How do you manage inflammatory back pain when X-rays and MRI show no evidence of sacroiliitis?  

While a normal MRI makes the diagnosis of axial spondyloarthritis unlikely, it doesn’t completely rule it out. This is specifically true in patients with inflammatory back pain or other features of spondyloarthritis. While classification criteria definitely should not be used for diagnosis, it...

I would also add that negative MRI results need to be interpreted in the context of current NSAIDs' use as anti-inflammatory meds that can mask sacroiliitis. Jones et al., British Society for Rheumatology 2023