Check thyroid nodules, ultrasound or CT? The article explains the significance and choice of 4 major types of thyroid examination

Clinical examples

Not long ago, the unit organized a physical examination, and Xiao Liu Bchao reported that there was a nodule of 0.8cm×0.7 cm in the right lobe of the thyroid gland, and ti-RADS was graded at 3 levels. Doctor B ultrasound told her that the nodule was benign, but could not completely rule out malignancy, and recommended that she follow up regularly.

Xiao Liu was very nervous after listening to it, and immediately called me to consult whether I needed to do a thyroid CT? Is CT clearer than B-super-resolution? I told her that the thyroid gland position is superficial, B ultrasound in the diagnosis of thyroid diseases has accurate, simple, safe, economical characteristics, more advantages than CT, like her case half a year -1 year B ultrasound review can be, there is no need to do CT examination.

Examples like Xiao Liu's are actually not uncommon in the clinic, which involves the reasonable choice of thyroid-related tests.

Thyroid-related tests mainly include laboratory tests, imaging tests, nuclear medicine tests, and thyroid aspiration cytology. The focus of each type of examination is different, involving many aspects such as functional status, morphological structure, good and evil nature, and etiology, and each examination item has its own advantages, disadvantages and indications.

Below, let's briefly introduce the clinical significance and indications of thyroid examinations, and how to use them reasonably in clinical work.

1. Laboratory examination

Thyroid function

Including TT3, TT4, FT3, FT4, TSH, etc., nail function test can understand the functional status of the patient's thyroid gland, and clinically is mainly used to diagnose "hyperthyroidism" or "hypothyroidism":

If TT3, TT4, FT3, ft4 are elevated, TSH is decreased, suggesting "primary hyperthyroidism";

If TT3, TT4, FT3, FT4 are low, and TSH is elevated, "primary hypothyroidism" is indicated.

Thyroid antibody itself

These include thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TGAb) and thyrotropin receptor antibodies (TRAb).

A positive thyroid antibody indicates an autoimmune disorder of the thyroid gland, and this test is primarily used to identify the cause of thyroid disease:

If the patient's TPOAb and TGAb are significantly elevated, the height suggests "Hashimoto's thyroiditis";

If the patient has a significantly elevated TRAb, height suggests "Hyperthyroidism" in graves.

Thyroglobulin (TG)

Secreted by thyroid follicular epithelial cells, it is an important indicator of thyroid tissue stock and synthetic function. Normally, very small amounts of thyroglobulin are released into the bloodstream (< 40 micrograms/L). Thyroglobulin in patients with total thyroid resection is usually less than 5 micrograms/L or even completely undetectable.

If serum TG levels are progressively elevated again after total thyroidectomy in patients with thyroid cancer, it suggests tumor recurrence or metastasis, so TG is often used as a monitoring indicator for postoperative recurrence of thyroid cancer.

Calcitonin (CT)

A hormone produced by thyroid paraveolar cells (C cells) that regulates calcium and phosphorus metabolism and is an important marker of medullary thyroid cancer. Elevated calcitonin (> 100 pg/ml) is highly suggestive of the possibility of "medullary thyroid carcinoma". Clinically, it is mainly used for the diagnosis and postoperative follow-up of "medullary thyroid carcinoma".

Erythrocyte sedimentation rate (ESR)

Patients with subacute thyroiditis ("methylene") tend to have significantly elevated erythrocyte sedimentation rates (>50 mm/h), and ESR is an important adjunctive test in patients with methyleneitis.

In addition, blood routine, liver function, blood lipids, etc. are also routine examination items for thyroid diseases, for example, hyperthyroidism can lead to leukopenia and abnormal liver function, and hypothyroidism can lead to anemia and hyperlipidemia.

2. Nuclear medicine examination

Thyroid iodine uptake rate 131 measured

Iodine 131 rate tests can understand the functional status of the patient's thyroid gland and are often used clinically to identify the cause of hyperthyroidism (e.g., "Graves hyperthyroidism" from "subacute thyroiditis").

In addition, we can also estimate the amount of iodine 131 required for the treatment of Graves hyperthyroidism according to the patient's iodine 131 rate, and if the patient's thyroid iodine 131 rate is low, the dose of iodine 131 should be increased accordingly.

Thyroid radionuclide imaging

i.e., 131 iodine imaging, which can be used to observe the location and functional status of thyroid nodules, is often used clinically for the diagnosis of "autonomous high-function thyroid tumor" and the differential diagnosis of Graves hyperthyroidism" and "subacute thyroiditis". In addition, nuclide imaging can also be used to troubleshoot thyroid cancer, if the nuclide imaging is a hot nodule, it can be diagnosed as a high-function thyroid adenoma and rule out thyroid cancer. In addition, "thyroglobulin (Tg)" combined with "131 iodine imaging" can also be used to monitor tumors with recurrent metastasis.

3. Imaging examination

Ultrasound B and "CT or MRI" have their own advantages and cannot be completely substituted for each other, and should be reasonably selected according to the purpose of each patient's examination.

Thyroid ultrasound

Ultrasound B is the most commonly used test to check thyroid morphology and thyroid nodules, mainly for understanding:

The size and shape of the thyroid gland;

Detect the number, size, morphology, boundaries, cystic solidity, presence or absence of calcification of thyroid nodules, etc.;

Clearness of the condition of cervical lymph nodes;

Preliminary judgment of the good and evil nature of the nodule;

As a localization tool for thyroid nodule puncture examination.

In terms of thyroid examination alone, ultrasound B is more valuable, more convenient and economical than CT and magnetic resonance imaging (MRI) diagnostic value, and should be the first choice.

CT or magnetic resonance imaging (MRI)

It can clearly show the size and shape of thyroid tumors, especially the location relationship between tumors and surrounding tissues (such as trachea, esophagus, blood vessels, nerves, etc.), and clarify the scope of cancer invasion, thereby providing scientific evidence for surgical operations; it is helpful to detect ectopic thyroid gland (such as retrosternal thyroid).

Thyroid CT/MRI is not recommended for routine screening and evaluation of nodules, but it is still of irreplaceable diagnostic value in some special cases.

4. Thyroid fine needle puncture cytology

Neither thyroid ultrasound nor other imaging tests (e.g., CT, MRI) can confirm the benign or malignant nature of the nodule, and can only make "suspicious malignancy" or "highly suspicious malignancy" of the nodule. In order to get a definite conclusion, it is necessary to rely on ultrasonic guidance for fine needle puncture of thyroid nodules, pathological examination of aspirated cells and tissues, which is currently the most convenient and reliable examination method for identifying benign and malignant thyroid nodules, and is the gold standard for diagnosing thyroid nodules, but it cannot rule out the possibility of "false negative".

Image source: 123RF

Text/Wang Jianhua, Chief Physician of Diabetes Diagnosis and Treatment Center of Jinan Hospital in Shandong Province

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