Evaluation of qualitative and quantitative PET parameters in primary prostate cancer patients: double-match comparison of 18F-flotufolastat- and 68Ga-PSMA-11-PET

Abstract

Abstract Purpose To qualitatively and quantitatively compare 18 F-flotufolastat-PET and 68 Ga-PSMA-11-PET urinary and lesion activity in a matched cohort of primary prostate cancer patients. Methods Data from patients who underwent 18 F-flotufolastat-PET or 68 Ga-PSMA‑11-PET (n=62 each) were cohort-matched by disease characteristics. An experienced nuclear medicine physician assessed radiopharmaceutical activity retained in the bladder using a three-point qualitative scale (0 [none]/1 [moderate]/2 [severe]), and conducted a semi-quantitative analysis of retention in the bladder (0mean/max ) were performed, and tumor-to-bladder ratios calculated and compared using Mann-Whitney-U-Tests. Results Overall interference from bladder activity was significantly greater with 68 Ga-PSMA-11-PET than 18 F-flotufolastat-PET (scores=0, 1 and 2 were n=47, n=10 and n=5 for 68 Ga-PSMA-11-PET, and n=60, n=2 and n=0 for 18 F-flotufolastat-PET; p =0.0006). Median bladder retention score was 2 for 68 Ga-PSMA-11-PET and 0 for 18 F-flotufolastat-PET. 18% (3/17) and 0% (0/24) of primary tumors located near the bladder could not be differentiated from bladder retention in 68 Ga-PSMA-11-PET and 18 F-flotufolastat-PET, respectively. Ureter retention was present in 21% (13/62) 68 Ga-PSMA-11-PET and 0% (0/62) 18 F-flotufolastat-PET. Twenty-three 68 Ga-PSMA-11-PET showed halo artifacts vs 4 18 F-flotufolastat-PET scans. Median SUV max in the bladder was 7.4 for 68 Ga-PSMA-11-PET and 3.3 for 18 F-flotufolastat-PET ( p p =0.1338). Resulting tumor-to-bladder ratios were significantly lower for 68 Ga-PSMA-11-PET ( p Conclusions 68 Ga-PSMA-11-PET was significantly more impacted by bladder activity than 18 F-flotufolastat-PET.