Crohn disease

Findings:

Inflammation

• segmental mural bilaminar hyperenhancement and moderate to severe asymmetric wall thickening accentuated along the mesenteric border with a corresponding hyperintense signal on T2w and high signal in diffusion-weighted images (b800)

• located in the mid, distal and terminal ileum

• small ulcerations

• long stricture with intermittent pseudosacculations along the anti-mesenteric border in the distal ileum

Penetrating disease

• sinus tracts in the ileum in the mid and left lower abdomen

• no complex fistulas, abscess or an inflammatory mass

Mesenteric inflammation

• signs of fibrofatty proliferation

• engorged vasa recta

• no signs of adenopathy

Other findings/complications

• mobile caecum cranially reverted

• no signs of mesenteric venous thrombosis or occlusion

• no signs of primary sclerosing cholangitis (PSC)

• no gallstones or kidney stones

• no signs of avascular necrosis (AVN)

• Periarticular fatty deposition in the sacrum and bony bridging of the left sacroiliac joint indicative of chronic sacroiliitis

Impression:

Active inflammatory small bowel Crohn’s disease in the mid/distal and terminal ileum with luminal narrowing/strictures and ulcerations.

Small blind-ending sinus tracts can be seen in the affected segment in the left and mid-lower abdomen.

A dedicated pelvic MRI was recommended for the assessment of perianal complications.

Signs of chronic left-sided sacroiliitis.

Inflammation

• segmental mural hyperenhancement (red arrows)

• moderate to severe asymmetric wall thickening accentuated along the mesenteric border (blue arrows)

• hyperintense signal on T2w and signs of restricted diffusion on b800 and respective ADC images (green arrows)

Stricture

• luminal narrowing/obstruction with signs of active inflammation and with upstream dilatation (blue arrowhead)

Ulceration

• small focal break in the intraluminal surface of the bowel wall (green arrowhead)

Pseudosacculation

• broad-based outpouchings usually along the anti-mesenteric border (red arrowhead)

Penetrating disease

• blind-ending sinus tracts in the distal ileum (orange arrow)

Mesenteric inflammation

• signs of fibrofatty proliferation (“creeping fat”) consistent with an increased amount of mesenteric fat adjacent to the abnormal small bowel loops most prominent on the mesenteric border (orange arrowheads)

• engorged vasa recta (“comb sign”)

Additional findings

• cranially reverted mobile caecum (yellow arrowhead)

• inflammatory changes of the terminal ileum (yellow arrow)

• sacroiliitis with a bony bridge (purple arrowhead)