Intraindividual Comparison of Physiologic [⁶⁸Ga]Ga-PSMA-11 and [¹⁸F]PSMA-1007 Uptake in Ganglia in Patients with Prostate Cancer: a retrospective, monocentric analysis

Ziel/Aim Several studies indicate a relatively high rate of detection of benign findings, in particular ganglia, in PSMA PET imaging. To date, no studies have directly compared [⁶⁸Ga]Ga-PSMA-11 and [¹⁸F]PSMA-1007 ganglionic uptake intraindividually and analyzed the different detection rates and underlying molecular and physical mechanisms. With this monocentric retrospective study, we sought to evaluate the intraindividual physiological ganglion uptake of different PSMA ligands.

Methodik/Methods Our cohort consists of 19 male patients (median age 72±9; range: 56 - 85) with biochemical recurrence of prostate cancer who underwent both [⁶⁸Ga]Ga-PSMA-11 and [¹⁸F]PSMA-1007 PET/CT in our clinic on the same scanner per standard care between March 2015 and March 2022. Tracer uptake was quantified by SUV_max for both PSMA ligands. Lesion-to-background ratios (LBRs) were determined to quantify the image contrast by dividing the SUV_max of the ganglia by the background value (SUV_max of blood pool in the descending aorta). We used descriptive analyses for demographics, tumor characteristics and performed two-way repeated measures ANOVA (Analysis of Variance) for SUV-metrics including LBR measurements.

Ergebnisse/Results In total, 177 ganglia were detected, 101 by PSMA-1007 and 76 by PSMA-11 imaging, respectively. There was no statistically significant difference in PSMA uptake in terms of SUV_max between PSMA ligands (p value: 0,052). In contrary, a comparison of LBRs revealed a significant difference in favor of [¹⁸F]PSMA-1007 (P ¹⁸F]PSMA-1007 and [⁶⁸Ga]Ga-PSMA-11 PET/CT scans. Furthermore, a separate comparison of ganglia with respect to their anatomical location demonstrated also statistically significant differences both within and between [¹⁸F]PSMA-1007 and [⁶⁸Ga]Ga-PSMA-11 PET/CT scans.

Schlussfolgerungen/Conclusions Our investigation demonstrated that the visual impression of presumably greater [¹⁸F]PSMA-1007 uptake in ganglia is not due to more intense PSMA-1007 uptake, but more favorable physical properties of the radionuclide F-18 and better biodistribution of this radiopharmaceutical. This conclusion can essentially be extrapolated to other benign, small structures as well.

Publication History

Article published online:
30 March 2023