Nonvisualization of an enlarged spleen on Ga-67 scintigraphy but demonstrated by CT after splenic irradiation.

Presence of enlarged spleen using CT with absence of splenic visualization in Ga-67 citrate images in a patient with chronic myelogenous leukemia and splenomegaly after splenic irradiation was observed. Since Howell-Jolly bodies had not been identified in the peripheral circulation, the finding of splenic nonvisualization was explained by disassociated splenic functions, which are not tightly coupled, and some activities that can be suppressed by irradiation without impairing others. The Ga-67 splenic localization mechanism is probably more sensitive and liable to disruption by irradiation, and was independent of spleen size. Ga-67 scintigraphy and Tc-99m sulfur colloid liver-spleen scintigraphy are two organ function-dependent imaging procedures, while CT provides anatomic information.