Impact of Uptake Period on 18F-DCFPyL-PSMA PET/CT Maximum Standardised Uptake Value.

Abstract

Background: The maximum standardised uptake value (SUV_max) can potentially be affected by the uptake period during PSMA PET imaging. The optimal image acquisition period for 2-(3-{1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (¹⁸F-DCFPyL)PSMA PET/CT is yet to be established. This study aims to evaluate the effect of the uptake period on the SUV_max in diagnosing localised, clinically significant prostate cancer using ¹⁸F-DCFPyL-PSMA PET/CT.

Methods: Sixty biopsy-naive men with one or more PI-RADS 4 or 5 lesions of at least 10 mm on multiparametric MRI (mpMRI) were enrolled to undergo ¹⁸F-DCFPyL-PSMA PET/CT. SUV_max was prospectively measured following an uptake period of 60, 90 and 120 min post injection of ¹⁸F-DCFPyL-PSMA radiotracer. Concordance with biopsy results or final histopathology was recorded.

Results: Mean absolute differences in SUV_max at 60 vs. 90, 60 vs. 120, and 90 vs. 120 min uptake periods were 3.23 (SD 4.76), 4.53 (SD 7.33), and 3.24 (SD 4.56), respectively. This represents a statistically significant systematic increase in SUV_max (p-value < 0.001) with increasing uptake period. The interval between the uptake period of 60 vs. 120 min represented the largest SUV_max change of 29.98%.

Conclusions: The SUV_max is a dynamic variable significantly affected by uptake period. Our study supports image acquisition at 120 min following injection of ¹⁸F-DCFPyL radiotracer. Further studies are needed to determine if this acquisition period can be applied to other Fluorine-18 based PSMA radiotracers.