title: Non-invasive quantification of hepatic steatosis in living, related liver donors using dual-echo Dixon imaging and single-voxel proton spectroscopy.
abstract: OBJECTIVE
  To evaluate the diagnostic implications of hepatic fat fraction calculated using dual-echo Dixon imaging and (1)H magnetic resonance spectroscopy (MRS) to detect hepatic steatosis in potential liver donors using histopathology as the reference standard.
  
  
  METHODS
  One hundred and forty-five potential liver donors were included in the study. Magnetic resonance imaging (MRI) was performed using a 1.5 T system using a three-dimensional dual-echo MRI sequence with automated reconstruction of in-phase (IP), out-of-phase (OP), fat-signal-only, and water-signal-only images. Hepatic fat fraction was calculated by drawing 15 regions of interest on the IP, OP, fat-only, and water-only images. Single-voxel MRS was performed at echo times (TEs) of 30 ms in the right and left lobes of liver. Liver fat fraction was calculated from water and fat peaks. One hundred and forty-five biopsies were prospectively evaluated for steatosis by a pathologist using traditional determination of the cell-count fraction. MRI and pathology values of steatosis were correlated using Pearson's correlation coefficient. The sensitivity and specificity of each of these methods was calculated using histopathology as the reference standard. Reproducibility was assessed in 40 patients who had repeat scanning within 4-40 days. Measurement error was calculated from the coefficient of variation (CoV) with histopathologically proven <5% fat (n=112).
  
  
  RESULTS
  The Bland-Altman limits of agreement with 95% confidence intervals (CI) was -2.9 to 5.3%. The intraclass correlation coefficient (ICC) for interobserver variability and reproducibility was 0.94 (95% CI: 0.91-0.97), 0.92 (95% CI: 0.91-0.97). The CoV was 7.6% (95% CI: 3.4-11.85). The area under the receiver operating characteristic (ROC) curve (AUC) for Dixon imaging 0.89 (95% CI: 0.87-0.91), for MRS 0.88 (95% CI: 0.86-0.90). The sensitivity for detecting <5% fat was 84% and specificity was 90%.
  
  
  CONCLUSIONS
  Combination of dual-echo Dixon imaging and proton MRS is a useful tool for the preoperative diagnosis of hepatic steatosis in potential living liver donors. This can help avoid unnecessary biopsies in these patients.
authors.affiliation: Department of Radiology Medanta Medicity, Gurgaon, India. Electronic address: sonalkrishan11@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Krishan
authors.affiliation: Department of Radiology Medanta Medicity, Gurgaon, India.
authors.forename: D
authors.initials: D
authors.lastname: Jain
authors.affiliation: Imaging and Computer Vision, Siemens Corporate and Research Technology, India.
authors.forename: Y
authors.initials: Y
authors.lastname: Bathina
authors.affiliation: Imaging and Computer Vision, Siemens Corporate and Research Technology, India.
authors.forename: A
authors.initials: A
authors.lastname: Kale
authors.affiliation: Medanta Institute of Liver Transplantation and Regenerative Medicine, India.
authors.forename: N
authors.initials: N
authors.lastname: Saraf
authors.affiliation: Medanta Institute of Liver Transplantation and Regenerative Medicine, India.
authors.forename: S
authors.initials: S
authors.lastname: Saigal
authors.affiliation: Medanta Institute of Liver Transplantation and Regenerative Medicine, India.
authors.forename: N
authors.initials: N
authors.lastname: Choudhary
authors.affiliation: Department of Radiology Medanta Medicity, Gurgaon, India.
authors.forename: S S
authors.initials: SS
authors.lastname: Baijal
authors.affiliation: Medanta Institute of Liver Transplantation and Regenerative Medicine, India.
authors.forename: A
authors.initials: A
authors.lastname: Soin
mesh_terms: D000328:Adult; D001706:Biopsy; D005234:Fatty Liver / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D019520:Living Donors; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D011522:Protons