Skeletal muscle lipid quantification in lean and diabetic subjects using in vivo proton MR spectroscopy

Sunil K Valaparla, Goldie Boone, Erika M Ripley, Daniele Giuseppe, Timothy Q Duong, Muhammad Abdul-Ghani, Geoffrey D Clarke

Abstract


Purpose: To quantify and compare the intramyocellular (IMCL), extramyocellular (EMCL) lipids and total fat fraction in human vastus lateralis muscle between lean and type 2 diabetic (T2DM) subjects using long echo time (TE) STEAM proton MR spectroscopy (1H-MRS).

Methods: 1H-MRS using single voxel (15 × 15 × 15 mm3) stimulated acquisition mode (STEAM) was performed in right vastus lateralis m. on 10 lean controls (age: 28.3 ± 3.94 yo, BMI: 24.25 ± 3.20 kg/m2) and 7 type 2 diabetic (age: 54.28 ± 6.42 yo, BMI: 31.34 ± 3.13 kg/m2) subjects with Siemens 3T MRI and a four-channel flex coil. Unsuppressed water spectra (NSA = 16) with TR/TE = 3000/30 ms, TM = 10 ms BW = 2000 Hz, and water-suppressed spectra (NSA = 128) with TR/TE = 3000/270 ms, TM = 10 ms, fixed water suppression BW = 50 Hz were acquired. Spectral intensity ratios of IMCL-CH2, EMCL-CH2 and total lipid (IMCL + EMCL) with unsuppressed water signal (W) were converted into absolute concentrations expressed in mmol/kg. Fat fraction (100 × F/(W+F)) was also calculated, where F includes the signal intensities of IMCL and EMCL methylene (CH2)n, peaks only.

Results: Comparison of IMCL (controls: 11.70 ± 6.7, T2DM: 21.74 ± 10.2, p < 0.01), EMCL (controls: 22.89 ± 18.42, T2DM: 77.21 ± 33.4, p < 0.001) and total lipid (64.35 mmol/kg less in controls, p < 0.001) showed statistical significance using two-tailed student’s t-test. Mean fat fraction (%) exhibited considerable inter-individual variability for controls (3.14 ± 2.09; range: 1.34 – 7.04) and T2DM (9.34 ± 2.88; range: 4.15 – 13.67) and deemed significant (p < 0.05).

Conclusion: Single voxel STEAM 1H-MRS at long TE provides a robust non-invasive method for characterizing lipids within localized muscle regions, with well-resolved IMCL/EMCL peak separation. Regional lipid estimate and fat fraction in vastus lateralis muscle is significantly different in T2DM compared to normal lean controls.

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Cite this article as: Valaparla SK, Boone GRE, Ripley EM, Giuseppe D, Duong TQ, Abdul-Ghani M, Clarke GD. Skeletal muscle lipid quantification in lean and diabetic subjects using in vivo proton MR spectroscopy. Int J Cancer Ther Oncol 2014; 2(2):020239. DOI: 10.14319/ijcto.0202.39


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International Journal of Cancer Therapy and Oncology (ISSN 2330-4049)

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