Useful in following treatment results in patients with active ankylosing spondylitis Superior to CT in the detection of cartilage inflammation and destruction Periarticular fat metaplasia of the sacroiliac joints Increased T2 signal correlates with edema or vascularized fibrous tissue Synovial enhancement on MR correlates with disease activity measured by inflammatory mediatorsĮnhancement of the interspinous ligaments is indicative of enthesitis May have a role in early diagnosis of sacroiliitis MRI is more sensitive than CT or plain radiography in detecting inflammatory changes (which precede structural changes) such as bone marrow edema (best demonstrated on STIR sequences), synovitis and capsulitis (on gadolinium enhanced T1 weighted sequences) 16,18 Sagittal reformats should be obtained as axial images poorly assess the transverse fracture plane Imaging modality of choice in patients with advanced ankylosing spondylitis in whom there is suspicion of cervical spine fracture Superior to radiographs and MRI in demonstrating injuries Supplements scintigraphy in evaluating areas of increased uptake Some normal variants of the SI joints may mimic features of sacroiliitis May be useful in selected patients with normal or equivocal findings on sacroiliac joint radiographsĬhronic structural changes such as joint erosions, subchondral sclerosis, and bony ankylosis are better visualized on CT than on MRI or radiographs 15-17 See: cardiovascular manifestations of ankylosing spondylitis CT Plain radiograph may be normal, or may reveal cardiomegaly. See: thoracic manifestations of ankylosing spondylitis Cardiac These lesions may resemble tuberculosis infection and bullae may become infected. Radiographs of the lungs may demonstrate progressive fibrosis and bullous changes at the apices. Marrow edema of the acromion process, at the site of origin of deltoid muscle, has been described as a very specific sign of the disease ref Glenohumeral joint involvement is not uncommon and demonstrates a large erosion of the anterolateral aspect of the humeral head, producing a 'hatchet' deformity ref Hands are generally involved asymmetrically, with smaller, shallower erosions and marginal periostitis. Knees demonstrate uniform joint space narrowing with bony proliferation. There can be bridging or fusion of the pubic symphysis. Whiskering of the pelvic bones primarily affects the ischial tuberosities, resulting from ossification of the ligamentous origins. Hip involvement is generally bilateral and symmetric, with uniform joint space narrowing, axial migration of the femoral head sometimes reaching a state of protrusio acetabuli, and a collar of osteophytes at the femoral head-neck junction. ![]() Pseudoarthroses may form at fracture sites Ossification of spinal ligaments, joints and discs (with fatty marrow within the ossified disc, best seen on MRI)Īpophyseal and costovertebral arthritis and ankylosis Linear ossification along the central spine representing interspinous ligament ossification can give a " dagger spine" appearance on frontal radiographs Syndesmophytes are classically described as paravertebral ossification running parallel to the spine Noninfectious spondylodiscitis: Andersson lesionĭiffuse syndesmophytic ankylosis can give a " bamboo spine" appearance Subchondral erosions, sclerosis, and proliferation on the iliac side of the SI jointsĪt end-stage, the SI joint may be seen as a thin line or not visibleĮarly spondylitis is characterized by small erosions at the corners of vertebral bodies with reactive sclerosis: Romanus lesions of the spine ( shiny corner sign) The sacroiliac joints first widen before they narrow Sacroiliitis is usually the first manifestation 5 and is symmetrical and bilateral The axial skeleton is predominantly affected, although in ~20% of cases the peripheral joints are also involved. Overall, ~5% of people positive for HLA-B27 develop ankylosing spondylitis. Although approximately 90% of Caucasian individuals with ankylosing spondylitis have the HLA-B27 gene, it is important to note this gene is present in 8-9% of people of Northern European ancestry 5. Other possibly contributing genes include ERAP-1, IL23R and TNF-associated genes 22. HLA-B27 is the gene with the strongest association. Patients are rheumatoid factor (RF) negative, hence seronegative. Inflammatory bowel disease: ulcerative colitis / Crohn diseaseĪpical/upper lobe predominant interstitial lung disease with small cystic spaces (in ~1% of patients) 4 ![]() The disease usually manifests in young adults, with the first symptoms becoming evident in the third decade, although up to 18% of cases manifest in the second decade. According to some research, men tend toward more severe disease 28. Traditionally it was thought there was a male predilection of 3:1 or more, however, the gender predilection of the disease is a matter of recent debate and research (females may be under-diagnosed).
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