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

Purpose: 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). Methods: Simultaneous Tc-99m-ECD/I-123-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. Results: 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). Conclusion: Dual-isotope studies are both feasible in and promising for the diagnosis of parkinsonian syndromes.