Assessment Of Coronary Artery Stent And Radiation Dose Using Dual Source CT

ObjectiveTo compare a prospective ECG-gated high-pitch spiral technique (Flash) and conventional retrospective ECG-gated spiral technique for the image quality of coronary artery stent and radiation dose with a dual source CT.MethodsOne hundred and fifty five coronary stents in one hundred and twenty patients (mean age 64.9±10.6 year-old, heart-rate<65bpm) were examined using a dual source CT. All patients were divided in two groups, receiving either Flash or conventional coronary artery CT angiography separately. After images of coronary artery were reconstructed using both the smooth (B26) and sharp (B46) kernel, the coronary stent image quality and stent lumen were scored by two observers individually using four point scale (1=excellent,4=invaluable). The effective radiation dose of volume CT dose index (CTDIvol, mGy) and dose length product (DLP, mGyxcm) were also calculated for each patient. x2-test analysis of image quality and t-test analysis of radiation dose were used respectively for statistical difference between two groups. ResultsInterobserver agreement for stent image quality was good (Kappa=0.764, P<0.001). The mean scores were 1.61±0.77 and 1.65±0.82 in Flash group and conventional group respectively. There was no significant difference in image quality between the two groups (x2=0.865, P=0.834). The effective radiation dose in Flash group was significantly lower than that in conventional group. The mean values of CTDIvol were 3.24±1.21 in Flash group and 31.26±10.79 in conventional group (t=19.83, P<0.001), and the mean values of DLP in Flash group and conventional group were 54.61±19.88 and 468.30±174.88 respectively (t=18.06, P<0.001).ConclusionsComparing with the conventional coronary artery CT angiography, the Flash technique of coronary artery CT angiography has a similar image quality for coronary stent, but at a lower radiation dose in patients with heart-rate lower than 65 beats per minute.