Cancers and Benign Processes on ⁶⁸ Ga PSMA PET-CT Imaging Other than Prostate Cancer

Background  Imaging plays an important role in the evaluation of prostate cancer patients. In recent years, much attention has been focused on gallium 68 prostate-specific membrane antigen positron emission tomography-computed tomography ( ⁶⁸ Ga PSMA PET-CT) in prostate cancer patients and has been widely used for staging, restaging, and therapy response for these patients. The aim of this study was to report ⁶⁸ Ga PSMA PET-CT in other cancers and benign processes incidentally detected on ⁶⁸ Ga PSMA PET-CT in patients with prostate cancer. Materials and Methods  A total of 600 ⁶⁸ Ga PSMA PET-CT scans were performed for initial staging, restaging, detection of suspected recurrence, and therapy response in prostate cancer patients between December 2018 and June 2020. A total of 38 patients with histopathologically proven prostate cancer were included in the current study with other malignancies and benign processes. Mainly histopathology in most of cases and clinical and radiological follow-up in few cases after PET/CT scanning served as the standard of reference. Results  A total of 38 patients (age range: 52-85 years; mean age: 68.6) with prostate cancer final histopathology results were included in the study. A total of 51 lesion sites were evaluated in 38 patients. Forty-one lesion regions of these 51 regions were based on histopathological diagnosis, whereas 10 of them were based on clinical follow-up and conventional radiological follow-up as differential criteria. Thirty of 51 lesion regions were evaluated as malignant and 21 were benign lesions. The most common ⁶⁸ Ga PSMA ligand avid malignancy was lung adenocarcinoma (6/38). Conclusions  Prostate-specific membrane antigen (PSMA) is a cell surface glycoprotein and mainly expressed in prostate epithelium. ⁶⁸ Ga PSMA PET-CT imaging is very sensitive and specific imaging modality in prostate cancer patients. However, other malignancies and some benign processes may also have ⁶⁸ Ga PSMA ligand avidity and some prostate cancer metastases may imitate other malignancies.