[en] Objective: To investigate the image quality and radiation dose of coronary computed tomography argiograply (CCTA) with wide-body detector CT in single cardiac cycle with different heart rate. Methods: A total of 821 patients with clinically suspected coronary artery lesions were performed CCTA examination continuously. They were divided into six groups:group A (< 65 bpm) with 132 cases, group B (66-75 bpm) with 244 cases, group C (76-85 bpm) with 145 cases, group D (86-95 bpm) with 101 cases, group E (96-105 bpm) with 101 cases and group F (106-135 bpm) with 98 cases. The CT values of the aorta root and the middle segment of LAD and RCA, the signal to noise ratios (SNRs), the contrast noise ratios (CNRs), the effective doses (E), the diagnostic rates and scores were compared among six groups of CCTA images. Results: There was no significant difference in objective quality between the six groups (P > 0.05). There was no significant difference in the diagnostic rates of LAD, LCX and RCA (all P > 0.05). However, there were significant differences in LAD, LCX and RCA with 4 points (excellent) among the six groups (x² = 27.614, 58.475, 39.571, P < 0.05). There were significant differences in radiation dose among the 6 groups (F = 37.32, P < 0.05). The radiation dose of group B was highest, and that of group D, group E and group F was the lowest. Conclusions The CCTA images with wide-body detector CT in single heart cycle with different heart rate can meet the clinical diagnostic requirements, but image quality declined with heart rate increasing. The higher heart rate groups (heart rate > 85 beats/min) had lower radiation doses. (authors)

[en] Objective: To evaluate effects on image quality and effective radiation with the dose reduction protocol adapted by body mass index (BMI) in coronary artery CT angiography with discovery 750 HD. Methods: Two hundred and seven patients suspected with coronary artery disease (CAD) were enrolled in Group A who were underwent CT angiography with routine radiation, and another 242 patients were enrolled in Group B who received a new scanning protocol with tube voltage and tube current modulation depending on the BMI. The scores of image quality, signal noise ratio(SNR), CT dose index (CTDI_vol), and effective dose (E) were compared and the correlation between the scanning parameters and E was analyzed. Results: The mean radiation dose in Group B(1.2, ranging from 0.8 to 2.5 mSv) was significantly lower than that in Group A(1.9, ranging from 1.5 to 2.3 mSv; Z = -6.24, P < 0.05). The multivariate regression analysis revealed that the first factor affecting effective radiation dose ranked as scanning mode, tube voltage, tube current, and scan length, respectively. The image quality between two groups was not significantly different. The SNR in Group B was greater than that in Group A (Z = -2.22, P < 0.05). Conclusions: Dose reduction protocol in coronary artery CT angiography with discovery 750 HD would help to reduce the radiation dose effectively without sacrificing image quality. (authors)