COMPARATIVE NIGROSTRIATAL DOPAMINERGIC IMAGING WITH IODINE-123-BETA-CIT-FP SPECT AND FLUORINE-18-FDOPA/PET/

SPECT imaging of the dopamine transporter is now an alternative to PET in the quantification of nigrostriatal dopaminergic function. We comp ared [I-123]beta CIT-FP/SPECT and [F-18]FDOPA/PET in the assessment of nigrostriatal dopaminergic function in Parkinson's disease (PD) and n ormal aging. Methods: We studied 12 mildly affected PD patients (mean age: 61.0+/-13.2 yr; H&Y Stage I-II) with both [I-123]beta CIT-FP and [F-18]FDOPA. Fifteen normal volunteers (mean age: 45.5+/-22.1 yr) serv ed as controls for both tracers. We measured the striato-occipital rat io (SOR) for both tracers at approximately 100 min postinjection. Resu lts: We found a highly significant correlation between SOR measures ob tained for both tracers (r= 0.79, p <0.0001). In normal volunteers a s ignificant age-related decline in striatal uptake was noted with [I-12 3]beta CIT-FP (r=-0.56, p <0.04) but not with [F-18]FDOPA. SOR values for both tracers discriminated PD patients from controls with comparab le accuracy (F[1,25]=52.1 and 53.0, p <0.0001 for [I-123]beta CIT-FP a nd [F-18]FDOPA, respectively). UPDRS motor ratings correlated with SOR values obtained by both imaging techniques (r=-0.69 and -0.60, p <0.0 4 for [I-123]beta CIT-FP and [F-18]FDOPA, respectively). Conclusion: T hese results indicate that [I-123]beta CIT-FP/SPECT can provide quanti tative descriptors of presynaptic dopaminergic function comparable to those obtained with [F-18]FDOPA/PET.