Low-dose tin-filtered computed tomography (CT) with iterative metal artifact reduction algorithm versus dual-energy CT for patients with lumbar metal implants.

Purpose: This study aimed to evaluate a low-dose tin-filtered (LD Sn) CT protocol with iterative metal artifact reduction (iMAR) to reduce metal artifacts and radiation dose compared to dual-energy CT (DECT) with iMAR in patients with lumbar metal implants.

Methods: The study included 70 patients, comprising 35 patients in the prospective LD Sn CT cohort and 35 matched patients in the retrospective DECT cohort, utilizing a hybrid design. Evaluations included DECT Mixed images, noise-optimized virtual monoenergetic imaging at 130 keV (DE Mono+), and LD Sn CT with and without iMAR. Objective assessments included the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM). A 5-point scoring system was used for subjective evaluations of image quality, including overall image quality, soft tissue visualization, bone architecture, and the degree of metal artifacts. Radiation dose metrics, including CT dose index (CTDIvol), dose length product (DLP), and effective dose (ED), were recorded.

Results: The LD Sn CT protocol achieved a 26 % lower effective dose than the DECT protocol (7.34 ± 1.45 mSv vs. 9.93 ± 2.00 mSv, P < 0.05). No significant differences were observed in SNR, CNR, or FOM between LD Sn and DE Mono+ (P = 0.238-0.310). Subjective assessments, including overall image quality, soft tissue visualization, bone architecture, and the degree of metal artifact, showed slight differences without statistical significance. LD Sn iMAR scores ranged from 2.00 to 2.11, while DE Mono+ iMAR scores ranged from 1.83 to 2.00 (P = 0.120-0.763).

Conclusions: The LD Sn iMAR protocol achieved the optimal balance between image quality and radiation dose. It is recommended for routine follow-up in patients with lumbar implants.