Simultaneous Visualization of Arteries, Veins, and Cerebral Microbleeds from 7T MRA-SWI Images for Assessing the Effects of Radiation Therapy on the Brain

Author(s): Avadiappan, Sivakami | Advisor(s): Lupo, Janine M | Abstract: The use of radiation therapy for treatment of brain tumor is controversial due to its long-term effects on neurocognitive function, especially in pediatric patients. Developing objective criteria for evaluating the severity of radiation-related injury is critical for children, due to their longer survival times and impact on early cognitive development. Cerebral microbleeds (CMB) which are deposits of hemosiderin that initially accumulate around vessels and can appear as early as 6 months post radiation therapy and continue to increase in number over time, however their vascular etiology is unknown. The aim of this project is to develop a method for simultaneous visualization of arteries, veins, and CMBs in order to automatically calculate vascular metrics from the fusion of MRA and SWI images obtained from a multi echo sequence at 7 Tesla. A strategy to assess the distribution of CMB’s relative to surrounding arteries and veins would help establish a connection between CMB formation and underlying vascular pathology. The tools developed in this study will be evaluated in pediatric patients with CMBs who have been treated with uniform supratentorial cranial radiation therapy for childhood brain tumors in order to ultimately determine whether metrics describing vascular structure could serve as quantitative markers for radiation injury, help in identifying regions of the brain that are most susceptible to radiation, and predict the formation of new CMBs and subsequent cognitive impairment.