Gadopentetate dimeglumine as an intradiscal contrast agent.

STUDY DESIGN Magnetic resonance discography using gadolinium as an intradiscal contrast agent was investigated in a prospective study. OBJECTIVE To evaluate the utility of magnetic resonance discography using gadolinium as an intradiscal contrast agent, as compared with the current standard of computed tomographic discography using intradiscal iodinated contrast agent. SUMMARY OF BACKGROUND DATA Magnetic resonance arthrography with gadolinium has been used to evaluate shoulder, elbow, wrist, hip, knee, and other joints. Gadolinium has not been used as an intradiscal contrast agent. The authors' preliminary results using gadolinium as an intradiscal contrast agent for magnetic resonance discography were reported previously. They report the results of their completed study. METHODS For this study, 42 disc levels were studied in 13 patients. Water-soluble iodinated contrast and gadopentetate dimeglumine were injected at each disc level. After discography, anteroposterior and lateral radiographs, computed tomography scans, and T1-weighted magnetic resonance imaging were performed. Six physicians interpreted the results from each disc level in a blinded fashion. Interscan and interobserver interpretation variability was determined for magnetic resonance discography and computed tomographic discography using the Pearson correlation-coefficient (r) test. RESULTS Interscan variability was highly correlated between computed tomographic discography and magnetic resonance discography when used to determine disc normality (r = 0.87), general degeneration (r = 0.87), anular fissure (r = 0.89), disc herniation (r = 0.92), and contrast leakage (r = 0.77). Interscan variability was assessed by the Pearson test, and all values of r for all the readers were noted to be statistically significant at P values less than 0.01. Interobserver variability was significantly correlated among the four more experienced readers (neuroradiologists and spine surgeons), but not among the spine fellows. Interobserver variability was also significantly correlated by computed tomographic (CT) and magnetic resonance imaging (MRI) discography for disc normality (CT r = 0.60; MRI r = 0.56), general degeneration (CT r = 0.76; MRI r = 0.71), anular fissure (CT r = 0.79; MRI r = 0.84), and disc herniation (CT r = 0.63; MRI r = 0.64). The readings for contrast leakage did not reach statistical significance for computed tomographic or magnetic resonance discography. CONCLUSIONS The high interscan and interobserver correlation rates obtained for magnetic resonance discography using gadolinium, as compared with the standard computed tomographic discography technique, indicate that magnetic resonance discography may be an acceptable substitute for the imaging of disc pathology. Magnetic resonance discography with gadolinium can be recommended for patients allergic to iodinated contrast agents and for patients who wish to limit their radiation exposure.