Prospective Comparison of 18F-DCFPyL PET/CT with 18F-NaF PET/CT for Detection of Skeletal Metastases in Biochemically Recurrent Prostate Cancer

1584 Objectives: 18F-DCFPyL is a promising 18F-labeled agent for PSMA PET imaging, available at our institution through a research access program. Here we compared 18F-DCFPyL PET/CT and 18F-NaF PET/CT for the detection of skeletal metastases in patients with biochemically recurrent prostate cancer (BCR PC). Methods: We prospectively enrolled 50 patients (52-91 years old, 71.2 ± 7.4 years) who had 18F- DCFPyL PET/CT at BCR PC after definitive treatment with prostatectomy (30 patients) and/or radiation therapy (20 patients). A total of 16 of the 50 patients (63-86 years old, 73.6 ± 5.9 years) also had 18F-NaF PET/CT for identification of bone metastases. Up to 7 bone lesions were recorded per patient for each tracer. Results: Three patients did not have bone metastases. A total of 41 skeletal lesions were found. 18F DCFPyL PET/CT identified 32 bone lesions (78%) and 18F NaF PET/CT identified 35 lesions (85.4%). Congruent findings between 18F-DCFPyL and 18F NaF were found in 26/41 (63.4%) lesions. 18F DCFPyL identified 1 lesion missed on 18F NaF in 4 participants (4/41, 9.8%). However, 18F DCFPyL was negative in 2 patients with lesions found on 18F NaF (4/41 lesions, 9.8%). CT alone identified 21 lesions (51.2%). Conclusions: The performance of 18F DCFPyL PET/CT for detecting bone metastases is similar to that of 18F NaF PET/CT. Taken together with the accuracy of 18F-DCFPyL PET/CT in the detection of non-bone metastases and disease at low PSA presented separately, 18F DCFPyL PET/CT may be used as a “one stop shop” for evaluation of patients with BCR PC. However, more patients have to be evaluated to support these findings.