The role of dual tracer PSMA and [18F]FDG PET/CT in primary renal tumors.

BACKGROUND: In this study, we compared the diagnostic performances of [¹⁸F]FDG PET/CT and [⁶⁸Ga]Ga-PSMA PET/CT in the evaluation of primary kidney tumors. MATERIAL AND METHODS: Preoperative dual-tracer PET/CT imaging was performed on patients with kidney tumors. Demographic data and pathological parameters were obtained. SUVmax and the tumor-to-background ratio (TBR) of primary renal tumor were calculated on both PET/CT images. Patients were divided into two groups based on the concordance of [¹⁸F]FDG PET/CT and [⁶⁸Ga]Ga-PSMA PET/CT: concordant negative (no PSMA or FDG uptake) and concordant positive (PSMA-FDG uptake). The concordant positive group was divided into three groups: high PSMA (PSMA > FDG), high FDG (FDG > PSMA), and PSMA = FDG. RESULTS: Of the 12 patients included in the study, 11 (91.7%) were male and 1 (8.3%) was female. The mean age was 59.5 ± 15.21 (31-82) years. Pathological evaluation revealed oncocytoma in 2 patients (16.7%) and renal cell carcinoma in 10 patients (83.3%). In the correlation analysis, a very weak negative relationship was found between SUVmaxpFDG and SUVmaxpPSMA (p = 0.463; r = -0.246), while a strong positive relationship was found between TBRFDG and TBRPSMA (p = 0.007; r = 0.755). Metastasis was detected in 3 patients (25%) (tumor embolism in one patient and lung metastasis in two patients). Two patients (16.7%) were in the concordant negative group and 10 patients (83.3%) were in the concordant positive group. CONCLUSIONS: For PET imaging in RCC, [⁶⁸Ga]Ga-PSMA PET/CT is compatible with [¹⁸F]FDG PET/CT; these two examinations can be used together. [⁶⁸Ga]Ga-PSMA expression in lesions is higher than [¹⁸F]FDG uptake. However, due to the high renal uptake in both examinations, the use of TBR will be more accurate than SUVmax.