Age changes in the lumbar intervertebral disc studied with magnetic resonance and cryomicrotomy

Abstract

AbstractThis is an original evaluation made on the correlation between sagittal gross and histologic cryomicrotome sections and magnetic resonance (MR) images of the lumbar intervertebral discs according to age groups. Age‐related structural changes were recognized in the anatomic sections and MR images of the discs in cadavers from birth to 73 years of age. In T2‐weighted MR images, the nucleus and fibrocartilaginous inner anulus have a bright signal while the peripheral annular fibers have a low signal intensity. With aging the discs become progressively more fibrous: the peripheral anulus widens and becomes densely fibrous and the inner anulus extends centrally to encroach upon the nucleus, sometimes producing a bilobed nucleus. In the newborn the components of the disc are sharply demarcated with a large, centrally located nucleus pulposus and a relatively narrow anulus fibrosus. In the adult, the nucleus and inner anulus continue to have a relatively bright signal in MR images and characteristically contain a dark band of low signal intensity which does not correspond to clefts or tears of the disc but to increased fibrous tissue content. The thickened peripheral annular fibers have a very low signal intensity. By the eighth decade of life the discs have a very high fibrous content throughout, indicated in MR images by a decreased signal intensity with no sharp distinction between nucleus and anulus in the anatomic sections. The dark band in the central portion of the disc remains as a characteristic feature in MR images of the adult disc. Degenerative changes in the discs are identified in MR images by contrasting signal intensities.