (14/15), 97 % (29/30), and 82 % (14/17), respectively. The sensitivities of ST- and non-ST-elevation ACSs were 89 % (16/18) and 93 % (13/14), respectively, without significant difference (P > 0.99). Of the CT-detectable ACS, non-ST-elevation on the electrocardiogram and a normal creatine kinase-myocardial band were observed in 41 % (12/29) and 24 % (7/29), respectively. CONCLUSION: ACS is highly detectable even using conventional parenchymal phase CT imaging. Therefore, even when CT is non-gating, radiologists should carefully evaluate the heart to avoid overlooking ACS.

    DOI: 10.1007/s11604-016-0527-5

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  • CT measurement of splenic volume changes as a result of hypovolemic shock.

    Takao Kiguchi, Takeshi Higuchi, Naoya Takahashi, Toshikazu Shimokoshi, Motohiko Yamazaki, Norihiko Yoshimura, Hidefumi Aoyama

    Japanese journal of radiology   33 ( 10 )   645 - 9   2015年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    PURPOSE: To evaluate the changes in splenic volume during hypovolemic shock and after recovery by use of multidetector computed tomography (MDCT). MATERIALS AND METHODS: We investigated 22 cases who underwent MDCT during hypovolemic shock up to 3 h after presentation, compared the splenic volume with that after recovery, and evaluated the volume difference. We compared the volume ratio (recovery/shock) for two age groups: under 60 years (n = 10) and 60 years and over (n = 12). For cases (n = 10) undergoing CT examination twice after treatment, we compared the volume ratios by using the initial recovery CT and the second CT images. RESULTS: The average spleen volume in shock was 63 cm(3); under normal conditions it was 132 cm(3) (P < 0.001). The average volume ratio for groups under 60 years old was 2.34; for groups 60 years and over it was 2.05 (P = 0.051). The average volume ratio obtained by use of the initial post-recovery CT was 2.11; the ratio obtained by use of the second post-recovery CT was 2.16 (P = 0.386). CONCLUSIONS: Our results revealed that splenic volume was reduced during hypovolemic shock and rapidly increased after recovery. Splenic contraction is an important CT finding in shock.

    DOI: 10.1007/s11604-015-0470-x

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  • A combination of preoperative CT findings and postoperative serum CEA levels improves recurrence prediction for stage I lung adenocarcinoma. 国際誌

    Motohiko Yamazaki, Hiroyuki Ishikawa, Ryosuke Kunii, Akiko Tasaki, Suguru Sato, Yohei Ikeda, Norihiko Yoshimura, Takehisa Hashimoto, Masanori Tsuchida, Hidefumi Aoyama

    European journal of radiology   84 ( 1 )   178 - 184   2015年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    OBJECTIVES: To assess the prognostic value of combined evaluation of preoperative CT findings and pre/postoperative serum carcinoembryonic antigen (CEA) levels for pathological stage I lung adenocarcinoma. METHODS: This retrospective study included 250 consecutive patients who underwent complete resection for ≤ 3-cm pathological stage I (T1-2aN0M0) adenocarcinomas (132 men, 118 women; mean age, 67.8 years). Radiologists evaluated following CT findings: maximum tumor diameter, percentage of solid component (%solid), air bronchogram, spiculation, adjacency of bullae or interstitial pneumonia (IP) around the tumor, notch, and pleural indent. These CT findings, pre/postoperative CEA levels, age, gender, and Brinkman index were assessed by Cox proportional hazards model to determine the best prognostic model. Prognostic accuracy was examined using the area under the receiver operating characteristic curve (AUC). RESULTS: Median follow-up period was 73.2 months. In multivariate analysis, high %solid, adjacency of bullae or IP around the tumor, and high postoperative CEA levels comprised the best combination for predicting recurrence (P<0.05). A combination of these three findings had a greater accuracy in predicting 5-year disease-free survival than did %solid alone (AUC=0.853 versus 0.792; P=0.023), with a sensitivity of 85.7% and a specificity of 74.3% at the optimal threshold. The best cut-off values of %solid and postoperative CEA levels for predicting high-risk patients were ≥ 48% and ≥ 3.7 ng/mL, respectively. CONCLUSION: Compared to %solid alone, combined evaluation of %solid, adjacency of bullae or IP change around the tumor, and postoperative CEA levels improves recurrence prediction for stage I lung adenocarcinoma.

    DOI: 10.1016/j.ejrad.2014.10.009

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  • Analysis of decrease in lung perfusion blood volume with occlusive and non-occlusive pulmonary embolisms. 国際誌

    Yohei Ikeda, Norihiko Yoshimura, Yoshiro Hori, Yosuke Horii, Hiroyuki Ishikawa, Motohiko Yamazaki, Yoshiyuki Noto, Hidefumi Aoyama

    European journal of radiology   83 ( 12 )   2260 - 2267   2014年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    PURPOSE: The aim of this study was to determine if lung perfusion blood volume (lung PBV) with non-occlusive pulmonary embolism (PE) differs quantitatively and visually from that with occlusive PE and to investigate if lung PBV with non-occlusive PE remains the same as that without PE. MATERIALS AND METHODS: Totally, 108 patients suspected of having acute PE underwent pulmonary dual-energy computed tomography angiography (DECTA) between April 2011 and January 2012. Presence of PE on DECTA was evaluated by one radiologist. Two radiologists visually evaluated the PE distribution (segmental or subsegmental) and its nature (occlusive or non-occlusive) on DECTA and classified perfusion in lung PBV as "decreased," "slightly decreased," and "preserved". Two radiologists used a lung PBV application to set a region of interest (ROI) in the center of the lesion and measured HU values of an iodine map. In the same slice as the ROI of the lesion and close to the lesion, another ROI was set in the normal perfusion area without PE, and HUs were measured. The proportion of lesions was compared between the occlusive and non-occlusive groups. HUs were compared among the occlusive, non-occlusive, and corresponding normal groups. RESULTS: Twenty-five patients had 80 segmental or subsegmental lesions. There were 37 and 43 lesions in the occlusive and non-occlusive groups, respectively. The proportion of decreased lesions was 73.0% (27/37) in the occlusive group, while that of preserved lesions in the non-occlusive group was 76.7% (33/43). There was a significant difference in the proportion of lesions (P<0.001) between the two groups. HUs of the iodine map were significantly higher in the non-occlusive group than in the occlusive group (33.8 ± 8.2 HU vs. 11.9 ± 6.1 HU, P<0.001). There was no significant difference in HUs for the entire lesion between the non-occlusive (33.8 ± 8.2 HU) and corresponding normal group (34.5 ± 6.8 HU; P=0.294). CONCLUSION: Iodine perfusion tended to be visually and quantitatively preserved in lungs with nonocclusive PE. Lung PBV is required to evaluate pulmonary blood flow.

    DOI: 10.1016/j.ejrad.2014.08.015

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  • Relationship between CT features and high preoperative serum carcinoembryonic antigen levels in early-stage lung adenocarcinoma. 国際誌

    M Yamazaki, H Ishikawa, R Kunii, A Tasaki, S Sato, Y Ikeda, N Yoshimura, H Aoyama

    Clinical radiology   69 ( 6 )   559 - 66   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    AIM: To assess the relationship between thin-section computed tomography (CT) features of primary tumour and high preoperative serum carcinoembryonic antigen (CEA) levels that reportedly suggest poor prognoses in early-stage lung adenocarcinoma. MATERIALS AND METHODS: Two hundred and seventy-five consecutive patients who underwent resection of pathological stage I (T1-2aN0M0) adenocarcinomas with a maximum diameter of ≤ 3 cm (144 men, 131 women; mean age 67.8 years) were enrolled. CT features of the primary tumours and clinical characteristics of these patients were statistically evaluated to identify the factors associated with high serum CEA levels (>5 ng/ml). RESULTS: Eighty-one patients (29.5%) had high serum CEA levels. In univariate analysis, lower ground-glass opacity ratio (p < 0.001), lower tumour shadow disappearance rate (TDR: the ratio of tumour area in mediastinal window to that of lung window, p < 0.001), presence of notch (p = 0.015), and coexistence with bullae or honeycomb cysts (p < 0.001) were observed more frequently in the group with high serum CEA levels than that of the group with normal levels. TDR [odds ratio (OR) 0.984; 95% confidence interval (CI): 0.976-0.993; p < 0.001] and coexistence with bullae or honeycomb cysts (OR = 3.08; 95% CI: 1.55-6.12; p = 0.001) remained significant, even after adjusting patients' age, gender, and smoking status. CONCLUSIONS: Adenocarcinomas with lower TDR and coexisting with bullae or honeycomb cysts are associated with high preoperative serum CEA levels. Although some CEA elevations may be due to benign pulmonary diseases, such tumours are suspected to have poor prognoses, even for early-stage diseases.

    DOI: 10.1016/j.crad.2013.12.009

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共同研究・競争的資金等の研究

  • 腫瘍周囲肺のテクスチャ解析を用いた肺癌の新しい予後予測法の確立

    研究課題/領域番号:20K16693  2020年4月 - 2022年3月

    日本学術振興会  科学研究費助成事業 若手研究  若手研究

    山崎 元彦

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    配分額:2600000円 ( 直接経費:2000000円 、 間接経費:600000円 )

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