Yang Y, Wen H, Mattay V S, Balaban R S, Frank J A, Duyn J H
Laboratory of Diagnostic Radiology Research, OIR, National Institutes of Health, Bethesda, Maryland, 20892, USA.
Neuroimage. 1999 Apr;9(4):446-51. doi: 10.1006/nimg.1998.0422.
In order to investigate the merit of high field strength for BOLD-contrast-based functional magnetic resonance imaging (fMRI) studies, multishot gradient-echo fMRI experiments during motor cortex activation were performed on 1.5- and 4.0-T scanners with equivalent hardware, on the same volunteers. In these studies, artifactual vascular enhancement related to inflow effects was minimized, and large brain areas were covered by using a 3D scan technique. Temporal signal stability was optimized by using spiral readout gradients. The sensitivity for detection of activated regions was assessed by measuring the number of "activated voxels" and their average t score in predefined regions of interest. When comparing fMRI experiments with the same total scan time, performed on six subjects, and with acquisition parameters optimized for each field strength separately, the 4.0-T scanner proved to give superior results, with a 70% greater number of activated voxels and a 20% higher average t score for the activated voxels.
为了研究高场强在基于血氧水平依赖性功能磁共振成像（fMRI）研究中的优势，在配备等效硬件的1.5T和4.0T扫描仪上，对同一组志愿者进行了运动皮层激活期间的多激发梯度回波fMRI实验。在这些研究中，与流入效应相关的伪血管增强被最小化，并且通过使用三维扫描技术覆盖了大面积的脑区。通过使用螺旋读出梯度优化了时间信号稳定性。通过测量预定义感兴趣区域中“激活体素”的数量及其平均t分数，评估了检测激活区域的灵敏度。当比较在六个受试者身上进行的具有相同总扫描时间、且针对每个场强分别优化采集参数的fMRI实验时，4.0T扫描仪显示出更好的结果，激活体素数量多70%，激活体素的平均t分数高20%。
