Decreased signal intensity of the middle cerebellar peduncle on diffusion-weighted MRI in patients with large supratentorial lesions.

Purpose: The purpose of this work was to evaluate signal intensity change of the middle cerebellar peduncles on diffusion-weighted imaging in patients with large supratentorial lesions. Methods: Signal intensity of the middle cerebellar peduncles was measured using a region of interest in 40 normal control subjects and in 28 patients with moyamoya disease on axial diffusion-weighted imaging with the motion-probing gradient perpendicular to the image. An additional six patients without moyamoya but with large supratentorial sequelae of hemorrhage or infarction were also included. Results: There was no difference in signal intensity between both middle cerebellar peduncles in normal subjects, but lower signal intensity was consistently observed in the contralateral middle cerebellar peduncle in 12 moyamoya patients with large supratentorial lesions in the middle cerebral artery distribution. This finding was observed in the six non-moyamoya patients, too. Conclusion: Decreased signal intensity of the contralateral middle cerebellar peduncle might be a remote effect caused by a large supratentorial lesion in a crossed cerebellar fashion.