MR Metal Artifact Reduction In Patients With Anterior Cruciate Ligament Reconstruction

Objective:To compare the image quality of oblique sagittal MAVRIC-SL inversion recovery(inversion recovery IR)sequence with conventional oblique sagittal T2WI fat suppression(fat saturation FS)sequence and PDWI sequence the postoperative review of patients with metal-fixed anterior cruciate ligament reconstruction(ACLR)at 3.0T MR.The possibility of MAVRIC-SL IR sequence in assisting diagnosis was also discussed.Materials and Methods:Twenty-seven patients(left knee:14 cases;right knee:13 cases)with metal fixtures in ACLR were recruited.The FSE sequences(T2WI FS and PDWI)and the MAVRIC-SL IR were performed at 3.0T MRI and scan time was recorded.Select the maximum artifact slice,draw the region of interest(ROI),then record the implant and artifact area;record the number of artifact-influence slices;draw the ROI,calculate the image signal-to-noise ratio(SNR).Four experienced radiologists rated the degree of image artifacts,measurability,and the degree of artifacts within the scan range except for the implant.Friedman M test and pairwise comparison were used to compare and analyze the quantitative and qualitative data.The intraclass correlation coefficient(ICC)was used to evaluate the score consistency.Results:The MAVRIC-SL IR significantly reduced the metal implant artifacts(249.60±29.03mm~2 on MAVRIC-SL;1350.06±152.82mm~2 on T2WI FS;491.40±67.60mm~2 on PDWI;p<0.01)and the number of slices the artifacts affect(7(6,7)on MAVRIC-SL;14(13,15)on T2WI FS;11(11,12)on PDWI;p<0.01).Moreover,the image signal-to-noise ratio(SNR)was improved(179.8(76.26,222.34)dB on MAVRIC-SL;52.39(34.49,75.38)dB on T2WI FS;101.92(69.57,171.38)dB on PDWI;p<0.05).In terms of image scores,the MAVRIC-SL artifact score significantly decreased,while the measurability score of the adjacent structure increased,and the observation of the structures affected by other metal artifacts in the imaging range was optimal.The difference was statistically significant(p<0.05).The consistency of score was excellent(ICC?0.75).The difference was statistically significant(p<0.05).In terms of imaging time,the acquisition time of MAVRIC-SL is 6'04'',which is longer than that of 1'53''of T2WI FS and 0'57''of PDWI.Conclusion:Although the scanning time was relatively prolonged,the MAVRIC-SL significantly reduced the metal artifacts and provided more information in the postoperative MRI review of the patients with metal-fixed ACLR.Therefore,when necessary,o-sag MAVRIC-SL IR sequence can be used for assisting the diagnosis of conventional o-sag T2WI FS sequence and PDWI sequence.