Lumbar disc degeneration. Correlation between CT and CT/discography.

Computed tomography (CT) images of 59 discs in 30 patients suffering from low back pain were compared with CT/discography images of the same discs in order to assess the correlation between intradiscal damage and changes in annular configuration and density. The discs were graded in CT as not bulging, slight protrusion, advanced protrusion or disc herniation, and were checked for local areas of hypodensity. General degeneration and annular disruption in CT/discography were evaluated separately according to the Dallas Discogram Description, on a scale of non-existent, slight, moderate, or severe. Most discs with a slight protrusion in CT showed severe annular disruption in CT/discography. Discs with advanced protrusion showed in addition a severe general degeneration. Disc herniation was associated only with severe annular disruption. Local hypodensity proved to be a specific but insensitive sign of annular disruption. It is concluded that a bulging disc is a sign of intradiscal damage and should be noted even when there is no nerve entrapment present.