Spinal changes in patients with spondyloarthritis: comparison of MR imaging and radiographic appearances

Since the advent of highly effective TNF-alpha inhibitors for treating spondyloarthritides, referring rheumatologists have been requesting the sensitive visualization of inflammatory changes not only of the sacroiliac joints but of the entire spine. Given that changes in spondyloarthritis may be very subtle, their visualization by means of magnetic resonance (MR) imaging relies critically on selecting the proper imaging protocol. Spinal changes associated with spondyloarthritis are florid anterior spondylitis (or Romanus lesion), florid diskitis (or Andersson lesion), ankylosis, insufficiency fractures of the ankylosed spine, syndesmophytes, arthritis of the apophyseal and costovertebral joints, and enthesitis of the interspinal ligaments. A comparison of MR imaging findings with those of conventional radiography in individual patients reveals strengths and weaknesses of both modalities. Results of this comparison suggest that syndesmophytes are depicted better with radiography; ankylosis, equally well with both imaging techniques; and all other lesions, better with MR imaging. Classification of the different findings based on the typical signal-intensity changes seen on MR images enables standardized reporting, and scoring the lesions may be helpful in clinical trials.