Measurement of Human Skeletal Muscle Oxidative Capacity by 31P-MR Spectroscopy: A Cross-Validation With In Vitro Measurements.
Lanza, Ian R. PhD 1; Bhagra, Sumit MD 1; Nair, Sreekumaran K. MD, PhD 1; Port, John D. MD, PhD 2*
[Article] Journal of Magnetic Resonance Imaging. 34(5):1143-1150, November 2011.

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Purpose: To cross-validate skeletal muscle oxidative capacity measured by 31P-MR spectroscopy with in vitro measurements of oxidative capacity in mitochondria isolated from muscle biopsies of the same muscle group in 18 healthy adults.

Materials and Methods: Oxidative capacity in vivo was determined from PCr recovery kinetics following a 30-s maximal isometric knee extension. State 3 respiration was measured in isolated mitochondria using high-resolution respirometry. A second cohort of 10 individuals underwent two 31P-MRS testing sessions to assess the test-retest reproducibility of the method.

Results: Overall, the in vivo and in vitro methods were well-correlated (r = 0.66-0.72) and showed good agreement by Bland Altman plots. Excellent reproducibility was observed for the PCr recovery rate constant (CV = 4.6%; ICC = 0.85) and calculated oxidative capacity (CV = 3.4%; ICC = 0.83).

Conclusion: These results indicate that 31P-MRS corresponds well with gold-standard in vitro measurements and is highly reproducible. J. Magn. Reson. Imaging 2011;. (C) 2011 Wiley Periodicals, Inc.

Copyright (C) 2011 John Wiley & Sons, Inc.