Project Summary/Abstract Obesity has reached epidemic proportions in the USA, with more than 40% of the population classified as obese (body mass index (BMI) > 30 kg/m2), and nearly 10% as severely obese (BMI > 40 kg/m2). Cardiovascular disease (CVD), especially heart failure, is highly associated with obesity. Reliable non-invasive cardiovascular imaging tests are needed to provide accurate diagnosis and prognosis in this patient group. Unfortunately, obese patients present a diagnostic challenge to current non-invasive cardiovascular imaging modalities. Computed tomography and single-photon emission computed tomography can require excessive radiation for successful imaging of obese patients, while echocardiography suffers from limited windows and signal attenuation leading to degraded image quality. Magnetic resonance imaging (MRI) of obese patients at conventional field strengths (1.5T and 3.0T) is primarily limited by narrow patient bore and table weight limits. As lower field strength allows greater flexibility in magnet design, a new low-field (0.55T) MRI with a unique, ultra-wide 80 cm bore and 700 lb. table weight limit that can accommodate severely obese patients was recently announced by Siemens. One of the first such systems in the USA will be installed at our institution this summer. In this project, we will develop cardiovascular MRI techniques for this system, and demonstrate their clinical value in severely obese patients. Our group and others have recently shown initial feasibility of cardiovascular imaging at low field. We believe that this new low-field MRI platform, when combined with the advanced pulse sequences and image reconstruction methods developed by our team, can unlock the potential of this novel system as a more reliable means to provide non-invasive cardiovascular imaging to patients with severe obesity. Furthermore, the reduced field strength will make MRI safer and more effective in the growing number of patients with implanted devices. We will prove low-field MRI utility for CVD assessment. Aim 1 will establish the feasibility of low-field cardiovascular MRI regardless of body habitus. We will develop image acquisition and reconstruction techniques specifically designed to compensate for the reduced MR signal at 0.55T compared to higher field. This will offer a comprehensive assessment of cardiovascular structure and function, and myocardial tissue. Aim 2 will validate these techniques in normal weight to severely obese healthy individuals and CVD patients, by head-to-head comparison with standard 70 cm bore 1.5T MRI in those able to safely fit in both machines. Aim 3 will apply the validated techniques to evaluate the efficacy of a low-field cardiovascular MRI exam in heart failure patients who are severely obese (BMI > 40 kg/m2) and cannot be safely imaged on standard MRI systems. We will compare the comprehensive diagnostic value of 0.55T MRI against echocardiography, and will correlate MRI markers to clinical...