Your Donations in Action: Joseph Leach, MD, PhD

Understanding of the biologic and biomechanical factors underlying progressive abdominal aortic aneurysm disease

Joseph Leach
RE Foundation

Abdominal aortic aneurysms (AAA) are common and are often fatal when they rupture. They are estimated to cause approximately 11,000 deaths annually in the U.S. Current risk stratification of patients with AAA disease relies primarily on the radiologically assessed maximum aneurysm diameter, with aneurysms measuring greater than 5.5 cm typically referred to for intervention. This simple threshold fails to capture the estimated 10% of aneurysms that rupture despite being considered small (< 5 cm). This metric also ignores two factors which have been associated with aneurysm progression and rupture risk, namely vessel wall inflammation and biomechanical aneurysm stress/strength distributions, respectively.

With his 2018 Richard L. Baron, MD Research Fellow Grant, Joseph Leach, MD, PhD, University of California, San Francisco, and his colleagues developed a framework to construct patient-specific computational mechanics models of AAAs, using multi-sequence MRI data.

MRI permits accurate understanding of not only the AAA geometry but also the material composition. MRI can also depict areas of vascular inflammation, using ultrasmall supraparamagnetic iron oxide (USPIO) contrast media and possibly measures of contrast kinetics. The team also correlated aneurysm wall stress distributions to MRI maps of vascular inflammation markers, to determine if there were synergistic effects between biological and biomechanical factors in AAA progression.

“We hope that we may more fully utilize MRI to risk-stratify AAA patients into those at low risk of progression or rupture and those who may benefit from early intervention,” Dr. Leach said.

Dr. Leach acknowledged the valuable time that the grant provided for this research. “The RSNA R&E Foundation grant allowed for protected time to pursue my research,” Dr. Leach said. “This permitted the necessary education and learning, technical developments, and collaboration that have propelled my career in academic medicine.”

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