LAUSR

OBJECTIVE In this study, we aimed to compare the role of 68Ga-labeled FAP inhibitor (68Ga-FAPI)-04 PET/computed tomography (CT) and 18F-fluorodeoxyglucose (18F-FDG) PET/CT in the evaluation of primary tumor and metastases in patients diagnosed with malignant mesothelioma. MATERIALS AND METHODS Our prospective study included 21 patients with histopathological diagnosis of malignant mesothelioma who underwent both 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT imaging between April 2022 and September 2022. Maximum standardized uptake value (SUVmax), metabolic tumor volume, total lesion glycolysis, tumor-to-background ratio (TBR) and highest SUVpeak (HPeak) values and lesion numbers were calculated from primary and metastatic lesions on FDG and FAPI PET/CT images. Findings obtained from FAPI and FDG PET/CT were compared. RESULTS More lesions were detected in 68Ga-FAPI-04 PET/CT compared to 18F-FDG PET/CT in primary tumor and lymph node metastases. Statistically significantly higher SUVmax and TBR values were found with FAPI PET/CT (primary lesion SUVmax and TBR, P = 0.001 and P < 0.001, respectively; lymph node SUVmax and TBR, P = 0.016 and P = 0.005, respectively). With FAPI PET/CT, upstage was observed according to tumor-node-metastasis staging in a total of seven patients including three patients with pleural origin, three patients with peritoneal origin and one patient with pericardial origin. CONCLUSION In addition to the stage change with 68Ga-FAPI-04 PET/CT in malignant mesothelioma patients, a statistically significant superiority was observed in SUVmax, TBR and volumetric parameters in primary tumors and metastases.