Separation of diffusion and perfusion in intravoxel incoherent motion MR imaging.

TLDR

IVIM imaging visualizes microscopic water motions, encompassing both molecular diffusion and capillary microcirculation in biological tissues. The study aims to quantify perfusion’s contribution to the apparent diffusion coefficient and to develop a technique that separates diffusion and perfusion images. Using high‑resolution multisection sequences at 0.5 T without contrast, the authors quantified IVIM images with an apparent diffusion coefficient that integrates diffusion and perfusion, then applied the method to phantoms and patients. Phantom experiments confirmed the method’s ability to separately assess diffusion and perfusion, while clinical results demonstrated its promise for characterizing perfusion patterns and microcirculation in brain tumors, bone tumors, and ischemia.

Abstract

Intravoxel incoherent motion (IVIM) imaging is a method the authors developed to visualize microscopic motions of water. In biologic tissues, these motions include molecular diffusion and microcirculation of blood in the capillary network. IVIM images are quantified by an apparent diffusion coefficient (ADC), which integrates the effects of both diffusion and perfusion. The aim of this work was to demonstrate how much perfusion contributes to the ADC and to present a method for obtaining separate images of diffusion and perfusion. Images were obtained at 0.5 T with high-resolution multisection sequences and without the use of contrast material. Results in a phantom made of resin microspheres demonstrated the ability of the method to separately evaluate diffusion and perfusion. The method was then applied in patients with brain and bone tumors and brain ischemia. Clinical results showed significant promise of the method for tissue characterization by perfusion patterns and for functional studies in the evaluation of the microcirculation in physiologic and pathologic conditions, as, for instance, in brain ischemia.