Prostate Specific Membrane Antigen Targeted ¹⁸F-DCFPyL Positron Emission Tomography/Computerized Tomography for the Preoperative Staging of High Risk Prostate Cancer: Results of a Prospective, Phase II, Single Center Study

Purpose We prospectively evaluated the diagnostic performance of prostate specific membrane antigen targeted ¹⁸F-DCFPyL positron emission tomography/computerized tomography in the preoperative staging of men at high risk for harboring metastatic prostate cancer despite a negative conventional staging evaluation. Materials and Methods Men with clinically localized high or very high risk prostate cancer were imaged with ¹⁸F-DCFPyL positron emission tomography/computerized tomography before undergoing radical prostatectomy with standardized pelvic lymph node dissection. The scans were interpreted by 2 blinded nuclear medicine readers and assessed for interreader variability as well as diagnostic accuracy for pelvic lymph node staging. Surgical pathology served as the reference standard to which ¹⁸F-DCFPyL scan findings were compared. Results A total of 25 men contributed analyzable data to this study. Seven of these patients (28%) were found to have 1 or more positive lymph nodes on surgical pathology. Sites of radiotracer uptake were identified in the prostate of all imaged patients. The 2 readers identified the same number of prostatic lesions in 22 patients (88%), of whom all had at least 1 intraprostatic lesion in common between the 2 reads. Additionally, the readers assigned the same N stage to 46 of 50 individual lymph node packets (92%). Following reconciliation of the relatively few discordant imaging reads, 7 patients (28%) were found to have 1 or more sites of radiotracer uptake in the pelvis consistent with N1 disease, resulting in 71.4% sensitivity (95% CI 29.0–96.3) and 88.9% specificity (95% CI 65.3–98.6). Analysis at the level of individual nodal packets resulted in 66.7% sensitivity (95% CI 29.9–92.5) and 92.7% specificity (95% CI 80.1–98.5). Three men (12%) had evidence of M1a disease. Conclusions ¹⁸F-DCFPyL positron emission tomography/computerized tomography allowed for accurate detection of prostate cancer sites in men believed to have clinically localized disease based on conventional imaging. Our results support the need for a larger study to more precisely define the diagnostic accuracy of this novel molecular imaging test.