• John T Martin, Christopher M Collins, Kensuke Ikuta, Robert L Mauck, Dawn M Elliott, Yeija Zhang, D Greg Anderson, Alexander R Vaccaro, Todd J Albert, Vincent Arlet, and Harvey E Smith.
• Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania; Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania.
• J. Orthop. Res. 2015 Jan 1; 33 (1): 140-8.

AbstractMagnetic resonance imaging (MRI) with T2-weighting is routinely performed to assess intervertebral disc degeneration. Standard clinical evaluations of MR images are qualitative, however, and do not focus on region-specific alterations in the disc. Utilizing a rabbit needle puncture model, T2 mapping was performed on injured discs to develop a quantitative description of the degenerative process following puncture. To do so, an 18G needle was inserted into four discs per rabbit (L3/L4 to L6/L7) and T2 maps were generated pre- and 4 weeks post-injury. Individual T2 maps were normalized to a disc-specific coordinate system and then averaged for pre- and post-injury population composite T2 maps. We also developed a method to automatically segment the nucleus pulposus by fitting the NP region of the T2 maps with modified 2-D and 3-D Gaussian distribution functions. Puncture injury produced alterations in MR signal intensity in a region-specific manner mirroring human degeneration. Population average T2 maps provided a quantitative representation of the injury response, and identified deviations of individual degenerate discs from the pre-injury population. We found that the response to standardized injury was modest at lower lumbar levels, likely as a result of increased disc dimensions. These tools will be valuable for the quantitative characterization of disc degeneration in future clinical and pre-clinical studies.© 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

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