title: Non-invasive assessment of portal hypertension using quantitative magnetic resonance imaging.
abstract: Hepatic venous pressure gradient (HVPG) measurement is currently the only validated technique to accurately evaluate changes in portal pressure. In this study, we evaluate the use of non-contrast quantitative magnetic resonance imaging (MRI) as a surrogate measure of portal pressure.
  
  
  
  Thirty patients undergoing HVPG measurement were prospectively recruited. MR parameters of longitudinal relaxation time (T1), perfusion of the liver and spleen (by arterial spin labelling), and blood flow in the portal, splanchnic and collateral circulation (by phase contrast MRI) were assessed. We estimated the liver stiffness measurement (LSM) and enhanced liver fibrosis (ELF) score. The correlation of all non-invasive parameters with HVPG was evaluated.
  
  
  
  The mean (range) HVPG of the patients was 9.8 (1-22) mmHg, and 14 patients (48%) had clinically significant portal hypertension (CSPH, HVPG ⩾10mmHg). Liver T1relaxation time, splenic artery and superior mesenteric artery velocity correlated significantly with HVPG. Using multiple linear regression, liver T1and splenic artery velocity remained as the two parameters in the multivariate model significantly associated with HVPG (R=0.90, p<0.001). This correlation was maintained in patients with CSPH (R=0.85, p<0.001). A validation cohort (n=10) showed this linear model provided a good prediction of HVPG. LSM and ELF score correlated significantly with HVPG in the whole population but the correlation was absent in CSPH.
  
  
  
  MR parameters related to both hepatic architecture and splanchnic haemodynamics correlate significantly with HVPG. This proposed model, confirmed in a validation cohort, could replace the invasive HVPG measurement.
  
  
  
  In patients with cirrhosis, the development and progression of portal hypertension is related to worse outcomes. However, the standard technique of assessing portal pressure is invasive and not widely used in clinical practice. Here, we have studied the use of non-invasive MRI in evaluating portal pressure. The MRI measures of liver architecture and blood flow in the splenic artery correlated well with portal pressure. Therefore, this non-invasive method can potentially be used to assess portal pressure in clinical trials and monitoring treatment in practice.
authors.affiliation: National Institute for Health Research (NIHR) Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals NHS Trust and University of Nottingham, United Kingdom.
authors.forename: Naaventhan
authors.initials: N
authors.lastname: Palaniyappan
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Cox
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bradley
authors.affiliation: National Institute for Health Research (NIHR) Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals NHS Trust and University of Nottingham, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Scott
authors.affiliation: Royal Derby Hospital, Derby, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Austin
authors.affiliation: Department of Radiology, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: O'Neill
authors.affiliation: Department of Radiology, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom.
authors.forename: Greg
authors.initials: G
authors.lastname: Ramjas
authors.affiliation: Department of Radiology, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Travis
authors.affiliation: Department of Radiology, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom.
authors.forename: Hilary
authors.initials: H
authors.lastname: White
authors.affiliation: Royal Derby Hospital, Derby, United Kingdom.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Singh
authors.affiliation: Royal Derby Hospital, Derby, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Thurley
authors.affiliation: National Institute for Health Research (NIHR) Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals NHS Trust and University of Nottingham, United Kingdom.
authors.forename: Indra Neil
authors.initials: IN
authors.lastname: Guha
authors.affiliation: Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom.
authors.forename: Susan
authors.initials: S
authors.lastname: Francis
authors.affiliation: National Institute for Health Research (NIHR) Nottingham Digestive Diseases Biomedical Research Unit, Nottingham University Hospitals NHS Trust and University of Nottingham, United Kingdom. Electronic address: guru.aithal@nottingham.ac.uk.
authors.forename: Guruprasad Padur
authors.initials: GP
authors.lastname: Aithal
mesh_terms: D006801:Humans; D006975:Hypertension, Portal; D008103:Liver Cirrhosis; D008279:Magnetic Resonance Imaging; D017082:Portal Pressure
keywords: Hepatic venous pressure gradient; Longitudinal T(1) relaxation time; Magnetic resonance imaging; Portal hypertension