Gastrointestinal Bleeding

Multiphase CT Enterography

MCTE image of a hemangioma in the small bowel.

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Multiphase CT enterography (MCTE) is a new non-invasive procedure that uses very fast CT scanning combined with liquid intake to obtain detailed images of the abdomen. In a report on its use in more than 700 cases ( PubMed reference), Mayo doctors said that CT enterography had several advantages over conventional bowel imaging: it showed the entire thickness of the bowel wall; it was able to image all of the long loops of the small intestine; and it can also evaluate surrounding mesentery and fat tissues.

Mayo Clinic has been a leader in the development of this procedure and have used in more than 3,000 cases. Mayo doctors have found MCTE to be a helpful complement to capsule endoscopy in identifying and localizing bleeding sources. It is particularly valuable in evaluating patients with Crohn's disease.

Before the procedure, the patient drinks several glasses of a water solution with a trace of barium in order to expand the intestine (for better viewing) and provide contrast.

Just before scanning, the patient is given an IV through which contrast dye will be injected. After the dye is injected, the radiologist typically performs three scans at different intervals (when the dye has just fully filled the arteries, then 20 and 90 seconds later, for example). This is important because abnormalities may become more visible at different stages of blood flow.

The outlines of angiodysplasias (small vascular abnormalities), for example, show up best when the arteries are fullest, whereas active venous bleeding becomes more visible later on, after then veins have started to empty. Also, some small tumors do not bleed continuously, but have more of a transitory "blush," which is more likely to be caught if scanning is done in multiple phases.

The higher speed of the special equipment (a 64 channel system) makes capturing these different phases possible.

Because it's a cross-sectional technique, MCTE can also see tumors that are more embedded in the intestinal wall and barely visible on its surface (making them easy to miss with endoscopy or capsule endoscopy).

Drawbacks are radiation exposure (as with any CT scanning) and risks associated with the contrast dye.