Program Information
Measurement of Skeletal Muscle Lipids in Type 2 Diabetes Using in Vivo Proton MR Spectroscopy
S Valaparla*, G Boone , E Ripley , M Abdul-Ghani , T Duong , G Clarke , UT Health Science Center, San Antonio, TX
Presentations
TU-C-12A-1 Tuesday 10:15AM - 12:15PM Room: 12APurpose: To quantify and compare the intramyocellular (IMCL), extramyocellular (EMCL) lipids and total fat fraction in human vastus lateralis (VL) muscle between lean controls and type 2 diabetic (T2DM) subjects using long echo time in vivo proton MR spectroscopy (¹H₋MRS)
Methods: ¹H₋MRS single voxel (15 Χ 15 Χ 15 mm³) stimulated acquisition mode (STEAM) was performed in right vastus lateralis m. on 10 lean controls (age: 28.3±3.94 yrs, BMI: 24.25±3.20 kg/m²) and 7 type 2 diabetic (age: 54.28±6.42 yrs, BMI: 31.34±3.13 kg/m²) subjects with Siemens 3T MRI and four₋channel flex coil. Unsuppressed water spectra (NSA = 16) with TR/TE = 3000/30 msec, TM = 10 msec, BW = 2000 Hz, and water₋suppressed spectra (NSA = 128) with TR/TE = 3000/270 msec, TM = 10 msec, and 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 Χ F/(W+F)) was 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 t₋test. 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 VL m. was significantly different in T2DM compared to lean controls.
Funding Support, Disclosures, and Conflict of Interest: American Heart Association Southwest Affiliate Pre-doctoral Fellowship
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