123I]FP-CIT-SPECT asymmetry index to differentiate Parkinson’s disease from vascular parkinsonism

Abstract

Differential diagnosis between vascular parkinsonism (VP) and Parkinson's Disease (PD) is often difficult, due to the overlap in clinical presentation and the lack of specificity at neuroimaging. Aim of the study was to identify a possible reliable marker at SPECT imaging useful to distinguish the two conditions. We studied 20 PD, 20 VP and 20 essential tremor (ET) patients as control group, who had undergone a cerebral [(123) I] FP-CIT SPECT. A semiquantitative analysis was performed on DaTSCAN SPECT imaging and to establish the degree of asymmetry of the ligand uptake the Striatal Asymmetry Index (SAI) was used. The binding of the ligand in the most affected side resulted significantly lower in VP than in ET patients but higher compared to PD patients. SAI was significantly higher in PD compared to VP (P < 0.001) and ET (P < 0.001) groups. We found that a cut-off of SAI greater than 14.08 could differentiate PD from VP with a 100% specificity and a 50% sensitivity. SAI detected using [(123) I]FP-CIT SPECT can be used to differentiate VP and PD with a good degree of certainty.