MR去金属伪影序列在前交叉韧带重建手术中的应用:MAVRIC-SL与常规FSE序列比较

MR metal artifact reduction in patients with anterior cruciate ligament reconstruction:comparison of MAVRIC-SL with conventional FSE sequences

目的与常规快速自旋回波(FSE)序列脂肪抑制(FS)-T2WI和质子密度加权像(PDWI)比较,探讨多采集可变共振成像组合-层面选择技术(MAVRIC-SL)反转恢复(IR)序列图像在膝关节前交叉韧带重建术(ACLR)中植入金属固定物的患者术后复查中减少金属伪影的价值。方法前瞻性纳入2018年6至11月中国医科大学附属第一医院27例行ACLR金属内固定的患者。术后进行常规FSE序列FS-T2WI、PDWI和MAVRIC-SL IR序列扫描。选取伪影最大层面,勾画ROI,记录植入物的伪影面积,记录伪影影响层数,计算图像信噪比(SNR)。同时对图像的伪影程度(门型钉伪影程度及其对周围结构诊断的影响)、可测量性(门型钉上缘与移植物胫骨入口下缘距离的可测量性)及其他伪影程度(扫描范围内,除门型钉外是否存在影响结构观察的其他金属伪影)进行评分。采用Friedman M检验比较定量数据和主观评分的差异。结果FS-T2WI、PDWI和MAVRIC-SL IR序列图像间伪影面积、伪影层数和SNR的差异均有统计学意义(P均<0.001)。成对比较结果显示MAVRIC-SL IR图像的金属植入物伪影面积和层数均小于、SNR高于FS-T2WI和PDWI(校正后P均<0.05)。FS-T2WI、PDWI和MAVRIC-SL IR序列图像间3项内容评分差异均有统计学意义(P均<0.001)。成对比较结果显示MAVRIC-SL IR序列的伪影程度评分低于、可测量性和其他伪影程度评分高于FS-T2WI和PDWI(校正后P均<0.05)。结论在有金属植入物的ACLR患者术后MRI中,MAVRIC-SL IR序列可有效减少金属伪影,提高图像质量,可辅助常规FSE序列FS-T2WI和PDWI进行诊断。

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)-T2WI 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-T2WI 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-T2WI,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-T2WI and PDWI(all P<0.05 after correction).The differences of the three scores among FS-T2WI,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-T2WI 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-T2WI and PDWI.