Recent advances and insights into imaging of axial spondyloarthritis

Imaging of the axial skeleton is a critical component of the diagnosis, management and follow-up of axial spondyloarthritis which may be difficult on clinical grounds and biological data alone. The sacroiliac joints (SIJ) are anatomically complex with high incidence of normal variation and degenerative change and techniques used to image the SIJ vary widely. Interpretation of MRI scans of the axial skeleton is facilitated by employing consistent protocols in which sequences are designed for the sensitive detection of inflammatory lesions, fat metaplasia and bone erosion. Considerable research has been undertaken in recent years to improve the accuracy of detection of these findings in early disease and detection of structural damage changes that would allow improvements in diagnosis and management of SpA patients. This review will examine recent advances in our understanding of axSpA and discuss innovations in MRI and CT, focusing on how to optimize a standard acquisition protocol for MRI of the SIJ, and discussing how to avoid some common technical pitfalls that may be encountered in MRI clinical practice.