68Ga-PSMA PET/CT and Prostate Cancer Diagnosis: Which SUVmax Value?

ABSTRACT

BACKGROUND/AIM: To evaluate the diagnostic accuracy of 68Ga-prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) in the diagnosis and staging of prostate cancer (PCa). PATIENTS AND METHODS: From January 2021 to December 2022, 160 men (median age 66 years) with PCa (median PSA of 11.7 ng/ml) before prostate biopsy underwent 68Ga-PET/CT imaging examinations (Biograph 6; Siemens, Knoxville, TN, USA). The location of focal uptake on 68Ga-PSMA PET/TC and standardized uptake values (SUVmax) were reported on a per-lesion basis for each International Society of Urological Pathology (ISUP) grade group (GG) PCa. RESULTS: Overall, the median intraprostatic 68Ga-PSMA SUVmax was 26.1 (range=2.7-164); in the 15 men with not clinically significant PCa (ISUP grade group 1) median SUVmax was 7.5 (range=2.7-12.5). In the 145 men with csPCa (ISUP GG≥2) median SUVmax was 33 (range=7.8-164). A SUVmax cut-off of 8 demonstrated a diagnostic accuracy in the diagnosis of PCa equal to 87.7% vs. 89.3% vs. 100% in the presence of a GG1 vs. GG2 vs. GG≥3 PCa, respectively. In addition, median SUVmax in the bone and node metastases was 52.7 (range=25.3-92.8) and 47 (range=24.5-65), respectively. CONCLUSION: 68GaPSMA PET/CT with a SUVmax cut-off of 8 demonstrated a good accuracy in the diagnosis of csPCa (100% in the presence of GG≥3) showing a good cost-benefit ratio as a single procedure for the diagnosis and staging of high-risk PCa.