Accurate staging in prostate cancer is key to planning initial treatments. In patients who undergo radical prostatectomy, the presence of pelvic lymph node metastases at time of surgery is correlated with biochemical failure.¹ However, conventional imaging used for staging, including computed tomography (CT), bone scan, and magnetic resonance imaging (MRI), is limited for the detection of metastatic disease, especially for nodal disease.² Therefore, improved detection of metastatic disease prior to definitive therapy is needed.

Rationale: The development of consensus guidelines for interpretation of Prostate-Specific Membrane Antigen (PSMA)-Positron Emission Tomography (PET) is needed to provide more consistent reports in clinical practice. The standardization of PSMA-PET interpretation may also contribute to increasing the data reproducibility within clinical trials. Finally, guidelines in PSMA-PET interpretation are needed to communicate the exact location of findings to referring physicians, to support clinician therapeutic management decisions. Methods: A panel of worldwide experts in PSMA-PET was established. Panelists were selected based on their expertise and publication record in the diagnosis or treatment of PCa, in their involvement in clinical guidelines and according to their expertise in the clinical application of radiolabeled PSMA inhibitors. Panelists were actively involved in all stages of a modified, nonanonymous, Delphi consensus process. Results: According to the findings obtained by modified Delphi consensus process, panelist recommendations were implemented in a structured report for PSMA-PET. Conclusions: The E-PSMA standardized reporting guidelines, a document supported by the European Association of Nuclear Medicine (EANM), provide consensus statements among a panel of experts in PSMA-PET imaging, to develop a structured report for PSMA-PET in prostate cancer and to harmonize diagnostic interpretation criteria.

Background: Target volume delineations for prostate cancer (PCa) salvage radiotherapy (SRT) after radical prostatectomy are usually drawn in the absence of visibly recurrent disease. Gallium-68 Prostate Specific Membrane Antigen Positron Emission Tomography/Computed Tomography (⁶⁸Ga-PSMA-11 PET/CT) detects recurrent PCa with sensitivity superior to standard of care imaging at serum prostate specific antigen (PSA) values low enough to impact target volume delineations for routine SRT. Objective: To i) map the recurrence pattern of PCa early biochemical recurrence (BCR) after radical prostatectomy with ⁶⁸Ga-PSMA-11 PET/CT in patients with serum PSA levels <1 ng/ml, ii) determine how often consensus clinical target volumes (CTV) based on the Radiation Therapy Oncology Group (RTOG) guidelines cover ⁶⁸Ga-PSMA-11 PET/CT-defined disease, and iii) assess the potential impact of ⁶⁸Ga-PSMA-11 PET/CT on SRT. Patients and Methods: This is a post-hoc analysis of an intention-to-treat population of 270 patients who underwent ⁶⁸Ga-PSMA-11 PET/CT at 4 institutions for BCR after prostatectomy without prior radiotherapy at PSA<1 ng/mL. RTOG consensus CTV that included both the prostate bed and pelvic lymph nodes were contoured on the CT dataset of the PET/CT by a radiation oncologist blinded to the PET component. ⁶⁸Ga-PSMA-11 PET/CT images were analyzed by a nuclear medicine physician. PSMA-positive lesions not covered by planning volumes based on the consensus CTV were considered to have a major potential impact on treatment planning. Results: The median PSA at the time of ⁶⁸Ga-PSMA-11 PET/CT was 0.48 ng/ml (range 0.03-1). One-hundred-thirty-two/270 patients (49%) had a positive ⁶⁸Ga-PSMA-11 PET/CT. Fifty-two/270 (19%) had at least one PSMA-positive lesion not covered by the consensus CTV. Thirty-three/270 (12%) had extra-pelvic PSMA-positive lesions and 19/270 (7%) had PSMA-positive lesions within the pelvis but not covered by consensus CTV. The two most common ⁶⁸Ga-PSMA-11 PET-positive lesion locations outside the consensus CTV were bone (23/52, 44%) and perirectal lymph nodes (16/52, 31%). Conclusion: Post-hoc analysis of ⁶⁸Ga-PSMA-11 PET/CT implies a major impact on SRT planning in 52/270 patients (19%) with PCa early BCR (PSA<1.0 ng/ml). This justifies a randomized imaging trial of SRT with or without ⁶⁸Ga-PSMA-11 PET/CT investigating its potential benefit on clinical outcome.