Cardiac radiation toxicity assessment via MRI perfusion imaging.
Background and Significance
Radiotherapy (RT) is a critical component of breast cancer management, yielding a substantial survival benefit. However, even with advanced technology for treating the tumor effectively, organs that are in close proximity to the breast, such as the heart, are highly prone to radiation exposure. Each 1 Gy heart dose increases risk of heart events by 7%. Radiation can affect both vascular endothelium and muscle tissue directly.
Cardiac MRI can detect changes in regional perfusion around the heart left ventricle that have a dose-response relation with regional dose to the LV during RT in breast cancer patients.
We are acquiring cardiac magnetic resonance (CMR) images in 12 patients with left-sided breast cancer undergoing breast or chest-wall photon or proton therapy. Perfusion scans are acquired using a contrast wash-in kinetics, and late-contrast enhancement. Methods are being developed to compute regional time-course of contrast update. Future work
Working with Vishwas Jindal, the immediate tasks are to:
i. Perform 2D image registration of each perfusion, short-axis image over time to eliminate breathing-motion.
ii. Register the perfusion images to anatomical MRI scans to permit use of the accurate contour results from the anatomical scans.
iii. Overlay 3D radiation dose fields onto the perfusion scans.
iv. Automatic selection of myocardial points in 4-6 regions around the LV in each perfusion scan for comparision across time and across patients.