Comparative analysis of Gd vs Dy in DSC-MRI studies of a high grade glioma murine model

Introduction Present methods to image microvascular flow involve mainly the intravenous administration of a bolus injection from a paramagnetic contrast followed by the rapid, time-resolved, MR imaging of the kinetics of its first pass through the microvasculature of the imaged slice . This approach relies both on the chemical nature of the contrast agent used and on the inherent properties of the MR technique implemented. Most protocols combine the use of conventional contrast agents as Gd(III)DTPA (Bayer-Schering, Berlin, DE) or Gd(III)DOTA (Guerbet, Paris, FR, Bracco, Torino, IT) and rapid Echo Planar MR imaging methods to resolve in time the transit of the bolus of contrast agent through the imaging slice. In the case of the brain, analysis of the kinetic curves allows for the determination of the blood volume (CBV), blood flow (CBF), mean transit time (MTT) and eventually capillary permeability. In this line Dy-complexes have been proposed to measure cerebral blood volume and to delineate healthy and damaged tissues by MRI. On the other hand, dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) has already proven to be of clinical value, in order to distinguish between different tumor types of the human brain. In this work we show the comparative results obtain in bolus track measurements performed in a high grade glioma rat model, using Gdand Dy-containing compound as T2* contrast agents. Our main goal is to establish an optimal method to check the effectiveness of antiangiogenic therapies in high and low grade glioma murine models.