How useful is (123I) beta-CIT SPECT in the diagnosis of Parkinson's disease?

Because clinical features of parkinsonism can occur in other forms of parkinsonian syndromes in addition to Parkinson's disease, neuroimaging may have a role in determining true disease status. Iodine-123 ((123)I) (2beta-carboxymethoxy-3beta-[4-iodophenyl] tropane) or ((123)I) beta-CIT is a recently developed diagnostic biomarker of Parkinson's disease that provides in vivo information about nigrostriatal degeneration. In clinical trials, beta-CIT single photon emission computed tomography (SPECT) has been shown to be a highly sensitive diagnostic tool in differentiating clinically probable Parkinson's disease from normal subjects and essential tremor patients. As a tool for differentiating Parkinson's disease from atypical parkinsonian syndromes, ((123)I) beta-CIT SPECT may have more limited use because of more extensive postsynaptic pathology in the latter. Differentiating among various parkinsonian syndromes may be improved by methodological refinements, a combined strategy of imaging presynaptic and postsynaptic sites, or by metabolic imaging.