1. to determine the overall frequency of Inflammatory sacroiliitis among patients with Inflammatory bowel disease using magnetic resonance imaging
2. identify the association of sacroliitis in IBD patients clinical and laboratory markers

INFLAMMATORY BOWEL DISEASE (IBD) is a disorder in which an inappropriate response to an unknown antigen, combined with genetic and environmental factors, result in inflammation of the small bowel and colon . The two main forms of IBD are Crohn's disease (CD) and ulcerative colitis (UC) which are both associated with spondyloarthropathy (SpA), an inflammatory arthritis characterized by sacroiliitis and inflammatory back pain .

Articular manifestations of inflammatory bowel disease(IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), were first described in 1930 and have been considered as spondylarthropathies since 1978. They include peripheral arthritis and inflammatory axial involvement.

Extra-intestinal musculoskeletal manifestations associated with Inflammatory bowel disease, can be divided into axial and peripheral arthropathy, which can be a cause of significant morbidity that can adversely affect the quality of life in these patients. Peripheral arthropathy represent the most frequent (40%) extra-intestinal manifestation in IBD. These manifestations occur more frequently in patients with Crohn's disease.

Sacroiliitis (SI) is considered one of the common axial arthropathies with an estimated prevalence of around 10% of Crohn's patients.

It is crucial to differentiate inflammatory back pain due to axial SpA from other causes of chronic low back pain as they have different treatments and prognosis.

The diagnosis is based upon the presence of characteristic inflammatory type back pain with evidence of SI on imaging . Both clinical examination and plain radiographs have their own limitations of only detecting advanced disease.

Importantly, sacroiliitis, which is the hallmark of the spondyloarthropathies, may be clinically silent with an ambiguous or equivocal physical examination tests so imaginghas important role in its diagnosis Imaging findings in sacroiliitis are divided into acute and structural changes.The acute findings of sacroiliitis can be observed on magnetic resonance imaging (MRI) and include periarticular sacroiliac joint (SIJ) bone marrow edema(BME), soft tissue edema, and contrast enhancement. Structural changes including SIJ erosions, subchondral sclerosis and bony bridges appear relatively late in the disease .Indeed, findings compatible with acute inflammation may be seen on MRI years before late structural findings are evident.

MRI is a promising technology with a higher sensitivity and specificity for the diagnosis of SI. As MRI is being utilized more frequently in patients with Crohn's disease, more and more patients are found to have a positive MRI evidence of SI without clinical signs or symptoms so MRI is necessary for diagnosing and evaluating patients with early disease.

Incorporation of magnetic resonance imaging (MRI) to assess axial SpA allows early recognition of axial SpA in CD, especially when patients do not present with classic IBP symptoms.

The introduction of biological drugs from the tumor necrosis factor-alpha (TNF-a) receptor blocker group, has further emphasized the need for early diagnosis of sacroiliitis in patients with IBD, many of which, can be asymptomatic, nonradiographic, or both. These drugs, when administered early in the disease, are capable of changing the course, alleviating the symptoms and even producing withdrawal of early imaging findings, including BME and contrast enhancement.

Inclusion Criteria:

• subjects between 18 and 65 years.
• subjects met clinical, pathological or radiological criteria of IBD.

Exclusion Criteria:

1. Patients who refuse enter the study
2. Patients who not diagnosed as IBD
3. other inflammatory arthritis (e.g. rheumatoid arthritis, systemic lupus erythematosus, psoriatic or reactive arthritis)
4. co-existent autoimmune diseases (e.g. celiac disease, Behcets disease)
5. malignancy less than 5 years in remission .
6. having a contraindication to MRI.

All patients were selected from outpatient clinic of IBD of Elraghi hospital.