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A nuclear scan maps the distribution of a radiopharmaceutical that is specific for a physiologic property of a targeted tissue. As such, it is not limited by the anatomic changes necessary for CT and MR scans. It is just because of this that maps of specific metabolic precursors of adrenal medullary and cortical hormones offer information crucial to the therapeutic strategy of endocrine hypertension. NP-59 and MIBG scans can specify the nature of abnormalities revealed by anatomic images and because of the ease of surveying the whole body can give transcendent information about lesions remote from the adrenals. In instances when the origin of endocrine hypertension is not forthcoming from CT or MR imaging or when the anatomic and biochemical findings are in conflict, NP-59 or MIBG can almost always provide the answer.

Bilateral adrenal nodularity in Conn's and Cushing's syndrome leads to a more complex differential diagnosis than the presence of a unilateral mass or bilateral hyperplasia. In Conn's syndrome, bilateral nodularity is not synonymous with hyperplasia, and adrenal venous sampling is required to detect those cases of surgically correctable aldosteronoma. In Cushing's syndrome, bilateral nodularity can result from an ACTH-dependent or an autonomous adrenal cause of hypercortisolemia. The appropriate therapeutic decisions depend on the recognition of these different entities.

Localization procedures are performed only after the diagnosis of endocrine disease is established. Arteriography and venous sampling may be essential to locate a small hyperfunctioning endocrine tumor or to assist in distinguishing between disease caused by a solitary tumor and disease caused by diffuse hyperplasia. These procedures require a detailed knowledge of vascular anatomy and must be performed meticulously to avoid incorrect results. Close cooperation between the radiologist and the endocrinologist is essential for optimal results. These procedures are complex and are rarely performed outside of the few centers where endocrine problems are frequently evaluated. In many cases, the patient may be best served by referral to an institution where these radiologic studies are routine.

Ultrasound is an ancillary tool in adrenal imaging in adults and a primary tool in children. Intraoperative sonography is the method of choice for pancreatic endocrine tumors. In the scrotum, the benign adrenal rest tumors must be distinguished from the more common malignant mass.