Sct 211

CTA examinations were performed on a 256-slice CT (Brilliance iCT; Philips, Amsterdam, Netherlands) and a power injector (SCT-211; Medrad Inc., Indianola, PA, USA). The scan protocols were as follows: detector width, 80 mm; detector collimation, 128 × 0.625 mm; slice acquisition, 128 × 0.625 mm using a z-flying focal spot; gantry rotation time, 0.27 s. Tube voltage and current were set at 300–500 mAs per rotation and 120–140 kVp, respectively. The contrast material (Ultravist Solution 370 mg I/mL; Bayer Healthcare, Berlin, Germany) was intravenously injected through an antecubital vein using a 20-gauge needle connected to a power injector (SCT-211; Medrad Inc., Indianola, PA, USA). Contrast material injection timing was controlled by the bolus-tracking technique in the ascending aorta (signal attenuation threshold 100–120 Hounsfield units [HU]). Data acquisition was initiated with a mean delay of 6 s after reaching the threshold in the ascending aorta. A total amount of 60–80 mL of contrast material was injected at 5 mL/s followed by 30 mL of saline chaser. The mean effective radiation dose of the coronary CTA was 1.58 ± 0.36 mSv.

All studies were performed on a Toshiba 320-row MSCT scanner (Aquilion one TSX-301A, Tokyo, Japan) with respiratory and electrocardiogram gating. Imaging parameters were as follows: tube voltage 120 kV, tube current 350–450 mA, slice thickness 0.5 mm, interlayer spacing 0.5 mm, and spin time 350 ms. The patient was connected to a binocular high-pressure injector (SCT 211, Medrad Inc. USA). The scan was set from the upper margin of the aortic arch to the diaphragmatic surface. A 20 mL of the contrast agent was injected at a rate of 3–5 mL/s (Omnipaque 350 mg/mL, GE Healthcare Inc., Marlborough, MA, USA), followed by 15 mL of saline at the same rate. An intelligent bolus tracking technique was used to trigger the scanning when the CT value of the descending aorta reached 200–220 HU. The patients hold their breath for 4–7 s, and further 40–60 mL contrast agent was infused intravenously at a flow rate of 3–5 mL/s, followed by 15 mL of saline at the same rate.