Role of CT Enterography in Small Bowel Disorders

Creator: Dr. Narmatha. A
Published: 2023-01-12T16:59:09

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CT enterography is an imaging technique used to examine the small bowel. Read this article to understand more.

Written by

Dr. Narmatha. A

Medically reviewed by

Dr. Ghulam Fareed

January 12, 2023

May 17, 2023

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Contents

What Are the Indications of CT Enterography?
What Are the Contrast Agents Used in CT Enterography?
How Do Patients Prepare for CT Enterography?
How Is the CT Enterography Scan Performed?
What Are the Risks Associated With CT Enterography?

Introduction:

CT (computed tomography) enterography is a medical diagnostic tool used to detect diseases of the small intestine and the structures within the pelvis and abdomen. It is commonly used to visualize and locate the problems such as bleeding, swelling, and obstructions. CT enterography uses oral or intravenous contrast material (a special dye) for small bowel distension, which helps in the rapid and detailed information of the lumen and small intestinal wall.

What Are the Indications of CT Enterography?

CT enterography is helpful in the diagnosis of the following conditions.

Crohn's Disease - An inflammatory bowel disease that causes swelling of the lining of the intestine.
Celiac Disease - An autoimmune disorder that causes damage to the small intestine and is triggered by consuming food containing gluten.
Chronic Mesenteric Ischemia - An intestinal ischemia caused by the obstruction of the major blood vessels supplying the small intestine.
Radiation Enteritis - Swelling of the intestinal lining after radiation therapy.
Scleroderma - Scleroderma is an autoimmune disorder that replaces normal tissue with thick collagenous connective tissue.
Small Bowel Tumors - These includes polyposis syndromes and carcinoids (slow-growing cancer that begins in the stomach, intestine, or lungs).
Patients with possible intestinal (small bowel) hemorrhage.
Abscesses (a buildup of pus within the tissues) and fistulas of the small intestine (an abnormal connection between two structures).

What Are the Contrast Agents Used in CT Enterography?

Before the CT enterography procedure, patients are asked to drink neutral or low-density oral contrast liquid of about 1.5 to 2 liters. The low-density contrast agent, such as water methyl cellulose solution and polyethylene glycol, the neutral contrast, such as 0.1 percent volume (barium sulfate), and milk, is the commonly used oral contrast agent. The oral contrast is consumed over 45 to 60 minutes to fill the entire length of the small intestine. The contrast material used in this scan has CT attenuation properties similar to water. However, water alone cannot cause adequate small bowel distension due to rapid reabsorption.

How Do Patients Prepare for CT Enterography?

Patients should inform the physician about their medical conditions and regular medicines. They can take their regular medicines before the scan.
Patients with kidney diseases may be asked to take a blood test to detect whether the contrast material is safe to inject.
Patients should not have food or drink for about three hours before the scan.
Patients should inform their physician whether they had allergic reactions to contrast materials from the previous scans.
Pregnant women should inform the health provider about their pregnancy before the scan.
Glucagon may be given before the scan, slowing regular bowel movements. Sometimes glucagon may worsen glaucoma, alters normal heart rhythm, and makes urination difficult in prostate disease. Before a CT enterography scan, the patient should tell the health provider if they have any of the above conditions.

How Is the CT Enterography Scan Performed?

Before the CT enterography procedure, patients are asked to remove their clothes and wear hospital gowns. Then the glucagon is administered through intravenous (IV) lines, which help relax the small intestine. Sometimes, the radiologist injects intravenous contrast material into the vein in the arm.
Patients are instructed to lie flat on the procedure table during the scan. Then the table slowly moves through the scanner for scanning. Patients may go through the machine several times, and the scanner begins to rotate around the patient. X-rays from the scanner will pass through the body at different angles and are absorbed by the tissues in the body. The scanner will detect this and transmit it to the computer. The computer processes the information into slices. This process is repeated to get a number of slices. These slices are arranged to get the images (3D) on the computer screen. It offers a selection of pictures taken from various perspectives. To obtain high-quality images, patients might occasionally be required to hold their breath for a little period of time between scans. Any action, such as breathing or physical movement, could cause artifacts in the pictures.
Once the scan is finished, the technician will check the images and sometimes will ask patients to repeat the scan if the images are not clear or may require additional images. Patients can continue their regular activities and are instructed to drink plenty of water after the scan to flush out the excess contrast material from the body. Breastfeeding women should not feed for about two days after the scan as the contrast material may pass through breast milk.

What Are the Risks Associated With CT Enterography?

The risks of CT enterography are low. Some of them are:

Radiation exposure in pregnant women can cause birth defects to the fetus in the womb.
The contrast material used in the scan may worsen the condition in patients having kidney failure or kidney disorder.
The contrast material is expelled by loose stools for about two hours after the scan because they are not absorbed by the body.
Contrast materials used in CT enterography may cause allergic reactions such as headaches, itching, and hives (skin rashes). Some severe symptoms of contrast materials are difficulty breathing, rapid heart rate, low blood pressure, and swelling of the throat or other body parts.
CT enterography scan produces ionizing radiation. Ionizing radiation may damage the DNA and lead to cancer. But risks are significantly less. One in 2000 people who undergo CT scans will acquire cancer that is deadly. Every CT scan over the course of a lifetime could raise the risk.

Conclusion:

CT enterography is a non-invasive, painless procedure commonly used to detect Crohn's disease. The major advantage of CT enterography is that it can show the entire bowel wall thickness, unlike other small intestine imaging techniques. CT enterography is usually performed after negative endoscopy to detect small intestine bleeding. This procedure can quickly detect internal bleeding and injuries in emergency conditions and save many lives.

Frequently Asked Questions

1. In Assessing Small Bowel Disorders, What Role Does CT Enterography Play?

CT enterography, a sophisticated medical imaging approach, employs a CT scan in tandem with a contrast agent to meticulously delineate the intricacies of the small intestine. This advanced imaging modality is pivotal in diagnosing various small intestine ailments, including Crohn's disease and tumors. It aids in evaluating the extent of inflammation, the identification of fistulas or abscesses, and the localization of sites of hemorrhage. Furthermore, it facilitates the continuous monitoring of disease progression and is instrumental in preoperative planning for surgical interventions.

2. How Much Liquid Is Required for a CT Enterography?

Within CT enterography, a specialized contrast substance is employed, typically a radioopaque material, which serves to accentuate the intricate details of the small intestine. The standard procedure entails the patient consuming a volume of contrast solution, typically ranging from 0.26 to 0.52 gallons, gradually over one hour. This ensures the thorough saturation and expansion of the small intestine. In select instances, an intravenous injection is employed to introduce the contrast material, while on rare occasions, it is administered via an enema.

3. Which Organs Are Visible Through CT Enterography?

CT enterography typically places its primary emphasis on the small intestine and the intricate web of structures surrounding it. Specifically, this technique offers a detailed view of the jejunum and ileum within the small intestine. In cases where the upper part of the stomach lies near the small intestine, it might also become partially visible. While not the central focus, this imaging method can provide partial visibility of other abdominal organs like the liver, spleen, and pancreas. Furthermore, nearby pelvic structures, which encompass the bladder and reproductive organs, may also make their presence partially evident.

4. What Steps Are Involved in Preparing for Small Bowel Enterography?

In preparation for an enterography imaging procedure, the individual needs to abstain from consuming solid food for a minimum of three to six hours before the test. It is crucial to inform the healthcare specialist about any prior allergic reactions to the contrast agent, ensuring a safe and informed procedure. An hour before the examination, a specialized oral contrast solution is administered to enhance the imaging quality. Alternatively, if needed, it can be delivered intravenously.

5. What Benefits Does CT Enterography Offer?

CT enterography offers a wealth of high-resolution images, offering intricate insights to aid in disease characterization. It excels in pinpointing areas of inflammation, scrutinizing structural irregularities, and detecting tumors or bleeding sites. Moreover, it is a non-invasive procedure, sidestepping the need for endoscopy while concurrently reducing complications and expediting recovery. The swiftness of results and the minimization of patient discomfort further underscore its advantages.

6. What Is the Purpose of a Bowel CT Scan?

A CT scan of the bowels serves the vital role of diagnosing various abdominal conditions, encompassing inflammatory bowel diseases, gastrointestinal bleeding, infections, and colon cancer. Furthermore, it proves invaluable in assessing bowel obstructions arising from hernias, tumors, or obstructed fecal matter. The scope of its utility extends to the evaluation of abdominal pain and the scrutiny of tumors in proximity to the abdominal region, including those affecting the liver and pancreas. Additionally, it lends a hand in pre-operative planning and post-operative follow-up procedures, making it a comprehensive diagnostic tool for abdominal health.

7. What Potential Side Effects Are Associated With Enterography?

Although enterography is generally considered a safe procedure, it is important to be aware of potential complications. These may include allergic reactions triggered by the contrast material, manifesting as symptoms like itching, swelling, or breathing difficulties. The ingestion of a large quantity of oral contrast solution can lead to feelings of nausea and vomiting. In contrast, the contrast agent itself may result in diarrhea and loose stools, potentially increasing the risk of dehydration. Moreover, it is worth noting that enterography can impact kidney function. In the case of pregnant women, caution is advisable, as the contrast solution may pose harm, especially during the first trimester.

8. How Is CT Enterography Interpreted?

CT enterography interpretation is a task entrusted to the expertise of a radiologist. The core objective in the interpretation process is to meticulously scrutinize the bowel walls, seeking signs of inflammation, thickening, bleeding, or any deviations from the norm. Active bleeding manifests as heightened density in specific regions, while tumors present as irregular masses within tissue density alterations. It is crucial to emphasize that the interpretation of CT enterography should be a collaborative effort intertwined with the patient's clinical history, symptoms, and insights derived from other diagnostic tests.

9. What Can CT Enterography Detect or Diagnose?

CT enterography is a valuable tool for identifying a spectrum of conditions, including but not limited to inflammatory bowel diseases like Crohn's disease and celiac disease. Its diagnostic prowess extends to detecting small bowel obstructions, tumors, or masses in the small intestine, and the identification of vascular structure anomalies such as aneurysms or arteriovenous malformations. In addition, it aids in recognizing abnormal connections like fistulas, enlarged lymph nodes, bowel wall thickening, and any signs of perforations. Furthermore, this imaging technique allows for evaluating adjacent organs, broadening its diagnostic utility even further.

10. Can CT Enterography Reveal the Presence of Ulcers?

Certainly, CT enterography is capable of unveiling the existence of ulcers, which often arise as a result of inflammatory processes. These ulcers typically exhibit localized thickening, with their walls displaying abnormal thickness. Notably, these areas tend to manifest reduced contrast enhancement. Irregularities within the mucosal wall can lead to disruptions in the contrast material distribution, further aiding in identifying these pathological features.

11. What Is the Level of Accuracy Associated With CT Enterography?

In most cases, CT enterography exhibits a commendable level of accuracy when diagnosing a wide array of small intestine and gastrointestinal disorders. The overall accuracy of CT enterography typically hovers around 92.6 percent. It is important to note, however, that this accuracy is flexible and can vary depending on several factors, including the specific condition being diagnosed, the radiologist's level of expertise, and the quality of the imaging equipment in use.

12. What Does the Term Small Bowel Encompass?

Situated between the stomach and the large intestine, this segment of the digestive tract serves a crucial purpose. It plays a pivotal role in not only absorbing nutrients but also actively participating in the breakdown of food particles. This section consists of three distinct segments: the duodenum, which marks the starting point and facilitates digestion through the assistance of digestive enzymes; the jejunum, found in the middle, dedicated to nutrient absorption; and finally, the ileum, which forms the concluding portion responsible for absorbing and facilitating the passage of undigested food remnants.

13. What Is the Procedure for Conducting a CT Enterography?

Typically, the procedure lasts approximately 1 to 2 hours, with the initial hour devoted to the consumption of the oral contrast agent. In preparation for the CT scan, individuals are advised to refrain from eating for a period ranging from 3 to 6 hours. Following ingesting the contrast agent, the individual is carefully positioned on the CT table, and the machine then captures a series of cross-sectional images. Remaining still during this imaging process is essential to minimize motion artifacts affecting image quality. Subsequently, after the image data has been processed, the interpretation of the results is entrusted to the radiologist.

14. What Can You Anticipate After Undergoing a CT Enterography?

Once the CT enterography procedure is complete, individuals are typically free to return to normal activities, including resuming their regular diet. Healthcare professionals may recommend an increased fluid intake to facilitate the elimination of the contrast agent from the body. It is worth noting that changes in the color and consistency of urine and stool can occur due to the presence of the contrast agent. Additionally, any medications are temporarily discontinued before the procedure can be safely resumed.

15. What Is the Sensitivity of CT Enterography?

CT enterography exhibits a sensitivity of 93.88 percent, with a detection rate of 75 percent for stenosis and 50 percent for fistulas. However, this sensitivity is influenced by various factors, including the specific disease under evaluation, the quality of the equipment used, and the radiologist's interpretation. Notably, its sensitivity is notably high when assessing conditions like Crohn's disease, where it approaches an impressive 100 percent.

Sources

Dr. Ghulam Fareed

Medical Gastroenterology

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