This study investigated whether the combination of a high-concentration iodine contrast agent and a low-dose CT acquisition protocol could reduce radiation exposure during cerebral CT angiography (CTA) without compromising diagnostic image quality.
In this prospective randomized study, 150 patients undergoing cerebral CTA were assigned to one of three groups. All scans were performed at 80 kV and with the same total iodine load (21.6 g), but they differed in contrast agent concentration, iodine delivery rate (IDR), injection flow rate, and tube current-time product. Two groups underwent a low-dose protocol (80 kV / 90 mAs), whereas the reference group was scanned with an optimized standard protocol using 80 kV / 164 mAs.
Quantitative analysis demonstrated that increasing the IDR from 1.48 g/s to 2.0 g/s resulted in significantly higher vascular attenuation, while signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) remained comparable across all groups. Although image noise was slightly higher with the low-dose protocols, all examinations were considered diagnostically adequate, with no significant differences in subjective image quality scores.
Importantly, the low-dose protocols achieved approximately 46% radiation dose reduction compared with the standard-dose protocol, while maintaining equivalent image quality.
When a high-concentration contrast medium (iomeprol 400 mg I/mL) was used, the target IDR could be achieved with a lower injection flow rate than required with a lower-concentration agent, potentially improving patient comfort during administration.
According to the authors, these findings support the use of high-concentration iodine contrast media in combination with low-dose acquisition protocols as a practical strategy to substantially reduce radiation exposure in cerebral CTA while preserving diagnostic performance.