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

Abstract

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.