Rajanayagam V, Lee R R, Ackerman Z, Bradley W G, Ross B D
Huntington Medical Research Institute, Pasadena, CA 91105.
J Magn Reson Imaging. 1992 Mar-Apr;2(2):183-90. doi: 10.1002/jmri.1880020211.
To determine the cause of reduced urea synthesis in cirrhosis, absolute concentrations of phosphorus metabolites in the human liver have been measured in vivo with magnetic resonance (MR) spectroscopy. One-dimensional chemical shift imaging was used to obtain phosphorus-31 spectra from five healthy volunteers and five patients with alcoholic cirrhosis. A reference standard included in all studies enabled the calculation of absolute concentrations. In contrast to hepatic metabolite ratios, absolute concentrations reveal that in the cirrhotic patients, concentrations of adenosine triphosphate (ATP) were significantly reduced and concentrations of phosphomonoesters slightly reduced. Intracellular pH was unchanged. Histologic evidence suggests that the amount of ATP per cell was unchanged and could not account for the reduced urea production. Instead, urea synthesis depends on the functional liver cell mass, which was reduced by 31% in alcoholic cirrhosis. Quantitative in vivo P-31 MR spectroscopy of liver has potential clinical applications and can supplement the more generally used P-31 metabolite ratios.
为了确定肝硬化患者尿素合成减少的原因，采用磁共振（MR）波谱技术在体测量了人体肝脏中磷代谢物的绝对浓度。利用一维化学位移成像技术获取了5名健康志愿者和5名酒精性肝硬化患者的磷-31波谱。所有研究中包含的参考标准使得能够计算绝对浓度。与肝脏代谢物比率不同，绝对浓度显示，在肝硬化患者中，三磷酸腺苷（ATP）浓度显著降低，磷酸单酯浓度略有降低。细胞内pH值未发生变化。组织学证据表明，每个细胞中的ATP量未发生变化，无法解释尿素生成减少的原因。相反，尿素合成取决于功能性肝细胞数量，在酒精性肝硬化中，功能性肝细胞数量减少了31%。肝脏的定量活体磷-31 MR波谱技术具有潜在的临床应用价值，并且可以补充更常用的磷-31代谢物比率。
