Magnetization transfer histogram parameters reflect all dimensions of MS pathology, including atrophy

Introduction: Magnetization transfer ratio (MTR) histogram analysis can be used as a method for quantifying overall disease burden in MS. We studied c orrelations between MTR histogram and clinical parameters in MS subgroups. Contrary to earlier studies we placed special emphasis on the lower MTR ran ge, to explore the effect of partial volume averaging effects with CSF. Met hods: Seventy-nine patients with MS [26 primary progressive (PP), and 53 'r elapse-onset', including 26 secondary progressive (SP)I, and 23 healthy ind ividuals were studied. MR imaging included 3 mm 2D gradient-echo images wit h and without an off-resonance MT pulse. According to the visually determin ed cut-off, histogram parameters were classified as parenchymal or CSF-rela ted variables. Clinical measurements included the Expanded Disability Statu s Scale (EDSS) as a measure of global impairment/disability and the Paced A uditory Serial Addition Test (PASAT) as a measure of cognition. Results: SP MS patients differed from the other subgroups on many MTR variables, origi nating from both the lower and the higher MTR range. CSF-related low MTRs w ere clearly over-represented in SP patients, and showed a significant disti nction between the SP and PP MS group. In the total group, as well as in th e relapse-onset patients, significant correlations were found between MTR p arameters and clinical parameters. No associations were found in the PP gro up. Conclusion: This explorative study suggests that MTR histogram analysis can distinguish between MS patients and controls, and best identifies the SP phenotype, partly as a result of increased CSF volume (atrophy). in addi tion, we show that MTR histogram analysis gives information about the level of impairment and disability in patients with a 'relapse-onset' course of MS, and therefore provides a useful tool to monitor the evolution of the di sease in these patients. (C) 2001 Elsevier Science B.V. All rights reserved .