A new method for granulocyte labeling with technetium-99m: preliminary results in abscess detection.

A new method for 99mTc-labeling of granulocytes for clinical routine use has been developed. The labeling is simple to perform by means of a kit of radiopharmaceutical quality, utilizing dihydroxy-benzoic acid. Pretinning techniques are avoided. The technique has been applied clinically in 15 patients with indications of intra-abdominal abscess. In six patients, [99mTc]granulocyte scintigraphy at 3 hr and/or 24 hr after i.v. administration, correctly depicted the abscess, as verified by subsequent surgery. In the remaining patients, who were negative at surgery or recovered without operation, all scans were negative.

Comparison of In-111 granulocytes and Tc-99m albumin colloid for bone marrow scintigraphy by the use of quantitative SPECT imaging.

A comparison of In-111 oxinate labeled autologous granulocytes and Tc-99m albumin colloid for bone marrow scintigraphy is reported. The aim of this report was to determine if the intense uptake in the liver and spleen with nano-sized colloids, which hampers the evaluation of the skeletal parts surrounding the liver, is reduced by the use of radiolabeled granulocytes. This study is based on a retrospective analysis of 19 abdominal tomographic examinations with In-111 granulocytes performed to detect septic foci. After correction for attenuation and scattering of photons was performed, the uptake in the bone marrow of the lumbar spine was seen to be related to the liver, spleen, and tissue background activity. The results in this study were compared with corresponding data from 20 normal liver/spleen tomographic examinations performed with Tc-99m nanocolloid, which is routinely used for bone marrow scintigraphy. The bone marrow/liver activity ratio for granulocytes varied, but it exceeded the corresponding mean ratio for colloid in all examinations. The mean values for granulocyte uptake 3 and 20 hours after injection was, respectively, about 6 and almost 10 times higher than were those for colloid. The activity ratios between bone marrow and spleen as well as between bone marrow and tissue background was not improved and or may even have been reduced by the use of granulocytes. It is suggested that granulocytes labeled in vitro by Tc-99m hexamethylpropylene amineoxime (HMPAO) or in vivo by monoclonal antigranulocyte antibodies may provide techniques for improved bone marrow imaging.

Effect of size fractionation on the distribution of an albumin colloid in the reticuloendothelial system of the mouse.

To study if by varying the particle size of a 99mTc albumin colloid preparation its relative bone marrow accumulation could be increased, it was separated by gel filtration and different fractions were injected into mice. Particles around and smaller than the peak size of the colloid, 31 nm, exhibited a higher bone marrow/liver-spleen uptake ratio than larger particles but the uptake ratio was similar to that of the unseparated colloid. An antimony sulphide colloid showed a similar particle size distribution, but the corresponding uptake ratio was half of the albumin colloid. This indicates that characteristics other than size determine the distribution of a colloid in the reticuloendothelial system.

Polyclonal and monoclonal anti-CEA antibodies in immunolocalization of colorectal cancer.

Antibodies to carcinoembryonic antigen (CEA) from sheep and monkey were immunoadsorbent purified. Mouse monoclonal antibody (MAb) anti-CEA I-38S1 and Fab fragments of this antibody were prepared from mouse ascitic fluid. The IgG preparations were labelled with 123I or 131I, the Fab fragments with 131I. The antibody reactivity was unchanged after labelling. Patients with advanced colorectal carcinomas received an intravenous injection of 50-200 MBq 123I or 30-160 MBq 131I coupled to 250-500 micrograms antibody or antibody fragment. Patient examinations were performed using emission tomography (SPECT) and/or conventional gamma camera scintigraphy. The specific localization of labelled anti-CEA to tumor was compared to known tumor localized by CAT-scan, other x-ray methods or laparotomy, 50% of known tumors were accurately localized with sheep anti-CEA. In contrast, 70-80% of known tumor sites were correctly localized with polyclonal monkey anti-CEA antibodies, with monoclonal anti-CEA antibodies or with Fab fragments of the latter. A few previously unknown tumors were detected.