Observation of intramyocellular lipids by means of¹H magnetic resonance spectroscopy

Abstract

fax +41 31 382 24 86, email chris.boesch@insel.ch Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are being increasingly used for investigations of human muscle physiology. While MRI reveals the morphology of muscles in great detail (e.g. for the determination of muscle volumes), MRS provides information on the chemical composition of the tissue. Depending on the observed nucleus, MRS allows the monitoring of high-energy phosphates ( 31 P MRS), glycogen ( 13 C MRS), or intramyocellular lipids ( 1 H MRS), to give only a few examples. The observation of intramyocellular lipids (IMCL) by means of 1 H MRS is non-invasive and, therefore, can be repeated many times and with a high temporal resolution. MRS has the potential to replace the biopsy for the monitoring of IMCL levels; however, the biopsy still has the advantage that other methods such as those used in molecular biology can be applied to the sample. The present study describes variations in the IMCL levels (expressed in mmol/kg wet weight and ml/100 ml) in three different muscles before and after (0, 1, 2, and 5 d) marathon runs for a well-trained individual who followed two different recovery protocols varying mainly in the diet. It was shown that the repletion of IMCL levels is strongly dependent on the diet post exercise. The monitoring of IMCL levels by means of 1 H MRS is extremely promising, but several methodological limitations and pitfalls need to be considered, and these are addressed in the present review.

Role of proton MR for the study of muscle lipid metabolism

“…The possibility of studying this important relation noninvasively and with high accuracy [coefficient of variation as low as about 6% (2)] boosted interest in 1 H-MRS studies on IMCL and the number of succeeding publications considerably (15)(16)(17)(18)(19).…”

Dipolar coupling and ordering effects observed in magnetic resonance spectra of skeletal muscle

“…Knowledge about this physiological role has mainly been acquired from biopsies, so only a few data points have been obtained, due to the invasive nature of this examination. 1 H-MR spectroscopy is now able to determine IMCL in human muscle non-invasively [7][8][9][10][11]14 and repeatedly. Using this technique, it has been found that IMCL levels are extremely variable in response to physical exercise 8,11,15,16 and diet.…”

“…1 H-MR spectroscopy is now able to determine IMCL in human muscle non-invasively [7][8][9][10][11]14 and repeatedly. Using this technique, it has been found that IMCL levels are extremely variable in response to physical exercise 8,11,15,16 and diet. 8,17,18 It has also been shown that different muscle groups contain different levels of IMCL.…”

“…Using this technique, it has been found that IMCL levels are extremely variable in response to physical exercise 8,11,15,16 and diet. 8,17,18 It has also been shown that different muscle groups contain different levels of IMCL. 7,19,20 The role of IMCL in diabetes is not fully understood, however, an inverse correlation of IMCL levels and insulin sensitivity has been observed by several groups.…”

“…8,17,18 It has also been shown that different muscle groups contain different levels of IMCL. 7,19,20 The role of IMCL in diabetes is not fully understood, however, an inverse correlation of IMCL levels and insulin sensitivity has been observed by several groups. [21][22][23][24] Figure 3.…”