Anatomical and functional imaging of tumors in animal models: focus on pheochromocytoma

This review focuses on anatomical (computed tomography, magnetic resonance imaging) and functional (positron emission tomography) imaging methods for tumor localization and identification of experimentally induced tumors in animal models, especially pheochromocytoma. Although anatomical imaging can precisely locate primary and metastatic tumors, functional imaging has high specificity for some tumors, especially those of endocrine origin. This is due to the fact that endocrine tumor cells take up hormone precursors, express hormone receptors and transporters, and synthesize, store, and release hormones. These characteristic properties of endocrine tumors enable investigators to create highly specific radiopharmaceuticals, particularly for positron emission tomography. For example, localization of pheochromocytoma involves [18F]-6F-dopamine. It is a highly specific radiopharmaceutical since it uses the norepinephrine transporter system expressed in most pheochromocytoma cells. Here we review both anatomical and functional imaging methods that are used conjointly in order to localize and identify specific characteristics of tumors.