Dynamic Contrast Enhanced – Magnetic Resonance Imaging ( DCE-MRI ) : insights about Arterial Input Function definition , model selection and the quantitative Signal Difference method

Introduction: Dynamic contrast enhanced MRI (DCE-MRI) is a useful tool that can help assess vascular changes and drug efficacy, particularly in drug angiogenesis targeted therapies. However, in order to employ DCE-MRI successfully in multicenter trials with longitudinal measures, data acquisition and processing needs to be streamlined and reproducibility of results must be emphasized. The goal of this work was to evaluate different approaches for the efficient processing of DCE-MRI data. We evaluated 1) the use of a “raw” arterial input function [AIF] as a forcing function in the kinetic model which was compared to a forcing function based on a 2compartment model fitted to the same “raw” AIF data 2) the use of the signal difference [SD] method which assumes linearity between signal intensity and concentration compared to the standard concentration-based [CA] approach which requires accurate T1 measurements, and 3) the effect of estimating tlag, the time lag between the tissue and AIF uptake curves in the kinetic model, and its effect on estimates and interpretability of other model parameters, in particular the fractional blood plasma volume, vp.