Characterization of white matter lesions in multiple sclerosis and traumatic brain injury as revealed by magnetization transfer contour plots

BACKGROUND AND PURPOSE: Magnetization transfer imaging provides information about the structural integrity of macromolecular substances, such as myeli n, Our objective was to use this imaging technique and contour plotting to characterize and to define the extent of white matter lesions in multiple s clerosis and traumatic brain injury. METHODS: Magnetization transfer imaging was performed of 30 multiple sclero sis plaques and 10 traumatic white matter lesions. Magnetization transfer r atios (MTRs) were calculated for the lesions, for the normal- or abnormal-a ppearing surrounding white matter, and for remote normal-appearing white ma tter, MTR contour plots were constructed about these lesions. RESULTS: The contour plot appearance of MS plaques differed from that of tr aumatic white matter lesions, There was a gradual increase in MTR values at points at increasing distances from the center of the MS plaques; this was true for those lesions with and without surrounding T2 signal abnormality (halos), In contrast, there was an abrupt transition in MTR values between traumatic lesions and normal-appearing surrounding white matter, Additional ly, the size of the MTR abnormality exceeded the size of the T2 signal abno rmality for the MS plaques. CONCLUSION: MTR contour plots permit characterization and border definition of white matter lesions, Analysis of the contour plots suggests that MS is a centrifugal process with the lowest MTR within the center of the lesion. In contrast, traumatic white matter injuries are discrete lesions with abr upt transitions between the abnormal lesion and normal brain.