aPROMISE: A Novel Automated PROMISE Platform to Standardize Evaluation of Tumor Burden in 18F-DCFPyL Images of Veterans with Prostate Cancer.

Standardized staging and quantitative reporting are necessary to demonstrate the association of 18F-DCFPyL PET/CT imaging with clinical outcome. This work introduces an automated platform, aPROMISE, to implement and extend the Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) criteria. The objective is to validate the performance of aPROMISE in staging and quantifying disease burden in patients with prostate cancer who undergo prostate-specific antigen (PSMA) imaging. Methods: This was a retrospective analysis of 109 veterans with intermediate- or high-risk prostate cancer who underwent PSMA imaging. To validate the performance of aPROMISE, 2 independent nuclear medicine physicians conducted aPROMISE-assisted reads, resulting in standardized reports that quantify individual lesions and stage the patients. Patients were staged as having local disease only (miN0M0), regional lymph node disease only (miN1M0), metastatic disease only (miN0M1), or both regional and distant metastatic disease (miN1M1). The staging obtained from aPROMISE-assisted reads was compared with the staging by conventional imaging. Cohen pairwise κ-agreement was used to evaluate interreader variability. Correlation coefficients and intraclass correlation coefficients were used to evaluate the interreader variability of the quantitative assessment (molecular imaging PSMA [miPSMA] index) at each stage. Kendall tau and t testing were used to evaluate the association of miPSMA index with prostate-specific antigen and Gleason score. Results: All PSMA images of 109 veterans met the DICOM conformity and the requirements for the aPROMISE analysis. Both independent aPROMISE-assisted analyses demonstrated significant upstaging in patients with localized (23%, n = 20/87) and regional (25%, n = 2/8) tumor burden. However, a significant number of patients with bone metastases identified on conventional imaging (18F-NaF PET/CT) were downstaged (29%, n = 4/14). The comparison of the 2 independent aPROMISE-assisted reads demonstrated a high κ-agreement: 0.82 for miN0M0, 0.90 for miN1M0, and 0.77 for miN0M1. The Spearman correlation of quantitative miPSMA index was 0.93, 0.96, and 0.97, respectively. As a continuous variable, miPSMA index in the prostate was associated with risk groups defined by prostate-specific antigen and Gleason score. Conclusion: We demonstrated the consistency of the aPROMISE platform between readers and observed substantial upstaging in PSMA imaging compared with conventional imaging. aPROMISE may contribute to broader standardization of PSMA imaging assessment and to its clinical utility in the management of prostate cancer patients.

Prostate-specific Membrane Antigen PET in Prostate Cancer.

Prostate-specific membrane antigen (PSMA)-targeted radiopharmaceuticals are playing a large role at the time of initial staging and biochemical recurrence for localizing prostate cancer, as well as in other emerging clinical settings. PSMA PET has demonstrated increased detection rate compared with conventional imaging and has been shown to change management plans in a substantial percentage of cases. The aims of this narrative review are to highlight the development and clinical impact of PSMA PET radiopharmaceuticals, to compare PSMA to other agents such as fluorine 18 fluciclovine and carbon 11 choline, and to highlight some of the individual PSMA PET agents that have contributed to the advancement of prostate cancer imaging.