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Background: In vivo hepatic phosphorus-31 magnetic resonance spectroscopy (MRS) provides non-invasive information about phospholipid metabolism., Aims: To delineate MRS abnormalities in patients with chronic ductopenic rejection (CDR) and to characterise spectral changes by in vitro MRS and electron microscopy., Patients and Methods: Sixteen liver transplant recipients (four with CDR; 12 with good graft function) and 29 controls (23 healthy volunteers; six patients with biliary duct strictures) were studied with in vivo 31P MRS. Peak area ratios of phosphomonoesters (PME) and phosphodiesters (PDE), relative to nucleotide triphosphates (NTP) were measured. In vitro MRS and electron microscopy were performed on biopsy specimens from five patients with CDR, freeze clamped at retransplantation. Phosphoethanolamine (PE), phosphocholine (PC), glycerophosphorylethanolamine (GPE), and glycerophosphorylcholine (GPC) concentrations were measured., Results: The 12 patients with good graft function displayed no spectral abnormalities in vivo; the four patients with CDR showed significantly elevated PME:NTP (p < 0.01) and PDE:NTP ratios (p < 0.005). Patients with biliary strictures had significant differences in PME:NTP (p < 0.01) from patients with CDR, but not in mean PDE:NTP. In vitro spectra from CDR patients showed elevated PE and PC, mirroring the in vivo changes in PME, but reduced GPE and GPC concentrations were observed, at variance with the in vivo PDE findings. On electron microscopy, there was no proliferation in hepatocyte endoplasmic reticulum., Conclusions: The increase in PME:NTP reflects altered phospholipid metabolism in patients with CDR, while the increase in PDE:NTP may represent a significant contribution from bile phospholipid.

Magnetic resonance spectroscopy (MRS) allows the noninvasive measurement of whole organ metabolism due to the presence of the MR-sensitive nucleus phosphorus 31 in adenosine triphosphate (ATP), its precursors, and break-down products. In small animal liver transplant studies it has been used to analyze the metabolic effects of cold and warm ischemia, hypothermic reperfusion, and the relative efficacy of different organ preservation solutions. In recent large animal studies MRS has been developed to provide continuous dynamic information on ATP metabolism during graft reperfusion and the bioenergetic consequences of altering preservation solutions. These basic experimental data need to be critically evaluated in human liver transplantation. Encouraging preliminary data on many possible clinical applications have already been obtained, such as the assessment of human donor liver viability and posttransplant graft function. At present, the cost and technically demanding nature of MRS may restrict its application to research units.