Seronegative spondyloarthritidies (SpA) are inflammatory diseases that affect the axial skeleton, predominantly the sacroiliac joints (SIJs). With a prevalence of up to 2%, SpA are among the most common inflammatory rheumatic diseases in the general population . Until recently, SpA had been subdivided into ankylosing spondylitis (AS), psoriatic arthritis (PsA), enteropathic SpA, reactive arthritis, and undifferentiated SpA; however, there is now a trend to distinguish between predominantly axial spondyloarthritis and predominantly peripheral spondyloarthritis [2,3]. The most frequently involved sites of inflammation in SpA are the insertion of tendons, ligaments, and joint capsules to bone, designated entheses. Inflammatory back pain is the most suggestive symptom. In addition to laboratory findings and clinical signs, imaging plays a major role in the diagnosis of SpA and to assess outcome of treatment. Imaging modalities applied are conventional radiography, computed tomography (CT), magnetic resonance imaging (MRI), scintigraphy, and ultrasonography.