Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Centre Munich at the University of Tübingen (Paul Langerhans Institute Tübingen), Tübingen, Germany.
NMR Biomed. 2013 Feb;26(2):232-6. doi: 10.1002/nbm.2849. Epub 2012 Sep 12.
Visceral adipose tissue (VAT) is thought to play an important role in the pathogenesis of obesity and insulin resistance. However, little is known about the composition of VAT with regard to the amount of mono- (MUFAs) and polyunsaturated fatty acids (PUFAs) in triglycerides. Volume-selective MRS was performed in addition to MRI for the quantification of VAT. Analysis comprised proton signals from the vinyl-H group (H-C=C-H), including protons from MUFA+PUFA, and diallylic-H, i.e. methylene-interrupted PUFAs. The methyl (-CH(3) ) resonance, which is the only peak with a defined number of protons/triglyceride (n=9), served as reference. Twenty male subjects participated in this prospective study and underwent MRS of VAT on a 3-T whole-body unit. Spectra were recorded by a single-voxel stimulated echo acquisition mode (STEAM) technique (TE/TM/TR=20/10/4000 ms; volume of interest between 20 × 25 × 20 and 30 × 30 × 20 mm(3); 48-80 acquisitions depending on the size of the volume of interest; bandwidth, 1200 Hz). Post-processing was performed by a Java-based magnetic resonance user interface (jMRUI; AMARES). The volume of VAT was quantified in a separate session on a 1.5-T imager a few days prior to the MRS session by T(1) -weighted imaging. The relative amount of VAT was calculated as a percentage of body weight (%VAT). Ratios of vinyl-H to -CH(3) and diallylic-H to -CH(3) were calculated. All spectra recorded from VAT were of high quality, enabling reliable quantification of the mentioned resonances. %VAT and vinyl-H/CH(3) varied over a broad range (2.8-8.3% and 0.45-0.64, respectively). A strong negative correlation between %VAT and vinyl-H/CH(3) was found (r= -0.92), whereas diallylic-H/CH(3) alone was clearly less well correlated with %VAT (r= -0.21). The composition of VAT shows strong interindividual variations. The greater the total amount of VAT, the less unsaturated the fatty acids. This is a preliminary result in mainly obese male subjects, and it remains to be determined whether this correlation holds for other cohorts of different age, gender and body mass index. Furthermore, changes in VAT composition during weight loss or different forms of diet have yet to be examined.
内脏脂肪组织（VAT）被认为在肥胖和胰岛素抵抗的发病机制中起着重要作用。然而，关于 VAT 中甘油三酯中单不饱和脂肪酸（MUFAs）和多不饱和脂肪酸（PUFAs）的含量，人们知之甚少。除了 MRI 外，还进行了容积选择 MRS 以定量 VAT。分析包括来自乙烯基-H 基团（H-C=C-H）的质子信号，包括 MUFA+PUFA 和二烯丙基-H，即亚甲基中断的 PUFAs。甲基（-CH(3)）共振是唯一具有确定质子/甘油三酯数量的峰（n=9），用作参考。20 名男性受试者参与了这项前瞻性研究，并在 3T 全身单元上进行了 VAT 的 MRS。通过单容积激发回波采集模式（STEAM）技术（TE/TM/TR=20/10/4000 ms；感兴趣体积为 20×25×20 至 30×30×20 mm(3)；根据感兴趣体积的大小，采集 48-80 次；带宽，1200 Hz）记录光谱。通过基于 Java 的磁共振用户界面（jMRUI；AMARES）进行后处理。在 MRS 之前的几天，在 1.5T 成像仪上进行 T1 加权成像，以单独的会话定量 VAT 体积。VAT 的相对量以体重的百分比（%VAT）计算。计算乙烯基-H/-CH(3)和二烯丙基-H/-CH(3)的比值。从 VAT 记录的所有光谱质量都很高，能够可靠地定量这些共振。%VAT 和乙烯基-H/CH(3)变化范围很广（分别为 2.8-8.3%和 0.45-0.64）。发现%VAT 和乙烯基-H/CH(3)之间存在很强的负相关（r=-0.92），而二烯丙基-H/CH(3)与%VAT 的相关性明显较差（r=-0.21）。VAT 的组成存在很强的个体间差异。VAT 的总量越大，脂肪酸的不饱和程度越低。这是主要肥胖男性受试者的初步结果，尚待确定这种相关性是否适用于不同年龄、性别和体重指数的其他队列。此外，还需要检查 VAT 组成在减肥或不同饮食形式期间的变化。
