Imaging modalities for Meckel's diverticulum
To detect Meckel's diverticulum (Diverticulum ilei), a comprehensive approach is used, depending on the acuteness of the clinical presentation and the presence of complications.
- Ultrasonography (US): This is a valuable method that allows direct identification of the saccular pouch.
- Computed tomography (CT): Directly visualizing the diverticulum itself with CT is usually quite difficult. Nevertheless, this method is extremely important and is performed when a detailed evaluation of complications is necessary. CT is primarily ordered when mechanical intestinal obstruction (intestinal obstruction) is suspected or when there are clinical signs of developing peritonitis.
- Traditional barium contrast radiography: The method remains relevant and very useful when evaluating patients with chronic, persistent symptoms. Barium contrast is used in situations where the results of cross-sectional imaging (CT or MRI) and radionuclide studies are negative.
Radiological sign on contrast enhancement: The specialist visualizes a saccular, blind-ending pouch. It is located strictly on the antimesenteric (antimesenteric) border of the ileum. It is characterized by a specific triradiate fold pattern (triradiate fold pattern) that converges directly with the lumen of the ileum.
It is important to note that neoplasms in Meckel's diverticulum are extremely rare, and in childhood they are not observed at all.
Radiological presentation in acute complications
In emergency pediatric practice, there is often a need for a plain abdominal radiograph (abdominal radiograph).
A classic example is the examination of a child (e.g., a 2-year-old boy) presenting with acute abdominal pain and pronounced clinical signs of peritonitis. In such cases, the radiologist evaluates for the presence of the following signs:
- Dilated bowel loops.
- Gas-fluid levels (gas-fluid levels).
The presence of these symptoms reliably indicates the development of mechanical intestinal obstruction (mechanical ileus). Against the background of these changes, Meckel's diverticulum itself may be visualized on the image as a soft-tissue density saccular shadow located in the middle abdomen.
Differential diagnosis: GI malignancies
When bowel wall thickening or mass lesions in the abdominal cavity are detected in children, a differential diagnosis must be performed. Primary gastrointestinal malignancies (Gastrointestinal Malignancies) are rare in children.
- Colorectal cancer and gastrointestinal stromal tumors (GISTs): Encountered only sporadically and are typically part of a genetic syndrome.
- Lymphomas (Lymphomas): Represent a more significant pathology, accounting for 10% to 15% of all pediatric malignancies.
Extranodal involvement is very common in non-Hodgkin lymphoma (NHL), and in children, this type of involvement is observed much more frequently than in adult patients. Furthermore, the gastrointestinal tract is the most common site for the initial manifestation of the disease.
Typical localization of GI lymphomas: Distal ileum, cecum (caecum), appendix, and ascending colon. An important characteristic is that the involvement can be multifocal.
Radiological signs of lymphomatous involvement
Imaging diagnostics of intestinal lymphoma has a number of specific features. The key macroscopic sign is marked bowel wall thickening, which may be accompanied by either stenosis or dilatation of the affected segment.
- US: The lymphomatous infiltrate is visualized as a hypoechoic (hypoechoic) structure.
- CT or MRI: The infiltrate demonstrates soft tissue density (or signal intensity). Sparse (sparse) contrast enhancement is characteristic.
- MRI (diffusion-weighted imaging - DWI): Images clearly demonstrate a restricted diffusion pattern (restricted diffusion).
Differential diagnosis from inflammation: The main difference between lymphoma and inflammatory bowel processes is that in lymphomatous involvement, the loss of normal bowel wall stratification (loss of stratification) appears at very early stages.
In addition, concomitant involvement of mesenteric (mesenteric) and retroperitoneal (retroperitoneal) lymph nodes may be observed in Hodgkin and non-Hodgkin lymphomas.
Clinical imaging example (contrast-enhanced abdominal CT): In a 12-year-old adolescent with NHL presenting with severe abdominal pain, coronal and sagittal CT reconstructions reveal multifocal bowel wall thickening. The disease may be accompanied by the presence of free fluid in the abdominal cavity (ascites, ascites), as well as pleural effusion (pleural effusion).
Briefly: answers to topical questions
What complications of Meckel's diverticulum are encountered in clinical practice?
Complications of Meckel's diverticulum include:
- ulceration;
- bleeding;
- perforation;
- inflammation;
- intussusception;
- internal hernia;
- volvulus;
- adhesions.
What ectopic mucosa can be found within the wall of Meckel's diverticulum?
Meckel's diverticulum may contain islands of ectopic gastric mucosa, as well as ectopic pancreatic tissue.
- Ectopic gastric mucosa is present in 20% of adults and 95% of children presenting with bleeding symptoms.
- Persistence of heterotopic tissue in the bowel after surgical treatment can lead to recurrence; therefore, resection should be performed within unaffected tissues.
What is the prevalence of Meckel's diverticulum in the population?
The prevalence of Meckel's diverticulum is 0.5–3% of the population or 2–4% of the population. Meckel's diverticulum is the most common remnant of the omphalomesenteric (vitelline) duct. It causes symptoms in approximately 20–40% of cases.
To remember the radiopaque signs of Meckel's diverticulum, use the "Rule of Threes": 1) blind pouch, 2) antimesenteric border, 3) triradiate fold pattern.
Class and exam questions
What does Meckel's diverticulum look like on a barium study?
It is visualized as a saccular blind pouch on the antimesenteric border of the ileum. It is characterized by a triradiate fold pattern converging with the bowel itself.
In which cases is computed tomography (CT) prescribed to diagnose a diverticulum?
The diverticulum itself is difficult to find on CT. The study is performed primarily to evaluate developed complications, such as mechanical intestinal obstruction or peritonitis.
How to differentiate early-stage intestinal lymphoma from an inflammatory process using imaging methods?
The main distinguishing feature is that in lymphoma, the loss of normal bowel wall stratification occurs at the very early stages, unlike in inflammation. MRI (DWI sequence) will also visualize restricted diffusion.
What signs of a complicated diverticulum are visible on a plain abdominal X-ray?
When mechanical intestinal obstruction develops, dilated bowel loops are visible, along with gas-fluid levels. The diverticulum itself may be identified as a soft-tissue density shadow in the middle abdomen.
What else to study on this topic
- Radionuclide imaging methods in the evaluation of the gastrointestinal tract.
- Restricted diffusion on MRI (DWI): physical principles and clinical significance.
- Ultrasound semiotics of hypoechoic intestinal wall infiltrates.
- Imaging patterns of mechanical intestinal obstruction in infants and young children.
- Multifocal gastrointestinal involvement in non-Hodgkin lymphomas.
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