Meeting Management Challenges in axSpA

CHICAGO—How magnetic resonance imaging (MRI) is deployed for the diagnosis of axial spondyloarthritis (axSpA) can make a huge difference—much more important than clinical presentation and even other objective criteria, said Walter Maksymowych, MB ChB, professor of medicine at the University of Alberta, Edmonton, Canada, in a session at ACR Convergence 2025.

“Clinical features aren’t particularly helpful in making a diagnosis, and we, in fact, rely a lot more on the objective manifestations,” Dr. Maksymowych noted. “But even there, an elevated CRP (C-reactive protein) [is seen] in only 40% of patients. So if you’re relying on the CRP, that’s not going to get you very far.”

His review of the diagnosis of axSpA came in a session that also included updates on juvenile axSpA and mimics that clinicians have to keep in mind as they assess their patients.

MRI Findings Crucial to Diagnosis

Dr. Maksymowych

Most integral to the diagnosis of axSpA are findings on magnetic resonance imaging (MRI), Dr. Maksymowych said. As illustrated by the recent CLASSIC study, the specifications of the MRI are particularly important.¹

The CLASSIC study set out to validate the performance of the Assessment of SpondyloArthritis International Society (ASAS) classification criteria in a worldwide cohort, ultimately enrolling about 1,000 patients seen consecutively by a rheumatologist after at least three months of undiagnosed back pain. The researchers found that MRI was much better than most other measures at capturing axSpA, with 81.9% of axSpA diagnoses having an MRI indicative of the disease among local readings of the imaging and 61.6% of central readings.

The MRI protocol used in CLASSIC was T1 semi-coronal, STIR semi-coronal, STIR axial and a T1-weighted, fat-suppressed, 3D gradient echo, thin-slice sequence that is erosion-sensitive. These will help identify inflammatory as well as structural lesions and will allow bone marrow edema to be precisely located, Dr. Maksymowych said. It is the synthesis of all of these sequences that brings the picture into focus, he noted.

The upshot, he said, is that there is now a specific protocol that you “can take to a local radiologist and say, ‘I want you to do a certain acquisition protocol for diagnostic evaluation of the SI [sacroiliac] joint.’ This is the type of MRI that I want to see in my clinical practice.”

In the case of many patients with lower back pain who don’t respond to non-steroidal anti-inflammatory drugs, clinicians reach a pivotal moment when they need to decide whether to start someone on a biologic. “Now you’re struggling to decide, am I going to go into something that’s potentially lifelong therapy?” he said. “The imaging is going to be crucial to make that decision.”