Naoyuki Imada

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RATIONALE AND OBJECTIVES The purpose of our study was to compare test bolus techniques using undiluted or diluted contrast material for their ability to predict aortic enhancement on coronary computed tomographic angiography (c-CTA) images. MATERIALS AND METHODS We divided 200 consecutive patients who underwent c-CTA on a 64-MDCT scanner into two groups.(More)
PURPOSE To evaluate the image quality and effect of radiation dose reduction by setting for computed tomography automatic exposure control system (CT-AEC) in computed tomographic angiography (CTA) of lower extremity artery. METHODS Two methods of setting were compared for CT-AEC [conventional and contrast-to-noise ratio (CNR) methods]. Conventional method(More)
PURPOSE Massive calcification complicates the diagnosis of the blood vessel lumen in computed tomography angiography (CTA) of the arteries of the lower extremities. The purpose of this study was to evaluate subtraction CTA with the use of orbital synchronized helical scanning (OS-SCTA). METHOD Phantom study: We performed OS-SCTA and non-OSCTA of a(More)
OBJECTIVE The objective of our study was to compare contrast enhancement on CT angiography (CTA) images of the lower extremity in patients with suspected peripheral artery disease who did not undergo hemodialysis (HD) and patients who were scanned before or after HD. MATERIALS AND METHODS We divided 287 consecutive patients who underwent CTA of the lower(More)
PURPOSE On coronary MR angiography (CMRA), cardiac motions worsen the image quality. To improve the image quality, detection of cardiac especially for individual coronary motion is very important. Usually, scan delay and duration were determined manually by the operator. We developed a new evaluation method to calculate static time of individual coronary(More)
PURPOSE The purpose of this study was to investigate the association of vessel visibility and radiation dose using contrast-to-noise ratio (CNR) method with low tube voltage in coronary computed tomography angiography (c-CTA). METHODS We performed electrocardiogram-gated scan of 2.0-mm diameter simulated vessel in the center of the cardiac phantom by the(More)
RATIONALE AND OBJECTIVES We delivered the saline chaser via a spiral flow-generating tube or a conventional connecting tube and compared arterial enhancement at computed tomography angiography (CTA) of the lower extremities. MATERIALS AND METHODS We randomly assigned 100 patients whose ankle bronchial pressure index or clinical symptoms were suspect of(More)
BACKGROUND To figure out the relationship between image noise and contrast noise ratio (CNR) at different tube voltages, using anthropomorphic new-born and 1-year-old phantoms, and to discuss the feasibility of radiation dose reduction, based on the obtained CNR index from image noise. We performed helical scans of the anthropomorphic new-born and(More)
Whole-heart coronary magnetic resonance angiography (WH-MRA) is useful noninvasive examination. Its signal acquisition is performed during very short still timing in each cardiac motion cycle, and therefore the adequate still timing selection is important to obtain the better image quality. However, since the current available selection method is only(More)
OBJECTIVE We evaluated the effect of the age, sex, total body weight (TBW), height (HT) and cardiac output (CO) of patients on aortic and hepatic contrast enhancement during hepatic-arterial phase (HAP) and portal venous phase (PVP) computed tomography (CT) scanning. METHODS This prospective study received institutional review board approval; prior(More)