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AJNR - American Journal of Neuroradiology

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Normal-Appearing White Matter Changes Vary with Distance to Lesions in Multiple Sclerosis

H. Vrenken^a, J.J.G. Geurts^a, D.L. Knol^b, C.H. Polman^c, J.A. Castelijns^a, P.J.W. Pouwels^d and F. Barkhof^a

^a Department of Radiology, MR Center for MS Research, VU University Medical Center, Amsterdam, the Netherlands
^b Department of Clinical Epidemiology and Biostatistics, MR Center for MS Research, VU University Medical Center, Amsterdam, the Netherlands
^c Department of Neurology, MR Center for MS Research, VU University Medical Center, Amsterdam, the Netherlands
^d Department of Physics and Medical Technology, MR Center for MS Research, VU University Medical Center, Amsterdam, the Netherlands

View larger version (82K): [in a new window]   Fig 1. T2-weighted images coregistered to the T1 maps illustrating the definition of pixel classes in 1 female patient with primary progressive MS (aged 59.5 years; disease duration, 8.3 years; cerebral lesion volume, 14.9 mL; EDSS score, 4.0; MSFC score, 0.54). For greater clarity, the 2 pixel classes, lesion core and lesion rim, are displayed as a single class (Lesions) in this figure. The perilesional NAWM pixel classes (Layer 1 through Layer 4) are defined as consecutive layers of a single pixel width around these lesion masks. Distant NAWM consists of NAWM pixels that are at least 4 mm away from the lesion masks in all directions. Details of the definition of the pixel classes are provided in the text. Note that the coregistration of the lesion masks to the T1 maps was chosen to overestimate the lesions, to be conservative toward NAWM. Note also that because of less-reliable segmentation in deep gray matter and periventricular regions, these regions were excluded from the NAWM pixel classes. As a result, there are several lesions in this region without perilesional NAWM pixel layers around them (visible mainly in the images in the second row).

View larger version (22K): [in a new window]   Fig 2. MTR (A) and T1 (B) histogram peak positions for the 7 pixel classes in each of the 3 MS groups. The horizontal lines indicate the mean and SD of the values for control white matter. Statistically significant differences with distant NAWM, averaged over disease types, are indicated with black asterisks (*). Statistically significant differences with control white matter are indicated for each of the 3 MS disease types by daggers () in the corresponding color. See also Table 2. Details of the applied general linear mixed model are provided in the text. PP indicates primary progressive, RR, relapsing-remitting; SP, secondary progressive.