The relative efficacy of 99mTc sulfur colloid and in vitro-labeled 99mTc red blood cells in detecting and localizing gastrointestinal hemorrhage was evaluated in a prospective tandem study of 100 patients referred for suspicion of gastrointestinal tract hemorrhage. Thirty-eight true-positive scintigrams were obtained with 99mTc red blood cells, whereas 99mTc sulfur colloid detected only five sites of hemorrhage. Scintigraphic findings were corroborated by clinical, endoscopic, arteriographic, and surgical findings. 99mTc red blood cells were clearly superior, with a sensitivity of 93%, specificity of 95%, and overall accuracy of 94% in detecting and localizing gastrointestinal hemorrhage.
Radionuclide hepatobiliary imaging is a useful procedure for the diagnosis of acute cholecystitis. Visualization of the gallbladder essentially rules out acute cholecystitis. Nonvisualization suggests acute cholecystitis but may also be associated with chronic gallbladder disease or other conditions. We recently observed five patients in whom a rim of increased parenchymal liver activity was seen adjacent to the gallbladder fossa. All five patients had acute gangrenous cholecystitis. The rim of increased activity appears to be a useful secondary sign of acute cholecystitis.
99mTc glucoheptonate was used as a brain imaging agent in a consecutive series of 859 patients. Sensitivity was 94% in patients with proved CNS tumors. Static imaging of patients with infarction showed a sensitivity of 62%. When the perfusion study was included, this valve increased to 90%. Overall sensitivity was 83%, specificity 99%, and accuracy 95% without inclusion of perfusion results. When these results were included, overall sensitivity was 93%, specificity 99%, and accuracy 98%.
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