Neuroimaging techniques have substantially progressed over the past several years. These developments have provided new information about the degenerative processes involved in Parkinson's disease (PD). Functional imaging approaches such as positron emission tomography (PET) and single photon emission computerized tomography (SPECT) have been successfully employed to detect dopaminergic dysfunction in PD, even in preclinical stages. Myocardial scintigraphy with (123)I-metaiodobenzylguanidine ((123)I-MIBG) has been used to assess cardiac sympathetic function, and recent studies have revealed that the cardiac uptake of MIBG is significantly reduced in patients with PD and Lewy body dementia. In addition, substantia nigra (SN) hyperechogenicity, detected with transcranial sonography (TCS), might provide a marker of susceptibility to PD. We briefly review data regarding the clinical significance of these functional imaging studies in the diagnosis of PD, and discuss the diagnostic potential of the combining TCS of the SN with other functional imaging tools.
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