Imaging of dopamine transporters in Parkinson disease: a meta‐analysis of (18)F/(123)I‐FP‐CIT studies

OBJECTIVE: (18)F‐FP‐CIT and (123)I‐FP‐CIT are widely used radiotracers in molecular imaging for Parkinson’s disease (PD) diagnosis. Compared with (123)I‐FP‐CIT, (18)F‐FP‐CIT has superior tracer kinetics. We aimed to conduct a meta‐analysis to assess the efficacy of using (18)F‐FP‐CIT positron emission tomography (PET) and (123)I‐FP‐CIT single‐photon emission computed tomography (SPECT) of dopamine transporters in patients with PD in order to provide evidence for clinical decision‐making. METHODS: We searched the PubMed, Embase, Wanfang Data, and China National Knowledge Infrastructure databases to identify the relevant studies from the time of inception of the databases to 30 April 2020. We identified six PET studies, including 779 patients with PD and 124 healthy controls, which met the inclusion criteria. Twenty‐seven SPECT studies with 1244 PD patients and 859 controls were also included in this meta‐analysis. RESULTS: Overall effect‐size analysis indicated that patients with PD showed significantly reduced (18)F‐FP‐CIT uptake in three brain regions [caudate nucleus: standardized mean difference (SMD) = −1.71, Z = −3.31, P = 0.0009; anterior putamen: SMD = −3.71, Z = −6.26, P < 0.0001; and posterior putamen: SMD = −5.49, Z = −5.97, P < 0.0001]. Significant decreases of (123)I‐FP‐CIT uptake were also observed in the caudate (SMD = −2.31, Z = −11.49, P < 0.0001) and putamen (SMD = −3.25, Z = −14.79, P < 0.0001). INTERPRETATION: In conclusion, our findings indicate that both (18)F‐FP‐CIT PET and (123)I‐FP‐CIT SPECT imaging of dopamine transporters can provide viable biomarkers for early PD diagnosis.