Hittmair K, Umek W, Schindler E G, Ba-Ssalamah A, Pretterklieber M L, Herold C J
Department of Neuroradiology, University of Vienna, Austria.
Magn Reson Imaging. 1997;15(4):405-14. doi: 10.1016/s0730-725x(96)00381-5.
The purpose of this study was to compare the gradient spin-echo (GRASE) to the fast spin-echo (FSE) implementation of fast fluid-attenuated inversion recovery (FLAIR) sequences for brain imaging. Thirty patients with high signal intensity lesions on T2-weighted images were examined on a 1.5 T MR system. Scan time-minimized thin-section FLAIR-FSE and FLAIR-GRASE sequences were obtained and compared side by side. Image assessment criteria were lesion conspicuity, contrast between different types of normal tissue, image quality, and artifacts. In addition, contrast ratios and contrast-to-noise ratios were determined. Compared to FSF, the GRASE technique allowed a 17% reduction in scan time but conspicuity of small lesions in particular was significantly lower on FLAIR-GRASE images because of higher image noise and increased artifacts. Gray-white differentiation was slightly worse on FLAIR-GRASE. Physiological ferritin deposition appeared slightly darker on FLAIR-GRASE images and susceptibility artifacts were stronger. Fatty tissue was less bright with FLAIR-GRASE. With current standard hardware equipment, the GRASE technique is not an adequate alternative to FSE for the implementation of fast FLAIR sequences in routine clinical MR brain imaging.
本研究的目的是比较梯度自旋回波（GRASE）与快速自旋回波（FSE）实现的快速液体衰减反转恢复（FLAIR）序列在脑成像中的应用。对30例T2加权图像上有高信号强度病变的患者在1.5T MR系统上进行检查。获取扫描时间最短的薄层FLAIR-FSE和FLAIR-GRASE序列并进行并排比较。图像评估标准包括病变清晰度、不同类型正常组织之间的对比度、图像质量和伪影。此外，还测定了对比率和对比噪声比。与FSF相比，GRASE技术可使扫描时间减少17%，但由于图像噪声较高和伪影增加，FLAIR-GRASE图像上小病变的清晰度尤其显著降低。FLAIR-GRASE上的灰白质分化略差。生理性铁蛋白沉积在FLAIR-GRASE图像上显得略暗，且磁敏感伪影更强。FLAIR-GRASE下脂肪组织亮度较低。对于当前的标准硬件设备，在常规临床脑磁共振成像中，GRASE技术并非FSE实施快速FLAIR序列的合适替代方案。
