[Improved scintigraphic imaging of the adrenals with 6beta-131I-iodomethyl-cholesterol (author's transl)].

Scintigraphic visualization of the adrenals is greatly improved after substitution of 131I-19-I-Cholesterol by 6beta-131I-Iodomethyl-Cholesterol which was first seen as a radiochemical impurity during the synthesis of 131I-19-Iodocholesterol. The interpretation of the scintigraphic imaging is further improved by application of a cross section through the visualized adrenals. In an animal experiment the radioactivity of the adrenals and to a less degree that of different tissues was found up to four times higher after injection of 6beta-131I-Iodomethyl-Cholesterol than with the applications of 131I-19-Iodocholesterol. The high affinity of the tissue for 6beta-131I-Iodomethyl-Cholesterol results in high radiation exposure of the patients. However, since less activity of 6beta-131I-Iodomethyl-Cholesterol is necessary for visualization of the adrenals the overall radiation is also less than with the application of 131I-Iodocholesterol. Higher stability of the labelled molecule is suggested to be responsible for improved scintigraphic imaging of the adrenals.