[Inflammatory spinal disease: Spondyloarthritis: Importance of imaging].

Conventional radiography of the pelvis and lumbar spine is the method of choice for the initial evaluation of spondyloarthritis (SpA). Sacroiliitis is classified according to the modified New York grading criteria; however, to improve the early diagnosis of SpA, magnetic resonance imaging (MRI) should be performed as MRI enables the detection of early inflammation, such as subchondral bone marrow edema of the sacroiliac joints (SIJ), which defines sacroiliitis. Sacroiliitis and HLA-B27 are considered to be equivalent criteria for the diagnosis of SpA. In equivocal findings in the SIJ, an evaluation of the whole spine might be helpful because involvement of the thoracic and lumbar spine, shiny corner sign (Romanus lesions) and spondylodiscitis (Andersson lesions), as well as inflammation of the pedicles, zygoapophyseal joints and longitudinal ligaments, are typical findings in SpA. The prevalence of seronegative SpA is higher than has been previously assumed. Imaging in SpA plays an important role in selecting patients with inflammatory back pain and thus, helping to prevent irreversible changes through adequate early treatment.