How can nuclear medicine procedures assist in detecting ectopic gastric tissue?
As a source of pediatric GI bleeding, a Meckel diverticulum invariably contains ectopic gastric mucosal tissue. Because 99m Tc-pertechnetate is concentrated and extracted by gastric tissue, it is an ideal agent to localize sources of GI bleeding caused by a Meckel diverticulum, which can be difficult to detect with traditional radiographic studies.
The study is performed by injecting pertechnetate intravenously and imaging the abdomen for 60 minutes. Typically, ectopic gastric mucosa appears at the same time as gastric mucosa and does not move during imaging. Sensitivity is 85% for detection of bleeding from a Meckel diverticulum. Manipulations to increase the sensitivity of the study may include additional pharmaceuticals such as cimetidine (to block pertechnetate release from ectopic mucosa), pentagastrin (to enhance mucosal uptake), and glucagon (to inhibit bowel motility and prevent movement of the radiopharmaceutical).