Abstract 583: Validating Noninvasive Indices Of Thoracic Aortic Dissection With Magnetic Resonance Elastography

Abstract

Objective: Dissection-associated aneurysms (DAA) are the leading cause of death related to chronic Type-B aortic dissections (TBAD). Conventional imaging cannot distinguish high-risk DAAs that would benefit from early surgical intervention. We propose the feasibility of aortic stiffness as measured by magnetic resonance elastography (MRE) as a biomarker to help make this distinction. We validate MRE stiffness measures in 3D-printed PVA hydrogel phantoms with human-like dissection geometries and demonstrated the first successful application of MRE in a human thoracic aorta with a healthy volunteer. Methods: All phantoms had a 10% PVA true lumen and a 10%, 15%, 20%, or 25% false lumen. The phantoms and the thoracic aorta of a healthy volunteer were imaged in a 3T-MR scanner. A pneumatic driver created mechanical vibrations within the aorta. A cardiac-gated spin-echo echo planar imaging (SE-EPI) sequence was utilized. In vivo, end-diastolic images were chosen for analysis to minimize blood flow artifacts. Results: The MRE shear stiffness of the various PVA false lumen sides of the phantoms were 32.19, 51.48, 59.29, and 73.53 ± 2.66 kPa, respectively. Figure 1 shows the correlation (R 2 = 0.99) between MRE and rheometric stiffness measurements of the four phantoms with different PVA concentrations. Figure 2 shows MRE local frequency estimations of stiffness from the human aorta with a mean shear stiffness of 3.37±0.83kPa. Conclusion: We present a validation and feasibility study of MRE in the thoracic aorta. Future research will allow for developing predictive indices for TBAD DAA development.