SPECT measurement of iodine-123-β-CIT binding to dopamine and serotonin transporters in Parkinson’s disease: Correlation with symptom severity

Abstract

Iodine-123-β-CIT (2β-carbomethoxy-3β-(4-iodophenyl)tropane) binds with high affinity to dopamine (DA) and serotonin (5-HT) transporters. This study examined the correlation of single-photon emission computed tomographic (SPECT) measures of [123l]β-CIT binding to DA and 5-HT transporters with symptom severity in Parkinson’s disease (PD). Forty-six L-dopa-responsive PD patients (Hoehn-Yahr stage 1-3) had SPECT scans at 20-24 h after injection of [123l]β-CIT. Specific to nondisplaceable uptake ratios (designated V″3) were calculated in the striatum and hypothalamic/midbrain region, where the binding of [123l]β-CIT is associated primarily with DA and 5-HT transporters, respectively. Striatal ″3 was significantly correlated with Hoehn-Yahr stage and total, motor and activities of daily living scores of Unified Parkinson’s Disease Rating Scale (UPDRS). There was a significant correlation between the sum of lateralizing motor UPDRS subscores (tremor, rigidity; bradykinesia) calculated for each side of limbs and ″3 values in the contralateral striatum. No significant correlation was found between striatal ″3 and UPDRS rating of mentation, behavior, and mood. Hypothalamic/midbrain ″3 was not significantly correlated with either Hoehn-Yahr stage or UPDRS scores including both motor and non motor measures. The significant correlation of SPECT measures of striatal [123l]β-CIT binding with motor severity suggests that [123l]β-CIT binding to striatal DA transporters can serve as an in vivo indicator of disease severity in PD, with potential utility in the serial monitoring of disease progression. [Neurol Res 1999; 21: 255-261]