RESEARCH Magnetic resonance imag i T

Full list of author information is available at the end of the articleSpondyloarthopathy (SpA) is a type of arthritis with unique features of axial joint disease and abnormal new bone for-mation [1,2]. Sacroiliitis, arthritis of the sacroiliac (SI) joint, is a characteristic finding of spondyloarthropathy [1]. Many patients subsequently develop ascending arthritis of the spine and eventually ankylosis (fusion) [3]. Only a subset of including children with enthesitis-related, psoriatic, react-ive, and inflammatory-bowel-disease-related arthritis [4,5]. Juvenile SpA is diagnosed when the disease starts prior to age 16 years [6]. Children typically first present with enthe-sitis and lower extremity peripheral arthritis prior to devel-oping axial pathology [4,5]. Sacroiliitis can be asymptomatic and difficult to evaluate on physical exam. Radiography only detects structural damage that oc-curs late in the disease. Magnetic resonance imaging * Correspondence: clara.lin@childrenscolorado.org1Children’s Hospital Colorado Pediatric Rheumatology, 13123 East 16thAbstrac