Trattnig S, Breitenseher M, Kontaxis G, Helbich T, Rand T, Imhof H
Department of Radiology, University of Vienna, Austria.
Acta Radiol. 1997 Sep;38(5):880-4. doi: 10.1080/02841859709172429.
Ultra-fast gradient and spin-echo (GRASE) imaging is a hybrid of turbo spin-echo (TSE) and echo-planar imaging (EPI). One scan consists of several spin echoes (SEs) (turbo factor, TF), each of which consists of a number of gradient echoes (EPI factor, EF). The aim of our study was to evaluate different combinations of TF and EF in GRASE imaging and to test its usefulness in musculoskeletal imaging.
On a 1.0 T MR unit, 11 GRASE sequences with different combinations of TF and EF (TR/TE 2150/120 ms) were evaluated in phantom studies with respect to signal-to-noise (S/N) ratio, nonuniformity of images, and geometrical distortion. From this study, the optimal GRASE-sequence was applied to 25 patients with different joint pathologies and compared to a T2-weighted TSE sequence (TR/TE 2855/130 ms). Lesion visualization, conspicuity, overall image quality, and artifacts were qualitatively analyzed by two observers independently of each other.
With respect to S/N ratio, signal nonuniformity, and geometrical distortion, the GRASE sequence with TF/EF 7/3 (S/N 47; signal nonuniformity 11.7%; distortion 1 pixel) proved to be superior to the other GRASE sequences within a scanning time of less than 120 s. In a clinical study, the GRASE sequence proved superior to T2-weighted TSE (without fat suppression) in the visualization of bone-marrow and soft-tissue lesions (p < 0.001) and ligamentous injuries, although the image quality was inferior.
超快速梯度与自旋回波（GRASE）成像技术是快速自旋回波（TSE）与回波平面成像（EPI）的混合技术。一次扫描由多个自旋回波（SE）组成（快速成像因子，TF），每个自旋回波又由多个梯度回波（EPI因子，EF）组成。本研究旨在评估GRASE成像中TF和EF的不同组合，并测试其在肌肉骨骼成像中的应用价值。
在1.0T磁共振设备上，通过模体研究评估了11种具有不同TF和EF组合的GRASE序列（TR/TE 2150/120ms）的信噪比、图像不均匀性和几何变形情况。根据该研究结果，将最佳GRASE序列应用于25例患有不同关节病变的患者，并与T2加权TSE序列（TR/TE 2855/130ms）进行比较。由两名观察者分别对病变显示情况、清晰度、整体图像质量和伪影进行定性分析。
在扫描时间小于120秒的情况下，TF/EF为7/3的GRASE序列（信噪比47；信号不均匀性11.7%；变形1像素）在信噪比、信号不均匀性和几何变形方面优于其他GRASE序列。在临床研究中，GRASE序列在骨髓和软组织病变（p<0.001）以及韧带损伤的显示方面优于T2加权TSE序列（无脂肪抑制），尽管图像质量较差。
