(1)H-MR spectroscopy for analysis of cardiac lipid and creatine metabolism

Magnetic resonance spectroscopy (MRS) is the only non-invasive, non-radiation-based technique for investigating the metabolism of living tissue. MRS of protons (1H-MRS), which provides the highest sensitivity of all MR-visible nuclei, is a method capable of detecting and quantifying specific cardiac biomolecules, such as lipids and creatine in normal and diseased hearts in both animal models and humans. This can be used to study mechanisms of heart failure development in a longitudinal manner, for example, the potential contribution of myocardial lipid accumulation in the context of ageing and obesity. Similarly, quantifying creatine levels provides insight into the energy storage and buffering capacity in the heart. Creatine depletion is consistently observed in heart failure independent of aetiology, but its contribution to pathophysiology remains a matter of debate. These and other questions can in theory be answered with cardiac MRS, but fundamental technical challenges have limited its use. The metabolites studied with MRS are much lower concentration than water protons, requiring methods to suppress the dominant water signal and resulting in larger voxel sizes and longer scan times compared to MRI. However, recent technical advances in MR hardware and software have facilitated the application of 1H-MRS in humans and animal models of heart disease as detailed in this review.