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

Aim. 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/ccomputed tomography (SPECT/CT) in patients with acute lower gastrointestinal bleeding undergoing scintigraphy with Tc-99m-labelled red blood cells (RBC), and to assess the additional clinical value of fused images when compared to the standard radionuclide scan. Methods. Twenty-seven patients presenting with acute lower GI tract hemorrhage were studied with conventional dynamic and planar Tc-99m-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. Results. I mage 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 Tc-99m-RBC extravasation. SPECT/CT had significant impact 011L 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. Conclusion. SPECT/CT with a hybrid system is feasible and useful for facilitating imaging interpretation and improving the accuracy of Tc-99m-RBC scintigraphy in patients with acute lower GI bleeding.