Optimized Scanning Protocol for Triple Rule-Out CT Angiography with Contrast Media and Radiation Dose Reduction: A Retrospective Study

Abstract

Abstract Objective:To evaluate the feasibility of an optimized scanning protocol to reduce the volume of iodine contrast media (ICM), injection rate, and radiation dose in patients with acute chest pain (ACP) undergoing triple rule-out computed tomographic angiography (TRO-CTA). Methods: Patients with ACP undergoing TRO-CTA were randomly assigned to either group A (n=30) or group B (n=33). Patients in group A were imaged using the optimized scanning protocol with a scanning sequence of the pulmonary artery (PA), thoracic aorta (TA), and coronary arteries (CAs), ICM dosage of 55 mL, and injection rate of 4.5 mL/s. Patients in group B were imaged with a traditional triple scanning protocol with a sequence of the PA, CAs, and TA, ICM dosage of 75 mL, and injection rate of 5.0 mL/s. Both groups were scanned using a tube voltage of 100 kVp. The image quality (subjective and objective) and effective radiation dose were compared between the two groups. Results: There were no significant differences in age, height, weight, body mass index, heart rate, sex, or clinical history between the two groups. Other than the left PA, RA, and RV, there were no significant differences in the CT attenuation values of relevant vascular structures including the pulmonary trunk, right PA, aortic root, aortic arch, descending aorta, left anterior descending artery, left circumflex branch, right coronary artery, or erector spinae muscle between groups A and B. In addition, there were no significant differences in contrast to-noise ratio (CNR) values between the two groups for most vessel segments, with the exception of the distal left anterior descending artery and left circumflex branch. The image quality scores were comparable between groups A and B for all vessel segments except the CAs. However, there were significant differences between the two groups in total ICM (55 vs. 75 mL, respectively, p < 0.05), scanning time (14.33 ± 0.09 vs. 21.89 ± 3.02 s, respectively, p < 0.001) and effective radiation dose (ED) (6.74 ± 0.73 vs. 7.61 ± 1.90 mSv, respectively, p = 0. 023). Conclusions: The optimized TRO-CTA scanning protocol achieved a "double low" mode, while maintaining image quality with less ICM and lower radiation dose for all examinations.