Barbosa S, Blumhardt L D, Roberts N, Lock T, Edwards R H
Department of Neurological Science, University of Liverpool, UK.
Magn Reson Imaging. 1994;12(1):33-42. doi: 10.1016/0730-725x(94)92350-7.
Prolonged T1 and/or T2 relaxation times (RT) in the normal appearing white matter (NAWM) of patients with multiple sclerosis (MS) have been attributed either to a diffuse abnormality, or to "small lesions" undetected by visual inspection of conventional MR images. In a comparison of brain slices from five MS patients and five healthy control subjects, we have confirmed that the average T1 and T2 RTs obtained from NAWM in patients with MS are significantly prolonged (p < .04). Quantitative pixel-by-pixel mapping shows that this overall prolongation is due to the averaging of RTs from two subfractions of NAWM. In all patients a proportion (average 54% for T1 and 63% for T2) of the total white matter pixel sample from each MR brain slice had RT values indistinguishable from those found in the white matter of matched healthy control subjects (i.e., "normal normal appearing white matter," NNAWM). Scattered throughout the NAWM were multiple small areas, often of only one or two pixels, with abnormal RT values. These lesions, which were revealed only by pixel-by-pixel mapping of RT, made up a significant proportion (average 47% for T1 or 57% for T2 estimates) of the total (visible plus "invisible") lesion load per slice, and of the NAWM (average 36% for T1, 27% for T2), with wide interpatient variability. Further studies of these minute lesions are required to determine their total volume in the brain, their precise nature, evolution and relevance to the functional deficit in MS.
多发性硬化症（MS）患者正常外观白质（NAWM）中T1和/或T2弛豫时间（RT）延长，这要么归因于弥漫性异常，要么归因于常规MR图像肉眼检查未检测到的“小病灶”。在对5例MS患者和5例健康对照者的脑切片进行比较时，我们证实，MS患者NAWM的平均T1和T2 RT显著延长（p < 0.04）。逐像素定量映射显示，这种总体延长是由于NAWM两个亚部分的RT平均值所致。在所有患者中，每个MR脑切片的总白质像素样本中有一定比例（T1平均为54%，T2平均为63%）的RT值与匹配的健康对照者白质中的RT值无差异（即“正常正常外观白质”，NNAWM）。在NAWM中散布着多个小区域，通常只有一两个像素，其RT值异常。这些仅通过RT逐像素映射才能显示的病灶，占每个切片总（可见加“不可见”）病灶负荷的很大比例（T1估计平均为47%，T2估计平均为57%），也占NAWM的很大比例（T1平均为36%，T2平均为27%），且患者间差异很大。需要对这些微小病灶进行进一步研究，以确定它们在脑中的总体积、确切性质、演变及其与MS功能缺陷的相关性。
