Decreased fractional anisotropy of middle cerebellar peduncle in crossed cerebellar diaschisis: diffusion-tensor imaging-positron-emission tomography correlation study

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the clinical usefulness of diffusion tensor MR imaging (DTI) for the assessment of chronic stroke with crossed cerebellar diaschisis (CCD). METHODS: Twenty-two patients (15 men and 7 women; mean age, 60 years) with chronic stroke (13 ischemic and 9 hemorrhagic) were evaluated by diffusion-tensor MR imaging (DTI) and 18F-fluorodeoxyglucose (FDG)–positron-emission tomography (PET). Fractional anisot-ropy (FA) and color-coded vector maps were generated. To evaluate afferent fiber systems to the cerebellum, the FA of the bilateral middle cerebellar peduncle (MCP) was measured. Changes of FA values in the MCP were compared against PET results. RESULTS: In patients with a chronic infarct involving more than one-third of the unilateral hemisphere, MCP of the contralesional side showed an FA value of 0.5226 0.0174, which was significantly lower than that of the ipsilesional side MCP (0.5366 0.0159) (one-tail paired t test, P .0009). On FDG-PET scan, decreased glucose metabolism was observed in the affected cerebellum in 19 patients (86.4%). CONCLUSION: DTI can visualize an altered corticocerebellar circuit in the case of chroni