Analysis of magnetic resonance images from normal and degenerate lumbar intervertebral discs.

Degenerate discs can be identified quantitatively by measurement of magnetic resonance (MR) relaxation times. MR images have been recorded from 16-year-old and 82-year-old cadaveric L3-4 discs at the highest resolution attainable with a Picker International MR Imaging System operating at 0.26 Tesla. By recording images with a series of spin-echo and/or saturation-recovery sequences of differing time intervals, the values for sample magnetization, M infinity, and the T1 and T2 relaxation times, have been calculated from each pixel in the MR image. The distribution of M infinity values shows the relative degrees of hydration in different regions of the disc while the corresponding T1 and T2 values are sensitive to the chemical environment of the water molecules. Images from cadaveric discs allowed the nucleus pulposus and annulus fibrosus to be distinguished clearly, and the laminated structure of the annulus could be seen. Loss of water from the nucleus during aging was demonstrated by a reduction and change in the distribution of the M infinity values for an 82-year-old disc, as compared with a 16-year-old disc. Values of T1 and T2 indicated a difference in the chemical environment of water molecules in the nucleus pulposus and annulus fibrosus; the extent of this difference was much greater for younger than for older discs. High-resolution MR images from discs of living subjects showed almost as much detail as those from experimental specimens, but in the latter, the laminated structure of the annulus was resolved.(ABSTRACT TRUNCATED AT 250 WORDS)