Measurement of intracellular triglyceride stores by 1H spectroscopy:: validation in vivo
Measurement of intracellular triglyceride stores by 1H spectroscopy:: validation in vivo
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DOI：
10.1152/ajpendo.1999.276.5.e977
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发表时间：
1999-05-01
影响因子：
5.1
通讯作者：
Stein, DT
中科院分区：
文献类型：
--
作者：
Szczepaniak, LS;Babcock, EE;Stein, DT
我们通过分别在1.6 ppm和1.4 ppm监测TG亚甲基质子信号，验证了H-1磁共振波谱（MRS）用于定量区分脂肪细胞和细胞内甘油三酯（TG）储存的有效性。在两种细胞内TG积累的动物模型中，肝内和细胞内TG积累得到组织学证实。与组织学变化一致，1.4 ppm时肝脏和肌肉的亚甲基信号强度增加，而1.6 ppm时信号不变。作为诱导脂肪积累的反应，H-1 MRS引起的肝脏TG浓度从0增加到44.9 +/- 13.2 mu mol/g，这与生化测量的增加相匹配（2.1 +/- 1.1增加到46.1 +/- 10.9 mu mol/g）。支持肌肉中1.6 ppm亚甲基信号来源于膜间脂肪组织的证据是，在4名全身性脂肪营养不良（一种以缺乏界面脂肪为特征的疾病）患者中，1.6 ppm时未检测到亚甲基信号；然而，1.4 ppm是一个强烈的信号。在患有脂肪肝的人类受试者中获得了1.4 ppm的相同亚甲基化学位移，其中脂肪完全位于肝细胞内。实验动物体内H-1 MRS测定的肝脏TG含量与肝活检化学法测定的TG含量密切相关[R = 0.934；P < 0.0001；斜率0.98，置信区间（CI） 0.70 ~ 1.17；-截距0.26,CI -0.28 ~ 0.70]。当应用于人小腿肌肉时，该技术测量细胞内TG含量的变异系数在非肥胖者中为11.8%，在肥胖者中为7.9%，细胞外（脂肪细胞）脂肪的变异系数分别为22.6和52.5%。该研究首次证明，在1.5 t场强下，无创体内H-1 MRS测量细胞内TG（包括肌细胞内TG）是可行的，其准确性与生化测量相当。此外，在混合组织如肌肉中，与细胞内脂质相比，该方法在区分TG与污染脂肪组织方面明显有利。
We validate the use of H-1 magnetic resonance spectroscopy (MRS) to quantitatively differentiate between adipocyte and intracellular triglyceride (TG) stores by monitoring the TG methylene proton signals at 1.6 and 1.4 ppm, respectively. In two animal models of intracellular TG accumulation, intrahepatic and intramyocellular TG accumulation was confirmed histologically. Consistent with the histological changes, the methylene signal intensity at 1.4 ppm increased in both liver and muscle, whereas the signal at 1.6 ppm was unchanged. In response to induced fat accumulation, the TG concentration in liver derived from H-1 MRS increased from 0 to 44.9 +/- 13.2 mu mol/g, and this was matched by increases measured biochemically(2.1 +/- 1.1 to 46.1 +/- 10.9 mu mol/g). Supportive evidence that the methylene signal at 1.6 ppm in muscle is derived from investing interfascial adipose tissue was the finding that, in four subjects with generalized lipodystrophy, a disease characterized by absence of interfacial fat, no signal was detected at 1.6 ppm; however, a strong signal was seen at 1.4 ppm. An identical methylene chemical shift at 1.4 ppm was obtained in human subjects with fatty liver where the fat is located exclusively within hepatocytes. In experimental animals, there was a close correlation between hepatic TG content measured in vivo by H-1 MRS and chemically by liver biopsy [R = 0.934; P < .0001; slope 0.98, confidence interval(CI) 0.70-1.17; gamma-intercept 0.26, CI -0.28 to 0.70]. When applied to human calf muscle, the coefficient of variation of the technique in measuring intramyocellular TG content was 11.8% in nonobese subjects and 7.9% in obese subjects and of extramyocellular (adipocyte) fat was 22.6 and 52.5%, respectively. This study demonstrates for the first time that noninvasive in vivo H-1 MRS measurement of intracellular TG, including that within myocytes, is feasible at 1.5-T field strengths and is comparable in accuracy to biochemical measurement. In addition, in mixed tissue such as muscle, the method is clearly advantageous in differentiating between TG from contaminating adipose tissue compared with intramyocellular lipids.