What is the role of MRI and CT scanning in the workup of ankylosing spondylitis (AS) and undifferentiated spondyloarthropathy (USpA)?

Updated: Jul 17, 2018
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

MRI or CT scanning of the SI joints, spine, and peripheral joints may reveal evidence of early sacroiliitis, erosions, and enthesitis that are not apparent on standard radiographs. [9, 10] MRI using fat-saturating techniques such as short tau inversion recovery (STIR) or MRI with gadolinium is sensitive for inflammatory lesions of enthesitis. [87, 88] The so-called MR corner sign, characterized by inflammatory lesions at the corners of vertebral bodies, is common in the thoracolumbar region of the spine in patients with AS. [89]

Investigations of patients with AS using serial MRI over time has shown a link between inflammatory lesions and the later development of syndesmophytes. [90] MRI can be used as an adjunct to evaluate the inflammatory changes and to assess neural compromise (see the image below). However, MRI and CT are not part of the routine evaluation of AS patients, because of their relatively high cost.

Sagittal MRI of thoracolumbar spine of a patient w Sagittal MRI of thoracolumbar spine of a patient with ankylosing spondylitis. Degenerative disc disease and bridging osteophytes can be observed at multiple levels.

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