title: A rapid and reliable means of assessing hepatic steatosis in vivo via electrical bioimpedance.
abstract: BACKGROUND
  In liver transplantation, macrovesicular steatosis is a major determinant of graft outcome. Visual assessment of steatosis by the donor surgeon is highly inaccurate, whereas hepatic biopsy is user dependent and cumbersome. Our objective was to validate a novel bioelectrical impedance sensor as a means of objectively quantifying macrovesicular hepatic steatosis and to correlate the results with another surrogate measure of macrosteatosis, hepatic microcirculation.
  
  
  METHODS
  Fatty (n=36) and lean (n=18) male Zucker rats, 250 to 450 g, were used to achieve varying degrees of steatosis. After a bilateral subcostal incision, hepatic microcirculation was measured using laser Doppler microflowmetry. Low-frequency bioelectrical impedance (LF-BEI) was measured at 1 kHz using a custom-made sensor and instrumentation system. Complete hepatectomy was performed. Hepatic tissue was preserved and stained with hematoxylin-eosin for histology.
  
  
  CONCLUSIONS
  Both microflow and LF-BEI correlated well with macrosteatosis and each other: Pearson correlation coefficients -0.71, 0.73, and -0.81, respectively. Livers were grouped according to the degree of macrosteatosis: mild (<30%), moderate (30%-60%), and severe (>60%). Both LF-BEI and microflow varied significantly among groups on one-way analysis of variance, although only LF-BEI was capable of discriminating between mild and moderate macrosteatosis on post hoc analysis. Regarding their individual capacities to detect the presence of severe macrosteatosis, both tests were excellent classifiers: receiver operating curve area under the curve 0.885 and 0.9 for LF-BEI and microflow, respectively. However, the bioimpedance apparatus is more rapid and less susceptible to local factors and background noise and could more easily be used in the clinical liver transplantation setting.
authors.affiliation: Department of Surgery, Liver Transplant Unit, Hospital Clinic, University of Barcelona, Barcelona, Spain.
authors.forename: Amelia J
authors.initials: AJ
authors.lastname: Hessheimer
authors.forename: Damià
authors.initials: D
authors.lastname: Parramón
authors.forename: Anton
authors.initials: A
authors.lastname: Guimerà
authors.forename: Ivan
authors.initials: I
authors.lastname: Erill
authors.forename: Antoni
authors.initials: A
authors.lastname: Rimola
authors.forename: Juan C
authors.initials: JC
authors.lastname: García-Valdecasas
authors.forename: Rosa
authors.initials: R
authors.lastname: Villa
authors.forename: Constantino
authors.initials: C
authors.lastname: Fondevila
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D017097:Electric Impedance; D005234:Fatty Liver / Q000175:diagnosis* / Q000503:physiopathology*; D006498:Hepatectomy / Q000379:methods; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008099:Liver / Q000378:metabolism; D016031:Liver Transplantation / Q000379:methods; D008297:Male; D046210:Microfluidic Analytical Techniques / Q000379:methods; D008954:Models, Biological; D051381:Rats; D011924:Rats, Zucker; D015203:Reproducibility of Results