Dynamic magnetic resonance measurements of calf muscle oxygenation and energy metabolism in peripheral artery disease

Abstract

Background: Clinical assessments of peripheral artery disease (PAD) severity are insensitive to pathophysiological changes in muscle tissue oxygenation and energy metabolism distal to the affected artery. Purpose: To quantify the blood oxygenation level-dependent (BOLD) response and phosphocreatine (PCr) recovery kinetics on a clinical MR system during a single exercise-recovery session in PAD patients. Study Type: Case-control study. Subjects: Fifteen Fontaine stage II patients, and 18 healthy control subjects Field Strength/Sequence: Interleaved dynamic multiecho gradient-echo 1 H T 2 * mapping and adiabatic pulse-acquire 31 P-MR spectroscopy at 3T. Assessment: Blood pressure in the arms and ankles were measured to determine the ankle-brachial index (ABI). Subjects performed a plantar flexion exercise-recovery protocol. The gastrocnemius and soleus muscle BOLD responses were characterized using the T 2 * maps. High-energy phosphate metabolite concentrations were quantified by fitting the series of 31 P-MR spectra. The PCr recovery time constant (τ PCr ) was derived as a measure of in vivo mitochondrial oxidative capacity. Statistical Tests: Comparisons between groups were performed using two-sided Mann-Whitney U-tests. Relations between variables were assessed by Pearson's r correlation coefficients. Results: The amplitude of the functional hyperemic BOLD response in the gastrocnemius muscle was higher in PAD patients compared with healthy subjects (-3.8 AE 1.4% vs. -1.4 AE 0.3%; P < 0.001), and correlated with the ABI (r = 0.79; P < 0.001). PCr recovery was slower in PAD patients (τ PCr = 52.0 AE 13.5 vs. 30.3 AE 9.7 sec; P < 0.0001), and correlated with the ABI (r = -0.64; P < 0.001). Moreover, τ PCr correlated with the hyperemic BOLD response in the gastrocnemius muscle (r = -0.66; P < 0.01). Data Conclusion: MR readouts of calf muscle tissue oxygenation and high-energy phosphate metabolism were acquired essentially simultaneously during a single exercise-recovery session. A pronounced hypoxia-triggered vasodilation in PAD is associated with a reduced mitochondrial oxidative capacity. Level of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2020;51:98-107.

31P magnetic resonance spectroscopy in skeletal muscle: Experts' consensus recommendations

“…ergometer, 2 nd RF (Tx/Rx) channel VOI, positioning and shim • If a localisation sequence is used: the position and size of the VOI • Otherwise: the position of the RF coil in relation to muscle anatomy • The point spread function (which influences contamination from surrounding tissue, and thus the effective VOI size) Timing of the acquisition: how soon after exercise onset was the ST acquisition; performed within one or split over several exercise bouts Acquiring simultaneously or interleaved 1 H MR and 31 P MR signals enables the capture of complementary metabolic information during a single exercise bout 83. Studies have combined31 P MRS with 1 H MR to measure BOLD signals,82,86 perfusion,[87][88][89] Mb and intracellular…”

Repeatability of multinuclear interleaved acquisitions with nuclear Overhauser enhancement effect in dynamic experiments in the calf muscle at 3T

“…The interleaved sequence developed here simultaneously provides information on perfusion, PCr recovery and muscle activation and reoxygenation at a temporal resolution of 2.5 s. The potential of similar interleaved 1 H/ 31 P NMR tools for evaluating energy metabolism in humans has been demonstrated in the past 2,5,[7][8][9][10]16 and more recently at 7T. 15 Our results demonstrate that the technique is well-adapted for functional evaluations in exercise and ischemia-hyperemia paradigms while showing repeatability scores similar to other studies with comparable acquisition modalities.…”

“…Multiparametric studies have been performed using multinuclear interleaved 1 H/ 31 P pulse sequences and an adapted dual‐tune RF coil, where data from both nuclei were quasi‐simultaneously acquired in the muscle, in prototype or research systems 2,7‐9,15,16 but also in modern clinical scanners without the need of additional hardware modifications 10,17 …”

Failing Homeostasis of Quadriceps Muscle Energy- and pH Balance During Bicycling in a Young Patient With a Fontan Circulation

“…Also, using baseline CPET values in healthy controls would be worth considering. Future studies of this subject should preferably use additional methods, including dynamic MRI methodology, to investigate the presence of endothelial dysfunction in patients with a Fontan circulation (22, 23).…”