Untitled Document

CARDIAC IMAGING

Heart disease is the leading cause of death in the U.S. and worldwide. A very significant component in successful treatment of heart disease is accurate detection and characterization. With ongoing developments in imaging technology, we seek to develop more and more intimate pictures of cardiac structure, function, and physiology that translate into improved clinical treatments. Our group focuses on advancing the field of cardiac imaging in three main areas: (1) to develop tools to improve the detection and characterization of coronary atherosclerotic disease (CAD) and hence positively impact diagnosis and treatment selection. (2) to improve the assessment of cardiac viability – the metabolism and the integrity of cardiac cells to better choose treatment in patients with heart attacks (infarctions). (3) to develop methods for advanced MRI acquisition and analysis of the structure and function of the heart for application in the left ventricle in adult cardiac disease and in the right ventricle in congenital heart disease patients.

(1) CAD is a pathological narrowing of the coronary arteries feeding the heart muscle itself. Millions of people in the U.S. alone are imaged non-invasively each year for detection and characterization of CAD. Currently the most frequently used modalities include cardiac SPECT and stress echocardiography. One problem is that due to the inaccuracies in these non-invasive tests, approximately 30% of patients referred to cardiac catheterization, an invasive and relatively risky procedure, are normal. PET and MRI offer more accurate detection of CAD and we are working on tools to further improve their accuracy and to make the MRI approach more clinically feasible. We have made contributions in mathematical modeling techniques to improve the accuracy of the estimation of CAD, as well as developing image processing and analysis methods for more consistent and more accurate measures of CAD. With new state-of-the-art PET and MRI scanners soon to be available at the University of Utah , we expect to greatly advance the field. Advances in these modeling approaches also have great application in oncology and neurology including assessment of angiogenesis, blood flow to tumors, and cerebral blood flow.

2) The assessment of viability is a vital clinical question in some patients. Patients with extreme ischemic cardiomyopathy and non-viable tissue are unlikely to benefit from revascularization. Aggressive medical management for heart failure or cardiac transplant may then be considered instead of expensive and invasive revascularization procedures. Knowledge of the extent and location of the viable and non-viable tissue significantly impacts the decision whether or not to revascularize and has critical implications in patient care. Interventionalists and surgeons would very much like to know beforehand the likelihood that successful revascularization will lead to improved function. We are developing methods to improve this assessment of viability using MRI and PET.

(Upper panels) Non-viable apical region shown with FDG-PET, left, and contrast enhanced MRI, right.

(Lower panels) Non-viable inferoposterior region shown with FDG-PET, left, and contrast enhanced MRI, right. Arrows indicate regions of non-viability.

(3) MRI is the premier non-invasive technique to measure the structure and function of the heart. This applies to both infarcts and to right ventricle, patients with congenital heart defects. These methods allow comparisons of different treatments, for example determining when valve replacements or grafts are most timely. We are working on developing more quantitative methods for better understanding the material properties of the cardiac muscle and a better interpretation of what the changes in structure function mean in health and disease.