Technetium-99m IgG immunodetection of acute appendicitis in rats.

The efficacy of Tc-99m-labeled intact polyvalent human immune globulin (IgG) for the early localization and detection of acute appendicitis was evaluated by an animal model. Acute appendicitis was surgically produced in adult Sprague-Dawley white rats by ligating a 3-cm segment of the caecum and inoculating with E. coli. After 4-5 days, nuclear scintigraphy was performed following intravenous injection of 5 mCi of Tc-99m IgG via the tail vein. Appendiceal and colonic infections were clearly visualized by Tc-99m IgG scans within 30 min postinjection and confirmed by autopsy and tissue distribution data. With the exception of the liver, the kidneys, and the urinary bladder, abdominal tissue background activity was minimal. These findings suggest that Tc-99m-labeled intact IgG may have potential clinical application in the early detection and diagnosis of acute appendicitis in emergency medicine.