Comparison between 68Ga-labelled PSMA and 18F-FDG PET/CT in the diagnostic value of clear cell renal cell carcinoma
Since the prostate-specific membrane antigen (PSMA) is highly expressed in the cell surface of the solid tumor microvasculature including renal cell carcinoma (RCC), PSMA PET/CT imaging has been a promising method for RCC diagnosis, especially for clear cell RCC (ccRCC) patients. 18F-FDG PET/CT of whole body imaging is widely used as a valuable method for evaluating metastatic or recurrent lesions in patients with RCC. The aim of this study was to compare the diagnostic value of ccRCC between 68Ga-labelled PSMA PET/CT and traditional 18F-FDG PET/CT.
Twelve patients with ccRCC were involved in the study in which 8 patients suffered from metastasis. All patients underwent both 68Ga-PSMA PET/CT and 18F-FDG PET/CT. SUVmax was calculated for both primary RCCs and PET-positive metastatic lesions. We compared the SUVmax of same lesions between 68Ga-PSMA PET/CT and 18F-FDG PET/CT images. Metastatic bone, lymph node and lung lesions as well as the primary tumor were evaluated respectively.
Primary ccRCC lesions were found in 7 patients. The SUVmax value of primary lesions in 68Ga-PSMA and 18F-FDG PET/CT were 15.34±3.82 and 8.62±3.11, respectively (P=0.012). 68Ga-PSMA was much more sensitive than 18F-FDG in bone (SUVmax: 35.64±5.78 vs. 3.52±1.63 )and lymph node(SUVmax: 43.26±8.53 vs. 16.79±4.68) lesions. However, PSMA based PET/CT was not sensitive for lung metastatic lesions compared to 18F-FDG PET/CT.
PSMA based PET/CT imaging provided great diagnostic value on RCC. Compared to traditional 18F-FDG PET/CT, PSMA was more sensitive in primary lesions, bone and lymph node metastasis. But PSMA PET/CT was not as good as 18FDG PET/CT for lung metastatic lesions.