Angiography of Parathyroid Adenomas

The Preoperative localization of parathyroid adenomas has been a challenge to the roentgenologist. Recent improvement in the methods of clinical and laboratory diagnosis has led to the earlier recognition of these neoplasms. Only rarely is preoperative localization possible by virtue of tracheal or esophageal displacement. Both angiography and pneumomediastinal tomography have been employed in an attempt to improve localization of parathyroid adenomas. Seldinger (10) reported angiographic localization of parathyroid adenomas in 4 of 6 patients and Silinkova-Málková (11) was successful in 1 of 5. Both authors based localization on displacement of the inferior thyroid artery. Wanke (14) described 1 patient in whom a vascular blush was noted in a parathyroid adenoma in the superior mediastinum on preoperative arteriography. Opacification of 2 additional parathyroid adenomas was seen on direct operative arteriograms of the inferior thyroid gland (7,13). Gross Anatomy The parathyroid glands develop from outgrowths of the third and fourth branchial pouches. In the adult they are flat, oval structures, each about 3–4 mm wide and 6 mm long. Usually 2 superior and 2 inferior parathyroids are present; but fewer than 4 may be found in 1 per cent of cases and more than 4 are noted frequently (33 per cent) (5). The superior parathyroids arise embryologically from the fourth branchial pouch. They are usually located at the level of the lower border of the cricoid cartilage, behind the thyroid. The inferior parathyroids, arising from the third branchial pouch, pass the superior glands in their embryologic descent with the thymus. Their course is therefore much longer than that of the superior parathyroids and their position more variable. Customarily, the inferior parathyroids are found at the lower edge of the thyroid lobe or are related to the inferior thyroid artery. Occasionally, however, they may descend into the anterior mediastinum, more commonly so if they are enlarged by adenoma (2). Parathyroids are usually situated behind the thyroid but sometimes may be embedded within that gland. The parathyroids receive their blood supply primarily from the inferior thyroid arteries (3). Halsted and Evans (6), on vascular injection studies, found a separate small artery supplying each parathyroid in every case. In almost every instance the artery supplying the inferior parathyroid arose from a prominent branch of the inferior thyroid artery. The superior parathyroid was fed by a branch of the inferior thyroid artery or from an anastomotic channel joining the superior and inferior thyroid arteries. Abnormalities of the inferior thyroid arteries may be of value in localizing parathyroid adenoma, but evaluation of these vessels is complicated by variations in the origin and course of the inferior thyroid artery.