Yetkin F Z, McAuliffe T L, Cox R, Haughton V M
Department of Radiology, Medical College of Wisconsin, Milwaukee 53226, USA.
AJNR Am J Neuroradiol. 1996 Jan;17(1):95-8.
To determine the test-retest precision of functional MR maps of regions in the brain "activated" by sensory, motor, and cognitive tasks.
Echo-planar images were acquired at 1.5 T in four subjects during voluntary motor activity involving the thumb and fingers and during tactile stimulation of the palm. Each subject performed the two tasks twice. Functional images of each task were generated at three thresholds. Test-retest precision was calculated in terms of two ratios: 1) the pixels activated in both iterations of the tasks in proportion to the pixels activated by either iteration of the task, and 2) the ratio modified to include first-order neighboring pixels. The first is referred to as pixel precision, and the latter as first-order-neighbor pixel precision.
In each subject, activation from the first and second iteration of each task was located in the same region of the same gyrus. Pixel precision was .57 for the two tasks (at a threshold of 0.50). First-order-neighbor precision was greater than .80 for the two tasks at the same threshold.
High test-retest precision can be obtained in functional MR.
确定大脑中因感觉、运动和认知任务而“激活”区域的功能磁共振成像图的重测精度。
在1.5T条件下，对4名受试者在涉及拇指和手指的自主运动活动以及手掌触觉刺激过程中采集回波平面图像。每个受试者对两项任务各执行两次。在三个阈值下生成每项任务的功能图像。根据两个比率计算重测精度：1）任务两次迭代中均被激活的像素与任务任一迭代中被激活像素的比例；2）修改后的比率，纳入一阶相邻像素。前者称为像素精度，后者称为一阶相邻像素精度。
在每个受试者中，每项任务第一次和第二次迭代的激活位于同一脑回的相同区域。两项任务的像素精度为0.57（阈值为0.50）。在相同阈值下，两项任务的一阶相邻像素精度大于0.80。
功能磁共振成像可获得较高的重测精度。
