Abstract

Microvascular alterations have been observed in numerous brain pathologies, including brain tumours, brain ischemia, brain trauma and neurodegenerative diseases. Vascular density, morphology, permeability and reactivity as well as blood volume, flow and oxygenation may be affected. Characterization of these modifications may be of clinical interest for diagnosis, prognosis, treatment planning, and therapeutic follow-up. From a more fundamental point of view, this characterization may be useful for improving our understanding of the mechanisms underlying the evolution of these pathologies or the action of new therapies. The team has developed novel MRI methods to map the characteristic parameters of the cerebral microvasculature: blood volume, vessel diameters, and oxygenation. These methods were validated on healthy animal and bearing intracerebral gliomas. An integration of these methods with diffusion imaging, blood flow and permeability to two different contrast agents offer a multiparametric imaging protocol of the vasculature (duration 1h15min). We evaluated the interest of each of these parameters as indicators of therapeutic effect on glioma models in rats in the case of an antiangiogenic therapy (sorafenib) and an innovative method of radiotherapy, synchrotron microbeam radiation. Multiparametric MRI appears as an imaging modality with a high potential for preclinical evaluation of new therapeutic strategies and clinical as an indicator of therapeutic effect. The clinical transfer of these methods is in progress.