Individually adapted tube current selection and contrast medium injection protocol of coronary CT angiography based on test bolus parameters: a feasibility study

Background: Test bolus is mostly used to determine the starting point of a full cardiac scanning with respect to injection of a larger bolus of contrast material. So far there are limited data demonstrating the feasibility of using information obtained from a test bolus to adjust contrast delivery protocols and tube current individually during coronary computed tomography angiography (CCTA).

Purpose: To evaluate the feasibility of individually adapted tube current selection and contrast injection protocols of CCTA based on test bolus parameters.

Material and methods: Test bolus followed by CCTA was performed in 93 patients at 100 kV and in 81 patients at 120 kV, respectively. Simulated attenuation of the descending aorta (SimDA) of CCTA was calculated at a fixed contrast injection rate of 4 mL/s. Univariate and multivariate comparisons were performed to identify associations of SimDA and image noise of CCTA (NoiseCCTA) with test bolus information and patient-related factors including body weight (BW), body mass index (BMI), and body surface area (BSA).

Results: Compared with BW, BMI, and BSA, SimDA was more closely related to the peak time of left ventricle and peak enhancement of right ventricle obtained from test bolus (r = 0.495 and r = 0.642 for 100 and 120 kV protocol, respectively). Similarly, NoiseTB was much more closely related to NoiseCCTA (r = 0.740 and r = 0.630 for 100 and 120 kV protocol, respectively) when compared with BW, BMI, and BSA.

Conclusion: It is feasible to individually adapt tube current and contrast injection protocol of CCTA based on the information of test bolus.