Sarcopenia is a common comorbidity and predictor of mortality in heart failure that is characterized by a loss of muscle mass and functional strength. Sarcopenia, in heart failure and other chronic diseases, has been consistently predictive of poor outcomes. However, current tools to identify the presence of sarcopenia, such as functional tests and questionnaires are indirect, non-specific, and not effective until patients have reached an overtly cachectic state and significant muscle deterioration has already occurred. MRI can serve an important, noninvasive role in the assessment and management of sarcopenia by providing insight as to tissue microstructure and mitochondrial function. For example, MRI has shown significant changes in T2 relaxation time, diffusion fractional anisotropy, and lipid content in skeletal muscle of pre-frail/frail patients as compared to healthy volunteers. Post-exercise phosphocreatine (PCr) recovery, evaluated using phosphorus-31 (P) MR spectroscopy Imaging(P-MRSI), has shown impairment of mitochondrial function in pre-frail elderly as compared to active elderly. MR fingerprinting (MRF) is a promising tool for tissue characterization via rapid, robust quantification of T1 and T2 relaxation and has been shown to be accurate and reproducible across sites. Despite applications in neuroimaging and cardiac imaging, MRF has had limited use in musculoskeletal imaging and has not been investigated for use in characterizing sarcopenia. Similarly, P-MRS imaging has not been employed for evaluation of sarcopenia in heart failure patients, a population which may have a unique etiology from other sarcopenia phenotypes. Characterization of sarcopenia may support a range of rapidly developing treatment options in this population. While evidence suggests exercise therapy can improve frailty status, for instance in 39% of patients at 12 month follow-up, it is not yet well-understood which patients will respond to treatment. With a range of treatment options such as nutritional supplementation, hormone therapy, and cardiovascular drugs, MRF and P-MRSI could serve as powerful noninvasive tools to provide a personalized approach for sarcopenic phenotypes, match them to appropriate therapy, and monitor therapeutic response.
The goal of the proposed research is to investigate Magnetic Resonance (MR) Fingerprinting and P-MRS (Phosphorus-31 MR Spectroscopy) imaging for characterization of skeletal muscle in heart failure patients with sarcopenia. Heart failure patients with and without sarcopenia will be scanned using MR Fingerprinting and an existing Post-exercise phosphocreatine (PCr) recovery MR imaging protocol to obtain characteristic profiles of quantitative T1, T2, and PCr recovery rate.