Assessment of cell proliferation in renal cell carcinoma using dual-phase ¹⁸F-fluorodeoxyglucose PET/CT

The present study aimed to examine the association between ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake and cell proliferation markers; in addition, the correlation between ¹⁸F-FDG uptake and biological characteristic in patients with renal cell carcinoma (RCC) was investigated using dual-phase ¹⁸F-FDG-positron emission tomography/computed tomography (PET/CT). Dual-phase ¹⁸F-FDG PET/CT was performed on 31 RCC patients and the maximum standardized uptake values at 1 h (SUV1) and 2 h (SUV2) as well as the retention index (RI; %) in the primary tumors were calculated. Monoclonal antibodies for Ki-67, minichromosome maintenance 2 (MCM2) and topoisomerase II α (topo II α) were used to assess the expression levels of their respective proteins in excised tumor tissue using immunohistochemistry. The results demonstrated that RI and SUV2 in patients with Stage I/II + grade 1 (G1) RCC were significantly decreased compared with all patients with other stages/grades (RI, P=0.0065; SUV2, P=0.043); in addition, significantly increased uptake and RI were detected in patients with metastases compared with patients without metastases (SUV1, P=0.029; SUV2, P=0.0003; RI, P<0.001). All proliferation markers significantly correlated with RI (Ki-67, r=0.501, P=0.004; MCM2, r=0.359, P=0.047; topo II α, r=0.402, P=0.024), while SUV1 and SUV2 correlated with Ki-67 only. In conclusion, the results of the present study demonstrated that dual-phase ¹⁸F-FDG-PET/CT was more useful for predicting cell proliferation in RCC compared with single-phase imaging alone. However, follow-ups are required in order to determine whether dual-phase ¹⁸F-FDG-PET/CT provides independent prognostic information.