Non-invasive imaging of atherosclerosis by MRI and ultrasound

The concept of the unstable, so-called " high risk " or vulnerable atheroma tous plaque has been accepted for several years and its biological, mechani cal and cellular features (collagen top, lipid core with macrophages, metal loproteinases...) have been determined. However, the means of investigating these lesions remain limited. A description of their composition has becom e essential as the prognosis of coronary, aortic and carotid artery disease is no longer evaluated only by morphometric data (degree of stenosis).MRI with T1 or T2 contrast sequences, density of spin, chemical shift, diffusio n, magnetisation transfer or spectroscopy Provides a noninvasive tool for t heir study. This method, based on the detection of magnetic atomic nuclei (such as prot on H1, carbon 13, sodium 23, potassium 49) enables tissue characterisation by means of the variations in chemical environment and their consequences o n the degree of magnetisation of the nuclei studied. High frequency ultraso und could also be used to this end by measuring the coefficients of attenua tion and back-scattering. These methods, used clinically and in different animal models, should impro ve our understanding of the physiopathology, facilitate diagnosis and impro ve the prognostic accuracy in patients with atherosclerosis.