Abstract
Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) provides a quantitative measure of pharmacokinetic (PK) parameters in body tissues; it entails collection of a series of T1-weighted images following the administration of a paramagnetic contrast agent (CA). Current state-of-the-art models for estimating the PK parameters do not account for intervoxel movement of the contrast agent. We introduce an optimal mass transport (OMT) formulation that naturally handles intervoxel CA movement and distinguishes between advective and diffusive flows. Ten patients with head and neck squamous cell carcinoma (HNSCC) were enrolled in the study between June 2014 and October 2015 and underwent DCE MRI imaging prior to beginning treatment. Converting DCE image intensity to CA tissue concentration, this information was taken as the input in the OMT model, generating estimates of forward flux (ΦF) and backward flux (ΦB). We decompose computed flux into advective and diffusive flows which are known to occur due to the typical pressure gradients on the tumor boundary. We additionally show that we can capture the reflux with our backward flux (ΦB). We extensively test our approach on HNSCC data and provide additional quantitative information such as ΦF, ΦB, advective and diffusive flows. The approach given in the present paper is essentially data driven in which a novel optical flow scheme is applied to the imagery in order to analyze the flow.