Quantifying Cardiac Mechanical Dysfunction Following Radiation Treatment for Breast Cancer
Background and Significance
Breast cancer patients who have “ectomies” often undergo radiation therapy post-”ectomy” in an attempt to eradicate residual cancer tissue. Although extreme care is used when positioning the radiation beams in an attempt to minimize the amount of normal tissue radiated, the myocardial tissue is invariably hit. There is a higher percentage of heart attacks in women who receive radiation for left-sided breast cancer versus right-sided.
The purpose of the research project I will be working on, with the help of Dan Murff and Dr. Walter O’Dell, is to create an accurate three-dimensional (3D) model of heart mechanical strain using pre- and post- radiation therapy breast cancer patient cardiac MRI. We will focus on the left ventricle of the heart, as this is the most critical location of myocardial dysfunction. The 3D strain maps will enable the effects and extent of myocardial damage post radiation in breast cancer patients to be quantified. In addition, our clinical collaborators are interested in using these tools to quantify the difference in myocardial damage between x-ray and proton beam therapies.
A number of image processing steps are needed to go from a time series of cardiac MR images to a 3D model of myocardial strain. Using Dr. O’Dell’s in-house software tools, the inner and outer wall of the left ventricle will be semi-automatically traced on both the short and long axis views of the heart. Our program then employs an algorithm to track the cardiac tags in the images and record the three-dimensional motion of points in left ventricle wall. The 3D strain maps have been used successfully in the past to identify focal region of wall dysfunction to aid clinicians in studying, diagnosing and treating myocardial disease. Similarly, the model would provide information to clinicians on the comparable differences between the myocardial damage of x-ray versus proton therapy treatment.