Quantitative simultaneous 99mTc-ECD/123I-FP-CIT SPECT in Parkinson's disease and multiple system atrophy

The purpose of this study was to investigate the feasibility and utility of dual-isotope SPECT for differential diagnosis of idiopathic Parkinson's disease (IPD) and multiple system atrophy (MSA). Simultaneous 99mTc-ECD/123I-FP-CIT studies were performed in nine normal controls, five IPD patients, and five MSA patients. Projections were corrected for scatter, cross-talk, and high-energy penetration, and iteratively reconstructed while correcting for patient-specific attenuation and variable collimator response. Perfusion and dopamine transporter (DAT) function were assessed using voxel-based statistical parametric mapping (SPM2) and volume of interest quantitation. DAT binding potential (BP) and asymmetry index (AI) were estimated in the putamen and caudate nucleus. Striatal BP was lower in IPD (55%) and MSA (23%) compared to normal controls (p<0.01), and in IPD compared to MSA (p<0.05). AI was greater for IPD than for MSA and controls in both the caudate nucleus and the putamen (p<0.05). There was significantly decreased perfusion in the left and right nucleus lentiformis in MSA compared to IPD and controls (p<0.05). Dual-isotope studies are both feasible in and promising for the diagnosis of parkinsonian syndromes. (orig.)