A radiopharmaceutical for the study of the liver: 99mTc-DTPA-asialo-orosomucoid

A natural glycoprotein, asialo-orosomucoid (AOM), was desialylated by neuraminidase and labelled with iodine (131I and 125I) or with 99mTc. Labelling with Technetium was performed using the diethylenetriaminopentaacetate amino derivative by an original method suitable to simple ''kit'' preparation. The labelled molecule has been experimented in animals. The results obtained show that: 1) iodine labelled asialo-orosomucoid is rapidly taken up and metabolized by the liver; 2) it is possible to label AOM with 99mTc using DTPA and a simple method; 3) the labelling procedure with Technetium does not impair the liver uptake of AOM when a low DTPA/AOM molar ratio is used; 4) the hepatic uptake of 99mTc-DTPA-AOM is as rapid as for 131I-AOM, while dismission of hepatic activity is slower. Radioactivity is predominantly excreted by the kidneys bound to low molecular weight compounds; an additional fraction of radioactivity is excreted through the bile; 5) excellent images of the liver can be easily obtained by injecting low radioactive quantities