Coronary computed tomography angiography using the diluted contrast material protocol: a technique for achieving uniform coronary artery enhancement

PURPOSE: A diluted contrast material (CM) protocol is used to achieve consistent coronary artery enhancement. In this study, we aimed to evaluate the feasibility of the diluted CM protocol compared with the fractional dose (FD) protocol for coronary computed tomography angiography (CCTA) performed at a low tube voltage (100 kVp). MATERIALS AND METHODS: We analyzed 103 patients (mean age, 68 ± 14 years; 54 males) who underwent CCTA between July 2022 and September 2024. A total of 50 and 53 patients underwent the diluted CM and the FD protocols, respectively. The diluted CM protocol involves individualized contrast dilution based on a simulated time-attenuation curve to attain a target arterial attenuation of 450 Hounsfield units (HU). In the FD protocol, contrast material volume and injection rate were determined using the patient's body weight. The aortic and coronary attenuation values were measured and compared. Subsequently, the variability in enhancement and iodine dose per body weight was analyzed. RESULTS: The mean coronary artery attenuation across all coronary segments was significantly higher in the diluted CM protocol group than the FD protocol group (424.0 ± 26.0 HU vs. 393.0 ± 59.4 HU, P < 0.001). The diluted CM protocol demonstrated significantly lower variability in contrast enhancement across all coronary segments. CONCLUSION: The diluted CM protocol resulted in more consistent coronary enhancements compared with the FD protocol during CCTA performed at a tube voltage of 100 kVp. This suggests its potential value in optimizing image quality.