Interleaved 31P-MRS/1H-MRI during dynamic exercise to simultaneously measure skeletal muscle energetics and blood flow

Motivation: Impaired skeletal muscle energetics are associated with exercise intolerance and fatigue in several cardiovascular diseases including heart failure. However, it remains unclear if muscle energetic deficits are due to primary mitochondrial abnormalities or a result of reduced arterial blood flow. Goal(s): To develop an interleaved MRS/MRI method to simultaneously measure skeletal muscle energetics and blood flow during exercise. Approach: Phosphorus MRS was interleaved with phase contrast MRI to simultaneously measure skeletal muscle high-energy phosphates and popliteal artery blood flow at rest, during exercise, and recovery. Results: Interleaved-derived skeletal muscle phosphate concentrations and popliteal blood flow measures agreed favorably with independently acquired measures. Impact: Simultaneous assessment of skeletal muscle energetics and blood flow via interleaved 31P-MRS and phase contrast MRI will allow for mechanistic simultaneous assessment of underlying contributions to impaired energetics seen in a variety of clinical populations.