RADIOPHARMACOLOGY OF INHALED XE-133 IN SKELETAL SITES CONTAINING DEPOSITS OF GAUCHER CELLS

Gaucher's disease is a lysosomal storage disease in which cells of the reticuloendothelial system accumulate the lipid glucocerebroside. It is characterized by slowly progressive visceral and osseous involvemen t. One of the latter manifestations includes lipid infiltration of bon e marrow. We monitored the rate of inhaled Xe-133 uptake and wash-out over diseased and normal metaphyseal and epiphyseal areas of the knee. Twenty-two patients (15 adults, 7 children) with various degrees of p reviously diagnosed Gaucher's disease were positioned supine under a g amma-camera interfaced to a computer system. All patients rebreathed X e-133 gas from a closed system for 10 min followed by 14 min of wash-o ut. Digitized images of the lung, liver, spleen, bony sites and soft t issue were obtained at 1 min intervals during the wash-in and wash-out phases. Counts for each ROI were normalized per 100 pixels and plotte d as a function (time). Maximum uptake was also calculated by relating the counts/ROI/100 pixels to the 10 min integrated lung count during equilibrium (the administered ''dose''). There was essentially no Xe-1 33 uptake in liver and spleen involved with Gaucher's disease. Monopha sic uptake and biphasic wash-out curves were observed in the limited i nvestigative population. Skeletal Gaucher deposits released the Xe-133 at a greater rate relative to soft tissue.