Enhanced Intervertebral Disc in Post-discectomy Patients

Sagittal, fat-suppressed T1W MR images of the spine without (above) and with (below) IV contrast show two band enhancement of L4/5 disc (arrows), which parallel to the endplates of an asymptomatic post remote-discectomy patient. 

 Facts: Imaging of Postoperative Lumbar Discectomy

• Intervertebral disc enhancement, annular enhancement and vertebral body enhancement are generally suggestive signs of disc space infection in post-discectomy patients
• However, some patients without clinical signs/symptoms of infection may have abnormal enhancement of disc/endplate and annulus. 
• In a study of 94 patients without clinical infection, post-operative MRI (3-6 months after surgery) shows anular enhancement in almost all cases and 20% of patients have disc enhancement that are not present on preoperative MRI
• Suggestive pattern of "incidental" enhancement: linear enhancement within the disc (two thin bands paralleling the end plates). Authors postulate that this could be due to accelerated degenerative disc change, unrelated to infection

Reference:

Ross JS, Zepp R, Modic MT. The postoperative lumbar spine: enhanced MR evaluation of the intervertebral disk. AJNR Am J Neuroradiol 1996;17:323-331.