The improvement of conventional imaging techniques has led to an increased detection rate of different adrenal tumors. Since those tumors can belong to a variety of entities the therapeutic consequences also show considerable variation. In order to definitely determine the type of tumor, invasive procedures like CT guided biopsies are often required, which could be avoided by a tumor specific imaging method. The presently available scintigraphic procedures are either time consuming and lead to high radiation exposure or are technically demanding. The steroidogenic enzymes CYP11B1 (11ß-hydroxylase)and CYP11B2 (aldosterone synthase)are expressed exclusively in the adrenal cortex and therefore represent suitable targets for a specific imaging technique. In our project we evaluate 123I-Iodometomidate which binds to both CYP11B enzymes as radiotracer for adrenal scintigraphy.