Diagnostic accuracy of Ga-68-PSMA-11 PET/CT in patients with recurrent prostate cancer

Ziel/Aim The high sensitivity of Ga-68-PSMA-11 PET/CT has been shown in numerous studies. Recently, many case reports have been published describing various benign and malignant entities exhibiting PSMA-ligand uptake. The present evaluation was performed in order to further analyze the positive predictive value of Ga-68-PSMA-11 PET/CT.

Methodik/Methods A retrospective analysis was performed for all patients who underwent Ga-68-PSMA-11 PET/CT between January 2017 and March 2019 at our institute in order to detect recurrent PC (n = 523). Hitherto, 76 patients were identified who had received radiation therapy, histology or surgical removal of PSMA-positive lesions, enabling a comparison with PSMA-avidity in the previous PET/CT.

Ergebnisse/Results So far, 83 PSMA-positive lesions in the 76 patients have undergone external radiation, were biopsied or surgically removed. 78 of them (94%) were true-positive PC lesions (proven by falling PSA following external radiation or by histology). Amongst the mentioned lesions were 42 local relapses, 11 lymph node metastases and 25 distant metastases.

Schlussfolgerungen/Conclusions Our analysis demonstrates the high positive predictive value of Ga-68-PSMA-11 PET/CT. To our conviction, PSMA-positive lesions with a CT-correlate in patients with recurrent PC can be classified as PC lesions with high confidence. Although uptake of PSMA-ligands in various non-prostatic tissues have been described, it must be assumed that their numbers represent only a fraction of the overwhelming numbers of PC lesions detected daily in clinical practice by Ga-68-PSMA-11 PET/CT worldwide.