Murugan Subramaniam MD, Presenter: Nothing to Disclose

Rajasekaran Shanmuganathan MS, Abstract Co-Author: Nothing to Disclose

To document the temporal pattern of diffusion in normal human lumbar discs and to study the influence of the vascularity of vertebral body and the status of end plate on diffusion in the normal and degenerative discs.

The diffusion pattern over twenty four hours following paramagnetic contrast medium (Gadodiamide) injection was studied in 150 discs ( 96 normal & 54 degenerate). Signal intensity values for three regions of interest in bone - vertebral body (VB), subchondral bone (SCB), endplate or tidal zone (TZ) and seven in the disc, were calculated and normal percentiles of diffusion for these regions derived. Enhancement percentage (EP) for each time period, peak EP (PEP) for each region and the time taken to achieve PEP (TMAX) were used to define and compare diffusion characteristics and to plot a time-intensity curve to document the 24 hour temporal pattern. The correlation of blood flow of the bone as measured by PEP of vertebral body (VB), the status of the end plate or tidal zone as measured by the PEP and Tmax of the TZ were correlated with the diffusion of the disc.

In normal discs, a ‘diffusion march’ from the VB to the center of disc was noted with the SI max being observed at five minutes in VB and SCB; at two hours in TZ and at six hours in nucleus pulposus. A significant difference in mean PEP of the vertebral body and the discs was observed between those less than 10 years and those above the age of twenty (p < 0.001). Alterations in TZ produced distinct MRI signs of disturbance in diffusion, which offered a reliable noninvasive method of identifying endplate cartilage damage. Stepwise linear regression analysis showed that the significant variable influencing diffusion to the center of the nucleus pulposus of the total sample was PEP of TZ (R2 = 0.216; p< 0.001); that of degenerate discs was PEP of TZ ( R2 =0.322; p< 0.001) and that of normal discs was age (R2 = 0.324; p< 0.001).

Serial post contrast MRI studies offer a reliable method of assessing the diffusion of the discs and the functional status of the endplate cartilage. Endplate cartilage damage increases with age and produces considerable changes in diffusion.

Subramaniam, M, Shanmuganathan, R, Diffusion into Human Lumbar Discs Studied with MR Imaging and Paramagnetic Contrast Medium.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4411495.html