A Prospective Study on [۶۸Ga]-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 [۶۸Ga]-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, ۶۸.۵±۶.۲ years; range ۵۵–۸۳ years) were enrolled in this prospective study between September ۲۰۱۸ and June ۲۰۲۰ and underwent a [۶۸Ga]-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 [۶۸Ga]-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 [۶۸Ga]-PSMA PET/CT exam. Seventeen patients (۵۸%) showed [۶۸Ga]-PSMA avidity in both prostate lobes and ۸ (۳۲%) had unilateral uptake. SUVmax in the primary tumor significantly correlated with serum PSA values (r=۰.۵۷, P=۰.۰۰۳). PSMA PET/CT depicted regional lymph node metastases in ۳۲% of patients, distant lymph node metastases in ۲۰%, osseous metastases in ۱۶% and pulmonary metastases in ۸% of patients. Sixty percent of PSMA-positive bone metastases and ۲۱.۴% of intraprostatic tumoral lesions were missed on the contemporaneous bone scintigraphy and magnetic resonance imaging, respectively.Conclusion: [۶۸Ga]-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.

Keywords:

Prostate cancer , PSMA PET/CT , Primary staging