Effects of iterative metal artifact reduction techniques on diagnostic performance in patients with dental artifacts on carotid computed tomography angiography.

Background: Metal artifacts (MAs) induced by dental prostheses in carotid computed tomography angiography (CTA) significantly impair diagnostic accuracy. This study aimed to assess the efficacy of the iterative metal artifact reduction (iMAR) technique in mitigating these artifacts.

Methods: Eighty-one patients with suspected vascular disorders and dental prostheses who underwent CTA imaging were retrospectively included. The CTA images were reconstructed with and without iMAR (iMAR-CTA and non-iMAR-CTA) for evaluation. Additionally, 81 matched patients without dental prostheses who underwent CTA imaging (standard CTA) served as a reference group for objective image quality assessment. Objective image quality involving signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and artifact index (AI) were analyzed. Subjective image quality was evaluated using a five-point Likert scale. Diagnostic performance was assessed by examining luminal stenosis, calcification, and aneurysm, with digital subtraction angiography (DSA) as the reference standard. Intramodality and inter-radiologist agreements were calculated using the intraclass correlation coefficient (ICC).

Results: Image quality score was significantly higher for iMAR-CTA images than non-iMAR-CTA images [radiologist 1, 5 (5-5) 3 (2-3); radiologist 2, 5 (4-5) 3 (3-3); radiologist 3, 5 (5-5) 2 (2-3), all P<0.001]. There was no significant difference in scores between iMAR-CTA and normal CTA. In the objective analysis, iMAR-CTA exhibited higher SNR and CNR and lower AI compared to non-iMAR-CTA (P<0.001). Furthermore, the objective image quality of iMAR-CTA was comparable to that of standard CTA, with no statistically significant differences in SNR (P=0.324) or CNR (P=0.109). For diagnostic performance evaluation, iMAR-CTA exhibited good to excellent agreement with DSA for luminal stenosis and aneurysm (ICC, 0.859-0.946), exceeding the moderate to good agreement of non-iMAR-CTA (ICC, 0.583-0.777). Regarding luminal stenosis severity, iMAR-CTA had higher accuracy rates (90.63-93.75%; 58/64-60/64) than non-iMAR-CTA (57.81-65.63%; 37/64-42/64). In aneurysm detection, iMAR-CTA achieved higher accuracy rates (77.78-88.89%; 7/9-8/9) than non-iMAR-CTA (44.44-66.67%; 4/9-6/9). For luminal stenosis severity and calcification, iMAR-CTA demonstrated excellent agreement (ICC, 0.908-0.910), whereas non-iMAR-CTA exhibited moderate agreement (ICC, 0.694-0.747).

Conclusions: iMAR effectively reduces MAs, achieving image quality comparable to standard CTA without artifacts, facilitating a more reliable evaluation of carotid artery disorders in patients with dental prostheses.