Achieving lower radiation dose of cerebral computed tomography angiography: The role of high-concentration contrast medium

OBJECTIVES: To investigate whether high-concentration iodine contrast medium (HICM) combined with low-dose radiation scanning protocols can further reduce the radiation dose of cerebral computed tomography angiography (CTA) scans without compromising image quality. MATERIALS AND METHODS: The prospective study included 150 eligible patients who underwent cranial CTA examinations. The patients were randomly divided into three groups (A, B, and C). All patients received a total iodine dose of 21.6 g and underwent scanning at tube voltage of 80 kV. Each group included 50 patients. Different protocols were applied as below. Group A: Iomeprol 400, iodine delivery rate (IDR) 2.0 g/s, tube current-time product (TCTP) 90 mAs; Group B: Iopromide 370, IDR 1.48 g/s, TCTP 164 mAs; Group C: Iopromide 370, IDR 2.0 g/s, TCTP 90 mAs. Radiation doses (Computer Tomography Dose Index Volume, Dose-Length Product, Effective Dose) were recorded, and CT attenuation values, image noise, Signal-to-Noise Ratio (SNR), and Contrast-to-Noise Ratio (CNR) were measured. RESULTS: There were no statistically significant differences in the SNR and CNR of intracranial vessels among groups A, B, and C. Group A and C showed higher CT attenuation values and image noise, but lower radiation dose (reduced by 46.53% and 45.62% compared with Group B). The injection flow rate was lower in Group A. CONCLUSION: A higher IDR is effective in reducing radiation dose. Moreover, higher iodine concentration (iomeprol 400) enables a lower injection flow rate to achieve a target IDR. A 46% reduction in radiation dose can be achieved using iomeprol 400 combined with a low-dose protocol, without compromising image quality, at an optimized injection flow rate.