Enhanced and unenhanced MR with magnetization transfer in multiple sclerosis.

PURPOSE To evaluate the use of magnetization transfer and the apparent enhancement of lesions on contrast-enhanced MR images in patients with multiple sclerosis. METHODS Contrast-enhanced T1-weighted spin-echo MR images obtained in 20 patients with relapsing-remitting multiple sclerosis, with and without magnetization transfer, were evaluated to determine the number of enhancing plaques. Comparison was made with unenhanced T1-weighted magnetization transfer images. Contrast-to-noise ratios were obtained for these lesions on both the enhanced and unenhanced magnetization transfer T1-weighted spin-echo MR images. RESULTS Ten plaques were considered enhancing only when the enhanced magnetization transfer T1-weighted images (11% or more) were used; however, they were all hyperintense on unenhanced T1-weighted magnetization transfer images. The contrast-to-noise ratios of these lesions were 16.52 for the enhanced images and 15.65 for the unenhanced images. The two values were not statistically different. CONCLUSIONS In patients with multiple sclerosis, examination with contrast-enhanced magnetization transfer MR images alone may overestimate the number of enhancing plaques.