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Suspected non-radiographic axial spondyloarthritis — MSRA MCQ

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HardMRISuspected non-radiographic axial spondyloarthritisMSRA

A 29-year-old woman is assessed in rheumatology following GP referral for 15 months of low back pain. Symptoms began at age 27 and are associated with waking in the second half of the night, alternating buttock pain, improvement with movement and marked improvement within 48 hours of taking naproxen. She has chronic plaque psoriasis. There is no history of trauma, fever, weight loss, cancer, neurological deficit or bladder/bowel disturbance. Examination shows reduced lumbar flexion but normal lower-limb neurology. CRP is normal and HLA-B27 is negative. Plain radiographs of the sacroiliac joints do not show sacroiliitis meeting modified New York criteria. She can undergo MRI. Which is the most appropriate next diagnostic investigation?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Request unenhanced MRI using an inflammatory back pain protocol of the whole spine and sacroiliac joints

Explanation lettering: B = shown as A · D = shown as B · E = shown as C · C = shown as D · A = shown as E

This presentation remains strongly suggestive of axial spondyloarthritis (axSpA): onset before age 45 years, chronic back pain with inflammatory features, rapid NSAID response and associated psoriasis. Normal CRP and negative HLA-B27 do not exclude axSpA. Likewise, absence of sacroiliitis meeting modified New York criteria on plain radiographs does not exclude disease; it raises the possibility of non-radiographic axSpA. NICE recommends unenhanced MRI using an inflammatory back pain protocol when sacroiliac radiographs do not demonstrate sacroiliitis meeting modified New York criteria. The protocol includes STIR and T1-weighted sequences of the whole spine in sagittal view and sacroiliac joints in coronal-oblique view. Therefore, C is the correct next investigation. A is inappropriate because MRI should follow a non-diagnostic radiograph rather than waiting for radiographic change. B is attractive because MRI of the sacroiliac joints detects inflammation, but contrast and imaging of the sacroiliac joints alone do not constitute the NICE inflammatory back pain protocol. D is incorrect because NICE advises against scintigraphy for suspected axSpA. E incorrectly treats negative inflammatory markers, HLA-B27 and radiographs as exclusion criteria.

Reference: Spondyloarthritis in over 16s: diagnosis and management — Recommendations (2017) — https://www.nice.org.uk/guidance/NG65/chapter/Recommendations Spondyloarthritis in over 16s: diagnosis and management — Recommendations (2017) — https://www.nice.org.uk/guidance/NG65/chapter/Recommendations Quality statement 2: Diagnosis of axial spondyloarthritis using imaging (2018) — https://www.nice.org.uk/guidance/qs170/chapter/quality-statement-2-diagnosis-of-axial-spondyloarthritis-using-imaging