Publications by authors named "Sadatoshi Kuwahara"
Objective: Our aim was to evaluate effects of the energy level and contrast on the spatial resolution of virtual monochromatic imaging (VMI).
Methods: With 2 types of computed tomographic (CT) scanners (Discovery CT750 HD and Revolution CT), we scanned an elliptical cylinder acrylic phantom with 20- or 40-fold dilutions of contrast medium and obtained VMI data sets at 40, 50, 60, and 70 keV. We evaluated the effects of energy levels and contrast on modulation transfer function (MTF) and the effect of energy levels on noise power spectra (NPS).
Objectives: To evaluate the accuracy of vascular diameter measurement on computed tomographic (CT) angiography using adaptive statistical iterative reconstruction (ASIR).
Methods: We scanned 9 vascular models with 3 wall thicknesses and filled with 3 densities of contrast material using a 64-detector CT unit, reconstructed images using ASIR (0%, 20%, 40%, 60%, 80%, and 100%), and repeated 20 separate diameter measurements for each model. We evaluated the distribution of image noise for the 0% and 100% ASIR.
Objectives: To evaluate the precision and accuracy in CT attenuation measurement of vascular wall using region-of-interest (ROI) supported by differentiation curves.
Study Design: We used vascular models (actual attenuation value of the wall: 87HU) with wall thicknesses of 1.5, 1.
It is difficult to precisely identify the locations of tunnels after double-bundle anterior cruciate ligament (ACL) reconstruction postoperatively. Using our novel transparent 3-dimensional computed tomography (T-3DCT), we evaluated intra-articular outlet locations and the angles of the anteromedial (AM) and posterolateral (PL) tunnels after anatomic double-bundle ACL reconstruction using the trans-tibial technique. A prospective study was performed with 123 consecutive patients.
View Article and Find Full Text PDFObjective: We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans.
Materials And Methods: As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube.
Objective: To evaluate the performance of 40-detector row computed tomography (CT) in the detection of in-stent stenosis of coronary stents.
Methods: Seven patent vascular models, 7 stenotic models, and 7 obstructed models were scanned with a 40-detector CT. We made the vascular models using 3 types of stent (Bx-Velocity, Express2, Driver) with an inner diameter of about 2.
Objective: To evaluate the performance of 40-detector row computed tomography (CT) in the assessment of coronary stents in comparison with 16-detector row CT.
Methods: A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 types of stent (Bx-Velocity, Express2, and Driver) with an approximately 3.5-mm inner diameter filled with contrast material (450 Hounsfield units) were scanned with 2 computed tomographic scanners (collimation, 16 x 0.
Objective: To assess the effect of tube voltage on the in-stent visibility of coronary stents in vitro on computed tomography (CT) angiography.
Methods: A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 kinds of stent (Bx Velocity, Express2, and Driver) with an inner diameter of approximately 3.5 mm and filled with contrast material (CT attenuation, 450 Hounsfield units) were scanned by means of a 16-detector row CT.
Objectives: We sought to assess the effects of measurement point, wall thickness, and intravascular density of contrast material on attenuation measurement of vascular wall.
Materials And Methods: We used vascular models (actual attenuation value of the wall: 83 HU) with wall thicknesses of 1.5, 1.
Background: The aim of the present study was to assess the accuracy and efficiency of left ventricular ejection fraction (LVEF) analysis by multidetector row computed tomography (CT).
Methods And Results: The CT data of 21 patients were analyzed by semi-automated software on a workstation. In analysis of LVEF using systolic volumes in the 6 phases (30-55%), systolic images of 10% interval (35, 45, 55%) were underestimated with a mean measurement error of -0.
Background: The aims of the present study were to assess the effect of the stent diameter, convolution kernel, and vessel orientation to the z-axis on the evaluation of coronary stents, in vitro with computed tomography (CT) angiography.
Methods And Results: Seven vascular models (2 models without stenosis, 2 with obstruction, and 3 with stenosis) with an approximate inner diameter of 3 or 4 mm, filled with contrast material (79 or 330 HU) were scanned with a 16-detector CT. The diameter measurement of the stent lumen and stenosis evaluation were both done in an orientation parallel to the z-axis of the scanner using 4 convolution kernels.