title: Restricted or severely hindered diffusion of intramyocellular lipids in human skeletal muscle shown by in vivo proton MR spectroscopy.
abstract: Although magnetic resonance spectroscopy can be used as a unique tool to study molecular diffusion, it is rarely used to measure the diffusion properties of intramyocellular and extramyocellular lipids. Lipids have very low apparent diffusion coefficients (ADCs), which make these measurements difficult and necessitate strong diffusion gradients and long diffusion times. Consequence is that these measurements have inherently low signal-to-noise ratio and are prone to artifacts. The addition of physiological triggering and individual storage and processing of the spectra is seen to be a possible approach to maximize signal intensity and achieve high reproducibility of the experiments. Thus, the optimized measurement protocol was used to investigate the diffusion properties of lipids in human skeletal muscle in vivo. At a diffusion time of about 110 ms, intramyocellular lipids show a significantly lower ADC (2.0 × 10(-6) mm(2)/s, 95% confidence interval 1.10 × 10(-6) to 2.94 × 10(-6) mm(2)/s) than extramyocellular lipids (1.58 × 10(-5) mm(2)/s, 95% confidence interval 1.41 × 10(-5) to 1.75 × 10(-5) mm(2)/s). Because the chemical properties of both lipid pools can be assumed to be similar, the difference can only be attributed to restricted or severely hindered diffusion in the intramyocellular droplets.
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Vaclav
authors.initials: V
authors.lastname: Brandejsky
authors.forename: Roland
authors.initials: R
authors.lastname: Kreis
authors.forename: Chris
authors.initials: C
authors.lastname: Boesch
mesh_terms: D016477:Artifacts; D001853:Bone Marrow / Q000502:physiology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005110:Extracellular Space / Q000378:metabolism; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D042541:Intracellular Space / Q000378:metabolism; D050356:Lipid Metabolism / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008962:Models, Theoretical; D032342:Muscle Cells / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D012016:Reference Values; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio