Key result
17O MRS imaging at 16.4T successfully quantified oxygen consumption rates in rat brain (1.97 μmol/g/min) and resting skeletal muscle (0.32 μmol/g/min).
Why the study?
Oxygen-17 MRS imaging, successfully used in the brain, needed extension to image oxygen metabolic rates in resting skeletal muscle and evaluate total whole-body oxygen consumption.
17O MRS imaging at 16.4 T is feasible for quantifying oxygen consumption rates in low metabolizing organs like resting skeletal muscle in rats.
Quantifies oxygen use in rat muscle; extends preclinical 17O MRS but leaves open human translation.
Purpose Oxygen‐17 ( 17 O) MRS imaging, successfully used in the brain, is extended by imaging the oxygen metabolic rate in the resting skeletal muscle and used to determine the total whole‐body oxygen metabolic rate in the rat. Methods During and after inhalations of 17 O 2 gas, dynamic 17 O MRSI was performed in rats ( n = 8) ventilated with N 2 O or N 2 at 16.4 T. Time courses of the H 2 17 O concentration from regions of interest located in brain and muscle tissue were examined and used to fit an animal‐adapted 3‐phase metabolic model of oxygen consumption. CBF was determined with an independent washout method. Finally, body oxygen metabolic rate was calculated using a global steady‐state approach. Results Cerebral metabolic rate of oxygen consumption was 1.97 ± 0.19 μmol/g/min on average. The resting metabolic rate of oxygen consumption in skeletal muscle was 0.32 ± 0.12 μmol/g/min and >6 times lower than cerebral metabolic rate of oxygen consumption. Global oxygen consumed by the body was 24.2 ± 3.6 mL O 2 /kg body weight/min. CBF was estimated to be 0.28 ± 0.02 mL/g/min and 0.34 ± 0.06 mL/g/min for the N 2 and N 2 O ventilation condition, respectively. Conclusion We have evaluated the feasibility of 17 O MRSI for imaging and quantifying the oxygen consumption rate in low metabolizing organs such as the skeletal muscle at rest. Additionally, we have shown that CBF is slightly increased in the case of ventilation with N 2 O. We expect this study to be beneficial to the application of 17 O MRSI to a wider range of organs, although further validation is advised.
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Wiesner et al. (2020) studied this question. 17O MRS imaging was evaluated on Metabolic rate of oxygen consumption. 17O MRS imaging at 16.4T successfully quantified oxygen consumption rates in rat brain (1.97 μmol/g/min) and resting skeletal muscle (0.32 μmol/g/min).
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