Masafumi Kidoh1, Daisuke Utsunomiya2, Seitaro Oda2, Hideaki Yuki2, Yoshinori Funama3, Tomohiro Namimoto2, Megumi Yamamuro4, Yasuyuki Yamashita2. 1. Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan. Electronic address: masafkidoh@yahoo.co.jp. 2. Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan. 3. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. 4. Department of Cardiovascular Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
Abstract
RATIONALE AND OBJECTIVES: Subtraction coronary computed tomography (CT) angiography (CCTA), which enables the removal of calcium and coronary stents from CCTA images, has been clinically introduced on a second-generation 320-row CT scanner. However, this technique for clinical use is not optimized. The long breath-holding time for two data acquisitions, which causes image misregistration and patient's discomfort, may limit the clinical availability of this subtraction technique. MATERIALS AND METHODS: This study received approval from the institutional review board; prior informed consent to participate was obtained from all patients. We performed subtraction CCTA of five patients using the test injection method and optimized the interval time between the first (pulmonary-arterial phase) and the second (coronary-arterial phase) scans to achieve robust subtraction. The patients' breath-holding times were recorded. We compared breath-holding times between our new protocol and previous study's protocol (estimated). RESULTS: Mean breath-holding time in our new protocol was 18.3 ± 3.4 seconds and that in previous protocol was 29.8 ± 3.6 seconds (difference in mean breath-holding time was 11.5 seconds). Misregistration artifacts were not shown in final subtraction CCTA images. These images improved luminal visualization in the calcified lesion. CONCLUSIONS: Our test injection protocol can shorten the breath-holding time, which is helpful for successful subtraction CCTA imaging, potentially resulting in an increase of subtraction CCTA examinations in many institutions.
RATIONALE AND OBJECTIVES: Subtraction coronary computed tomography (CT) angiography (CCTA), which enables the removal of calcium and coronary stents from CCTA images, has been clinically introduced on a second-generation 320-row CT scanner. However, this technique for clinical use is not optimized. The long breath-holding time for two data acquisitions, which causes image misregistration and patient's discomfort, may limit the clinical availability of this subtraction technique. MATERIALS AND METHODS: This study received approval from the institutional review board; prior informed consent to participate was obtained from all patients. We performed subtraction CCTA of five patients using the test injection method and optimized the interval time between the first (pulmonary-arterial phase) and the second (coronary-arterial phase) scans to achieve robust subtraction. The patients' breath-holding times were recorded. We compared breath-holding times between our new protocol and previous study's protocol (estimated). RESULTS: Mean breath-holding time in our new protocol was 18.3 ± 3.4 seconds and that in previous protocol was 29.8 ± 3.6 seconds (difference in mean breath-holding time was 11.5 seconds). Misregistration artifacts were not shown in final subtraction CCTA images. These images improved luminal visualization in the calcified lesion. CONCLUSIONS: Our test injection protocol can shorten the breath-holding time, which is helpful for successful subtraction CCTA imaging, potentially resulting in an increase of subtraction CCTA examinations in many institutions.