Demonstrating Intertumoural Differences in Vascular-Metabolic Phenotype with Dynamic Contrast-Enhanced CT-PET

Purpose. To assess whether the differences in vascular-metabolic relationships between lymphoma masses and colorectal liver metastases predicted from previous histopathological studies can be demonstrated by dynamic contrast-enhanced CT (DCE-CT) combined with fluorodeoxyglucose positron emission tomography (FDG-PET). Methods. DCE-CT and FDG-PET studies were drawn from an imaging archive for patients with either lymphoma masses (n = 11) or hepatic metastases from colorectal cancer (CRM: n = 12). Tumour vascularity was assessed using DCE-CT measurements of perfusion. Tumour glucose metabolism was expressed as the mean FDG Standardised Uptake Value (SUV(FDG)). The relationship between metabolism and vascularity in each group was assessed from SUV(FDG) /perfusion ratios and Pearson correlation coefficients. Results. An SUV(FDG) threshold of 3.0 was used to designate lymphoma masses as active (AL, n = 6) or inactive lymphoma (IL, n = 5). Tumour perfusion was significantly higher in AL (0.65 mL/min/mL) than CRM (0.37 mL/min/mL: P = .031) despite similar SUV(FDG) (5.05 and 5.33, resp.). AL demonstrated higher perfusion values than IL (0.24 mL/min/mL: P = .006). SUV(FDG)/perfusion was significantly higher in CRM (15.3 min) than IL (4.2 min, P < .01). There was no correlation between SUV(FDG) and perfusion for any patient group.