Feasibility of low-dose carotid CT angiography (CTA) for quantitative carotid plaque evaluation

To evaluate the feasibility and accuracy of low-dose carotid CT angiography (CTA) for quantitative assessment of carotid plaque characteristics.

In this prospective study, patients with carotid atherosclerosis underwent both low- and conventional-dose carotid CTA on the same day. Each patient received one of three low-dose protocols-80 kVp/40 mL (subgroup A), 60 kVp/40 mL (B), or 60 kVp/20 mL (C)-along with the conventional protocol (100 kVp/40 mL) as the reference standard. Quantitative plaque analysis was performed using automated software, including total plaque volume, volume of each plaque component (calcification, fiber, fibrolipid, and lipid), and stenosis-related measurements. Radiation dose metrics, including CTDI_vol, dose-length product (DLP), and effective dose (ED), were recorded and compared. Intra-individual comparisons were conducted between low-dose and conventional-dose scans.

A total of 154 plaques (from 67 patients) were analyzed. Compared with conventional-dose CTA, low-dose protocols significantly reduced radiation exposure (ED: 0.33 ± 0.15 mSv vs. 0.98 ± 0.10 mSv, p < 0.001), corresponding to a reduction of approximately 66 %. No significant differences were observed between low-dose and conventional-dose CTA in total plaque volume, plaque component volumes, diameter stenosis, or maximal area stenosis (all p > 0.05). Subgroup analysis demonstrated that quantitative plaque measurements remained stable across subgroups A, B, and C compared with the conventional-dose group (all p > 0.05). Across different plaque types (calcified, mixed, and non-calcified), quantitative assessment of plaque components remained consistent between low-dose and conventional-dose CTA.

Low-dose CTA using 60 kVp enables substantial radiation dose reduction while preserving reliable quantitative assessment of carotid plaque characteristics.