Scintigraphy with 131I-19-iodocholesterol in adrenal disease

Adrenal scintigraphy after i.v. injection of 131I-19-iodocholesterol has been performed in 4 patients with primary aldosteronism, 5 with Cushing's syndrome and 1 patient with phaeochromocytoma. In primary aldosteronism a unilaternal adrenocortical adenoma was demonstrated in 2 patients, while the method failed in 1 patient to visualize a tumour that was localized by measurements of aldosterone concentrations in the adrenal veins and by adrenal venography; in 1 patient none of the methods demonstrated a tumour. In Cushing's syndrome, adrenal scinitgraphy indicated bilateral adrenocortical hyperplasia in 1 patient and visualized the tumour in 2 patients with adrenocortical adenoma. In all patients with Cushing's syndrome due to unilateral adrenocortical tumour, the accumulation of radioactivity in the contralateral adrenal was suppressed. However, a delayed and slight accumulation of the isotope in the suppressed gland contralateral to an adrenocortical carcinoma was misinterpreted and led to exploration on the wrong side since the tumour did not concentrate radioactivity at all. The method failed in 1 patient to localize the adrenocortical tissue responsible for the relapse of Cushing's syndrome after bilateral adrenalectomy for hyperplasia. In the patient with phaeochromocytoma, no radioactivity was found on the tumour. It is conculded that adrenal scintigraphy is a safe and valuable method for localization of adrenal tumours and their differentiation from adrenocortical hyperplasia. Some diagnostic pitfalls do, however, exist, as demonstrated in this series of patients.