Matched‐pair comparison of 18F‐DCFPyL PET/CT and 18F‐PSMA‐1007 PET/CT in 240 prostate cancer patients; Inter‐reader agreement and lesion detection rate of suspected lesions.

Abstract

Introduction Tens of different Prostate Specific Membrane Antigen (PSMA) targeting radiopharmaceuticals for both imaging and therapy have been synthesized. Although variability in biodistribution and affinity for binding to the PSMA receptor between different PSMA targeting radiopharmaceuticals are known, little is known about the clinical implications of those variabilities. Therefore, in this study differences in inter-reader agreement and detection rate between two regularly used 18F‐labeled PSMA‐receptor targeting radiopharmaceuticals [18F]‐DCFPyL and [18F]‐PSMA‐1007 were analyzed. Material and methods One hundred and twenty consecutive patients scanned with [18F]‐PSMA‐1007 were match‐paired with 120 patients scanned with [18F]‐DCFPyL. All 240 PET/CTs were reviewed by two readers and scored according to PSMA‐RADS reading criteria for PSMA PET/CT. Inter‐reader agreement and detection rate of suspected lesions were scored for different anatomical locations including prostate/prostatic fossa, lymph nodes, bone, and other locations. Results Large equality between [18F]‐DCFPyL and [18F]‐PSMA‐1007 was found; however, some clinically relevant and statistically significant differences were observed. [18F]‐PSMA‐1007 detected suspected prostatic/prostatic fossa lesions in a higher proportion of patients and especially in the subcohort of patients scanned for biochemical recurrence. [18F]‐DCFPyL and [18F]‐PSMA‐1007 showed equal ability for detection of suspected lymph nodes, although inter‐reader agreement for [18F]‐DCFPyL was higher. [18F]-DCFPyL showed less equivocal skeletal lesions and higher inter‐reader agreement for skeletal lesions. The majority of equivocal lesions found with PSMA‐1007 (at least were determined to be aof non-metastatic origin. Conclusion Clinically relevant differences, which may account for diagnostic dilemmas, were observed between of [18F]‐DCFPyL and [18F]‐PSMA‐1007. Those findings encourage further studies, as they may have consequences for selection of the proper PSMA targeting radiopharmaceutical.