Using the Test Bolus Technique with Saline Flush to Improve Image Quality in 16-Detector Row CT Coronary Artery Angiography

Abstract

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.