10 results on '"Yuzo Yamasaki"'
Search Results
2. Importance of the heart rate in ultra-high-resolution coronary CT angiography with 0.35 s gantry rotation time
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Tsukasa Kojima, Takashi Shirasaka, Yuzo Yamasaki, Masatoshi Kondo, Hiroshi Hamasaki, Ryoji Mikayama, Yuki Sakai, Toyoyuki Kato, Akihiro Nishie, Kousei Ishigami, and Hidetake Yabuuchi
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Rotation ,Computed Tomography Angiography ,Heart Rate ,Humans ,Radiology, Nuclear Medicine and imaging ,Coronary Angiography ,Tomography, X-Ray Computed - Abstract
We investigated the effects of the heart rate (HR) on the motion artifact in coronary computed tomography angiography (CCTA) with ultra-high-resolution-CT (U-HRCT), and we clarified the upper limit of optimal HR in CCTA with U-HRCT in a comparison with conventional-resolution-CT (CRCT) on a cardiac phantom and in patients with CCTA.A pulsating cardiac phantom equipped with coronary models was scanned at static and HR simulations of 40-90 beats/min (bpm) at 10-bpm intervals using U-HRCT and CRCT, respectively. The sharpness and lumen diameter of the coronary model were quantitatively compared between U-HRCT and CRCT stratified by HR in the phantom study. We also assessed the visual inspections of clinical images in CCTA with U-HRCT.At the HRs ≤ 60 bpm, the error of the lumen diameter of the U-HRCT tended to be smaller than that of the CRCT. However, at the HRs 60 bpm, the inverse was shown. For the image sharpness, the U-HRCT was significantly superior to the CRCT (p 0.05). In the visual assessment, the scores were negatively correlated with HRs in patients (Spearman r = - 0.71, p 0.01). A receiver-operating characteristic analysis revealed the HR of 61 bpm as the optimal cutoff of the non-diagnostic image quality, with an area under the curve of 0.87, 95% sensitivity, and 71% specificity.At HRs ≤ 60 bpm, U-HRCT was more accurate in the imaging of coronary arteries than CRCT. The upper limit of the optimal HR in CCTA with U-HRCT was approx. 60 bpm.
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- 2022
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3. Virtual monochromatic spectral CT imaging in preoperative evaluations for intraductal spread of breast cancer: comparison with conventional CT and MRI
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Yuko Matsuura, Takeshi Kamitani, Koji Sagiyama, Yuzo Yamasaki, Takuya Hino, Makoto Kubo, Hideki Ijichi, Hidetaka Yamamoto, Hidetake Yabuuchi, and Kousei Ishigami
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Radiology, Nuclear Medicine and imaging - Abstract
Purpose To investigate the efficacy of virtual monochromatic spectral computed tomography imaging (VMI) in the preoperative evaluation for intraductal spread of breast cancer. Materials and methods Twenty-four women who underwent spectral CT and were pathologically diagnosed with ductal carcinoma with a ≥ 2-cm noninvasive component were retrospectively enrolled in Group 1. Twenty-two women with 22 lesions pathologically diagnosed with ductal carcinoma in situ or microinvasive carcinoma were enrolled in Group 2. We compared the contrast-to-noise ratios (CNRs) of the lesions on conventional 120-kVp CT images and 40-keV VMIs in Group 1. Two board-certified radiologists measured the maximum diameters of enhancing areas on 120-kVp CT, 40-keV VMI, and MRI in Group 2 and compared with histopathological sizes. Results The quantitative assessment of Group 1 revealed that the mean ± SD of the CNRs in the 40-keV images were significantly greater than those in the 120-kVp images (5.5 ± 1.9 vs. 3.6 ± 1.5, p p = 0.017, 0.048), whereas both readers identified no significant differences between the lesion size measured on 40-keV VMI and the histopathological data. In a comparison with MRI, 40-keV VMI provided measurement within a 10-mm error range in more lesions as compared to the conventional 120-kVp CT. Conclusion VMI improves the evaluation of intraductal spread and is useful for the preoperative evaluations of breast cancer.
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- 2023
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4. New transluminal attenuation gradient derived from dynamic coronary CT angiography: diagnostic ability of ischemia detected by 13N-ammonia PET
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Akiko Sakai, Yuzo Yamasaki, Masateru Kawakubo, Atsushi Yamamoto, Kenji Fukushima, Hidetake Yabuuchi, Toyoyuki Kato, Takashi Shirasaka, Michinobu Nagao, Eri Watanabe, Risako Nakao, Tsukasa Kojima, and Shuji Sakai
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medicine.diagnostic_test ,Receiver operating characteristic ,business.industry ,Ischemia ,030204 cardiovascular system & hematology ,medicine.disease ,Coronary artery disease ,03 medical and health sciences ,Contrast medium ,0302 clinical medicine ,Positron emission tomography ,medicine.artery ,Ascending aorta ,medicine ,Cutoff ,030212 general & internal medicine ,Cardiology and Cardiovascular Medicine ,business ,Nuclear medicine ,Electrocardiography - Abstract
Coronary computed tomography angiography (CCTA) has low specificity for detecting significant functional coronary stenosis. We developed a new transluminal attenuation gradient (TAG)-derived dynamic CCTA with dose modulation, and we investigated its diagnostic performance for myocardial ischemia depicted by 13N-ammonia positron emission tomography (PET). Data from 48 consecutive patients who had undergone both dynamic CCTA and 13N-ammonia PET were retrospectively analyzed. Dynamic CCTA was continuously performed in mid-diastole for five cardiac cycles with prospective electrocardiography gating after a 10-s contrast medium injection. One scan of the dynamic CCTA was performed as a boost scan for conventional CCTA at the peak phase of the ascending aorta. Absolute TAG values at five phases around the boost scan were calculated. The dynamic TAG index (DTI) was defined as the ratio of the maximum absolute TAG to the standard deviation of five TAG values. We categorized the coronary territories as non-ischemia or ischemia based on the 13N-ammonia PET results. A receiver operating characteristic (ROC) analysis was performed to determine the optimal cutoff of the DTI for identifying ischemia. The DTI was significantly higher for ischemia compared to non-ischemia (8.8 ± 3.9 vs. 4.6 ± 2.0, p
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- 2020
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5. Detectability of the artery of Adamkiewicz on computed tomography angiography of the aorta by using ultra-high-resolution computed tomography
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Yuzo Yamasaki, Hidetake Yabuuchi, Yuki Sakai, Soichiro Tsutsui, Tadashi Furuyama, Koji Sagiyama, Takeshi Kamitani, Yuko Matsuura, and Takuya Hino
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Adult ,Male ,Computed Tomography Angiography ,Contrast Media ,Arterial Occlusive Diseases ,Computed tomography ,Iterative reconstruction ,Signal-To-Noise Ratio ,030218 nuclear medicine & medical imaging ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,medicine.artery ,Image Interpretation, Computer-Assisted ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Bolus tracking ,Aorta ,Aged ,Retrospective Studies ,Computed tomography angiography ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Reproducibility of Results ,Arteries ,Middle Aged ,Ultra high resolution ,medicine.disease ,Radiographic Image Enhancement ,Spinal Cord ,030220 oncology & carcinogenesis ,Female ,Artery of Adamkiewicz ,Nuclear medicine ,business - Abstract
To evaluate the detectability of AKA on aortic computed tomography angiography (CTA) using ultra-high-resolution computed tomography (UHRCT). Twenty-eight patients were enrolled. They underwent aortic CTA with UHRCT (UHRCTA) and had previously undergone aortic conventional CTA (CCTA). The injection protocol of UHRCTA was the same as that of CCTA. The bolus tracking technique was used. UHRCTA images were reconstructed with adaptive iterative dose reduction (strong) and with forward-projected model-based iterative reconstruction solution. The matrix size and slice thickness on UHRCT were 1024 and 0.25 mm, respectively, and those on conventional CT were 512 and 0.5 or 0.67 mm, respectively. The UHRCTA and CCTA images were visually compared by using four scales. A score of 4 or 3 indicated that the AKA was assessable. In this instance, the contrast-to-noise ratios of each UHRCTA were measured. The exposure dose and signal-to-noise ratios were also investigated. The AKA visualization scores obtained with UHRCTA with forward-projected model-based iterative reconstruction solution were significantly higher than those with adaptive iterative dose reduction (p = 0.018) and CCTA (p = 0.0024). UHRCT can contribute to the better visualization of the AKA on aortic CTA.
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- 2020
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6. Evaluation of coronary artery variations using dual-source coronary computed tomography angiography in neonates with transposition of the great arteries
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Nobuko Kawamura, Yuzo Yamasaki, Shiro Ishikawa, Hiroshi Honda, Yuko Odawara, and Joji Hashimoto
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Male ,medicine.medical_specialty ,Computed Tomography Angiography ,Coronary Vessel Anomalies ,Transposition of Great Vessels ,Computed tomography ,Coronary Angiography ,medicine ,Humans ,Dual source ,Radiology, Nuclear Medicine and imaging ,Retrospective Studies ,medicine.diagnostic_test ,business.industry ,Infant, Newborn ,Coronary computed tomography angiography ,Reproducibility of Results ,Coronary ct angiography ,Coronary Vessels ,Coronary arteries ,medicine.anatomical_structure ,Echocardiography ,Great arteries ,Female ,Radiology ,business ,Artery - Abstract
The purpose of this study was to investigate whether the origins and courses of the coronary arteries could be better assessed using ECG-gated dual-source computed tomography (CT) than with echocardiography in neonates with transposition of the great arteries (TGA). A total of 17 neonates within 14 days old who underwent both echocardiography and retrospective ECG-gated coronary CT angiography were retrospectively reviewed. The patients were sedated and intubated during CT examinations, and CT images were obtained with a breath-hold. CT images were reconstructed by multiple cardiac phases, and the coronary artery assessment was performed in the most static phase. Coronary anomalies were classified by Shaher’s classification and validated by surgical findings. CT correctly classified 16 of 17 cases (Shaher type 1: 7, type 2: 4, type 9: 3, type 3: 1, type 4: 2), whereas echocardiography classified only 8 of 17 cases correctly. Dual-source CT had a significantly higher diagnostic ability than echocardiography (p = 0.0078). Dual-source coronary CT angiography has a higher diagnostic ability than echocardiography in the assessment of the origins and courses of the coronary arteries in neonates with TGA.
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- 2019
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7. Correction to: Development of a new phantom simulating extracellular space of tumor cell growth and cell edema for diffusion-weighted magnetic resonance imaging
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Koji Kobayashi, Yuzo Yamasaki, Mitsuhiro Kimura, Ryoji Mikayama, Hidetake Yabuuchi, Takeshi Kamitani, Koji Sagiyama, Yasuo Yamashita, and Ryoji Matsumoto
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Physics ,Radiological and Ultrasound Technology ,medicine.diagnostic_test ,Cell ,Biophysics ,Magnetic resonance imaging ,Tumor cells ,Imaging phantom ,Diffusion-Weighted Magnetic Resonance Imaging ,Nuclear magnetic resonance ,medicine.anatomical_structure ,Edema ,medicine ,Extracellular ,Radiology, Nuclear Medicine and imaging ,medicine.symptom - Published
- 2020
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8. One-stop shop assessment for atrial septal defect closure using 256-slice coronary CT angiography
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Ichiro Sakamoto, Hidetake Yabuuchi, Kenichiro Yamamura, Torahiko Yamanouchi, Koji Sagiyama, Hiroshi Honda, Yuzo Yamasaki, Takeshi Kamitani, Michinobu Nagao, and Satoshi Kawanami
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Male ,Cardiac Catheterization ,medicine.medical_specialty ,Computed Tomography Angiography ,Septum secundum ,030204 cardiovascular system & hematology ,Coronary Angiography ,Heart Septal Defects, Atrial ,Atrial septal defects ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Coronary Circulation ,Internal medicine ,Image Processing, Computer-Assisted ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Stroke ,Retrospective Studies ,Neuroradiology ,medicine.diagnostic_test ,business.industry ,Ultrasound ,Reproducibility of Results ,Coronary ct angiography ,Interventional radiology ,General Medicine ,Middle Aged ,medicine.disease ,Shunting ,Cardiology ,Feasibility Studies ,Female ,Radiology ,business ,Echocardiography, Transesophageal - Abstract
To investigate the feasibility and accuracy of measurement of the pulmonary to systemic blood flow ratio (Qp/Qs) and defect and rim sizes in secundum atrial septal defects (ASDs) using 256-slice CT, compared to the reference transoesophageal echocardiography (TEE) and right heart catheterization (RHC) measurements. Twenty-three consecutive adult patients with secundum ASDs who underwent retrospective ECG-gated coronary CT angiography (CCTA), TEE and RHC were enrolled in this study. Right ventricular (RV) and left ventricular (LV) stroke volumes (SV) were calculated by biventricular volumetry of CCTA. Qp/Qs-CT was defined as RVSV/LVSV. The sizes of the defect and rim were measured by multi-planar reconstruction CT images. Correlations between Qp/Qs-CT and Qp/Qs–RHC and between the defect diameter obtained by CT and TEE were analyzed by Pearson’s coefficient analysis. Rim sizes by CT and TEE were compared by paired t-test. Qp/Qs-CT was significantly correlated with Qp/Qs-RHC (r = 0.83, p
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- 2016
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9. Detection of ground-glass opacities by use of hybrid iterative reconstruction (iDose) and low-dose 256-section computed tomography: a phantom study
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Hiroshi Honda, Shunya Sunami, Ko Higuchi, Yoshio Matsuo, Hidetake Yabuuchi, Masamitsu Hatkenaka, Yuzo Yamasaki, Mikako Jinnouchi, Michinobu Nagao, Masato Yonezawa, and Takeshi Kamitani
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Image quality ,Physical Therapy, Sports Therapy and Rehabilitation ,Computed tomography ,Hybrid iterative reconstruction ,Iterative reconstruction ,Imaging phantom ,chemistry.chemical_compound ,medicine ,Humans ,Idose ,Radiology, Nuclear Medicine and imaging ,Radiation ,medicine.diagnostic_test ,Radon transform ,Phantoms, Imaging ,business.industry ,Low dose ,Solitary Pulmonary Nodule ,General Medicine ,chemistry ,Radiographic Image Interpretation, Computer-Assisted ,Radiography, Thoracic ,Glass ,Tomography, X-Ray Computed ,Nuclear medicine ,business ,Algorithms - Abstract
The detection of ground-glass opacities (GGOs) is an important issue in lung cancer screening with low-dose CT. The iterative reconstruction (IR) technique has the ability to improve the image quality relative to the filtered back projection (FBP) technique with low-dose CT. Our purpose was to investigate the ability to detect GGO in a chest phantom using a low-dose CT and hybrid IR, named iDose. Simulated GGOs in a chest phantom were scanned with 256-section CT at tube current second products of 20, 50, 100, and 200 mAs. Five radiologists visually assessed the detectability of GGOs in the phantom. The contrast-to-noise ratio (CNR) for GGOs was used as an estimate of image quality. Comparison of the detectability and CNR between standard images with 200 mAs-FBP and low-dose images with 20, 50, and 100-mAs FBP/iDose were performed by ANOVA with Dunnett’s and Tukey’s test. The detectability was significantly lower at 20-mAs FBP/iDose and 50-mAs FBP than that at 200-mAs FBP (p < 0.05). There was no significant difference between 50-mAs iDose and 200-mAs FBP and between 100-mAs iDose/FBP and 200-mAs FBP. The CNR was significantly higher on iDose images than that on FBP images at each mAs value. The CNR at 200-mAs FBP was the same as that at 50-mAs iDose (CNR:1.8). The hybrid IR technique and low-dose CT imaging with 50 mAs enabled noise and to maintain the detectability for GGOs in a chest phantom that is equivalent to the reference acquisitions of 200 mAs with FBP.
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- 2013
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10. Evaluation of chronic ischemic heart disease with myocardial perfusion and regional contraction analysis by contrast-enhanced 256-MSCT
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Mikako Jinnouchi, Michinobu Nagao, Masato Yonezawa, Ko Higuchi, Yuzo Yamasaki, Yoshio Matsuo, Taiki Higo, Hiroshi Honda, Yasushi Mukai, Kenji Sunagawa, Shingo Baba, Koichiro Abe, and Takeshi Kamitani
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Adult ,Male ,medicine.medical_specialty ,Wall thinning ,Myocardial Ischemia ,Contrast Media ,Coronary Angiography ,Chronic ischemic heart disease ,Myocardial perfusion imaging ,Internal medicine ,Image Processing, Computer-Assisted ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Myocardial infarction ,Endocardium ,Aged ,Aged, 80 and over ,Tomography, Emission-Computed, Single-Photon ,medicine.diagnostic_test ,Cardiac cycle ,Contraction analysis ,business.industry ,Myocardial Perfusion Imaging ,Reproducibility of Results ,Middle Aged ,medicine.disease ,Myocardial Contraction ,Iopamidol ,Radiographic Image Enhancement ,Chronic Disease ,Cardiology ,Female ,Tomography, X-Ray Computed ,business ,Perfusion - Abstract
To investigate myocardial viability in chronic ischemic heart disease by myocardial perfusion and regional contraction analysis using 256-slice MSCT coronary angiography (CCTA). In 30 patients with prior myocardial infarction (MI), CCTA with retrospective ECG-gating and stress-redistribution thallium-201 SPECT were performed. Using the same raw data as used for CCTA, myocardial perfusion imaging (CT-MPI) was reconstructed at four phases during the cardiac cycle. Mean myocardial attenuation and wall thickness at end-systole and end-diastole were measured in the MI areas depicted by SPECT, and they were compared between viable and non-viable segments categorized by SPECT. End-systolic thickness was significantly greater for viable than for non-viable segments (12.0 ± 3.2 vs. 9.6 ± 3.5 mm, p = 0.0017). There was no difference in end-diastolic thickness. Myocardial attenuation was significantly higher for viable than for non-viable segments in the subendocardium (62 ± 13 vs. 70 ± 11 HU, p = 0.003) and the epicardium (65 ± 13 vs. 80 ± 15 HU, p = 0.0002). The systolic wall thinning and epicardial low-attenuation areas were the indicative findings of CT-MPI for non-viable segments in the prior MI.
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- 2012
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