Quantitative MRI water content mapping of porcine intervertebral disc during uniaxial compression

Abstract

Background: Intervertebral disc (IVD) diseases are major public health problem in industrialized countries where they affect a large proportion of the population. In particular, IVD degeneration is considered to be one of the leading causes of pain consultation and sick leave. The aim of this study was to develop a new method for assessing the functionality of IVD in order to diagnose IVD degeneration. Methods: For this purpose, we have designed a specific device that enables to mechanically load porcine IVD ex vivo in the 4.7-Tesla horizontal superconducting magnet of a magnetic resonance (MR) scanner. Proton density weighted imaging (ρ_H-MRI) of the samples was acquired. Findings: The post-processing on MR images allowed (1) to reconstruct the 3D deformation under a known mechanical load and (2) to infer the IVD porosity assuming an incompressible poroelastic model. Interpretation: This study demonstrates the ability to follow the change in morphology and hydration of an IVD using MR measurements, thereby providing valued information for a better understanding of IVD function.

Keywords:

• IVD
• ρ_H-MRI
• porosity
• poroelasticity

Acknowledgements

The authors thank the staff of the Centre d’Enseignement et de Recherche Chirurgical (CERC, North Hospital, Marseilles, France) for providing porcine intervertebral disc.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Centre d’Enseignement et de Recherche Chirurgical, North Hospital, Marseilles, France.

2. Animal procedures were carried out in strict accordance with the guidelines of the European Communities Council Directive 86/609/EEC for care and use of laboratory animals, and the French law on the protection of animals (Decree 87-848), and were performed in the animal care facilities approved by the ‘Direction Départementale des Services Vétérinaires des Bouches du Rhône’ (agreement C-13-055).

3. The stretch ratio defines the deformation of a sample in the direction of the compressive load.

4. Diurnal cycle: Water is expressed during the day by the increase in load and reimbibed at night when the load is removed.