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A questionnaire is proposed for any imaging examination requiring contrast agent administration. Information about important risk factors is essential and drug history is also important because of possible interactions between contrast agents and other drugs. This information should be available before the appointment, so that prophylactic measures can be planned or an alternative imaging technique not requiring contrast agent administration can be advised.

The symptoms and signs that lead to medical consultation or further work-up examinations after careful clinical examination (often performed for other reasons) are a visible and/or palpable mass and/or fistula of the neck.

Multinodular goiter is a quite common condition with a marked female preponderance and it affects about 13% of the world population. Large differences in goiter prevalence have been found in different regions: 37.3% in the Eastern Mediterranean area, 28.3% in Africa, 20.6% in Europe, 15.4% in Southeast Asia, 6.1% in the Western Pacific, and 4.7% in the Americas. The cause of multinodular goiter remains unclear but is probably multifactorial. Iodine deficiency, naturally occurring goitrogens, drugs, thyroid growth factors, and heredity have been postulated as possible contributors to goiter development.

The primary intention of this chapter is to focus on the diagnosis and treatment of the two most prevalent hyperthyroid states, i.e., Graves’ disease and solitary and multinodular goiter. In addition, we aim to provide some concise information on thyroid physiology and thyroid function tests.

After diabetes mellitus, thyroid diseases are one of the most frequent endocrine disorders. There are established age-related changes in hyperthyroidism, hypothyroidism, and cancer of the thyroid, with hyperthyroidism and hypothyroidism giving rise to special diagnostic problems.

A number of reports have suggested the wider use of Iodine-123 as the ideal radioisotope of iodine because of its theoretical advantages. A short Half-life of 13,3 h, a primary gamma photon of 159 keV of high abundance and absence of beta particle emission result in a dose reduction variously estimated at 30–100 fold over commonly used Iodine-131. In addition, the low energy 159 keV gamma and a lesser abundant 28 keV X-ray offer promise of improved imaging resolution utilizing low energy high resolution collimators.

The use of radioiodine for thyroid tests still comprises some 57 % of the proce-dures performed in Nuclear Medicine Laboratories according to the recent Stanford Research Institute Survey conducted by the Bureau for Radiological Health [1]. Wide diagnostic use of Iodine-131 for thyroid tests results in what has been considered a tolerable absorbed radiation dose to the thyroid. Certainly there has been no direct study indicating a significant deleterious effect from Iodine-131 in such use and probabilities are against any study ever conclusively demonstrating measurable permanent radiation effects. However, a recent review by Hempleman has raised the possibility that adenomas are induced by as little as a 20 rad dose of external radiation to the thyroid of young individuals [2]. As an approximate figure, an adult with a normal uptake and gland and a 100 μCi administered dose of Iodine-131 might be expected to receive 150 rad to the thyroid. Younger individuals would, of course, receive relatively larger doses because of smaller glands, but similar uptake values. Absorbed doses associated with scanning procedures with Iodine-131 then may approach the levels questioned by Hempleman as inducing adenomas. Thus, only marginal evidence would prompt one to suspect the diagnostic use of Iodine-131 as having permanent deleterious radiation effects on the thyroid, except perhaps in children. Certainly, at this time, a dose reduction motive alone would probably not warrant abandoning the convenience and economics of Iodine-131.