Abstract
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Objectives The role of 18F-fluorodeoxyglucose (18F-FDG)-positron emission tomography (PET)/computed tomography (CT) for renal cell carcinoma (RCC) diagnosis has not been clearly defined; only a limited number of patients have been studied so far. We evaluated the usefulness of early dynamic (ED) 18F-FDG PET/CT and the current standard protocol for RCC diagnosis.
Methods One hundred patients (107 tumors) underwent kidney ED 18F-FDG PET/CT for 10 minutes, starting with 18F-FDG (3.5 MBq/kg, bolus injection). Four frames at 15-second intervals followed by 9 frames at 60-second intervals were reconstructed (ED phase). Whole body (WB) was scanned 75 minutes after injection (WB phase). In visual evaluation, tumor uptake higher than aorta was judged as positive. Maximum standardized uptake values (SUVmax) of RCC and the tumor-to-normal tissue ratio (TNR) were determined. Using these indicators and quantitative visual assessment, we compared histological type (clear cell carcinoma, CCC; non-clear cell carcinoma, N-CCC), Fuhrman grade (high grade group, grade3-4; low grade group, grade1-2), stage (high stage groups, stage 3-4; low stage group, stage1-2), and with/without microscopic venous (V) and lymphatic (Ly) invasion in the ED and WB phases.
Results One hundred consecutive patients (107 tumors) underwent ED 18F-FDG PET/CT (90, CCC; 17, N-CCC). Visually, there were statistically significant differences (P < .05) in high grade, high stage, and presence of V and Ly invasion between the positive and negative RCC WB-phase groups. In the ED phase, SUVmax was significantly higher for CCC than for N-CCC (12.8 ± 5.8 vs. 6.9 ± 3.8). In the WB phase, there was no significant difference in histological type between the two groups, but SUVmax and TNRs were higher in the patients with high grade, high stage, and V and Ly invasion than the other patients (P < .05).
Conclusions Findings from 18F-FDG-PET/CT that included ED-phase imaging were useful for diagnosis of histological type, stage, grade, and V and Ly invasion in RCC patients.