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Population average T2 MRI maps reveal quantitative regional transformations in the degenerating rabbit intervertebral disc that vary by lumbar level
Author(s) -
Martin John T.,
Collins Christopher M.,
Ikuta Kensuke,
Mauck Robert L.,
Elliott Dawn M.,
Zhang Yeija,
Anderson D. Greg,
Vaccaro Alexander R.,
Albert Todd J.,
Arlet Vincent,
Smith Harvey E.
Publication year - 2015
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.22737
Subject(s) - intervertebral disc , population , magnetic resonance imaging , lumbar , medicine , anatomy , nuclear medicine , radiology , environmental health
Magnetic 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. J Orthop Res 33:140–148, 2015.