SPECT/CT with a hybrid imaging system in the study of lower gastrointestinal bleeding with technetium-99m red blood...

Lower gastrointestinal (GI) hemorrhage is a complex clinical problem that requires disciplined evaluation for successful management. This study was conducted to evaluate the applicability of single photon emission computed tomography/computed tomography (SPECT/CT) in patients with acute lower gastrointestinal bleeding undergoing scintigraphy with 99mTc-labelled red blood cells (RBC), and to assess the additional clinical value of fused images when compared to the standard radionuclide scan.

Twenty-seven patients presenting with acute lower GI tract hemorrhage were studied with conventional dynamic and planar 99mTc-RBC imaging. In 19 patients with positive findings on scans taken within 6 hours, a SPECT/CT study was immediately performed using a hybrid system composed of a dual-head, variable angle gamma camera and an X-ray tube. The number of patients in whom SPECT/CT changed the scintigraphic interpretation with regard to the presence or site of GI blood loss as confirmed by other diagnostic or therapeutical procedures was recorded.

Image fusion was easy and successful in all patients showing perfect correspondence between SPECT and CT data and allowing precise anatomical localization of the sites of 99mTc-RBC extravasation. SPECT/CT had significant impact on the scintigraphic results in 7/19 patients (36.8%): in 6 patients it precisely localized the bleeding foci whose location could not be identified in standard scans and in one it excluded the presence of an active GI hemorrhage.

SPECT/CT with a hybrid system is feasible and useful for facilitating imaging interpretation and improving the accuracy of 99mTc-RBC scintigraphy in patients with acute lower GI bleeding.