[99mTc-HMPAO labeling of leukocytes and thrombocytes. Characteristics and diagnostic consequences].

The lipophilic complex 99mTc-hexamethylpropylene-amineoxime (HMPAO) is suitable for labelling of leukocytes and platelets in vitro. With a labelling efficiency of 35 to 70% of marked cells between 0.3 and 0.5 GBq of the 99mTc are re-injected into the patient. Problems in differential diagnosis arise particularly in lesions in the pelvis and abdomen because of the rapid renal elimination of the 99mTc complex, with accumulation in the kidneys and bladder. Two hours after injection, biliary excretion leads to intestinal activity. After 24 hours there was activity in the colon in all patients. In summary, labelling of cells with 99mTc-HMPAO provides a practical method based on an available radio nuclide which can be used as an alternative to 111In-oxine, but cannot altogether replace the latter method because of the specific properties and the short physical half-life of 99mTc.