Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94143, USA.
Skeletal Radiol. 2013 Apr;42(4):499-510. doi: 10.1007/s00256-012-1550-y. Epub 2012 Dec 11.
Our goals were to quantify the reduction of the magic angle effect using short-tau inversion recovery (STIR) imaging and to determine the value of adding an axial STIR sequence to the magnetic resonance imaging ankle protocol.
Axial STIR sequences were used to measure normal tendon T1 and to estimate signal loss due to the inversion recovery preparation of our clinical protocol. In addition, 102 ankles were imaged with axial fat-suppressed intermediate-weighted fast spin echo and STIR sequences. Two radiologists analyzed the tendons for signal intensity, size, abnormalities, and magic angle effect. The diagnostic value and image quality of the two sequences were compared.
We calculated a 50% reduction of signal intensity in healthy tendons on the STIR sequence at TI = 170 ms compared with TI = 0 ms, explaining the decrease in the magic angle effect. Using the STIR sequence, our study demonstrated significantly lower signal intensity within the tendons, more precise tendon size, and a lower magic angle effect compared with the standard intermediate-weighted FSE sequence (p < 0.001). Diagnostic classification of tendon abnormalities using the STIR sequences showed higher sensitivity (82.35% vs. 75.27%) and better agreement with a reference standard than the intermediate-weighted sequences, and superior image quality (p < 0.01).
Axial STIR sequences reduce magic angle effects and improve visualization of ankle tendon pathology.
我们的目标是通过短回波时间反转恢复（STIR）成像量化魔角效应的减少，并确定在磁共振成像踝关节方案中添加轴向 STIR 序列的价值。
使用轴向 STIR 序列测量正常肌腱的 T1 值，并估计我们临床方案中反转恢复准备引起的信号丢失。此外，102 例踝关节使用轴向脂肪抑制中权重快速自旋回波和 STIR 序列进行成像。两位放射科医生分析肌腱的信号强度、大小、异常和魔角效应。比较了两种序列的诊断价值和图像质量。
我们计算出在 STIR 序列上 TI = 170 ms 时，健康肌腱的信号强度比 TI = 0 ms 时降低了 50%，这解释了魔角效应的降低。与标准中权重 FSE 序列相比，使用 STIR 序列，我们的研究显示肌腱内的信号强度显著降低，肌腱大小更精确，魔角效应更低（p < 0.001）。使用 STIR 序列对肌腱异常进行诊断分类显示出更高的敏感性（82.35%比 75.27%）和与参考标准更好的一致性，以及更好的图像质量（p < 0.01）。
轴向 STIR 序列可减少魔角效应，改善踝关节肌腱病变的可视化效果。
