Dopamine transporter imaging as a diagnostic tool for parkinsonism and related disorders in clinical practice

• Dopamine transporter imaging has been used in Parkinson disease and related disorders.
• It provides evidence of presynaptic dopaminergic dysfunction.
• It does not provide information regarding a specific diagnosis.
• The test has limitations. The diagnosis of Parkinson's remains a clinical diagnosis.

BackgroundAccurate diagnosis of Parkinson disease (PD) and other degenerative parkinsonian syndromes is important for management and prognostic purposes. Diagnosis can be challenging in early disease and in atypical cases.MethodsWe reviewed the literature on the application of dopamine transporter single-photon emission computed tomography (DAT-SPECT) in degenerative parkinsonism and related disorders as a diagnostic tool.ResultsThe use of DAT-SPECT shows some utility in the early diagnosis of PD and differentiation from other non-degenerative parkinsonian disorders (i.e. essential tremor, dystonic tremor, drug-induced and in most cases of psychogenic parkinsonism), since it can accurately detect the presynaptic dopaminergic deficit. The test has been shown to have high sensitivity/specificity by multiple studies. DAT imaging may also have some prognostic value for disease progression. However, it has limited value in differentiating among degenerative causes of parkinsonism. DAT imaging has some limitations. In most studies, true test accuracy is unknown since the gold standard is clinical diagnosis by a movement disorders neurologist. Therefore, the sensitivity of the test cannot exceed that of the clinical diagnosis. In addition, false negative scans occur and highlight the need for clinical follow-up.ConclusionClinical assessment remains the most important aspect in evaluating these patients. DAT-SPECT is a sensitive modality to detect nigrostriatal degeneration. In spite of increasing data using this technique, however, more long-term clinical studies are required to determine how DAT-SPECT scan can guide decision-making.