Department of Radiology, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008 Zurich, Switzerland.
Radiology. 2012 Oct;265(1):204-14. doi: 10.1148/radiol.12112408. Epub 2012 Aug 24.
To compare the new "warp" sequence (slice-encoding metal artifact correction [SEMAC], view-angle tilting [VAT], and increased bandwidth) for the reduction of both through-plane and in-plane magnetic resonance (MR) artifacts with current optimized MR sequences in patients with total hip arthroplasty (THA).
The institutional review board issued a waiver for this study. Forty patients with THA were prospectively included. SEMAC, VAT, and increased bandwidth were applied by using the warp turbo-spin-echo sequence at 1.5 T. Coronal short tau inversion-recovery (STIR)-warp and transverse T1-weighted warp (hereafter, T1-warp) images, as well as standard coronal STIR and transverse T1-weighted sequence images optimized with high bandwidth (STIR-hiBW and T1-hiBW), were acquired. Fifteen additional patients were examined to compare the T1-warp and T1-hiBW sequence with an identical matrix size. Signal void was quantified. Qualitative criteria (distinction of anatomic structures, blurring, and noise) were assessed on a five-point scale (1, no artifacts; 5, not visible due to severe artifacts) by two readers. Abnormal imaging findings were recorded. Quantitative data were analyzed with a t test and qualitative data with a Wilcoxon signed rank test.
Signal void around the acetabular component was smaller for STIR-warp than STIR-hiBW images (21.6 cm2 vs 42.4 cm2; P=.0001), and for T1-warp than T1-hiBW images (17.6 cm2 vs 20.2 cm2; P=.0001). Anatomic distinction was better on STIR-warp compared with STIR-hiBW images (1.9-2.8 vs 3.6-4.6; P=.0001), and on T1-warp compared with T1-hiBW images (1.3-2.8 vs 1.8-3.2; P<.002). Distortion, blurring, and noise were lower with warp sequences than with the standard sequences (P=.0001). Almost half of the abnormal imaging findings were missed on STIR-hiBW compared with STIR-warp images (55 vs 105 findings; P=.0001), while T1-hiBW was similar to T1-warp imaging (50 vs 55 findings; P=.06).
STIR-warp and T1-warp sequences were significantly better according to quantitative and qualitative image criteria, but a clinically relevant artifact reduction was only present for STIR images.
比较新的“扭曲”序列（切片编码金属伪影校正[SEMAC]、视角倾斜[VAT]和增加带宽）在减少全髋关节置换术（THA）患者的平面内和平面外磁共振（MR）伪影方面的效果，与当前优化的 MR 序列进行比较。
本研究经机构审查委员会豁免。前瞻性纳入 40 例 THA 患者。在 1.5 T 场强下，使用扭曲涡轮自旋回波序列应用 SEMAC、VAT 和增加带宽。获得冠状短反转时间（STIR）-扭曲和横断 T1 加权扭曲（以下简称 T1-扭曲）图像，以及优化高带宽的标准冠状 STIR 和横断 T1 加权序列图像（STIR-hiBW 和 T1-hiBW）。另外 15 例患者用于比较 T1-扭曲和 T1-hiBW 序列与相同矩阵大小的图像。量化信号缺失。两位读者采用五分制（1，无伪影；5，严重伪影导致无法观察）对解剖结构区分、模糊和噪声等定性标准进行评估。记录异常影像学发现。定量数据采用 t 检验进行分析，定性数据采用 Wilcoxon 符号秩检验进行分析。
髋臼组件周围的信号缺失在 STIR-warp 图像中小于 STIR-hiBW 图像（21.6 cm2 比 42.4 cm2；P=.0001），在 T1-warp 图像中小于 T1-hiBW 图像（17.6 cm2 比 20.2 cm2；P=.0001）。STIR-warp 图像与 STIR-hiBW 图像相比，解剖结构的区分更好（1.9-2.8 比 3.6-4.6；P=.0001），T1-warp 图像与 T1-hiBW 图像相比也更好（1.3-2.8 比 1.8-3.2；P<.002）。扭曲序列的失真、模糊和噪声低于标准序列（P=.0001）。与 STIR-warp 图像相比，STIR-hiBW 图像漏诊了近一半的异常影像学发现（55 个比 105 个发现；P=.0001），而 T1-hiBW 与 T1-warp 成像相似（50 个比 55 个发现；P=.06）。
根据定量和定性图像标准，STIR-warp 和 T1-warp 序列明显更好，但仅 STIR 图像的伪影减少具有临床相关性。
