Before the advent of high-frequency ultrasonography, thyroid nuclear imaging was the most commonly used method to assess the nature of thyroid nodules. This test was designed to take advantage of the thyroid cells’ preference for radioactive iodine. They are usually classified as “hot nodules”, “warm nodules” and “cold nodules” according to the iodine uptake capacity of the thyroid cells, which corresponds to high to low iodine uptake to no iodine uptake. Since most benign nodules, like thyroid cancer, have low iodine uptake, they become so-called “cold nodules”, especially those with a high cystic component, and therefore have little diagnostic value. Therefore, thyroid nuclide imaging has diagnostic value only for about 10% of hot nodules (autonomous high-functioning thyroid adenomas), while the diagnosis is still uncertain for the remaining 90% of nodules.