USING COMPUTED-TOMOGRAPHY DISCOGRAPHY AND ENHANCED MAGNETIC-RESONANCE-IMAGING TO DISTINGUISH BETWEEN SCAR TISSUE AND RECURRENT LUMBAR DISC HERNIATION

Study Design. Patients who had lumbar spine surgeries and experienced residual symptoms were prospectively studied using computed tomography /discography and enhanced magnetic resonance imaging. Objectives. Dete rmining the sensitivity and specificity of gadolinium-enhanced magneti c resonance imaging versus computed tomography/discography in distingu ishing scarring from recurrent disc herniation was the first objective . The second goat was to determine if there were any imaging character istics unique to either scar or recurrent disc herniation. Summary of Background Data. The results of reoperation for recurrent disc herniat ion are uniformly good, whereas the results of reoperation for scar ti ssue are poor. There have been no studies comparing the ability of enh anced magnetic resonance imaging and computed tomography/discography t o distinguish between scar and herniation material. Methods. Two neuro radiologists who were blinded to the surgical findings in 33 patients independently reviewed the imaging studies and labeled abnormalities a s disc herniation or scar tissue. Their responses were compared with s urgical findings to determine the accuracy, sensitivity, and specifici ty of each test. Also, imaging studies were used to determine if disc material or scar tissue had specific imaging characteristics. Results. Computed tomography/discography was more sensitive and specific in di stinguishing between scar tissue and recurrent disc herniation. Inform ation from both studies improved the sensitivity over either test alon e. Characteristics associated with recurrent disc herniation included nonenhanced or rim-enhanced abnormality surrounding a low signal inten sity lesion on magnetic resonance imaging and extension of contrast in to the epidural space and an enhancing abnormality on computed tomogra phy/discography. Conclusions. Using computed tomography/discography al one or with enhanced magnetic resonance imaging enables surgeons to di stinguish between scarring and recurrent disc herniation so they can d etermine the need to re-enter the spinal canal.