Meckel's diverticulum other imaging findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Sudarshana Datta, MD [2]
Overview
A technetium-99m (99mTc) pertechnetate scan is the investigation of choice for the diagnosis of Meckel's diverticulum. This scan detects gastric mucosa; since approximately 50% of symptomatic Meckel's diverticula have ectopic gastric (stomach) cells contained within them. A Meckel's diverticulum containing gastric mucosa manifests as a small rounded area of increased activity in the right lower quadrant, while normal activity simultaneously appears in the stomach.
Other Imaging Findings
Technetium-99m pertechnetate radioisotope scanning
- September 2014: Guidelines for the Scintigraphy for Meckel’s diverticulum were laid down by:[1]
- Society of Nuclear Medicine and Molecular Imaging (SNMMI)
- European Association for Nuclear Medicine (EANM)
- Technetium-99m pertechnetate scanning helps in the detection of a symptomatic bleeding Meckel’s diverticulum.
- It is preferred as the investigation of choice for the diagnosis of Meckel's diverticula in children due to the following features:[2]
- High accuracy
- Noninvasive nature
- 95% specificity
- 85% sensitivity
- Approximately 50% of symptomatic Meckel's diverticula have ectopic gastric or pancreatic cells contained within them[3]
- Technetium-99m pertechnetate scanning is not preferred in adults as false negative rates are high with specificity of 9% and sensitivity of 62%.
- False-positives are seen in the following conditions:
- Intussusception
- Volvulus
- Obstruction of the small intestine
- Acute appendicitis
- Carcinoid of the appendix
- Carcinoma of the cecum
- On intravenous administration, the Technetium-99m pertechnate radioisotope is taken up by the gastric mucosa.
- In order to obtain a positive result, atleast 1.8 cm2 of ectopic gastric mucosa in Meckel's diverticulum is required.
- A Meckel's diverticulum containing gastric mucosa manifests as a small rounded area of increased activity in the right lower quadrant.
- Normal activity simultaneously appears in the stomach.
- Technetium-99m pertechnetate scanning requires 30 images, taken at 1-minute intervals to demonstrate terminal ileum activity.
- The use of Pentagastrin in Technetium-99m pertechnetate scanning has a synergistic effect:
- Role of Pentagastrin:
- Histamine-2 (H2) receptor blocker
- Enhances radioisotope uptake by the cells:
- Promotes isotope retention
- Blocks intraluminal release of isotope
- Minimizes false negative results
- Meckel's diverticulum is identified as a saccular, blind-ending structure located on the antimesenteric border of the ileum.
- Meckel's diverticulum is usually found in the right lower quadrant and pelvic region.
- The junction of the diverticulum with the ileum may show a mucosal triangular plateau or triradiate fold pattern (represents the site of omphalomesenteric duct attachment to the ileum).
Angiography
- Angiography may assist in determining the location and severity of bleeding in case of a bleeding Meckel's diverticulum.
- In patients presenting with acute GI bleeding, superior mesenteric angiography is effective if blood loss exceeds 0.5 mL/min(brisk bleeding).[2]
- Conventional contrast mesenteric arteriography has the following indications:
- If a source of gastrointestinal bleeding is brisk and may require transfusion
- If the source has not been identified using other imaging modalities
- In patients with ongoing hemorrhage, active contrast extravasation may be visible
- Detection of an anomalous branch of the superior mesenteric artery that feeds the diverticulum. This anomalous branch usually has the following features:
- Non branching
- Long
- Terminates in irregular, small branches after traversing the mesentery
- High-resolution CT angiography is preferred in patients when bleeding is less brisk (as little as 0.3 mL/minute).
- CT angiography may help detect active signs of bleeding diverticulum, that may be undetectable with other modalities such as
- Tagged red blood cell scan
- Colonoscopy
- Conventional arteriography
- Disadvantage:
- Patient is subject to ionizing radiation
- Invasive
Single-photon emission computed tomography (SPECT)/CT fusion imaging
- The role of Single-photon emission computed tomography (SPECT)/CT fusion imaging as a diagnostic modality is currently under exploration.
References
- ↑ Spottswood SE, Pfluger T, Bartold SP, Brandon D, Burchell N, Delbeke D, Fink-Bennett DM, Hodges PK, Jolles PR, Lassmann M, Maurer AH, Seabold JE, Stabin MG, Treves ST, Vlajkovic M (2014). "SNMMI and EANM practice guideline for meckel diverticulum scintigraphy 2.0". J Nucl Med Technol. 42 (3): 163–9. doi:10.2967/jnmt.113.136242. PMID 24948825.
- ↑ 2.0 2.1 "Fundamentals of Pediatric Surgery - Google Books".
- ↑ Martin JP, Connor PD, Charles K (2000). "Meckel's diverticulum". Am Fam Physician. 61 (4): 1037–42, 1044. PMID 10706156.