Abstract
Although nr-axSpA is a distinct clinical entity with characteristic clinical and radiologic features, it is mimicked by a variety of other stress-induced, degenerative, infectious diseases or other conditions both clinically and radiologically, especially when it comes to the interpretation of imaging methods such as magnetic resonance imaging (MRI). Overall, the sensitivity and specificity of MRI in the diagnosis of nr-axSpA has limitations and must be interpreted in the context of the clinical picture. Furthermore, the interpretation of sacroiliac joint MRI is critical to avoid overdiagnosis as nr-axSpA because bone marrow oedema adjacent to the sacroiliac joint may also be frequently observed in people without axSpA such as post-partum women and athletes, even in the general population. In this review article we present recent updates about the various disease entities and conditions that may mimic nr-axSpA and how to differentiate among them especially by imaging with MRI.