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Table 1 Classification of intervertebral disc degeneration

From: Evaluation of canine intervertebral disc degeneration in colour-coded computed tomography

Grade Structure Distinction between NP and AF Attenuation Height of IVD
1 Homogeneous Lost Isodense to M. long. dorsi Normal
2 Homogeneous Slightly-clearly visible NP isodense to M. long. dorsi; AF hyperattenuating to M. long. dorsi Normal
3 Nonhomogeneous Clearly visible One dot-like homogeneneous, hyperattenuating Mineralisation often within the NP; AF iso-/hyperattenuating to M. long. dorsi Normal to slightly decreased
4 Nonhomogeneous Clear or hidden by mineralised material Multiple small or one bigger hyperattenuating Mineralisation, which cover up to 1/3 of the IVD AF iso-/hyperattenuating to M. long. dorsi Normal to moderatly decreased
5 Nonhomogeneous Hidden by mineralised material Hyperattenuating, inhomogeneous Mineralisation which cover at least 1/3 of the IVD; diffus hyperattenuating to M. long. dorsi; AF iso-/hyperattenuating to M. long. dorsi Collapsed disc space
  1. Self-developed grading system to classify canine intervertebral disc degeneration
  2. Abbreviations: AF Anulus fibrosus; IVD Intervertebral disc; M. long. dorsi Musculus longissimus dorsi; NP Nucleus pulposus