How is MRI and CT scanning beneficial in the evaluation of ankylosing spondylitis (AS) in patients with fused spines?

Updated: Feb 02, 2021
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

In patients with inflammatory back pain who have normal plain radiographs, MRI imaging of the pelvis (sacroiliac joints) may be very useful to confirm a diagnosis of axial SpA. This is illustrated in the images below, which are of a patient with nr-axSpA who presented with inflammatory back pain and had an excellent response to NSAIDs.

This 15-year-old female patient presented with recent onset of right-sided low back pain. Plain radiography findings were normal.

This 15-year-old female patient presented with rec This 15-year-old female patient presented with recent onset of right-sided low back pain. Plain radiography findings were normal.

MRI of the same patient whose radiography findings were normal (previous image). She underwent further evaluation, including MRI. The MRI (short tau inversion recovery [STIR]) showed increased sinal intensity in the right sacroiliac joint, revealing sacroiliitis. Other laboratory study findings were essentially normal. The patient was started on indomethacin and rapidly improved.

MRI of the same patient whose radiography findings MRI of the same patient whose radiography findings were normal (previous image). She underwent further evaluation, including MRI. The MRI (short tau inversion recovery [STIR]) showed increased sinal intensity in the right sacroiliac joint, revealing sacroiliitis. Other laboratory study findings were essentially normal. The patient was started on indomethacin and rapidly improved.

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