The role of [123I]-FP-CIT SPECT in the diagnosis and clinical management of Parkinson’s Disease.

The diagnosis of Parkinson’s Disease (PD) is based on clinical features with imaging confirmation. Especially early in the course of the disease, the clinical diagnosis can be difficult. Neuro imaging of presynaptic dopamine transporters has provided a possible diagnostic probe in the evaluation of PD. In particular [123I]-FP-CIT SPECT (DAT scan) has been successfully used to detect the loss of dopaminergic nigrostriatal neurons in PD. The purpose of this study was to evaluate the impact of DAT scan on the diagnosis and clinical management of patients with a suspicious of PD.Materials and Methods: 136 consecutive patients (69 male, 67 female, mean age 69 yh) with suspected clinical PD were prospectively studied. All patients underwent to neurological examination, Magnetic Resonance Imaging (MRI) for the identification of basal ganglia alterations and DAT scan for the study of nigrostriatal neurons uptake. The radiotracer uptake was classified in 4 severity degrees: normal (type 0), abnormal putamen omolateral (type 1), abnormal putamen bilateral (type 2) and abnormal putamen and caudate bilateral (type 3). We verified the correlation between this classification with that based on neurological findings (HY scale). We also tested the efficacy of DAT scan for the differentiation between PD and other type of tremors comparing diagnosis before and after DAT scan, to verify the impact of DAT scan in the management of PD. Finally we compared MRI and DAT scan results.Results: A significant linear correlation was founded between the classification of patient based on DAT scan degrees and on HY scale (p < 0.1%). On the other hand the 2 test demonstrated a significant difference between diagnosis of PD before and after DAT scan, in particular in doubt cases. Finally, from the comparison of DAT scan and MRI with 2 test application, we founded a significant difference: a 61% positive DAT scan versus 26% positive MRI.Conclusions: Our study shows the direct relation between DAT scan and neurological findings, in particular when the diagnosis of PD is clinically difficult to do. On the other hand the difference between positive results on DAT scan and MRI is related to the absence of morphological alterations on nigrostriatal neurons detectable on typical PD. The results of DAT scan have changed the diagnosis in the 20% of all our patients and in the 92% of doubt cases, conditioning the clinical management of patient.