Medical University of Vienna, Department of Radiology, Vienna General Hospital, Waeringer Guertel 18-20, A-1090 Vienna, Austria.
Eur J Radiol. 2012 Aug;81(8):1846-50. doi: 10.1016/j.ejrad.2011.05.023. Epub 2011 Jun 12.
The purpose of this study was to compare 3T and 7T signal-to-noise and contrast-to noise ratios of clinical sequences for imaging of the ankles with optimized sequences and dedicated coils. Ten healthy volunteers were examined consecutively on both systems with three clinical sequences: (1) 3D gradient-echo, T(1)-weighted; (2) 2D fast spin-echo, PD-weighted; and (3) 2D spin-echo, T(1)-weighted. SNR was calculated for six regions: cartilage; bone; muscle; synovial fluid; Achilles tendon; and Kager's fat-pad. CNR was obtained for cartilage/bone, cartilage/fluid, cartilage/muscle, and muscle/fat-pad, and compared by a one-way ANOVA test for repeated measures. Mean SNR significantly increased at 7T compared to 3T for 3D GRE, and 2D TSE was 60.9% and 86.7%, respectively. In contrast, an average SNR decrease of almost 25% was observed in the 2D SE sequence. A CNR increase was observed in 2D TSE images, and in most 3D GRE images. There was a substantial benefit from ultra high-field MR imaging of ankles with routine clinical sequences at 7T compared to 3T. Higher SNR and CNR at ultra-high field MR scanners may be useful in clinical practice for ankle imaging. However, carefully optimized protocols and dedicated extremity coils are necessary to obtain optimal results.
本研究的目的是比较踝关节成像中优化序列和专用线圈在 3T 和 7T 下的信号噪声比（SNR）和对比噪声比（CNR）。10 名健康志愿者分别在两个系统上使用三种临床序列进行检查：（1）3D 梯度回波，T1 加权；（2）2D 快速自旋回波，PD 加权；（3）2D 自旋回波，T1 加权。在六个区域计算 SNR：软骨；骨；肌肉；滑液；跟腱；和 Kager 的脂肪垫。获得软骨/骨、软骨/液、软骨/肌肉和肌肉/脂肪垫的 CNR，并通过重复测量的单向方差分析进行比较。与 3T 相比，7T 下的 3D GRE 的平均 SNR 显著增加，分别为 60.9%和 86.7%。相比之下，2D SE 序列的平均 SNR 下降了近 25%。在 2D TSE 图像中观察到 CNR 增加，在大多数 3D GRE 图像中也观察到 CNR 增加。与 3T 相比，踝关节常规临床序列在 7T 下进行超高场磁共振成像具有明显优势。超高场磁共振扫描仪的 SNR 和 CNR 更高，可能在踝关节成像的临床实践中有用。然而，需要仔细优化的方案和专用的四肢线圈才能获得最佳结果。
