Myocardial Tissue Characterization Technical Foundations: How is it done?

Even within the context of MRI, the term “myocardial tissue characterization” could encompass a wide variety of techniques. In this presentation, the focus will be entirely on those methods designed to evaluate myocardium based on magnetic resonance relaxation times T1 (preand post-contrast), T2, and T2*. These relaxation time constants that form the basis for image contrast in many pulse sequences can be sensitive indicators of pathological changes in the myocardium, as they are for most tissues of the body. While the basic concepts behind T1-, T2-, and T2*-weighted imaging of the heart have been in place for a number of years, there has been a recent resurgence of interest in techniques designed to quantify and map myocardial relaxation times on a pixel-by-pixel basis. These quantitative methods have led to improved techniques to evaluate global as well as regional changes in myocardial tissue. This talk will cover the basic techniques utilized for T1and T2-weighted imaging of the heart, as well as more recently described methods for quantitative relaxation time parameter mapping.