Feasibility analysis on reducing iodine delivery rate of coronary CT angiography with 100 kVp to 60% of 120 kVp standard

Abstract

Objective: To investigate the feasibility of reducing the iodine delivery rate (IDR) of coronary CT angiography(CCTA)with 100 kVp to 60% of 120 kVp standard. Methods: A total of 205 patients (105 males and 100 females, aged from 23 to 87 years) underwent CCTA due to suspected coronary artery disease in Department of Radiology of Peking University Third Hospital from February to July 2022 were enrolled. Those patients were divided into five subgroups according to their body weight: <50 kg, 50 to 59 kg, 60 to 69 kg, 70 to 79 kg and ≥ 80 kg, respectively. All the cases were scanned with 100 kVp tube voltage and combined with mixed iterative reconstruction technology KARL 3D. The IDR injection protocol was set to 60% of the 120 kVp IDR standard (10% lower than the guideline), and the IDR of each group was 0.9, 1.0, 1.1, 1.3 and 1.4 gI/s, respectively. The CT attenuations (CT value) and noise (SD value) of the aortic root, proximal left anterior descending branch and the distal segments of the right coronary artery, the signal-to-noise ratio (SNR) and contrast noise ratio (CNR) of proximal left anterior descending branch and the distal segments of the right coronary artery, the whole subjective image quality scores of the coronary artery, and effective dose (ED) of CCTA in the five groups were compared. The One-way ANOVA or Kruskal-walls test was used for statistical analysis. Results: There was no significant difference in CT attenuations and noise of aortic root, proximal left anterior descending and the distal segments of the right coronary artery, SNR and CNR of proximal left anterior descending branch and the distal segments of the right coronary artery, and subjective image quality scores among the five groups (all P>0.05). The difference of the dosage of contrast medium and ED among the five groups were statistically significant (all P<0.05). The dosage of contrast medium in the five groups were 30, 34, 38, 43 and 48 ml, and the ED in the five groups was 2.24 (1.88, 2.56), 2.62 (2.24, 3.17), 2.70 (2.48, 3.20), 4.13 (3.85, 4.40) and 4.44 (4.01, 5.02) mSv, respectively. Conclusion: It is feasible to reduce the IDR injection protocol of coronary CT angiography with 100 kVp to 60% of the standard injection protocol with 120 kVp, which is worthy of promotion.