a prospective study on [68ga]-psma pet/ct imaging in newly diagnosed intermediate- and high-risk prostate cancer

Objective(s): prostate-specific membrane antigen (psma) ligand positron emission tomography/computed tomography (pet/ct) is an emerging modality to detect metastatic disease in patients with prostate cancer (pca). this prospective study aimed to evaluate the role of [68ga]-psma pet/ct in the initial workup of intermediate and high-risk pca. methods: twenty-five patients with newly transrectal ultrasound biopsy-proven, untreated intermediate- and high-risk pca (mean age, 68.5±6.2 years; range 55–83 years) were enrolled in this prospective study between september 2018 and june 2020 and underwent a [68ga]-psma pet/ct examination. all images were analyzed both visually and semiquantitatively by measuring the maximum standardized uptake value (suvmax) of the primary prostatic tumor and metastatic lesions. the diagnostic sensitivity of [68ga]-psma pet/ct for the diagnosis of pca was established by histopathology as the reference standard. the associations between suvmax of the primary tumors and prostate-specific antigen (psa) levels, gleason scores (gss), and metastatic extent of the disease were studied.results: all patients had a positive [68ga]-psma pet/ct exam. seventeen patients (58%) showed [68ga]-psma avidity in both prostate lobes and 8 (32%) had unilateral uptake. suvmax in the primary tumor significantly correlated with serum psa values (r=0.57, p=0.003). psma pet/ct depicted regional lymph node metastases in 32% of patients, distant lymph node metastases in 20%, osseous metastases in 16% and pulmonary metastases in 8% of patients. sixty percent of psma-positive bone metastases and 21.4% of intraprostatic tumoral lesions were missed on the contemporaneous bone scintigraphy and magnetic resonance imaging, respectively. conclusion: [68ga]-psma pet/ct shows promise as a valuable imaging modality with high diagnostic sensitivity in the setting of intermediate and high-risk pca. moreover, the suvmax of the primary tumor has a positive correlation with psa levels at the time of the scan.