[68Ga]Ga-PSMA Versus [18F]PSMA Positron Emission Tomography/Computed Tomography in the Staging of Primary and Recurrent Prostate Cancer. A Systematic Review of the Literature

In the past 10 yr, several agents based on prostate-specific membrane antigen (PSMA) for positron emission tomography imaging have been introduced in clinical practice for the management of patients with prostate cancer (PCa).To analyse the available data in the literature to clarify the advantages and disadvantages of [68Ga]Ga-PSMA and [18F]PSMA in different settings of PCa.A systematic literature search was made by using two main databases. Only studies published in the past 5 yr (2016-2021) in the English language with >20 enrolled patients were selected. Two reviewers independently appraised each article using a standard protocol. All the studies were analysed using a modified version of the Critical Appraisal Skills Programme checklist for diagnostic test studies.The systematic evaluation was made in 12 papers. Based on the quality assessment, the analysed studies demonstrated different methodologies. Three papers focused on the head-to-head comparison between 18F- and [68Ga]Ga-PSMA (n = 123 patients). A matched-pair comparison between 18F- and [68Ga]Ga-PSMA was reported in three papers, including 715 patients. The remaining papers used indiscriminately either 68Ga-PSMA or [18F]PSMA (n = 1.157 patients). [18F]PSMA-1007 is superior to [68Ga]Ga-PSMA-11 for the identification of local recurrence (less activity close to the bladder for [18F]PSMA-1007). Nonspecific/equivocal bone lesions are often recognised at [18F]PSMA-1007. [18F]DCFPyL is more reproducible for the identification of lymph nodes, and it shows fewer equivocal skeletal lesions and higher inter-reader agreement on skeletal lesions.Despite a large body of literature on PSMA radiopharmaceutical agents labelled with 68Ga or 18F, there are limited head-to-head or matched-pair comparative data. Certain clinical indications could trigger a preference, whilst caution is needed in interpreting potential false-positive findings, especially with [18F]PSMA-1007. Given the excellent performance of all accessible radiopharmaceuticals, the availability of specific tracers will likely guide choice.In this systematic review, we analysed the currently available literature focused on [68Ga] and [18F]-labelled prostate-specific membrane antigen. Our purpose is to identify which tracers would be correctly employed for the management of patients with prostate cancer.