Three-dimensional microstructural reconstruction of the ovine intervertebral disc using ultrahigh field MRI

Mirit Sharabi, Kelly R. Wade, Fabio Galbusera, Volker Rasche, Rami Haj-Ali, Hans Joachim Wilke

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: The intervertebral disc (IVD) is a complex organ that acts as a flexible coupling between two adjacent vertebral bodies and must therefore accommodate compression, bending, and torsion. It consists of three main components, which are elegantly structured to allow this: the annulus fibrosus (AF), the nucleus pulposus (NP), and the end-plates (EP). PURPOSE: Thus far, it has not been possible to examine the microarchitecture of the disc directly in three dimensions in its unaltered state and thus knowledge of the overall architecture of the disc has been inferred from a range of imaging sources, or by using destructive methods. STUDY DESIGN: A nondestructive ultrahigh field Magnetic Resonance Imaging (MRI) of 11.7 T was used together with image analysis to visualize the ovine IVDs. METHODS: Three-dimensional image stacks from eight IVDs harvested from sheep, half of which were 4 to 5 years old and the others approximately 2 years old were reconstructed and examined, and their microstructure were imaged. The overall structure of the disc, including the average of 14 AF lamellae (9–28), NP, and EP was then visualized with particular attention given to integrating elements as radial translamellar cross-links, AF–NP transition zone EP–AF integration and EP–NP insertion nodes (ie the connecting junctions between the EP and NP). Moreover, collagen fiber orientation was determined at different depths and locations throughout the annulus. RESULTS: It was found that there was a clearer demarcation in the AF–NP transition zone of the younger discs compared with the older ones. This difference was reflected in the visibility of AF–NP and EP–AF integration. It was also possible to view the fiber architecture of the AF–NP integration in greater depth than was possible previously with histological techniques. These fibers were mainly observed in the younger discs and their length was measured to be of 2.6 ± 0.2 mm. CONCLUSIONS: The present results provide a substantial advance in visualization of the three-dimensional architecture of an intact IVD and the integration of its components.

Original languageEnglish
Pages (from-to)2119-2127
JournalSpine Journal
Volume18
Issue number11
DOIs
Publication statusPublished - Nov 2018

Keywords

  • Annulus fibrosus
  • Imaging
  • Intervertebral disc
  • Microstructure
  • MRI

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

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