Background: Multiple sclerosis (MS) is a chronic disease that begins most commonly in young adults and is characterized pathologically by multiple areas of central nervous system (CNS) white matter inflammation, demyelination, and glial scarring. The most valuable aid for diagnosis is magnetic resonance imaging (MRI). New type of MRI has been developed on the basis of molecular diffusion which capable of detecting acute and active lesions. Early diagnosis and treatment is possible to stop or slow down progression of disease. The aim of this study is to compare the findings of conventional and diffusion- weighted (DW) MRI in detection cerebral lesions of MS.

Methods: Thirty patients with clinically definite MS and 30 healthy volunteers were studied in a descriptive-prospective survey over a twelve-month period of time. Conventional and DW MRI were used in both groups. Total number, morphology, location and the mean size of the intra-cerebral plaques of MS were compared between group. The sensitivity and the specificity of both imaging methods in detecting these plaques were determined.

Results: Thirty patients with MS with the mean age of 32.76±8.79 years and 30 healthy individuals with the mean age of 32.75± 9.23 years were enrolled. Plaque within the brain was significantly higher by the conventional method (P< 0.05). Ovoid lesions were greater in number in the conventional method group. More lesions were detected by the conventional method in the areas of periventricle, centrum semiovale and corpus callosum. Regarding the size of plaque, the minimum measurement was significantly lower in the conventional method group. The sensitivity of both methods was 100%. The specificity of conventional and DW MRI was 86.6% and 96.6%, respectively.

Conclusion: In our study the sensitivity of both methods was the same but the specificity of DW MRI was higher. DW MRI may detect lesions which are not detectable by the routine methods.