Takahashi Tsuneari, Takeshita Katsushi
Department of Orthopaedic Surgery, Ishibashi General Hospital, Shimotsuke, JPN.
Department of Orthopaedics, Jichi Medical University, Shimotsuke, JPN.
Cureus. 2023 Oct 1;15(10):e46338. doi: 10.7759/cureus.46338. eCollection 2023 Oct.
Background There are no studies of the efficacy of slice encoding for metal artifact correction (SEMAC) magnetic resonance imaging (MRI) at 3T for patients following unicompartmental knee arthroplasty (UKA), although the artifact is expected to increase compared with 1.5T. Purpose To clarify whether SEMAC MRI can better visualize UKA components and improve measurement accuracy at 3T MRI. Materials and methods The phantom consisted of femoral and tibial standard UKA components embedded in agarose gel. The MR images were scanned on a 3T MR system including proton density (PD) MR images. Six orthopedic surgeons blinded to the size and details of the components independently scored the diagnostic value for measurement and measured the lengths of the femoral posterior condyle, femoral peg, anterior-posterior (AP) tibial component, medial-lateral (ML) tibial component, and tibial keel, with and without SEMAC. Visualization scores were stratified as 0 = definitely nondiagnostic, 1 = probably nondiagnostic, 2 = possibly diagnostic, 3 = probably diagnostic, and 4 = definitely diagnostic. In addition, the differences between actual length and 95% confidence intervals of five measurement points were analyzed. Results The diagnostic values of the posterior condyle (2.0; 1.5 vs. 0; 0) and femoral peg (1.5; 1.0 vs. 0; 0) were significantly better in SEMAC-PD MRI than in non-SEMAC-PD MRI (P<0.05). On the other hand, there were no significant differences in the visualizations of AP, ML, and keel of the tibial components. Measurements of the femoral posterior condyle and tibial keel approached the actual length, but were not involved within the 95% confidence interval (actual length, 19.4 mm vs. 95% CI, 15.7-19.1 mm). Conclusion A significant reduction of metal artifacts was observed only around the femoral component in SEMAC-PD MRI. Despite artifact reduction, this sequence did not result in better visualization for measurement.
尽管预计单髁膝关节置换术（UKA）患者在3T场强下金属伪影比1.5T场强时更多，但尚无关于3T场强下用于金属伪影校正的容积内插体部检查（SEMAC）磁共振成像（MRI）疗效的研究。目的：明确SEMAC MRI在3T MRI时能否更好地显示UKA假体组件并提高测量准确性。材料与方法：模型由嵌入琼脂糖凝胶中的股骨和胫骨标准UKA假体组件组成。在3T MR系统上扫描MR图像，包括质子密度（PD）MR图像。6名对假体组件大小和细节不知情的骨科医生独立对测量的诊断价值进行评分，并测量股骨后髁、股骨柄、胫骨组件前后径（AP）、内外径（ML）和胫骨嵴的长度，测量时有无SEMAC。可视化评分分为：0 = 肯定无法诊断，1 = 可能无法诊断，2 = 可能可诊断，3 = 可能可诊断，4 = 肯定可诊断。此外，分析了5个测量点的实际长度与95%置信区间之间的差异。结果：SEMAC-PD MRI对后髁（2.0；1.5对0；0）和股骨柄（1.5；1.0对0；0）的诊断价值明显优于非SEMAC-PD MRI（P<0.05）。另一方面，胫骨组件的AP、ML和嵴的可视化无显著差异。股骨后髁和胫骨嵴的测量接近实际长度，但不在95%置信区间内（实际长度，19.4 mm对95% CI，15.7 - 19.1 mm）。结论：在SEMAC-PD MRI中，仅在股骨组件周围观察到金属伪影显著减少。尽管伪影减少，但该序列并未使测量的可视化效果更好。
