Can Dynamic Whole-Body FDG PET Imaging Differentiate between Malignant and Inflammatory Lesions?

Background: Investigation of the clinical feasibility of dynamic whole-body (WB) [ 18 F]FDG PET, including standardized uptake value (SUV), rate of irreversible uptake (Ki), and apparent distribution volume (Vd) in physiologic tissues, and comparison between inflammatory/infectious and cancer lesions. Methods: Twenty-four patients were prospectively included to undergo dynamic WB [ 18 F]FDG PET/CT for clinically indicated re-/staging of oncological diseases. Parametric maps of Ki and Vd were generated using Patlak analysis alongside SUV images. Maximum parameter values (SUV max , Ki max , and Vd max ) were measured in liver parenchyma and in malignant or inflammatory/infectious lesions. Lesion-to-background ratios (LBRs) were calculated by dividing the measurements by their respective mean in the liver tissue. Results: Seventy-seven clinical target lesions were identified, 60 malignant and 17 inflammatory/infectious. Ki max was significantly higher in cancer than in inflammatory/infections lesions (3.0 vs. 2.0, p = 0.002) while LBRs of SUV max , Ki max , and Vd max did not differ significantly between the etiologies: LBR (SUV max ) 3.3 vs. 2.9, p = 0.06; LBR (Ki max ) 5.0 vs. 4.4, p = 0.05, LBR (Vd max ) 1.1 vs. 1.0, p = 0.18). LBR of inflammatory/infectious and cancer lesions was higher in Ki max than in SUV max (4.5 vs. 3.2, p < 0.001). LBRs of Ki max and SUV max showed a strong correlation (Spearman's rho = 0.83, p < 0.001). Conclusions: Dynamic WB [ 18 F]FDG PET/CT is feasible in a clinical setting. LBRs of Ki max were higher than SUV max . Ki max was higher in malignant than in inflammatory/infectious lesions but demonstrated a large overlap between the etiologies.