Thyroid nodules: Nuclear imaging of thyroid nodules can be “hot nodules”, “warm nodules” or “cold nodules”. The significance of nuclear imaging is to understand the uptake function of the nodule and to further help determine the nature of the nodule. The overall shape of the thyroid can also be observed, providing an important reference for the surgical treatment of nodules. (a) Hot thyroid nodules: Hot nodules are less likely to be malignant. 1. Relative “hot nodules”: enhanced nuclear uptake at the nodule site, which can be suppressed by thyroid hormone suppression imaging, indicating that the nodule is non-autonomous. This can be seen in benign thyroid adenomas or physiological abnormalities of the thyroid gland, as well as in asymmetric goiter. 2. Autonomous high-functioning thyroid nodules: Enhanced uptake at the nodule site and sparse uptake of other thyroid tissue. On thyroid hormone suppression imaging, the nodule uptake is not suppressed and the surrounding thyroid tissue is clearly suppressed. This is seen in autonomic hyperfunctioning adenomas. Autonomous hyperfunctional adenomas may be untreated if the thyroid function is normal. If hyperthyroidism is present, theoretically the nodule should be removed or treated with high dose 131 iodine. However, if the disease is prolonged and the thyroid tissue is suppressed for a long time, there is no possibility of recovery, so nodal resection may lead to severe hypothyroidism. The author believes that surgical excision or high-dose 131 iodine treatment for high-functioning thyroid adenoma (Plummer’s disease) should be done with caution. (b) Thyroid “warm nodules”: Thyroid “warm nodules” appear as nodules whose uptake is consistent with the surrounding thyroid tissue, and are usually seen in benign adenomas. (c) “Cold nodules” of the thyroid gland: Absence of uptake at the nodule site indicates that the nodule has no thyroid function, which can be seen in benign nodules such as adenomas and cysts, or in thyroid cancer. Only 20% of cold nodules with radioactive iodine or peruate are malignant lesions. The specificity of all current radiopharmaceuticals for detecting malignancy is relatively low. Medullary carcinoma may be missed with growth inhibitor receptor imaging (SRI). Both benign and malignant lesions can aggregate 18F-FDG. 99mTc(V)-diglobinosuccinic acid (DMSA), 201Tl, and 99mTc-methoxyisobutylisocyanide (MIBI) all lack specificity. In conclusion, nuclear medicine is not specific in identifying malignant lesions in thyroid nodules. Nuclear imaging of thyroid nodules smaller than 1 cm is not ideal , and for small nodules found by ultrasound, nuclear imaging is not very helpful.