Matched-Pair Comparison of F-DCFPyL PET/CT and F-PSMA-1007 PET/CT in 240 Prostate Cancer Patients: Interreader Agreement and Lesion Detection Rate of Suspected Lesions.

Over 20 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 is known to exist between different PSMA-targeting radiopharmaceuticals, little is known about the clinical implications of this variability. Therefore, this study analyzed differences in interreader agreement and detection rate between 2 regularly used F-labeled PSMA receptor-targeting radiopharmaceuticals: F-DCFPyL and F-PSMA-1007. One hundred twenty consecutive patients scanned with F-PSMA-1007 were match-paired with 120 patients scanned with F-DCFPyL. All 240 PET/CT scans were reviewed by 2 readers and scored according to the criteria of the PSMA Reporting and Data System. Interreader agreement and the detection rate for suspected lesions were scored for different anatomic locations such as the prostate, prostatic fossa, lymph nodes, and bone. Great equality was found between F-DCFPyL and F-PSMA-1007; however, some clinically relevant and statistically significant differences were observed. F-PSMA-1007 detected suspected prostatic or prostatic fossa lesions in a higher proportion of patients and especially in the subcohort scanned for biochemical recurrence. F-DCFPyL and F-PSMA-1007 showed an equal ability to detect suspected lymph nodes, although interreader agreement for F-DCFPyL was higher. F-DCFPyL showed fewer equivocal skeletal lesions and higher interreader agreement on skeletal lesions. Most of the equivocal lesions found with F-PSMA-1007 at least were determined to be of nonmetastatic origin. Clinically relevant differences, which may account for diagnostic dilemmas, were observed between F-DCFPyL and F-PSMA-1007. Those findings encourage further studies, as they may have consequences for selection of the proper PSMA-targeting radiopharmaceutical.