Correlation of intra-tumor 18F-FDG uptake heterogeneity indices with perfusion CT derived parameters in colorectal cancer.

Florent Tixier,Pierre Ingrand,Ashley M Groves,Vicky Goh,Catherine Cheze Le Rest,Dimitris Visvikis,Mathieu Hatt,Chin-Tu Chen

doi:10.1371/journal.pone.0099567

Abstract

Application of textural features analysis to 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) images has been used to characterize intra-tumor uptake heterogeneity and has been shown to reflect disease outcome. A current hypothesis is that 18F-FDG uptake heterogeneity may reflect the physiological tracer uptake related to tumor perfusion. The purpose of our study was to investigate the correlations between intra-tumor uptake heterogeneity and vascular parameters derived from dynamic contrast enhanced (DCE) computed tomography (CT) obtained from an integrated 18F-FDG PET/perfusion CT examination.MethodsThirty patients with proven colorectal cancer prospectively underwent integrated 18F-FDG PET/DCE-CT to assess the metabolic-flow phenotype. Both CT blood flow parametric maps and PET images were analyzed. Correlations between PET heterogeneity and perfusion CT were assessed by Spearman's rank correlation analysis.ResultsBlood flow visualization provided by DCE-CT images was significantly correlated with 18F-FDG PET metabolically active tumor volume as well as with uptake heterogeneity for patients with stage III/IV tumors (|ρ|:0.66 to 0.78; p-value<0.02).ConclusionThe positive correlation found with tumor blood flow indicates that intra-tumor heterogeneity of 18F-FDG PET accumulation reflects to some extent tracer distribution and consequently indicates that 18F-FDG PET intra-tumor heterogeneity may be associated with physiological processes such as tumor vascularization.

Highlights

Colorectal cancer is associated with high morbidity, with a 5year survival of below 50% for rectal cancer [1]
Our study is the first to evaluate the correlation between positron emission tomography (PET) 18F-FDG uptake heterogeneity patterns and computed tomography (CT) perfusion parameters which have previously shown to reflect tumor vascularization and aggressiveness [31]
Several previous studies have in the past investigated the metabolism-perfusion correlation, comparing standard 18F-FDG PET image derived parameters providing a global tumor assessment (SUVmean, SUVmax) and various perfusion CT parameters

Summary

Introduction

Colorectal cancer is associated with high morbidity, with a 5year survival of below 50% for rectal cancer [1]. 18F-FDG PET is becoming an increasingly established imaging modality in colorectal cancer for staging and response assessment [3,4]. The prognostic and/or predictive value of PET derived parameters with regard to survival or early assessment of response to therapy (during or before treatment), has been the focus of several studies [5,6,7]. Extraction of parameters with significant predictive value from the baseline 18F-FDG PET scan has been proposed using metabolically active tumor volumes (MATV, the functional volume of the tumor as it can be seen and delineated on an 18F-FDG PET image) [8]

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