What Is a Thyroid Scan?

Thyroid scintigraphy can selectively absorb 131I, which can emit gamma rays. Scanning machine can be used to measure the distribution of 131I in the thyroid gland, and a thyroid scintillation map can be obtained. According to the graphic changes, it is of certain value for the diagnosis of certain thyroid diseases and thyroid masses.

Thyroid scintigraphy

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Thyroid scintigraphy can selectively absorb 131I, which can emit gamma rays. Scanning machine can be used to measure the distribution of 131I in the thyroid gland, and a thyroid scintillation map can be obtained. According to the graphic changes, it is of certain value for the diagnosis of certain thyroid diseases and thyroid masses.

Chinese name

Thyroid scintigraphy

Foreign name

Thyroid Scintiscan

Types of

Testing method

Belong to

Medical Terminology

131I function can be found in other parts of the body. In addition to the 131I tracer team for thyroid imaging, 123I, 99m can also be used. Scanning the thyroid with sodium perrhenate, the resulting scan is clearer than with 131I.

Identify the nature of thyroid nodules: Nodules are divided into four categories based on their ability and intensity to absorb 131I.

Thermal nodules: The ability of the nodules to absorb iodine is greater than normal thyroid tissue. Most are benign autonomous functional thyroid adenomas. Due to the secretion of a large amount of thyroid hormone at the nodule, the secretion of TSH was suppressed, leading to a decrease in 131I absorption in thyroid tissues other than the nodule. Therefore, 131I was not absorbed by the entire thyroid nodules.

Warm nodules: The radiation intensity at the nodule is not different from other thyroid tissues. Most are benign tumors.

Cool nodules: Nodule tissue has no function of iodine absorption, so nodules are not radioactive. Such knots save about 20% for cancer. It is more likely to be cancerous in individuals who are not clearly demarcated from surrounding tissues. With the determination of serum calcitonin, the diagnosis rate can be improved.

Assist in diagnosing thyroiditis: Most chronic lymphatic thyroiditis scans have clear outlines and are symmetrical. The distribution of sclerosing thyroiditis is uneven, and there is no radioactivity in the affected area. Subacute thyroiditis has uneven radioactive distribution, low intensity, and even no graphics. Acute suppurative thyroiditis scans showed reduced radiation intensity at the site of inflammation.

The normal thyroid scintillation pattern is butterfly-shaped, divided into left and right leaves, and the right leaf is often higher than the left leaf. There is a isthmus connected between the two leaves, which is thin. The radioactivity is uniformly distributed and no nodules.