Biomedical and Metabolic Imaging Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 10 Center Dr, CRC Building 10, Room 3-5340, MSC 1263, Bethesda, MD 20892-1263, USA.
Radiology. 2012 Nov;265(2):565-75. doi: 10.1148/radiol.12112344. Epub 2012 Aug 13.
To determine the feasibility of measuring choline and glycogen concentrations in normal human liver in vivo with proton (hydrogen 1 [1H]) magnetic resonance (MR) spectroscopy.
Signed consent to participate in an institutional review board-approved and HIPAA-compliant study was obtained from 46 subjects (mean age, 46 years±17 [standard deviation]; 24 women) consecutively recruited during 285 days. Navigator-gated MR images were used to select 8-mL volumes for point-resolved spectroscopy (PRESS) with a 35-msec echo time. Line widths were minimized with fast breath-hold B0 field mapping and further manual shimming. Navigator-gated spectra were recorded with and without water suppression to determine metabolite concentrations with water signals as an internal reference. In three subjects, echo time was varied to determine the glycogen and choline T2. Linear regression analysis was used to examine relations between choline, hepatic lipid content, body mass index, glycogen content, and age.
Choline concentrations could be determined in 46 of 48 studies and was found to be 8.6 mmol per kilogram of wet weight±3.1 (range, 3.8-17.6; n=44). Twenty-seven spectra in 25 individuals with narrow line widths and low lipid content were adequate for quantitation of glycogen. The glycogen (glucosyl unit) concentration was 38.1 mmol/kg wet weight±14.4. The T2 of combined glycogen peaks in the liver of three subjects was 36 msec±8. Choline levels showed a weak but significant correlation with glycogen (r2=0.15; P<.05) but not with lipid content.
Navigator-gated and gradient-echo shimmed PRESS 1H MR spectroscopy may allow quantification of liver metabolites that are important for understanding and identifying disorders of glucose and lipid metabolism.
利用质子（氢 1 [1H]）磁共振（MR）光谱技术，在活体正常人类肝脏中测定胆碱和糖原浓度的可行性。
在 285 天内连续招募了 46 名受试者（平均年龄 46 岁±17 [标准差]；24 名女性），他们签署了参与机构审查委员会批准和符合 HIPAA 规定的研究的同意书。使用导航门控 MR 图像选择 8 毫升体积进行点分辨光谱（PRESS），回波时间为 35 毫秒。通过快速屏气 B0 场映射和进一步手动调谐最小化线宽。记录带有和不带有水抑制的导航门控光谱，以用水信号作为内部参考确定代谢物浓度。在 3 名受试者中，改变回波时间以确定糖原和胆碱的 T2。线性回归分析用于检查胆碱、肝脂质含量、体重指数、糖原含量和年龄之间的关系。
48 项研究中的 46 项可确定胆碱浓度，其值为 8.6mmol/kg 湿重±3.1（范围为 3.8-17.6；n=44）。25 名个体中有 27 个光谱，线宽较窄，脂质含量较低，足以定量糖原。糖原（葡萄糖单位）浓度为 38.1mmol/kg 湿重±14.4。3 名受试者肝内结合糖原峰的 T2 为 36msec±8。胆碱水平与糖原呈弱但有统计学意义的相关性（r2=0.15；P<.05），但与脂质含量无关。
导航门控和梯度回波调谐 PRESS 1H MR 光谱技术可用于定量肝脏代谢物，这对于了解和识别葡萄糖和脂质代谢紊乱很重要。
