Contrast-enhanced CT of the abdomen

Main protocols and preparation

The choice of CT protocol depends on the clinical objective. If the goal is staging malignancies (e.g., esophageal cancer), the scan typically covers the chest, abdomen, and pelvis. Good distension of hollow organs is critically important for quality imaging. The patient is asked to drink 1–1.5 liters of water, as well as effervescent granules (effervescent granules). The scan itself is performed with intravenous contrast administration, often in the prone position (prone position).

When examining the colon, the standard protocol may include oral contrast (e.g., a 2% barium suspension or a water-soluble agent like Gastrografin). Contrast administration begins the day before the study and is combined with intravenous enhancement. In emergency cases where anastomotic leakage or wall perforation is suspected, contrast may be administered rectally.

Colon evaluation and CT colonography

Tomographic imaging methods have almost completely replaced traditional fluoroscopic examinations (such as double-contrast barium enema) in the diagnosis of polyps and cancer.

CT criteria for a normal colon:

• The wall thickness with sufficient lumen distension is no more than 3 mm.
• The pericolic adipose tissue appears homogeneous, with a small number of vascular channels.
• The mucous membrane shows normal enhancement after intravenous administration.

It is the pattern of contrast enhancement of the wall (mural enhancement pattern) that provides the radiologist with key information about the nature of the pathology.

A separate method is CT colonography (CT colonography, CTC). This is a CT scan of the colon whose lumen is distended with gas. A mandatory requirement is the "tagging" (tagging) of residual stool with oral high-osmolarity agents. This gives the intestinal contents a high X-ray attenuation (attenuation). Preparation for such a study can include complete bowel cleansing with laxatives or be performed without them (prep-less CTC).

Application in blunt abdominal trauma

Computed tomography is the method of choice for evaluating pelvic and abdominal trauma in hemodynamically stable patients. This is especially relevant in pediatric practice, where most trauma is blunt, the liver is most frequently injured, and management remains conservative in most cases.

The main drawback of CT is radiation exposure. Therefore, multiphase studies (multiphase CT) should be avoided. The modern standard is the split-bolus contrast technique (split bolus contrast technique). It allows simultaneous acquisition of the arterial and portal-venous phases during a single scanner pass.

Imaging of inflammation and ischemia

Non-contrast and contrast-enhanced CT are indispensable when severe complications are suspected. For example, in neutropenic enterocolitis (typhilitic colitis), coronal slices reveal generalized ascites and hyperenhancement of the small bowel loops.

Special attention is paid to the state of the cecum: its wall is significantly thickened. If a decrease in contrast enhancement is noted at the same time, this is regarded as a reliable sign of developing ischemia or necrosis, which can highly likely lead to perforation.

Class and exam questions

What else to study on this topic

• Topographic anatomy and histology of the stomach
• Single and double contrast imaging in fluoroscopy
• Comparison of barium and water-soluble contrast agents
• Abdominal manifestations of cystic fibrosis (DIOS syndrome, intussusception)
• Endoscopic treatment methods for esophageal pathologies

Other topics in the section "Diagnostic Radiology of the Abdominal Organs"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.