Prostate-specific Membrane Antigen PET: Clinical Utility in Prostate Cancer, Normal Patterns, Pearls, and Pitfalls

Abstract

Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein that is overexpressed in prostate cancer. Radiolabeled small molecules that bind with high affinity to its active extracellular center have emerged as a potential new diagnostic standard of reference for prostate cancer, resulting in images with extraordinary tumor-to-background contrast. Currently, gallium 68 (Ga)-PSMA-11 (or HBED-PSMA) is the most widely used radiotracer for PSMA positron emission tomography (PET)/computed tomography (CT) or PSMA PET/magnetic resonance (MR) imaging. Evolving evidence demonstrates superior sensitivity and specificity of PSMA PET compared to conventional imaging, with frequent identification of subcentimeter prostate cancer lesions. PSMA PET is effective for imaging disease in the prostate, lymph nodes, soft tissue, and bone in a "one-stop-shop" examination. There is emerging evidence for its clinical value in staging of high-risk primary prostate cancer and localization of disease in biochemical recurrence. The high sensitivity provided by PSMA PET, with frequent identification of small-volume disease, is redefining patterns of disease spread compared with those seen at conventional imaging. In metastatic castration-resistant prostate cancer, PSMA PET is frequently used for theranostic selection (eg, lutetium 177-PSMA radionuclide therapy), but its potential use for therapy monitoring is still under debate. However, evidence on its proper use to improve patient-related outcomes, particularly in the setting of early biochemical recurrence and targeted treatment of oligometastatic disease, is still missing. Despite the term prostate specific, PSMA functions as a folate hydrolase and is expressed in a range of normal tissues and in other benign and malignant processes. Knowledge of its physiologic distribution and other causes of uptake is essential to minimize false-positive imaging findings. RSNA, 2018.

Voxel‐wise correlation of positron emission tomography/computed tomography with multiparametric magnetic resonance imaging and histology of the prostate using a sophisticated registration framework

“…The value of mpMRI is now well established for the early detection and local staging of prostate cancer. PSMA PET is a novel modality with high tumour‐to‐background contrast and there is an evolving role for staging patients with intermediate‐ or high‐risk prostate cancer . Hence, the combined use of mpMRI and PSMA PET imaging for biologically guided prostate focal therapy will provide the ultimate in precision medicine, enhancing the ability to accurately detect tumours and characterise intra‐tumoral heterogeneity.…”

qPSMA: Semiautomatic Software for Whole-Body Tumor Burden Assessment in Prostate Cancer Using 68Ga-PSMA11 PET/CT

“…Usually, manual corrections are necessary to delineate the intestine from abdominal PSMA ligand-positive lymph nodes and to remove false-positive uptake within structures with unspecific uptake, such as the aorta, esophagus, ureter, and rectum. Typical pitfalls in PSMA ligand PET imaging (e.g., celiac and other ganglia, adrenal glands) should be considered (20). Different tools, such as ''brush,'' ''erase,'' ''remove in contour,'' and ''remove whole structure,'' assist the user in manual corrections.…”

Initial evaluation of PET/CT with 18F‐FSU‐880 targeting prostate‐specific membrane antigen in prostate cancer patients

“…With the increasing number of patients examined with PSMA‐targeted probes, many pitfalls are emerging . In this study, we experienced abnormal uptakes in addition to known metastases in 3 cases.…”