Thyroid static imaging

Static imaging of the thyroid gland utilizes the ability of the thyroid tissue to uptake and concentrate 131I or uptake 99mTc-perpenate. After the thyroid gland takes in radioactive iodine or strontium from the blood circulation, the distribution of the thyroid imaging agent is displayed in vitro by a developing device for observing the position, shape, size, and functional status of the thyroid gland. Both sputum and iodine belong to the same family, and can be ingested and concentrated by thyroid tissue, but 锝 can not be organicized, so 99mTcO4-thyroid imaging can only reflect the thyroid uptake function, and can not reflect the state of iodine metabolism or organicization. The physical properties of 99mTc are better than 131I, and its image quality is better than 131 iodine. It is the most commonly used thyroid imaging agent. However, when looking for ectopic thyroid and thyroid cancer metastases, it is still better to use 131 iodine. Basic Information Specialist classification: growth and development check classification: endocrine examination Applicable gender: whether men and women apply fasting: fasting Tips: Check before taboo: pay attention to normal diet, pay attention to normal work and rest, prevent endocrine disorders. Normal value The normal thyroid morphology is butterfly-shaped, divided into left and right leaves, on both sides of the trachea. The lower third of the two leaves are connected by the isthmus, and sometimes the isthmus is absent. Each leaf has a length of about 4.5 cm, a width of about 2.5 cm, a frontal area of ​​about 20 cm 2 and a weight of about 20 to 25 g. The two-leaf thyroid has a uniform radioactivity distribution and a neat and smooth edge. Clinical significance Abnormal results: 1. Localization diagnosis of ectopic thyroid: thyroid imaging has a unique diagnostic value. 131 iodine images are not seen in the normal thyroid area, and 131 iodine images appear in other parts, or the thyroid tissue image of the normal part extends to the sternum. Can be diagnosed. 2. Diagnosis of thyroid nodule function: simple thyroid static imaging can not judge the nature of thyroid nodules, therefore, if nodules are found in thyroid imaging, general thyroid tumor positive imaging should be performed (such as 99mTc-MIBI, 201Tl Like, etc., to help judge the nodule and malignancy. 3. Search for thyroid cancer metastases: When the serum TSH concentration is greater than 30mIU/L, the thyroid cancer metastasis imaging will be performed. If necessary, TSH can be injected to stimulate the lesion to take 131I and increase the positive rate of imaging. The primary lesions and metastases of medullary thyroid carcinoma can not concentrate 131I, so 131I can not be used to find metastases. 201Tl can be used as imaging agent, intravenous injection of 201TlCl74MBq (2mCi), and systemic display after 10~30min Like, a positive result can be obtained. Tumor-positive imaging can also be performed with 99mTc(V)-DMSA, 99mTc-MIBI or 131I-MIBG. 4. The relationship between the neck mass and the thyroid: when the mass is outside the thyroid outline, does not ingest 131 iodine or 99mTcO4, and the thyroid gland is intact, it is an extra-thyroid mass. When the shape of the thyroid gland is incomplete and the mass is within the contour of the thyroid gland, and the lump overlaps with the concentrated (or sparse) part of the imaging agent of the thyroid gland, it is a thyroid gland. 5. Diagnosis of thyroiditis: (1) Chronic lymphocytic thyroiditis: When the thyroid tissue is fibrotic, its texture becomes hard and nodular changes occur in the late stage of the disease, the thyroid imaging shows an irregular and densely distributed imaging agent distribution, ie Peaks, valleys, or worm-like distribution; and 99mTcO4- and 131 iodine imaging results may be inconsistent, that is, 99mTcO4- imaging is a hot nodule, while 131 iodine imaging is a cold nodule, suggesting the presence of thyroid Organic iodine barriers. (2) Subacute thyroiditis: the distribution of imaging agents is obviously sparse, or it is a sparse shadow with uneven distribution, even without developing or slightly higher than the surrounding background tissue. At this time, the serum thyroid hormone levels are significantly increased, and 131 iodine rates were significantly reduced in the thyroid gland, and some patients may also be associated with decreased TSH concentrations and positive TgAb and TmAb. Sometimes thyroid imaging only shows a localized cold nodule, or multiple imaging shows that the lesion develops from one leaf to another; during the recovery period, the thyroid image can gradually return to normal. (3) Acute thyroiditis: the distribution of imaging agents is sparse, while the blood flow imaging shows that the image of the blood pool is thickened. People who need to be examined: patients with ectopic thyroid, thyroid nodules, thyroid cancer, neck lumps, thyroiditis and other symptoms. Precautions Forbidden before examination: pay attention to normal diet, pay attention to normal work and rest, and prevent endocrine disorders. Requirements for inspection: Actively cooperate with the doctor's request. Inspection process Intravenous injection of 99mTcO4-74～185MBq (2～5mCi) for 20min (or 1~2h after oral administration) was performed, using a pinhole collimator or a universal parallel hole collimator. Conventional anterior plane acquisition is used. If necessary, the ectopic thyroid imaging is increased. After the oral administration of 131I1.85～3.7MBq (50～100μCi) on the fasting, the imaging is performed at the site to be examined and the normal thyroid gland at 24h. Type collimator, the rest of the conditions are the same as 99mTcO4-thyroid imaging. The thyroid cancer metastasis imaging was performed in the anterior and posterior whole body imaging after oral administration of 131I74～148MBq (2～4mCi) for 24～48h. The high-energy universal collimator was used to collect the whole body bone imaging. Tomographic imaging: SPECT line tomography was performed 20 minutes after intravenous injection of 99mTcO4-296~370MBq (8~10mCi), using low-energy high-resolution parallel-hole collimator, the acquisition matrix was 64×64 or 128×128, and the probe was rotated 360°. Collect 64 frames; for those with good sucking function, collect 15~20s per frame, or use fixed number acquisition, collect 80~120K counts per frame. After the end of the collection, the reconstruction was performed to obtain cross-sectional, sagittal, and coronal images. In addition, high-resolution pinhole collimator can also be used for thyroid tomography. The patient is placed in the supine position, the shoulder is raised, the patient's neck is stretched as much as possible, and the probe is rotated 180° from the right side of the thyroid to the left side, collecting 30 frames. (every 6°1 frame), 20~30s per frame, matrix 128×128, when using pinhole collimator, it is not suitable to use contour tracking system to collect, to keep the distance between collimator and thyroid as equal as possible, otherwise it will affect the inspection. As a result, the method of reconstructing the fault is the same as that of the parallel hole, but the image resolution is higher than that of the parallel hole collimator. This method is suitable for nodular thyroid disease, especially for detecting small nodules. The result is judged: 1. Normal image: The normal thyroid morphology is butterfly-shaped, divided into left and right leaves, on both sides of the trachea. The lower third of the two leaves are connected by the isthmus, sometimes the isthmus is absent. Each leaf has a length of about 4.5 cm, a width of about 2.5 cm, a frontal area of ​​about 20 cm 2 and a weight of about 20 to 25 g. The two-leaf thyroid has a uniform radioactivity distribution and a neat and smooth edge. Normal thyroid two-leaf development can be inconsistent, can form a variety of morphological variations, a small number of patients can see thyroid cone leaf variation. 2. Abnormal images: mainly thyroid enlargement, abnormal position, uneven distribution of thyroid radioactivity, abnormal shape or thyroid development. Not suitable for the crowd Inappropriate crowd: temporarily unknown. Adverse reactions and risks There are no related complications and hazards.

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