Annals of Nuclear Medicine, 2026 (SCI-Expanded, Scopus)
Purpose: Quantitative [11C]NNC112 PET imaging of dopamine D₁‑receptors conventionally requires 90–120 min of dynamic data, limiting workflow and patient comfort. In this study, we investigated how gradual scan duration shortening affects the calculation of non‑displaceable binding potential (BPND) of D1-receptors. Methods: Fourteen healthy volunteers (26 ± 4 years) underwent 90‑minute dynamic [11C]NNC112 PET/MRI scans. BPND was calculated with the simplified reference‑tissue model (SRTM) using cerebellar grey matter as reference. Time‑stability analyses were performed on truncated datasets of 75, 60, and 45 min. Absolute (non-relative) bias, percent error, and Bland–Altman limits of agreement (LoA) were calculated for 10 cortical and striatal regions. Regression analyses were performed to analyze the relationships of bias with imaging duration. Results: Reducing the acquisition to 75 min introduced a median absolute BPND bias of less than + 0.02 (+ 0.17% to + 2.19%) with a relatively acceptable LoA (− 2.88% to + 12.6%; <10% in all regions except the frontal cortex). A 60-minute protocol remained relatively reliable in the high-binding striatum, with LoA values at or near ± 10% (− 7.06% to + 12.8% for the caudate and − 5.69% to + 10.33% for the putamen). However, significant deviations were observed in low-binding cortical regions. Truncation to 45 min consistently overestimated BPND values in both cortical and striatal regions and widened LoA significantly. Conclusion: Dynamic [11C]NNC112 PET/MRI can potentially be shortened to 75 min with acceptable whole-brain quantitative accuracy. A 60-minute protocol may be feasible for striatal-focused studies. However, 45-minute acquisitions had significant deviations and should be approached with caution for accurate D₁-receptor quantification with [11C]NNC112 PET imaging.