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

Q J Nucl Med Mol Imaging. 2009 Jun;53(3):281-9. Epub 2008 Jul 3.


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/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.

Methods: 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.

Results: 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.

Conclusions: 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.

MeSH terms

  • Adult
  • Aged
  • Equipment Design
  • Equipment Failure Analysis
  • Erythrocytes / diagnostic imaging*
  • Female
  • Gastrointestinal Hemorrhage / diagnosis*
  • Humans
  • Intestinal Diseases / diagnosis*
  • Male
  • Middle Aged
  • Radiopharmaceuticals
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Subtraction Technique / instrumentation*
  • Technetium*
  • Tomography, Emission-Computed, Single-Photon / instrumentation*
  • Tomography, X-Ray Computed / instrumentation*


  • Radiopharmaceuticals
  • Technetium