MR metal artifact reduction in patients with anterior cruciate ligament reconstruction: comparison of MAVRIC-SL with conventional FSE sequences / 中华放射学杂志

ABSTRACT

Objective:To explore the value of metal artifact reduction in oblique sagittal multi-acquisition with variable resonance image combination slab selectivity (MAVRIC-SL) inversion recovery (IR) sequence compared with conventional fast spin-echo (FSE) fat saturation (FS)-T 2WI and proton density weighted imaging (PDWI) on the postoperative review of patients with metal-fixed anterior cruciate ligament reconstruction (ACLR) at 3.0 T MR. Methods:From June to November 2018, 27 patients with metal fixtures in ACLR were prospectively recruited in the First Hospital of China Medical University. The FSE sequences (FS-T 2WI and PDWI) and the MAVRIC-SL IR were performed at 3.0 T MRI system. The maximum artifact slice was selected and ROI was drawn, then the implant and artifact area and the number of artifact-influence slices were recorded. Image signal-to-noise ratio (SNR) was calculated. The degree of image artifacts (artifact degree of spiked ligament staple and its influence on the diagnosis of surrounding structures), measurability (measurability of distance between the upper edge of the staple and the lower edge of the graft entrance on tibia), and other degree of artifacts (whether there were metal artifacts other than implants that affect the observation of other structures within the scanning range) were scored. The Friedman M test and pairwise comparison were used to compare and analyze the quantitative and qualitative data. Results:The differences in artifact area, the number of artifact-influence slices and SNR among FS-T 2WI, PDWI and MAVRIC-SL IR images were statistically significant (all P<0.001). Pairwise comparison analysis suggested that the metal implant artifact area and the number of artifact-influence slices in the MAVRIC-SL IR image were smaller, and the SNR was higher than those of FS-T 2WI and PDWI (all P<0.05 after correction). The differences of the three scores among FS-T 2WI, PDWI and MAVRIC-SL IR were statistically significant (all P<0.001). Pairwise comparison analysis suggested that the degree of image artifacts score of MAVRIC-SL IR sequence was lower, and the measurability and other degree of artifacts scores were higher than FS-T 2WI and PDWI (all P<0.05 after correction). Conclusion:MAVRIC-SL can significantly reduce the metal artifacts and improve image quality in the postoperative MRI review of the patients with metal-fixed ACLR. Therefore, oblique sagittal MAVRIC-SL IR sequence can be used for assisting the diagnosis of conventional FS-T 2WI and PDWI.