In vivo and ex vivo measurements: noninvasive assessment of alcoholic fatty liver using 1H-MR spectroscopy.

PURPOSE: We aimed to evaluate the ability of 1H-magnetic resonance spectroscopy (1H-MRS) to detect and quantify hepatic fat content in vivo and ex vivo in an experimental rat model of alcoholic fatty liver using histopathology, biochemistry, and laboratory analyses as reference. METHODS: Alcoholic fatty liver was induced within 48 hours in 20 Lewis rats; 10 rats served as control. Intrahepatic fat content determined by 1H-MRS was expressed as the percent ratio of the lipid and water peaks and was correlated with intrahepatic fat content determined histologically and biochemically. Liver enzymes were measured in serum. RESULTS: Fatty liver could be detected in vivo as well as ex vivo using 1H-MRS, in all 20 animals. Histologic analysis showed a fatty liver in 16 of 20 animals. Histology and 1H-MRS results were highly correlated (in vivo, r=0.93, P = 0.0005; ex vivo, r=0.92, P = 0.0006). Also a strong correlation was noted between in vivo 1H-MRS measurements and the fat content determined biochemically (r=0.96, P = 0.0003). Ex vivo results showed a similarly strong correlation between 1H-MRS and biochemistry (r=0.89, P = 0.0011). CONCLUSION: 1H-MRS can be carried out in ex vivo models, as well as in vivo, to detect and quantify intrahepatic fat content in the acute fatty liver.

Noninvasive assessment of hepatic triglyceride content in humans with 13C nuclear magnetic resonance spectroscopy.

Hepatic lipid content was assessed noninvasively in 15 patients with hepatic steatosis by 13C nuclear magnetic resonance (NMR) spectroscopy, and compared in a double-blind fashion with histological grading and morphometric quantitation of fat in liver biopsies taken within 2 weeks of the study. The lipid content in the liver biopsies was expressed as the volume fraction of total parenchyma occupied by fat. Hepatic triglyceride content was determined by comparing the 13C NMR signal intensity in vivo with the signal intensity obtained from a lipid phantom of known concentrations. There was an approximately 30-fold increase in the 13C NMR signals of the saturated carbons (methyl/methylene [CH2]n) region of hepatic triglycerides from patients with grade 4 steatosis compared with those with grade 0, yielding a good dynamic range for measuring hepatic triglyceride content. The correlation coefficient between the morphometric and 13C NMR techniques was 0.89 (P < .01). These studies demonstrate that 13C NMR spectroscopy can be used to noninvasively assess hepatic triglyceride content in humans. This method may be clinically useful for diagnosis and follow-up of patients with hepatic steatosis.