title: MRI of the SI joints commonly shows non-inflammatory disease in patients clinically suspected of sacroiliitis.
abstract: OBJECTIVE
  To determine the prevalence of clinically relevant non-inflammatory disease on MRI of the sacroiliac (SI) joints in patients suspected of sacroiliitis. To assess the added value of axial imaging of the pelvis in these patients.
  
  
  METHODS
  In a retrospective study of 691 patients undergoing MRI of the SI joints from January 2006 to December 2012 for inflammatory back pain the prevalence of sacroiliitis and non-inflammatory disease was recorded.
  
  
  RESULTS
  In 285 (41%) patients MRI did not show any abnormal findings. In 36% of patients MRI features of sacroiliitis were present. Spinal degenerative changes were the most common non-inflammatory finding in 305 patients (44.1%) and consisted of disc degeneration in 222 (32%) patients, facet joint arthrosis in 58 (8.4%) patients and disc herniation in 25 (3.6%) patients. Hip joint disease in 44 (6.4%) patients, lumbosacral transitional anomaly in 41 (5.9%) patients, SI joint degenerative changes in 25 (3.6%) patients and diffuse idiopathic skeletal hyperostosis in 24 (3.5%) patients were also common. Osteitis condensans ilii in 17 (2.5%) patients, tumour in 11 (1.6%) patients, fracture in 8 (1.2%) patients, infection in 4 (0.6%) patients and acute spondylolysis in 2 patients (0.3%) were less frequently seen.
  
  
  CONCLUSIONS
  Our study shows that non-inflammatory disease is more common than true sacroiliitis on MRI of the SI joints in patients with inflammatory type back pain. Axial pulse sequences may demonstrate unexpected findings that remain undetected if only coronal images are obtained. Clinical relevance statement:, MRI of the SI joints may demonstrate conditions that clinically mimic sacroiliitis. Axial imaging of the pelvis may help detect these unexpected findings.
authors.affiliation: Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium. Electronic address: lennartjans@hotmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Jans
authors.affiliation: Department of Rheumatology, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Van Praet
authors.affiliation: Department of Rheumatology, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Elewaut
authors.affiliation: Department of Rheumatology, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Van den Bosch
authors.affiliation: Department of Rheumatology, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Carron
authors.affiliation: Department of Radiology, University of Alberta Hospital, 8440-112 Street, Edmonton T6G 2B7, Alberta, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Jaremko
authors.affiliation: Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Behaeghe
authors.affiliation: Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Denis
authors.affiliation: Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: W
authors.initials: W
authors.lastname: Huysse
authors.affiliation: Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Lambrecht
authors.affiliation: Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Verstraete
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001530:Belgium / Q000453:epidemiology; D002648:Child; D015897:Comorbidity; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000453:epidemiology*; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012446:Sacroiliac Joint / Q000473:pathology*; D058566:Sacroiliitis / Q000453:epidemiology* / Q000473:pathology; D013122:Spinal Diseases / Q000453:epidemiology* / Q000473:pathology; D055815:Young Adult
keywords: Back pain; Inflammation; Magnetic resonance imaging; Sacroiliac joint; Sacroiliitis