Comparison of CT Scan Between Patients With Axial Spondyloarthritis and Control Subjects

Inclusion Criteria : axSpA population: * Adults aged 18 to 69 years, * Diagnosis of axSpA according to the ASAS 2009 criteria, * Hospitalized in the Rheumatology Department of the NOVO Hospital (Pontoise site) from 01/01/2015 to 30/10/2022 and had a Chest CT scan with images available in the hospital's computer system, * Informed of the study and did not object. Control population: * Adults aged 18 to 69 years, * Day hospitalization in the pneumology department of the NOVO Hospital (Pontoise site) from 01/01/2015 to 30/10/2022 and having had a lung scan on this occasion, * Informed of the study and did not object. Exclusion Criteria : axSpA population: * Peripheral spondyloarthritis, * Unavailability of chest CT scan images in the hospital computer system, * Unknown result of pelvic X-ray. Control population: * Lung cancer or suspected lung cancer * Any of the following conditions: spondyloarthritis, rheumatoid arthritis, psoriatic arthritis, SAPHO syndrome, chest wall bone disease, tumour bone disease, severe scoliosis, malformative syndrome * History of thoracic trauma or thoracic surgery, * Unavailability of chest CT scan images in the hospital computer system.