Subregional cutoffs in ¹⁸F-FP-CIT PET: Comparison of Heuron Brain PET and PMOD

Despite the clinical utility of ¹⁸F-FP-CIT PET, standardized, clinically validated quantitative tools and subregion-specific thresholds to support routine visual interpretation have not been firmly established. Therefore, this study aimed to evaluate whether quantitative measurements obtained from Heuron Brain PET are consistent with those from PMOD. Additionally, we aimed to establish region-specific cutoff values for visually normal striatal uptake.

A total of 155 patients who underwent 18F-FP-CIT PET for suspected Parkinson's disease were retrospectively analyzed. Visual assessments were performed for the caudate nucleus and putamen, including anterior and posterior subdivisions. Quantitative metrics-including SUVRs normalized to the whole cerebellum and asymmetry indices-were obtained using Heuron and PMOD and compared using paired t-tests, correlation analyses, and Bland-Altman plots. Region-specific cutoff values for visually normal uptake were determined by evaluating performance across incremental thresholds for visual normality classification.

Heuron-derived SUVRs clearly distinguished visually normal from abnormal uptake. The optimal cutoff values were 2.58, 3.87, 3.61, and 4.15 for the caudate nucleus, anterior putamen, posterior putamen, and entire putamen, respectively. Although systematic differences in SUVR measurements were observed between Heuron and PMOD, the two platforms showed strong correlations and overall agreement in quantitative measurements. Asymmetry indices also demonstrated strong agreement between platforms.

Heuron Brain PET demonstrated quantitative performance consistent with that of PMOD, supporting the quantitative comparability of the two platforms for ¹⁸F-FP-CIT PET analysis. The region-specific cutoff values identified-particularly for the anterior and posterior putamen-may assist and standardize visual interpretation of striatal uptake.