Review Question - QID 106459

A technetium-99m (99mTc) pertechnetate scan is a radionucleotide study used to detect the presence of gastric mucosa cells, both those normally occurring in the stomach and those in ectopic locations (as in a Meckel's diverticulum).

A Meckel's diverticulum, the result of a failure to completely obliterate the vitelline duct during embryologic development, is the most common congenital malformation of the GI tract. When symptomatic, patients may present with lower GI bleeding, abdominal pain or obstructive symptoms. GI bleeding is often due to ulcerations caused by acid released from ectopic gastric cells within the Meckel's diverticulum. During 99mTc pertechnetate scintigraphy, ectopic gastric cells will show increased radionucleotide activity in the lower abdomen at the same time that activity is observed in the normal gastric cells of the stomach.

Martin et al. review the presentation and diagnosis of Meckel's diverticula. When symptomatic, Meckel's diverticula are often difficult to diagnose based on clinical presentation alone. 99mTc pertechnetate scanning allows for detection of ectopic gastric tissue, which is present in up to 55% of Meckel's diverticula. The scan may be more useful in children as it has a sensitivity and specificity of 85% and 95%, respectively in the pediatric population and only 65% and 9%, respectively in adults.

Kotecha et al. discuss imaging modalities that can be used to identify Meckel's diverticula. Though the sensitivity associated with the use of 99mTc pertechnetate scanning is 85%, the scanning modality has been associated with false positive readings due to intestinal inflammation, enteric duplication cysts and heterotropic gastric mucosa in the small intestine. Other diagnostic modalities can be also used to evaluate the diverticula. On computed tomography (CT), a Meckel's diverticula will appear as a blind-ending structure originating from the ileum, while on ultrasound (US), a Meckel's diverticulum will appear as a round cyst-like structure.

Illustration A shows the results of 99mTc pertechnetate scanning showing increased radionucleotide activity in both normal gastric cells (stomach) and ectopic gastric cells in a lower abdomen Meckel's diverticulum.

Answer 2: Ectopic pancreatic cells can be found in a Meckel's diverticulum but would not be detected by a 99mTc pertechnetate scan.
Answer 3: Cells from the small intestine would not cause increased radionucleotide activity in a technetium-99m (99mTc) pertechnetate scan.
Answer 4: Ectopic cells from the gallbladder are not found in a Meckel's diverticulum.
Answer 5: Ectopic cells from the liver are not found in a Meckel's diverticulum.