Selective spleen scintigraphy using 99mTc-heat denatured red blood cells in the era of fusion SPECT-CT imaging

Learning Objectives 1. Compare biodistribution of 99mTc labeled heat-damaged red blood cells (HDRBC), 99mTc sulfur colloid (SC), and undamaged 99mTc RBCs in 14 patients. 2. Contrast biodistribution of 99mTc labeled HDRBC in splenectomised and non-splenectomised patients. 3. Review the clinical role of selective spleen scintigraphy using HDRBC with emphasis on tomographic SPECT and SPECT-CT imaging.

Several clinical circumstances call for the specific detection and localization of splenic tissue, amongst them are 1) the evaluation of soft tissue masses where ectopic splenic tissue is suspected, 2) identification of remnant splenic tissue following splenectomy, and 3) surveying of splenic locations in order to characterize congenital anatomic abnormalities. Spleen scintigraphy can be performed using 99mTc labeled HDRBC or SC, the former resulting in more selective organ localization. Heat is known to cause reproducible changes to RBCs including an increase in rigidity, osmotic fragility and spherocytosis, leading to preferential localization of the damaged cells in the spleen. We review clinical data in 14 patients who underwent HDRBC SPECT-CT studies, 9 of whom were previously splenectomised, and compared these with findings in 7 patients who underwent SC spleen SPECT-CT studies and 3 patients who underwent undamaged 99mTc RBCs spleen scintigraphy. Clinical scenarios, qualitative imaging features, and quantitative measurements of uptake are reviewed. Clinical utility of selective spleen scintigraphy in the era of SPECT-CT is highlighted.