Active Inflammatory Lesions Detected by Magnetic Resonance Imaging in the Spine of Patients with Spondyloarthritis - Definitions, Assessment System, and Reference Image Set

Abstract

<h3>Objective.</h3> Currently available magnetic resonance imaging (MRI) assessment systems for spine inflammation in patients with spondyloarthritis (SpA) identify only the overall inflammation in the discovertebral units. We aimed to develop and illustrate a detailed anatomy-based set of definitions and an assessment system for active inflammatory lesions in the spine of patients with SpA. <h3>Methods.</h3> MRI definitions of different inflammatory lesions at various anatomical locations in the spine, and an accompanying assessment system, were agreed by consensus within the Canada-Denmark MRI working group. Subsequently, a reference image set of representative examples of the individual pathologies, as well as borderline cases and important artefacts, were collected. <h3>Results.</h3> The defined lesions were (a) vertebral body inflammatory lesions, subdivided into corner, non-corner, massive, and lateral inflammatory lesions; and (b) vertebral inflammatory lesions not involving the vertebral body, subdivided into facet joint and other posterior element inflammatory lesions. All definitions were based on presence of increased signal intensity on sagittal T2-weighted fat-suppressed or STIR-images, as compared with the normal bone marrow signal. Vertebral body inflammatory lesions are assessed at each vertebral endplate at all 23 spinal levels from C2/3 to L5/S1, whereas facet joint or posterior element inflammatory lesions are to be assessed by segmental level (cervical, thoracic, and lumbar). <h3>Conclusion.</h3> An anatomy-based set of definitions and an assessment system for active inflammatory lesions in the spine of patients with SpA was developed and illustrated. The system is designed to study the temporal and spatial patterns of inflammation and their relation to the development of structural damage.