比較顯影劑注射技術搭配生理食鹽水灌注及單獨以顯影劑注射技術在16切面電腦斷層冠狀動脈影像中所獲得的時間延遲，作爲主要電腦斷層冠狀動脈檢查的延遲時間點。44位患者（平均年齡51.66±10.33歲）接受16切面電腦斷層冠狀動脈檢查。每位患者接受2種顯影劑注射方式。第一種方式爲在掃描時注射20ml顯影劑後緊接著注射20ml生理食鹽水。第二種方式爲單獨注射20ml顯影劑。掃描完後，以ROI在升主動脈處量出最高顯影濃度對應時問的曲線圖，以此時間點當後續電腦斷層冠狀動脈檢查的延遲時間，並以T檢定統計分析。第一種及第二種注射方式的平均最高顯影濃度值分別爲155.30±33.81HU及104.82±30.98HU，第一種注射方式比第二種注射方式來得高，兩種差異爲50.48±2.83HU (P<0.001)。兩種注射方式得到的最高顯影濃度所對應的時間分別爲20.41±2.15秒及21.89±3.36，差異爲1.48±1.21秒(P<0.001)。顯影劑注射技術用來精準計算最高顯影濃度對應時間曲線並決定冠狀動脈電腦斷層檢查注射顯影劑的延遲時間。注射顯影劑後加以生理食鹽水灌注，較容易計算最高顯影濃度及所對應的時間，藉以提高影像品質。

To compare time delay in the test bolus technique for contrast bolus injection followed by saline flush versus contrast bolus injection alone at 16-detector row computed tomography (CT) coronary artery angiography. This study had institutional review board approval, and patients gave informed consent, Forty-four patients (mean age, 51.66�10.33 years; 19women) underwent 16-detector row CT coronary angiography. Patients were subjected to two angiographic test bolus procedures. For procedure 1, patients received a 20 ml test bolus of contrast material followed by a 20 ml saline flush. For procedure 2, patients received a 20 ml test bolus of contrast material only. After the test bolus scanning, region of interest (ROI) attenuation measurements were performed in the ascending aorta for both protocols Peak attenuation-time curves were created with the time to peak attenuation value as the delay rime for main angiographic bolus. Student t test was used to compare results. The average attenuation value was l55.30�33.81HU and 104.82�30.98HU for procedures 1 and 2, respectively. The vascular enhancement for procedure 1 was higher than for procedure 2. The difference between the two procedures was 50.48�2.83HU (P<0,001). The mean time to peak attenuation was 20.41�2.15 seconds and 21.89�3.36 seconds for procedures 1 and 2, respectively. The mean difference in time between procedures 1 and 2 was 1.48�1.21 sec (P<0.001). The Intra-class Correlation Coefficient (ICC) value was 0.997. The test bolus technique can be used to precisely calculate the peak attenuation-time curve and determine the delay time for the main angiographic bolus. The peak attenuation time is more easily calculated with test contrast bolus followed by saline flush versus contrast bolus alone. Saline flush also significantly reduces delay time. Theses results may help improve calculation of vascular enhancement and optimization of image quality with coronary artery angiography.