Radiation-induced enteritis

Teenager with
abdominal pain after eating with remote history of radiation therapy to abdomen. AP image from an upper GI and small bowel follow through exam shows marked thickening of the small bowel folds throughout the jejunum (stack of coins sign). The diagnosis was chronic small bowel ischemia secondary to chronic radiation induced enteritis.
pediatricimaging.org • CC-by-nc-sa 4.0
Schoolager
with vomiting after recent radiation therapy. AP image from a small bowel follow through exam shows diffuse luminal narrowing of the distal jejunum and proximal ileum in the center of the image.The diagnosis was acute radiation induced enteritis.
pediatricimaging.org • CC-by-nc-sa 4.0
Preschooler
who had Wilms tumor in the left kidney treated with radiation a year ago with difficulty stooling. AP image from an enema shows a fixed narrowing of the descending colon from the splenic flexure to the sigmoid colon with dilation of the colon proximal to it. The extremely dilated cecum is in the midline of the pelvis.The diagnosis was radiation induced enteritis involving the descending colon in a patient with Wilms tumor.
pediatricimaging.org • CC-by-nc-sa 4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Radiation-induced enteritis is a small bowel pathology resulting from toxic effects of radiotherapy on the small bowel wall and vasculature.

Epidemiology

5-15% of patients treated with radiotherapy (usually >4500 cGy) develop chronic radiation enteropathy.

Terminology

Enteritis is inflammation of the small bowel. If there is concurrent inflammation of the large bowel, then enterocolitis is a better term.

Clinical presentation

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.

Pathology

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.

Risk factors 
Classification
  • acute stage: concurrent or within 2 months of treatment
  • subacute: 2-12 months after treatment
  • chronic: >12 months after treatment

Radiographic features

Fluoroscopic enteroclysis
  • 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
    • ulcers
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.

Differential diagnosis

General imaging differential considerations include:

As a broader differential consider other forms of enteritis.

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