Radiation enteritis is a bowel pathology resulting from toxic effects of radiotherapy on the bowel wall and vasculature.
5-15% of patients treated with radiotherapy (usually > 4500cGy) develop chronic radiation enteropathy.
The clinical presentation is nonspecific with abdominal pain, vomiting, bloody diarrhoea and steatorrhoea. Patients with chronic radiation enteritis may develop deficiencies of calcium, iron and vitamin B12 deficiency.
In the acute phase, radiation affects bowel mucosa causing cell death with ulceration. It also causes inflammation with mucosal and submucosal oedema. In the subacute and chronic phases healing and fibrosis occurs. Additionally radiation induces endarteritis obliterans, which results in a state of chronic mesenteric ischaemia leading to bowel strictures.
- adhesions from previous abdominal surgery
- peritonitis prior to radiation therapy
- high radiation dose
- risk factors for atherosclerosis; hypertension and diabetes mellitus
- acute stage: concurrent or within 2 months of treatment
- subacute: 2-12 months after treatment
- chronic: >12 months after treatment
- acute radiation enteritis
- bowel loops appear spastic with luminal narrowing and oedema of mucosal folds
- chronic radiation enteritis
- thickening of bowel wall and folds due to oedema or fibrosis
- “stack of coins appearance” enlarged smooth, parallel mucosal folds
- single or multiple bowel stenoses
CT and MRI
- bowel wall thickening and luminal narrowing
- small bowel obstruction
- fistulas between the bowel (especially colon) and the bladder or vagina
Following pelvic radiotherapy, enteritis of the small bowel typically involves the more fixed terminal ileum and manifests as bowel wall thickening and submucosal edema at CT.
General imaging differential considerations include
As a broader differential consider other forms of enteritis.
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