2026/03/10 更新

写真a

ナカザ　マサトキ
仲座　方辰
nakaza masatoki
所属
付属病院 放射線科 助教
職名
助教
外部リンク

論文

  • Quantitative Evaluation of Carotid Artery Stenosis by Multi-VENC 4D Flow MRI: Incorporating Turbulent Kinetic Energy for Clinical Validity. 国際誌

    Takahiro Ando, Tetsuro Sekine, Satoshi Suda, Kentaro Suzuki, Yasuo Murai, Kotomi Iwata, Masatoki Nakaza, Masashi Ogawa, Makoto Obara, Gerard Crelier, Kazumi Kimura, Shin-Ichiro Kumita

    Journal of magnetic resonance imaging : JMRI   62 ( 4 )   1168 - 1177   2025年10月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    BACKGROUND: Cervical internal carotid artery stenosis (ICS) is a recognized risk factor for ischemic stroke, yet morphological severity alone may not fully reflect hemodynamic alterations. Turbulent kinetic energy (TKE), derived from multi-velocity-encoding (multi-VENC) four-dimensional (4D) flow MRI, may provide a robust marker for ICS assessment, though its utility in carotid arteries remains underexplored. PURPOSE: To investigate the reproducibility of TKE measurement and to assess correlations with MR angiography (MRA)-derived stenosis, black blood T1-weighted imaging (T1BB)-derived plaque scale, and ultrasound parameters. STUDY TYPE: Prospective. POPULATION: Twenty-three patients (6 [26%] female; median age: 72 years, IQR: 60-80) with suspected ICS based on cerebrovascular symptoms or screening carotid ultrasound. FIELD STRENGTH/SEQUENCE: 3-T, multi-VENC (33-100-300 cm/s) 4D flow MRI of the carotid arteries at 1.0 mm3 isotropic resolution, using k-space-time principal component analysis (k-t PCA) acceleration, time of flight-MRA (3D gradient-echo), and T1BB (turbo spin echo). ASSESSMENT: Two neuroradiologists measured TKE once per case for interobserver evaluation. TKE was measured in a volume from just proximal to the bifurcation and slightly distal to the ICA stenosis. TKEbeat was defined as the total TKE integrated over the cardiac cycle. Stenosis and plaque features were assessed by MRA and T1BB, respectively. Carotid ultrasound parameters included peak systolic velocity, resistance index, intima-media thickness (IMT), and plaque characteristics. STATISTICAL TESTS: Intraclass correlation coefficient (ICC) and Bland-Altman analyses were used for interobserver agreements. Associations between TKEbeat and conventional parameters were evaluated using Spearman's rank correlation. TKEbeat was compared between subgroups based on stenosis, plaque grade, and vascular risk factors using Mann-Whitney U-tests. Significance threshold: p < 0.05. RESULTS: The ICC was 0.922 for TKEbeat. TKE correlated with stenosis (r = 0.309), plaque scale (r = 0.392), and IMT (r = 0.543). TKEbeat was higher in the stenosis group. DATA CONCLUSION: Multi-VENC 4D flow MRI enables reproducible TKE measurement correlated with carotid stenosis and plaque features. EVIDENCE LEVEL: Level 1. TECHNICAL EFFICACY: Stage 1.

    DOI： 10.1002/jmri.70008

    PubMed

    researchmap

  • Multimodality imaging of ischaemia with non-obstructive coronary artery disease in a patient with coronary artery ectasia: a case report. 国際誌

    Masatoki Nakaza, Yukihiro Watanabe, Keishi Suzuki, Akira Shibata, Masashi Ogawa, Tetsuro Sekine

    European heart journal. Case reports   9 ( 6 )   ytaf246   2025年6月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    DOI： 10.1093/ehjcr/ytaf246

    PubMed

    researchmap

  • Dual-VENC 4D Flow MRI Can Detect Abnormal Blood Flow in the Left Atrium That Potentially Causes Thrombosis Formation after Left Upper Lobectomy.

    Masatoki Nakaza, Mitsuo Matsumoto, Tetsuro Sekine, Tatsuya Inoue, Takahiro Ando, Masashi Ogawa, Makoto Obara, Olgierd Leonowicz, Shinichiro Kumita, Jitsuo Usuda

    Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine   21 ( 3 )   433 - 443   2022年7月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    PURPOSE: The purpose of the current study was to clarify the blood flow pattern in the left atrium (LA), potentially causing the formation of thrombosis after left upper lobectomy (LUL). The blood flow in the LA was evaluated and compared between LUL patients with and without thrombosis. For the evaluation, we applied highly accelerated 4D flow MRI with dual-velocity encoding (VENC) scheme, which was expected to be able to capture slow flow components in the LA accurately. METHODS: Eight volunteers and 18 patients subjected to LUL underwent dual-VENC 4D Flow MRI. Eight patients had a history of thrombosis. We measured the blood flow velocity and stasis ratio (proportion in the volume that did not exceed 10 cm/s in any cardiac phase) in the LA and left superior pulmonary vein (LSPV) stump. For visual assessment, the presence of each collision of the blood flow from pulmonary veins and vortex flow in the LA were evaluated. Each acquired value was compared between healthy participants and LUL patients, and in LUL patients with and without thrombosis. RESULTS: In LUL patients, blood flow velocity near the inflow part of the left superior pulmonary vein (Lt Upp) and mean velocity in the LA were lower, and stasis ratio in the LA was higher compared with healthy volunteers (Lt Upp 9.10 ± 3.09 vs.13.23 ± 14.19 cm/s, mean velocity in the LA 9.81 ± 2.49 vs. 11.40 ± 1.15 cm/s, and stasis ratio 25.28 ± 18.64 vs. 4.71 ± 3.03%, P = 0.008, 0.037, and < 0.001). There was no significant difference in any quantification values between LUL patients with and without thrombosis. For visual assessment, the thrombus formation was associated with no collision pattern (62.5% vs. 10%, P = 0.019) and not with vortex flow pattern (50% vs. 30%, P = 0.751). CONCLUSION: The net blood flow velocity was not associated with the thrombus formation. In contrast, a specific blood flow pattern, the absence of blood flow collision from pulmonary veins, correlates to the thrombus formation in the LA.

    DOI： 10.2463/mrms.mp.2020-0170

    PubMed

    researchmap

  • 4D Flow MR Imaging of the Left Atrium: What is Non-physiological Blood Flow in the Cardiac System?

    Tetsuro Sekine, Masatoki Nakaza, Mitsuo Matsumoto, Takahiro Ando, Tatsuya Inoue, Shun-Ichiro Sakamoto, Mitsunori Maruyama, Makoto Obara, Olgierd Leonowicz, Jitsuo Usuda, Shinichiro Kumita

    Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine   21 ( 2 )   293 - 308   2022年3月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    Most cardiac diseases cause a non-physiological blood flow pattern known as turbulence around the heart and great vessels, which further worsen the disease itself. However, there is no consensus on how blood flow can be defined in disease conditions. Especially, in the left atrium, the fact that vortex flow already exists makes this debate more complicated. 3D time-resolved phase-contrast (4D flow) MRI is expected to be able to capture blood flow patterns from multiple aspects, such as blood flow velocity, stasis, and vortex quantification. Previous studies have confirmed that physiological vortex flow is predominantly induced by the higher-volume flow from the superior left pulmonary vein. In atrial fibrillation, 4D flow MRI reveals a non-physiological blood flow pattern, which information may add value to well-established clinical risk factors. Currently, the research target of LA analysis has also widened to lung surgeons, pulmonary vein stump thrombosis after left upper lobectomy. 4D flow MRI is expected to be utilized for many more variable diseases that are currently unimaginable.

    DOI： 10.2463/mrms.rev.2021-0137

    PubMed

    researchmap

  • Careful consideration should be paid in the new imaging modality evaluation. 国際誌

    Tetsuro Sekine, Masatoki Nakaza, Shinichiro Kumita

    Journal of thoracic disease   13 ( 1 )   422 - 424   2021年1月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    DOI： 10.21037/jtd-20-3229

    PubMed

    researchmap

  • 4D Flow MR Imaging Reveals a Decrease of Left Atrial Blood Flow in a Patient with Cardioembolic Cerebral Infarction after Pulmonary Left Upper Lobectomy.

    Mitsuo Matsumoto, Kyoshiro Takegahara, Tatsuya Inoue, Masatoki Nakaza, Tetsuro Sekine, Jitsuo Usuda

    Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine   19 ( 4 )   290 - 293   2020年12月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    We present the case of a 76-year-old woman who underwent left upper lobectomy for lung adenocarcinoma. Three days after the surgery, a thrombus was observed in the pulmonary vein (PV) stump. Four months after the surgery, we performed 4D flow MRI, which revealed decreased blood flow, not only in the left superior PV stump, but also over a widespread region around the left atrium-left superior PV junction. 4D flow MRI can clarify the altered hemodynamics underlying thrombus formation.

    DOI： 10.2463/mrms.ici.2019-0142

    PubMed

    researchmap

  • Multiparametric flow analysis using four-dimensional flow magnetic resonance imaging can detect cerebral hemodynamic impairment in patients with internal carotid artery stenosis. 国際誌

    Takahiro Ando, Tetsuro Sekine, Yasuo Murai, Erika Orita, Ryo Takagi, Yasuo Amano, Kotomi Iwata, Masatoki Nakaza, Masashi Ogawa, Makoto Obara, Shin-Ichiro Kumita

    Neuroradiology   62 ( 11 )   1421 - 1431   2020年11月

    　詳細を見る

    記述言語：英語   掲載種別：研究論文（学術雑誌）  

    PURPOSE: MRI-based risk stratification should be established to identify patients with internal carotid artery stenosis (ICS) who require further PET or SPECT evaluation. This study assessed whether multiparametric flow analysis using time-resolved 3D phase-contrast (4D flow) MRI can detect cerebral hemodynamic impairment in patients with ICS. METHODS: This retrospective study analyzed 26 consecutive patients with unilateral ICS (21 men; mean age, 71 years) who underwent 4D flow MRI and acetazolamide-stress brain perfusion SPECT. Collateral flow via the Willis ring was visually evaluated. Temporal mean flow volume rate (Net), pulsatile flow volume (ΔV), and pulsatility index (PI) at the middle cerebral artery were measured. Cerebral vascular reserve (CVR) was calculated from the SPECT dataset. Patients were assigned to the misery perfusion group if the CVR was < 10% and to the nonmisery perfusion group if the CVR was ≥ 10%. Parameters showing a significant difference in both groups were statistically evaluated. RESULTS: Affected side ΔV, ratio of affected to contralateral side Net (rNet), and ratio of affected to contralateral side ΔV were significantly correlated to CVR (p = 0.030, p = 0.010, p = 0.015, respectively). Absence of retrograde flow at the posterior communicating artery was observed in the misery perfusion group (p = 0.020). Combined cut-off values of the affected side ΔV (0.18 ml) and rNet (0.64) showed a sensitivity and specificity of 100% and 77.8%, respectively. CONCLUSION: Multiparametric flow analysis using 4D flow MRI can detect misery perfusion by comprehensively assessing blood flow data, including blood flow volume, pulsation, and collateral flow.

    DOI： 10.1007/s00234-020-02464-2

    PubMed

    researchmap

▼全件表示

MISC