The characteristics of renal cell carcinoma in F-18 FDG PET/CT: Relation to TNM staging, grading and other renal malignant neoplasm

Objectives The main objective of this study is to assess the tumor glucose metabolism according to tumor staging, grading and to compared with other renal malignant tumor, such as transitional cell carcinoma and renal metastasis.

Methods From June 2006 to August 2009, we studied 43 patients who were diagnoses as having renal cell carcinoma (RCC, n=27, age=64.6±10.1 years), transitional cell carcinoma (TCC, n=3, age=73±2.6 years) and renal metastasis (n=13, age=64.8±8.1 years). All patients were performed preoperative F-18 FDG PET/CT. F-18 FDG PET/CT images were qualitatively and semiquantitatively evaluated.

Results Among the 27 patients with RCC, 18 patients were confirmed by radical nephrectomy(16: clear cell type, 2: chromophobe cell type). The 13 patients with renal metastasis had proven malignancy as follow: lung cancer (n=12, 8: squamous cell carcinoma, 3: adenocarcinoma, 1: large cell undifferentiated carcinoma), thyroid cancer (n=1). In qualitative analyses of RCC, of the 27 RCC lesions, 16 lesions (59.3%) showed an isometabolism (equal to the renal parenchyma, SUVmax=3.06±0.45), 9 lesions (33.3%) showed a hypermetabolism (increased uptake compared with the renal parenchyma, SUVmax=7.70±3.48) and 2 lesions (7.4%) showed a hypometabolism (less than renal parenchyma, SUVmax=1.61±0.22). In semiquantitative analyses of RCC, significant differences were noted in SUVmax of lesions according to the primary tumor size (p=0.01) and TNM staging (p=0.008), but tumor grade was not significant (p=0.4). TCC (SUVmax=10.25±2.01) and renal metastasis (SUVmax=9.12±3.30) showed high glucose metabolism and significant difference were noted in SUVmax of lesions compared with RCC (p<0.05).

Conclusions In F-18 FDG PET/CT imaging, majority of the RCC showed isometabolism. There was significant differences in SUVmax between the lesions grouped by tumor size and TNM staging, but not in tumor grade. Unlike RCC, TCC and renal metastasis were noted high glucose metabolism