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Thyroid scintigraphy with TC has the role of determining the location, shape, size and internal anatomy of the thyroid gland. At the same time, this method is also indicated to evaluate and identify thyroid nodules, contributing to differential diagnosis of cervical and mediastinal tumors.1. The role of thyroid scan with TC
Thyroid cells have the ability to concentrate and capture pertechnetate ions (TcO4-). This ion will not be organicized for hormone synthesis, but it will only be retained in the thyroid gland for a short time, but still enough time to capture thyroid images.
Thyroid scintigraphy technique with TC can image the thyroid gland with the advantage of lower absorbed dose, better image quality than the 131I method, which is widely used today.
2. Indications and contraindications for thyroid scintigraphy with TC
Thyroid scintigraphy with TC is indicated in the following cases:
Determine the location, shape, size and internal anatomy of the thyroid gland. This method is also indicated to evaluate and identify thyroid nodules; Thyroid status in patients with thyroid cancer before and after surgery. Contribute to the differential diagnosis of cervical and mediastinal tumors; cases of acute thyroid pain and thyroiditis. Thyroid scan with TC is contraindicated in the following cases:
Pregnant women; Women who are breastfeeding.
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3. Procedure for performing thyroid scan with TC
Step 1: Prepare means, radioactive drugs, gamma radiation dosimeter, gamma radiation detector, tools and consumables; Step 2: Extract TC from Mo-Tc extraction flask to get Tc99m pertechnetate solution. Then aspirate a dose of DCPX Tc99m pertechnetate for each patient and inject radioactive TC pertechnetate into the patient's vein. Step 3: Ask the patient to drink water, swallow all saliva before taking the thyroid image. Gamma Camera machine mode setting, SPECT with low energy, high resolution as well as multi-purpose Collimator, 20% window; Step 4: The technician will record 15-20 minutes after injecting radioactive TC pertechnetate into the vein. During the recording process, ask the patient to lie in the supine position, not to move the head; Step 5: Use a medium-energy parallel collimator to record statically in the head and neck area with upright, right-angled, and left-tilt positions. Finally, still image the thyroid gland with a conical collimator, 500,000 Kcounts or over a period of 5-10 minutes.
4. What does a thyroid scan with TC say?
Thyroid picture is normal when:
Thyroid is butterfly-shaped, radioactive activity is uniform. The right lobe of the thyroid gland is slightly superior to the left lobe. The normal area of the thyroid gland in adults is ≤ 20cm2, children are 10-15cm2. Salivary glands can be seen. Image of thyroid pathology when scanning:
If the thyroid scan image with TC shows an enlarged thyroid gland, 1 or 2 lobe deformity with an enlarged isthmus and a high ability to capture radioactivity, it is possible to is a sign of hyperthyroidism. In "hot" nuclei, the radioisotope is higher than in surrounding tissues, which is likely to be a dominant adenoma disease (thyroid tumor).. With "cold" nuclei, the radioisotope concentration region less than the surrounding tissue, creating a radioactivity defect on the scintillation. For people with hypothyroidism or thyroiditis, thyroid scans show markedly decreased radioactivity or a shrinking thyroid gland. In summary, thyroid scintigraphy with TC cannot completely replace 131I in thyroid imaging. However, this method has the advantages of lower radiation dose absorption and better image quality, so it is widely used in thyroid imaging.
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