MR elastography of the liver:defining thresholds for detecting viscoelastic changes

Anneloes E Bohte, Philippe Garteiser, Annikki De Niet, Paul F C Groot, Ralph Sinkus, Jaap Stoker, Aart J Nederveen

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

PURPOSE: To define thresholds for detecting significant change in liver viscoelasticity with magnetic resonance (MR) elastography, both for whole-liver measurements and for voxel-wise measurements in relation to spatial resolution.

MATERIALS AND METHODS: This prospective study was approved by the institutional review board, and all participants provided written informed consent. Thirty participants (16 volunteers and 14 patients with hepatitis B or C; 18 men; median age, 30.4 years; age range, 18.9-58.6 years) underwent imaging twice while in the same position (intraimage reproducibility), after repositioning (within-day reproducibility), and 1-4 weeks later (between-weeks reproducibility). MR elastography parameters comprised elasticity, viscosity, attenuation parameter α, and propagation parameter β. Bland-Altman analysis was used to calculate repeatability indexes for each parameter. Analyses were performed in a region-of-interest and a voxel-by-voxel level. Voxel-wise results were calculated in relation to spatial resolution by applying Gaussian filtering to establish the optimal trade-off point between resolution and reproducibility.

RESULTS: For elasticity, α, and β, within-day and between-weeks results were significantly lower than intraimage results (P ≤ .018 for all). Within-day and between-weeks results did not differ significantly. Over-time changes of more than 22.2% for elasticity, 26.3% for viscosity, 26.8% for α, and 10.1% for β represented thresholds for significant change. The optimal trade-off between spatial resolution and reproducibility was found at a filter size of 8-mm full width at half maximum (FWHM) for elasticity and propagation parameter β and at 16-mm FWHM for viscosity and attenuation parameter α.

CONCLUSION: Repositioning causes a significant decrease in the reproducibility of MR elastography. The propagation parameter β is the most reliable parameter, with an over-time threshold for significant change of 10.1% and the ability to reproduce viscoelasticity up to a resolution of 8-mm FWHM. 

Original languageEnglish
Pages (from-to)768-776
Number of pages9
JournalRadiology
Volume269
Issue number3
DOIs
Publication statusPublished - Dec 2013

Keywords

  • Adolescent
  • Adult
  • Elasticity
  • Elasticity Imaging Techniques
  • Female
  • Hepatitis B
  • Hepatitis C
  • Humans
  • Male
  • Middle Aged
  • Patient Positioning
  • Prospective Studies
  • Reproducibility of Results
  • Time Factors
  • Viscosity

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