Reproducibility of [123I]PE2I binding to dopamine transporters with SPECT

Purpose The iodinated cocaine derivative [123I]PE2I is a new selective ligand for in vivo studies of the dopamine transporter (DAT) with SPECT. Recently, a bolus/infusion (B/I) protocol for [123I]PE2I measurements of DAT density was established [Pinborg LH et al. J Nucl Med 2005;46:1119–271]. The ai...
Ausführliche Beschreibung

Purpose The iodinated cocaine derivative [123I]PE2I is a new selective ligand for in vivo studies of the dopamine transporter (DAT) with SPECT. Recently, a bolus/infusion (B/I) protocol for [123I]PE2I measurements of DAT density was established [Pinborg LH et al. J Nucl Med 2005;46:1119–271]. The aims of this study were, firstly, to evaluate the test–retest variability using the B/I protocol and, secondly, to evaluate the B/I approach in a new group of healthy subjects using two outcome parameters, $ BP_{1} $ ($ C_{ROI} $/$ C_{plasma} $) and $ BP_{2} $ ($ C_{ROI} $/$ C_{REF} $). Methods Seven healthy subjects were subjected to [123I]PE2I SPECT scanning twice. For both studies, the two outcome parameters $ BP_{1} $ and $ BP_{2} $ were calculated based on two different methods for region of interest (ROI) delineation, namely manual delineation and probability map-based automatic delineation with MRI co-registration. Results With manual delineation, striatal test–retest variability (absolute difference between first and second scan as a percentage of the mean) of $ BP_{1} $ and $ BP_{2} $ was 13.9% (range 1.8–35.7%) and 4.1% (range 0.5–9.7%) respectively. The probability map-based automatic delineation resulted in striatal test–retest variability of 17.2% (range 4.3–40.5%) and 5.2% (range 0.1–10.9%) respectively. The B/I approach provided stable brain activity from 120 to 180 min post injection in both high- and low-count regions with a mean % change/hour in striatal $ BP_{2} $ of 10.6. Conclusion [123I]PE2I SPECT with the B/I approach yields a highly reproducible measure of striatal dopamine transporter binding. The appropriateness of a B/I protocol with a B/I ratio of 2.7 h (i.e. with a bolus worth 2.7 h of infusion) was confirmed in an independent sample of healthy subjects. Ausführliche Beschreibung