Background: Despite the improvement of cardiac CT, right heart visualization remains challenging. Objective: We herein describe a new method, called the time-adjusted gradual replacement injection protocol. The aim of this study was to compare this protocol with the split-bolus injection protocol. Methods: Fifty-two patients who had undergone dual-source cardiac CT were retrospectively recruited. Twenty-six patients were injected by using the split-bolus injection protocol, and 26 patients were injected by using the time-adjusted gradual replacement injection protocol. For this method, we injected contrast medium for 10seconds at a flow rate of 0.07× body weight mL/s, then gradually replaced the contrast material with saline until 2 seconds before finishing the scans. The CT attenuation was measured in 4 chambers, the aorta, and the coronary arteries. The visualization of the anatomic structures and the occurrence and severity of streak artifacts were scored for the cardiac structures in the heart. For the analyses, either Welch t-test or Student t-test was performed. Results: In the right heart, the CT values and visualization scores were significantly higher in the time-adjusted replacement injection group than in the split-bolus injection group, whereas the artifact scores were comparable between the 2 groups. The CT values, visualization scores, and artifact scores of the left heart were not significantly different between the 2 groups. Conclusions: In this study, the time-adjusted gradual replacement injection protocol provided excellent attenuation for visualization of the right heart. This method may help toaccurately evaluate the right cardiac anatomy and thereby identify any potential diseases.
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