ULTRASONIC TISSUE CHARACTERIZATION - REVIEW OF A NONINVASIVE TECHNIQUE FOR ASSESSING MYOCARDIAL VIABILITY

The determination. of myocardial perfusion and myocardial viability ha s prognostic and therapeutic implications, particularly in the current era of percutaneous transluminal coronary angioplasty and thrombolyti c therapy. Several modes of investigation, including positron emission tomography, thallium-201 scintigraphy, and nuclear magnetic resonance imaging are used to differentiate viable from nonviable myocardium. T hough these noninvasive tests are useful diagnostic modalities, they a re expensive, time consuming, and too cumbersome to be used in the acu te setting. Expeditious distinction between viable and nonviable myoca rdium, during acute coronary syndromes, is of great importance since r eperfusion can minimize the extent of ischemic injury and infarction. An expanding body of evidence confirms that ultrasonic tissue characte rization has great potential to become a practical bedside diagnostic tool in the search for salvageable myocardium. Further clinical invest igative studies would help accomplish a better understanding of the co mplex interaction between ultrasound and myocardium.