Objective To explore the image quality and diagnostic efficiency of coronary CTA (CCTA) in patients without heart rate (HR) control by optimizing acquisition phase with auto-ECG-gating technology using 256-row wide-volume detector.Methods Totally 200 patients with suspected coronary artery disease (CAD) were selected and underwent CCTA with auto-ECG-gating on a 256 row wide detector CT (Revolution CT).Patients were divided into 4 groups according to the real-time HR,group A (n=50):HR≤69 bpm;group B (n=50):HR 70-80 bpm;group C (n=50):HR 81-90 bpm;group D:HR≥91 bpm (n=50).CCTA images quality and diagnostic rate were assessed by two experienced radiologists blindly,and effective radiation dose were compared among 4 groups.Results There were no significant differences of age,sex,and body mass index among 4 groups (all P＞0.05),and there was significant difference of image quality score among 4 groups (P＜0.05).Totally,800 coronary arteries and 2 575 segments in 200 patients were assessed.There had no significant difference of diagnostic rate among four groups derived from the segment,coronary artery and patients (all P＞0.05).The effective radiation dose in A D groups were (1.05t0.48)mSv,(2.41± 1.20)mSv,(1.27±0.55) mSv,(2.66±1.12)mSv,and the difference was significant (F=29.22,P＜0.001).Conclusion It is feasible to perform CCTA in single cardiac cycle in patients with arbitrary heart rate by auto-ECG-gating using Revolution CT equipped widevolume detector.And it can improve image quality and success ratio in patients with moderate and high heart rate.

Objective To access the effects of 70 kV tube voltage combined with low dose and low concentration of contrast medium in coronary CT angiography (CCTA)by evaluating the image quality,radiation dose and contrast medium dosage.Methods Ninety patients suspected with coronary artery disease with body mass index(BMI)of less than 25 kg/m2and heart rate (HR)of less than 75 beats per minute were enrolled.The patients were randomly divided into three groups (n=30 for each group):Group A,100 kV of tube voltage with 370 mg I/mL iopromide,1 mL/kg;Group B,80 kV with 270 mg I/mL iodixanol,1 mL/kg;Group C,70 kV with 270 mg I/mL iodixanol,0.8 mL/kg.All the patients underwent CCTA with a 256 row wide-coverage volumetric CT.Automatic tube current modulation technique was applied.The images were reconstructed by adaptive statistical iterative reconstruction V (ASIR-V).The subjective image quality scores were compared with rank-sum test.The signal-to-noise ratio (SNR),contrast-to-noise ratio(CNR),effective dose(ED)and the total iodine intake were calculated and compared with one-way ANOVA.Results No statistically differences in age,gender,heart rate and BMI were observed among the three groups (P>0.05).Subjective image quality scores had no difference among the three groups (P>0.05).The CT values of group C were higher than those of group A(P<0.05).The image noise of group C was higher than that of group A and group B (P<0.05).No significant differences in SNR and CNR were noticed among the three groups (P>0.05).The ED of group B (0.39±0.08)mSv and group C (0.19±0.01)mSv were lower than that of group A (0.81±0.19)mSv (each P<0.05).Compared with group A,the decrease rates of ED of group B and C were 51.8% and 76.5% respectively.Compared with group A and group B,the total iodine intake of group C was decreased by 25% and 21.4% (P<0.05).Conclusion 70 kV of tube voltage combined with low dose and low concentration of contrast medium in CCTA can reduce the radiation dose and iodine intake without compromising image quality.