ConvectionMRI, a Novel Method for Measuring Tumour Interstitial Fluid Velocity

Simon Walker-Samuel¹, Rajiv Ramasawmy¹, Peter Johnson², Jack Wells¹, Bernard Siow¹, Barbara Pedley², Mark F. Lythgoe¹

Tumours exhibit raised interstitial fluid pressure (IFP), which acts as a barrier to drug delivery and results in convection currents that radiate from the centre of the tumour to the periphery. We report a novel method named extra-vascular convectography (EVAC) for measuring interstitial fluid velocity (IFV), that does not require a contrast agent, and have evaluated it in two tumour models. The method consists of vascular nulling using a double inversion preparation, a recovery delay, and a velocity encoding readout. Using EVAC we have identified both radial and laminar interstitial convection patterns with a median velocity of 0.28 mm/s.