Determination of triglyceride in the human myocardium by magnetic resonance spectroscopy: reproducibility and sensitivity of the method
ABSTRACT The primary aim of this investigation was to determine the reliability and sensitivity of 1H magnetic resonance spectroscopy (1H-MRS) as a method for quantifying myocardial triglyceride (TG) content in humans over time and in response to metabolic perturbations. Three separate experiments were designed to quantify myocardial TG content 1) over a 90-day period, 2) after a high-fat meal, and 3) after a 48-h fast. Proton spectra were collected from a 10 x 20 x 30-mm3 voxel placed within the intraventricular septum, with measurements acquired at end-systole and end-expiration, using cardiac triggering and respiratory gating. Minimal variation was observed between myocardial TG content determined 90 days apart (r = 0.98, CV = 5%), whereas TG values were unaffected by a high-fat meal despite a significant twofold increase (P < 0.05) in serum TG. In contrast, myocardial TG content increased threefold (P < 0.05) after a 48-h fast despite a 25% reduction in serum TG. Body mass index was significantly related to myocardial TG (r = 0.58, P < 0.05) and the change in myocardial TG after a 48-h fast (r2 = 0.60). 1H-MRS is a reliable method for the determination of myocardial TG in humans and is relatively unaffected by the consumption of one high-fat meal but sensitive to changes following a prolonged fast.
SourceAvailable from: Martin Krssak[Show abstract] [Hide abstract]
ABSTRACT: In past decades, type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease developed into a global public health disease with an endemic scale. Although up to now the pathogenesis of T2DM is still poorly understood, ectopic lipid accumulation is one of the strongest predictors for T2DM and is closely associated with insulin resistance.This review aims (i) to overview recent literature on the impact of intracellular lipid deposition, (ii) to point out changes in ectopic fat accumulation during diabetes progression or shortly after initializing individual therapy, and finally (iii) to expose unsolved questions and future perspectives in the role of ectopic lipids for the development of insulin resistance and T2DM.Wiener Medizinische Wochenschrift 07/2014; DOI:10.1007/s10354-014-0292-y
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ABSTRACT: 1H-MRS is regularly applied to determine lipid content in ectopic tissue – mostly skeletal muscle and liver – to investigate physiological and/or pathologic conditions, e.g. insulin resistance. Technical developments also allow non-invasive in vivo assessment of cardiac lipids; however, basic data about methodological reliability (repeatability) and physiological variations are scarce. The aim of the presented work was to determine potential diurnal changes of cardiac lipid stores in humans, and to put the results in relation to methodological repeatability and normal physiological day-to-day variations.Optimized cardiac- and respiratory-gated 1H-MRS was used for non-invasive quantification of intracardiomyocellular lipids (ICCL), creatine, trimethyl-ammonium compounds (TMA), and taurine in nine healthy young men at three time points per day on two days separated by one week. This design allowed determination of (a) diurnal changes, (b) physiological variation over one week and (c) methodological repeatability of the ICCL levels.Comparison of fasted morning to post-absorptive evening measurements revealed a significant 37 ± 19% decrease of ICCL during the day (p = 0.0001). There was a significant linear correlation between ICCL levels in the morning and their decrease during the day (p = 0.015). Methodological repeatability for the ICCL/creatine ratio was excellent, with a coefficient of variance of ~5%, whereas physiological variation was found to be considerably higher (22%) in spite of a standardized physiological preparation protocol. In contrast, TMA levels remained stable over this time period.The proposed 1H-MRS technique provides a robust way to investigate relevant physiological changes in cardiac metabolites, in particular ICCL. The present results suggest that ICCL reveal a diurnal course, with higher levels in the morning as compared to evening. In addition, a considerable long-term variation of ICCL levels, in both the morning and evening, was documented. Given the high methodological repeatability, these effects should be taken into account in studies investigating the metabolic role of ICCL. Copyright © 2014 John Wiley & Sons, Ltd.NMR in Biomedicine 11/2014; 27(11). DOI:10.1002/nbm.3186 · 3.56 Impact Factor
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ABSTRACT: Cardiac steatosis is a manifestation of ectopic fat deposition and is associated with obesity. The impact of chronic cocaine use on obesity measures and on the relationship between obesity measures and cardiac steatosis is not well-characterized. The objectives of this study were to compare obesity measures in chronic cocaine users and nonusers, and to explore which factors, in addition to obesity measures, are associated with myocardial triglyceride in African Americans, using noninvasive magnetic resonance spectroscopy.Journal of Addiction Medicine 10/2014; 9(1). DOI:10.1097/ADM.0000000000000078 · 1.71 Impact Factor