Separations between the annular fibers or between the annular fibers and their attachments to the vertebral body. These appear as linear foci of hyperintensity on T2-weighted and short tau inversion recovery (STIR) sequences (ie, high-signal-intensity zone). Disk degeneration includes desiccation, mucinous degeneration of the annulus, and fibrosis, which appears as low signal on T2-weighted sequences with varying grades of obscuration of the [[nucleus pulposus]] and annulus margins
((Pfirrmann CW, Metzdorf A, Zanetti M, Hodler J, Boos N. Magnetic resonance classification of lumbar intervertebral disc degeneration. Spine (Phila Pa 1976). 2001;26(17):1873–1878.)).