To demonstrate similar image quality with deep learning image reconstruction (DLIR) in reduced contrast medium (CM) and radiation dose (double-low-dose) head computed tomography (CT) angiography (CTA), in comparison with standard-dose and adaptive statistical iterative reconstruction-Veo (ASIR-V).

A prospective study was performed in 63 patients who under head CTA using 256-slice CT. Patients were randomized into either the standard-dose group (n = 38) with 40 ml of Iopromide (370 mgI ml−1 at 4.5 ml s−1); or a double-low-dose group (n = 25) with CM of 25 ml at 3.0 ml s−1. For image reconstruction, the double-low-dose group used DLIR-M and DLIR-H strength, and the standard-dose group used ASIR-V with 50% strength. The CT value and standard deviation (SD), SNR and CNR of posterior fossa, neck muscles, carotid, vertebral and middle cerebral arteries were measured. The image noise, vessel edge and structure blurring and overall image quality were assessed by using a 5-grade method.

The double-low-dose group reduced CM dose by 37.5% and CT dose index (CTDIvol) by 41% compared with the standard-dose group. DLIR further reduced the SD value of the middle cerebral artery and posterior fossa and provided better overall subjective image quality (p < 0.05).

DLIR significantly reduces image noise and provides higher overall image quality in the double-low-dose CTA.

Advance in knowledge: It is feasible to reduce CM dose by 37.5% and volume CTDI by 41% with the combination of 80kVp and DLIR in head CTA. Compared with ASIR-V, DLIR further reduces image noise and achieves better image quality with reduced contrast and radiation dose.