Radiation-induced enteritis is a small bowel pathology resulting from toxic effects of radiotherapy on the small bowel wall and vasculature.
5-15% of patients treated with radiotherapy (usually >4500 cGy) develop chronic radiation enteropathy.
Enteritis is inflammation of the small bowel. If there is concurrent inflammation of the large bowel, then enterocolitis is a better term.
The clinical presentation is non-specific with abdominal pain, vomiting, bloody diarrhea and steatorrhea. 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 edema. In the subacute and chronic phases healing and fibrosis occurs. Additionally, radiation induces endarteritis obliterans, which results in a state of chronic mesenteric ischemia 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 edema of mucosal folds
- chronic radiation enteritis
- thickening of bowel wall and folds due to edema 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.
- 1. Federle MP. Diagnostic imaging, Abdomen. Amirsys Inc. (2004) ISBN:1416025413. Read it at Google Books - Find it at Amazon
- 2. Addley HC, Vargas HA, Moyle PL et-al. Pelvic imaging following chemotherapy and radiation therapy for gynecologic malignancies. Radiographics. 2010;30 (7): 1843-56. doi:10.1148/rg.307105063 - Pubmed citation
- 3. Brant WE, Helms C. Fundamentals of Diagnostic Radiology. Lippincott Williams & Wilkins. ISBN:1608319121. Read it at Google Books - Find it at Amazon
Related Radiopaedia articles
external beam radiation therapy (EBRT)
- conventional (2D) radiation therapy
- 3D conformal radiation therapy
- intensity-modulated radiation therapy (IMRT)
- stereotactic radiosurgery
- electron therapy
- particle (hadronic) therapy
- sealed source radiation therapy (brachytherapy)
- unsealed source radiation therapy
- external beam radiation therapy (EBRT)
- complications related to radiation therapy
- acute radiation syndrome
- complications of cranial radiation therapy
- radiation-induced thyroid cancer
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complications of thoracic radiation therapy
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- bony thoracic cage
- complications of abdominopelvic radiation therapy
- radiation-induced bone marrow signal changes - MRI