Scintigraphy of gastrointestinal hemorrhage: superiority of 99mTc red blood cells over 99mTc sulfur colloid

Abstract

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.

The SNMMI Procedure Standard/EANM Practice Guideline for Gastrointestinal Bleeding Scintigraphy 2.0

“…99m TcRBCs are the radiopharmaceutical of choice for performing GIBS because of an intravascular half-life that allows continuous imaging of the gastrointestinal tract over many hours (40)(41)(42). The superior clinical utility of 99m Tc-RBCs over early studies using 99m Tc-sulfur colloid has been demonstrated in comparison studies (40)(41)(42).…”

Radionuclide Evaluation of the Lower Gastrointestinal Tract

“…Although both 99m Tc-sulfur colloid and 99m Tc-labeled RBCs have been used for gastrointestinal bleeding scintigraphy, clinical studies comparing the 2 radiopharmaceuticals in the same patients demonstrate the clear superiority of the 99m Tc-RBC procedure (43,44). The Society of Nuclear Medicine procedure guidelines for gastrointestinal bleeding scintigraphy recommend the use of in vitro labeled 99m TcRBCs to minimize elution of the label from the RBCs (36).…”

Clinical Applications of Nuclear Medicine in Gastroenterology

“…The advantage of 99mTc sulfur colloid is that it is a readily available, quickly prepared radiopharmaceutical that can accurately lo cate active GI bleeding; its disadvantage is that it is insensitive for the detection of GI bleeding. In a study of 100 patients referred for suspicion of GI bleeding and studied sequentially with both radiolabels, hem orrhage was found in 30 patients using 99raTc red cells and in only 5 of the same 30 patients with 99mTc sul fur colloid [48]. Thus, we prefer to use 99mTc red blood cells, which although less convenient to pre pare, are more sensitive for the detection and local ization of bleeding, especially in this population that often is bleeding intermittently.…”