A Study of Dopamine Transporter Imaging and Comparison of Noninvasive Simplified Quantitative Methods in Normal Controls and Parkinson'S Patients

The purpose of this study was to compare the specific binding ratio method with model based methods in estimating the transporter parameter k3/k4 in normal controls and Parkinson's patients with [I-123]IPT SPECT and to evaluate the usefulness of [I-123]IPT SPECT. 6.5 ± 1.1 mCi (239.0 ± 40.3 MBq) of [123]IPT was intravenously injected as a bolus into six normal controls(age:45 ± 13) and seventeen patients(age:55 ± 8) with Parkinson's disease(PD). The transporter parameter k3/k4 was derived using the Ichise's graphical method(Rv) and Lassen's area ratio method(RA) for the dynamic IPT SPECT data without blood samples. Then, the relationships between the transporter parameter Rv, RA and the ratio of (BG-OCC)/OCC at 115 minutes were evaluated by linear regression analysis. Rvs by Ichise's graphical method for NC and PD were 2.08 ± 0.29 and 0.78 ± 0.31, respectively. RAs by Lassen's area ratio method for NC and PD were 1.48 ± 0.16 and 0.65 ± 0.24, respectively. The correlation coefficients between (BG-OCC)/OCC and Rv, (BG-OCC)/OCC and RA, and RV, and RA were 0.93, 0.90, 0.99 and their corresponding slopes were 0.54, 0.34, and 0.65, respectively. The Rv and RA of NC were significantly higher than the ones of PD. That is, the k3/k4 Of NC was clearly separated from the one of PD. k3/k4 showed a good correlation with the ratio of (BG-OCC)/OCC. The results indicate that the noninvasive simplified quantitative methods may be useful to measure the transporter parameter k3/k4 and the specific binding ratio method can be used for quantitative studies of dopamine transporter with [I-123]IPT SPECT in humans brains.