THE RADIATION-DOSIMETRY AND NORMAL VALUE STUDY OF TC-99M-HMPAO-LABELED LEUKOCYTES

RATIONALE AND OBJECTIVES. Indium-(111) (In-111)-labeled leukocyte scan ning has been used frequently in patients suspected of having infectio ns. Recently, technetium-99m hexamethylpropylene amine oxime ((TC)-T-9 9m-HMPAO) has been used to label leukocytes. This study was undertaken to determine the distribution and dosimetry of Tc-99m-HMPAO leukocyte s in healthy subjects. METHODS. Five healthy volunteers had leukocytes labeled with Tc-99m-RMPAO. After injection of the labeled leukocytes, whole body images and blood and urine samples were obtained at multip le time points. RESULTS. Visual interpretation of the images demonstra ted significant bowel activity as early as 2 hours and increasing with time such that on the 8- and 24-hour images, the amount of bowel acti vity would preclude using Tc-99m-HMPAO leukocyte scanning for abdomina l processes. The dosimetry for this study is similar to that of other studies and is in an acceptable diagnostic range. CONCLUSIONS. Tc-99m- HMPAO leukocyte studies are an acceptable alternative to In-111-labele d leukocyte studies in terms of dosimetry. Use of such studies in the abdomen should be limited to early images, usually before 2 hours, to avoid confusion with the normal route of excretion in the bowel.