Meckel’s Diverticulum Scan
The Meckel’s scan uses ⁹⁹ᵐTc-pertechnetate, which is taken up by ectopic gastric mucosa within a Meckel’s diverticulum — the most common cause of lower-GI haemorrhage in previously healthy infants and young children. A focus of uptake appearing in the right lower quadrant in parallel with gastric activity is the classic finding. Overall sensitivity ≈85% and specificity ≈95%; yield is lower in adults.
Approximately 57% of Meckel’s diverticula contain ectopic gastric mucosa; pertechnetate concentrated by these cells makes the diverticulum visible. Pharmacological enhancement (e.g. H2-blocker or proton-pump inhibitor) can improve sensitivity but is not considered necessary.
When to image
- Painless lower-GI bleeding, especially in children/young adults.
- Suspected Meckel’s diverticulum with negative endoscopy.
How to read it
- A focus appearing at the same time as gastric activity, usually in the right lower quadrant, that increases over time.
- Distinguish from urinary tract and bowel activity.
- Absence of ectopic gastric mucosa gives a false-negative.
Protocol
- Fasting 3–4 h if possible (not mandatory); optional H2-blocker/PPI pre-treatment; stop GI-irritating drugs 2–3 days before.
- Dynamic anterior imaging (1 frame/30–60 s) for at least 30 min, up to 60 min; beyond 60 min gastric activity entering bowel confounds reading.
- Lateral/post-void views to separate urinary activity.
Pitfalls
- Diverticula without gastric mucosa are not detected.
- False positives: urinary tract activity, bowel inflammation, duplication cyst with gastric mucosa, intussusception/obstruction, peptic ulcer and vascular lesions.
- Recent in vivo red-cell labelling (stannous pyrophosphate) or perchlorate reduces gastric-mucosal uptake and can cause a false negative.
Evidence & guidelines
- SNMMI/EANM Meckel diverticulum scintigraphy guideline 2.0 (Spottswood et al., J Nucl Med Technol 2014;42:163–169).
- Higher diagnostic yield in the paediatric population.
In depth
- ⁹⁹ᵐTc-pertechnetate is taken up by the mucin-producing cells of gastric mucosa, independently of the acid-producing parietal cells; overall sensitivity is 85%, specificity 95% and accuracy 90% for a diverticulum containing gastric mucosa.
- Paediatric activity is 1.85 MBq/kg (minimum 9.25 MBq), as in the 2010 North American consensus guidelines.
- Perform the study when the patient is NOT actively bleeding (active bleeding is better studied with labelled-RBC scintigraphy); a 3–4 h fast may shrink the gastric silhouette but is not required.
- H₂ blockers or proton pump inhibitors can improve sensitivity by limiting release of pertechnetate into the lumen; glucagon is an optional adjunct that slows peristalsis and washout of secreted tracer (avoid in diabetics). Recent perchlorate reduces mucosal uptake and should be avoided.
- Protocol: flow images at 1–5 s/frame for up to 1 min, then dynamic imaging at one frame every 30–60 s for at least 30 min (up to 60 min); imaging beyond 60 min is discouraged because gastric activity passes into the bowel.
- Ectopic gastric mucosa appears at the same time as the stomach, is usually most prominent at 10–15 min, and is typically in the right lower quadrant but may be elsewhere or move during the study.
- Post-void, lateral or SPECT/CT views help separate diverticular activity from renal, ureteric or bladder activity; false negatives occur with brisk bleeding, small foci of mucosa (<1.8 cm²), or prior barium studies or perchlorate.
Sources: SNMMI/EANM practice guideline for Meckel diverticulum scintigraphy 2.0 (Spottswood et al., J Nucl Med Technol 2014 · 42:163) · SNMMI/EANM Meckel guideline 2.0 (2014) · North American consensus guidelines (PMID 27909182)
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