As the incidence of thyroid nodules continues to rise, more and more people are becoming concerned about their thyroid gland. Generally, when a thyroid nodule is found, people’s first reaction is: “Is it cancer?” and “Will it metastasize? and “Will it metastasize?” . Many patients undergo surgery for fear of malignancy, only to find out after surgery that it is just an adenoma or nodular goiter, or in some cases, just thyroiditis. Although the surgery is minor, the post-operative complications can be a life-long problem for many people. Laryngitis, lymphadenitis, insomnia, frozen shoulder, hypocalcemia, hoarseness, and difficulty swallowing. These are all minor problems, but they affect the patient’s life and mood at all times. Therefore, it is very necessary to identify the benign and malignant thyroid nodules, do not go for surgery within the lack of evidence of malignancy, otherwise the only ones who suffer are the patients themselves. In fact, there are many ways to determine whether a thyroid nodule is malignant, some small details (such as gender, age, growth rate of thyroid nodules, activity and hoarseness, etc.) can already make a preliminary screening, if you are still not sure, you can pass all kinds of relevant tests, basically you can determine the benignity and malignancy of thyroid nodules, the relevant means of examination mainly include: a. Ultrasound: To identify the benignity and malignancy of nodules, the most common, easy and economical means of examination is naturally the ultrasound of the neck. Ultrasound examination of the thyroid gland can not only clarify the location, number, size, cystic or solid nodules, clarity of nodule margins, and the presence of vascular spots and microcalcifications in the nodules, but also indirectly provide important evidence of malignant thyroid tumors, such as hypoechogenicity, rich blood flow, microcalcifications, irregular morphology, and lymph node enlargement. For details, please click here to refer to my article “How to identify benign and malignant thyroid nodules by ultrasound? CT of the neck: Although CT of the neck is not as popular as ultrasound in the diagnosis of thyroid nodules, it has some significance, and the diagnosis and differential diagnosis of thyroid nodules are based on the number of nodules, morphology, border, density, envelope and calcification. CT examinations can also help to understand the adjacent relationship between the nodule and surrounding structures (trachea, esophagus, larynx, carotid sheath, etc.) as well as the involvement of lymph nodes in the neck in preparation for surgery. However, it is expensive compared to ultrasound and has some radiation exposure. For details, please refer to my article “Can CT identify benign and malignant thyroid nodules? Radionuclide scans: Although radionuclide scans are not routinely performed to evaluate thyroid nodules, they should be preferred if a functional thyroid nodule or ectopic goiter is clinically considered. A nuclide scan generally uses 99mu or 131 iodine as the imaging agent and can be classified as “hot nodules”, “warm nodules” or “cold nodules” depending on the nodule’s ability to take up radionuclides. The “hot nodules” are the nodules that can take up radionuclides. The “hot nodules” are the more functional nodules, most of which are autonomous functional adenomas and can basically exclude malignancy; the “warm nodules” are mostly simple adenomas with normal function; the “cold nodules” are cancerous. The possibility of cancer in “cold nodules” is generally about 10%-20% malignant, while the remaining 80%-90% are benign, and a single “cold nodule” is more likely to be malignant, while multiple “cold nodules” are mostly nodular swelling, inflammatory nodules, intra-nodular hemorrhage or cystic nodules. The majority of “cold nodules” are nodular swellings, inflammatory nodules, intra-nodular hemorrhages or cystic nodules. Of course, many thyroid nodules are too small to be detected by nuclear scanning due to the limitation of resolution, so SPECT/CT is more beneficial for the localization and diagnosis of nodules. Four, thyroid fine needle aspiration cytology biopsy: is the application of fine needle from the thyroid nodules in the extraction of some cells for pathological examination, its sensitivity and specificity up to 70% a 90%, but closely related to the operator’s experience, experienced operators can make the accuracy rate of 95% or more. Cytologic aspiration can reduce unnecessary thyroid surgery, improve the detection of intraoperative malignancies, and reduce costs associated with treatment. Fine needle aspiration is the most appropriate diagnostic method when ultrasound and CT are not available and the patient has no immediate plans for surgery. V. 18F-FDG PET/CT tumor imaging: PET/CT is the most advanced technique for malignant tumor diagnosis nowadays, but its role is limited in the diagnosis of thyroid cancer, mainly in the following aspects: 1. Once PET/CT is negative (especially for nodules >15mm), the nodules can be basically judged as benign nodules. Diffuse positive FDG concentrations are a sign of thyroiditis, while focal FDG concentrations cannot determine the benignity of the nodule. 3. Once thyroid cancer is clearly diagnosed, the higher its SUV, the higher its malignancy and invasiveness. Thyroid hormone laboratory tests: including thyroid function, antibodies and serum calcitonin. Although most of the thyroid cancers have no abnormalities in various laboratory indicators, thyroid function and antibody tests are essential because some thyroid nodules are part of the clinical manifestations of hyperthyroidism, thyroiditis, and hypothyroidism. It is generally believed that people with obvious hyperthyroidism or hypothyroidism have a low chance of having malignant thyroid nodules. Antibodies to the thyroid gland are elevated in all types of thyroid disease and are not specific, but if they are too high, malignancy is unlikely. In contrast, serum calcitonin screening is useful for early detection of medullary thyroid cancer.