Magnetic resonance imaging in parkinsonism

High field strength magnetic resonance imaging (MRI) is a relatively simple, safe in vivo technique that has proven to be of great value in evaluating patients with parkinsonism. MRI studies demonstrate signal hypointensity in the putamen of patients with atypical parkinsonism and in the substantia nigra of patients with both atypical parkinsonism and Parkinson's disease. MRI changes can be used to differentiate these patient populations and to predict the subsequent course and response to dopa replacement therapy. MRI studies that may provide a clue as to the pathogenesis of Parkinson's disease and atypical parkinsonism are discussed.