Diagnostic localization of pheochromocytoma - The coming of age of positron emission tomography

Pheochromocytoma is a rare but clinically important tumor of catecholamine-secreting chromaffin cells. This tumor constitutes a surgically curable cause of hypertension. Therefore, correct localization of pheochromocytoma is essential for effective management of this tumor. Several conventional and nuclear imaging modalities are currently available to localize pheochromocytoma. Computed tomography (CT) and magnetic resonance imaging (MRI) have good sensitivity but poor specificity for detecting pheochromocytoma, and nuclear imaging approaches such as I-131-metaiodobenzylguanidine scintigraphy or [In-111]-DTPA-D-Phe-pentetreotide (Octreoscan) have limited sensitivity. However, specificity of I-131-metaiodobenzylguanidine scintigraphy is very good and this means of imaging provides a method for confirming that a tumor is a pheochromocytoma and rules out metastatic disease. Recently, we introduced a new imaging method, 6-[F-18] fluorodopamine positron emission tomography, that can be used successfully for the detection of solitary and metastatic pheochromocytomas. Our preliminary data suggest that this method is superior to other nuclear imaging methods including metaiodobenzylguanidine and octreotide scintigraphy. In this report we provide an update regarding nuclear imaging of primary and metastatic pheochromocytoma, particularly using 6-[F-18]fluorodopamine positron emission tomographic scanning.