Takashi Shirasaka1, Michinobu Nagao2, Yuzo Yamasaki3, Tsukasa Kojima4, Masatoshi Kondo4, Yamato Shimomiya5, Takeshi Kamitani3, Hiroshi Honda3. 1. Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3 Chome-1-1 Maidashi, Higashi Ward, Fukuoka, Fukuoka Prefecture 812-8582, Japan. Electronic address: shirasa@med.kyushu-u.ac.jp. 2. Department of Diagnostic Imaging & Nuclear Medicine, Tokyo Women's Medical University, 8-1 Kawata-cho, Shinjuku-ku, Tokyo 162-0054, Japan. 3. Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3 Chome-1-1 Maidashi, Higashi Ward, Fukuoka, Fukuoka Prefecture 812-8582, Japan. 4. Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3 Chome-1-1 Maidashi, Higashi Ward, Fukuoka, Fukuoka Prefecture 812-8582, Japan. 5. Ziosoft Inc., Mita Kokusai Bldg, 5F 1-4-28, Mita, Minato-ku, Tokyo 108-0073, Japan.
Abstract
PURPOSE: A 320-row CT scanner can briefly scan the entire heart. Therefore, the feasible scan timing is required. The aim of this study was to propose a refined method for feasible scan timing for coronary CT angiography (CCTA) using a time-density curve of the ascending aorta (AAo). METHODS: One-hundred and twenty-nine patients were prospectively enrolled. All patients were performed test-bolus method. For the initial 65 patients, the scan timing was determined as a 3.0 s delay at the peak time in the AAo, which was defined as the conventional protocol (COV-P). For the next 64 patients, a scan timing of 1.0, 3.0, or 5.0 s delay was determined according to the interval from the contrast media arrival to peak time in the AAo, which was defined as the arrival to peak protocol (AP-P). The optimal scan timing was identified by the measurement of CT number in the left atrium, left ventricle, AAo, and descending aorta. The coronary enhancement and heterogeneity were compared between the two protocols. RESULTS: The optimal scan timing was significantly higher in the AP-P than in the COV-P (85.9% vs. 61.5%, p = 0.0017). The CT number in the left circumflex artery (LCX) was significantly higher in the AP-P than the COV-P (344.5 Hounsfield units vs. 316.3 Hounsfield units, p = 0.0484). The heterogeneous index of the LCX was significantly greater for the COV-P than the AP-P (-36.8 vs. -25.8, p = 0.0028). CONCLUSIONS: The AP-P can be used to determine the optimal scan timing for CCTA and contributes to stable coronary enhancement.
PURPOSE: A 320-row CT scanner can briefly scan the entire heart. Therefore, the feasible scan timing is required. The aim of this study was to propose a refined method for feasible scan timing for coronary CT angiography (CCTA) using a time-density curve of the ascending aorta (AAo). METHODS: One-hundred and twenty-nine patients were prospectively enrolled. All patients were performed test-bolus method. For the initial 65 patients, the scan timing was determined as a 3.0 s delay at the peak time in the AAo, which was defined as the conventional protocol (COV-P). For the next 64 patients, a scan timing of 1.0, 3.0, or 5.0 s delay was determined according to the interval from the contrast media arrival to peak time in the AAo, which was defined as the arrival to peak protocol (AP-P). The optimal scan timing was identified by the measurement of CT number in the left atrium, left ventricle, AAo, and descending aorta. The coronary enhancement and heterogeneity were compared between the two protocols. RESULTS: The optimal scan timing was significantly higher in the AP-P than in the COV-P (85.9% vs. 61.5%, p = 0.0017). The CT number in the left circumflex artery (LCX) was significantly higher in the AP-P than the COV-P (344.5 Hounsfield units vs. 316.3 Hounsfield units, p = 0.0484). The heterogeneous index of the LCX was significantly greater for the COV-P than the AP-P (-36.8 vs. -25.8, p = 0.0028). CONCLUSIONS: The AP-P can be used to determine the optimal scan timing for CCTA and contributes to stable coronary enhancement.