Thallium-201 scintigraphy in the diagnosis of pheochromocytoma.

6 patients were studied by 201Tl scintigraphy; 1 of them suffered from a benign, and another from a malignant adrenal pheochromocytoma. 1 patient had a hormonal inactive adrenal tumor, 3 others multiple organ metastases of malignant pheochromocytomas. At the same time, 3 of the patients were studied by 131I-metaiodobenzylguanidine (131I-MIBG) scintigraphy. Using different techniques like kinetic studies, whole-body scan or a 201Tl-99m-Tc difference scan, benign and malignant pheochromocytoma tissues could be localized by 201Tl scintigraphy. Benign and malignant pheochromocytomas showed different kinetics of 201Tl. In 2 patients with multiple organ metastases of malignant pheochromocytomas, the metastases were partly imaged by 131I-MIBG, the others by 201Tl.