Clinical Application of Magnetic Resonance Spectroscopy of the Liver in Patients Receiving Long-Term Parenteral Nutrition

Abstract

Background: Intestinal failure–associated liver disease (IFALD) may have progressed to an advanced stage by the time it becomes evident via laboratory or physical signs. A safe, noninvasive technique for assessing the liver could significantly aid in monitoring the effects of therapeutic intervention, improve the timing of liver and small intestinal transplantation, and increase our understanding of the causes of IFALD. Methods: Six female patients fed intravenously for >1 year and 6 controls matched for body mass index (BMI) underwent liver magnetic resonance scanning with acquisition of ¹H and ³¹P resonance spectra. Areas under the curve for lipid (the sum of CH, CH₂, and CH₃), water, and choline peaks were calculated and expressed semi-quantitatively as ratios of lipid:water and choline:lipid. Phosphomonoester (PME) and phosphodiester (PDE) peak areas were similarly expressed as a ratio. Controls and cases were compared using Mann-Whitney U test; least squares regression analysis was used to compare the effect of measured variables on the lipid:water peak area ratio. Results: Patients and controls were well matched for BMI. Parenteral feeding was associated with a highly significant increase in lipid:water peak ratio (P < .005). Choline:lipid (P < .05) and choline:water (not significant) ratios were reduced in patients compared with controls. The increase in lipid:water ratios in patients was independent of BMI and choline:water ratios. A ratio of PME:PDE of >0.3 (and >3 SD from the control mean) predicted the 2 patients at most risk of advanced liver disease. Conclusions: This pilot study confirms the potential of magnetic resonance spectroscopic techniques in evaluating IFALD and could contribute significantly to our understanding and management of this condition.