Application of microcomputed tomography to calculate rat intervertebral disc volume as a surrogate measure of degeneration

ABSTRACT

Chronic low back pain (LBP) is a global socioeconomic crisis. Etiological research suggests the predominant pathology associated with chronic LBP is disc degeneration. The disc is a composed of a cartilaginous end plate, nucleus pulposus, and annulus fibrosus. The disc is predominantly avascular and aneural, predisposing it to degeneration. Disc degeneration in humans can be diagnosed using X-ray imaging and quantified using a measurement known as disc height index (DHI). DHI is also the current gold standard for evaluating disc degeneration in animal models. Unfortunately, X-ray imaging suffers poor spatial resolution, limiting the precision of DHI in rodents. Further, the application of disc height as a surrogate for degeneration involves subjective choices by experimenters, decreasing reliability. Microcomputed tomography (µCT) generates 3D reconstructions with profound spatial resolution. µCT has been used to measure disc degeneration, however, this work used costly contrast agents that increase procedure time. The objective of this work was to create a novel method for using µCT to assess disc degeneration in real-time, non-invasively and without contrast agents. Herein we describe a method for quantifying disc volume in vivo using µCT and the data suggest that this metric is precise, reliable, and sensitive to disc degeneration.

KEYWORDS:

• Microcomputed tomography
• disc degeneration
• disc height index

Acknowledgements

We would like to acknowledge the staff at the Life Sciences Annex at the University of Nebraska – Lincoln, especially veterinarian, Anna Fitzwater, who performed the animal surgeries.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

David J. Lillyman – Study design, method development, data collection, data processing, manuscript writing

Evie C. Barnett – Data processing, manuscript writing

Tyler J. Miller – Data collection, data processing

Rebecca A. Wachs – Study design, data collection, manuscript editing

Additional information

Funding

This research was funded in part by the Nebraska Tobacco Settlement Biomedical Research Development Fund and the National Institutes for Health (1 DP2 EB025760-01).