• inflammatory bowel disease (IBD)
• MRE
• MRI
• pediatric
• sacroiliitis

OBJECTIVE
To establish the prevalence of sacroiliac (SI) joint inflammation in a group of pediatric patients with inflammatory bowel disease (IBD) investigated with magnetic imaging enterography (MRE) performed for IBD diagnosis or follow-up.

METHOD AND MATERIAL
We retrospectively reviewed MRE scans performed in pediatric patients with IBD. We looked for signs of sacroiliitis taking the ASAS (Assessment of SpondyloArthritis international Society) criteria as a model. Presence of bone marrow edema (using T2W sequences with fat suppression), diffusion restriction in Diffusion Weighted Imaging (DWI) or Diffusion Weighted Imaging with Background Suppression (DWIBS), and dynamic contrast enhancement were evaluated. Each SI joint was divided into 4 quadrants: upper iliac, lower iliac, upper sacral, and lower sacral. Two blinded observers with experience in pediatric and skeletal imaging independently evaluated the images. Cases upon which there was a disagreement were evaluated by the two reviewing radiologists and a third radiologist with similar experience together.

RESULTS
We enrolled 34 patients (24 males and 10 females, range: 5-19 years) for a total of 59 examinations. Five patients (all asymptomatic with regard to back symptoms) had radiological signs of SI inflammation, albeit of mild degree. All patients with SI joint edema also had a restricted diffusion in DWIBS or DWI and almost everyone had contrast media uptake.

CONCLUSIONS
We found radiological SI inflammation in patients with IBD who did not complain of back symptoms. The use of gadolinium did not seem to improve diagnostic specificity.