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Thyroid disease By Dr Fahad Anatomy of the Thyroid Gland Location: ant neck at C5-T1, overlays 2nd – 4th tracheal rings Average width: 12-15 mm (each lobe) Average height: 50-60 mm long Method of Imaging Investigation Ultrasound N/M MRI/ CT TC THYROID SCAN NORMAL UPTAKE THYROID ULTRASOUND NORMAL 0.99 X 1.07 CM 1.25 X 1.14 CM 3.75 X 1.16 CM 3.18 X 1.03 CM THYROID COMPUTED TOMOGRAPHY NORMAL 0.99 X 1.07 CM 3.75 X 1.16 CM Thyroid Diseases Thyrotoxicosis Hypothyroidism Thyroid nodules Thyrotoxicosis VS Hyperthyroidism Thyrotoxicosis: a group of symptoms and signs due to elevated thyroid hormones in the body of any cause. Hyperthyroidism: a group of symptoms and signs due to increased production of thyroid hormones by hyper functioning thyroid gland. Causes of Thyrotoxicosis Hyperthyroidism 1- Diffuse toxic goiter (Graves’ disease) 2- Single toxic nodule 3- Toxic multi-nodular goiter Early phase sub-acute thyroiditis Exogenous thyroid hormone intake Thyroid scan and uptake Radioactive Iodine (RAI) is used for thyroid scan and uptake. RAI is given orally. Image and uptake are obtained after 24 hours Follicular cell traps Iodine and organifys it to be incorporated with thyroid hormone. Imaging findings Symmetric or asymmetric lobes. Homogeneous or inhomogeneous uptake Nodules; cold or hot 24-hour RAI uptake Measure photons in the given RAI by a special probe (uptake probe) just before taking RAI. After 24 hours, measure photons in the neck (thyroid gland). Calculate % of photons concentrated in thyroid gland. Normal range of 24 RAI uptake is 10%30% Increase uptake Hyperthyroidism Iodine starvation Thyroiditis Hypoalbominemia lithium decrease uptake Hypothyroidism Thyroid hormon therapy, PTU ,Lugol’s solution Medication(contrast , multivitamins ) Thyroiditis Diffuse Toxic goiter (Graves’ Disease) Diffuse enlargement of thyroid gland. Homogeneous uptake. No significant focal abnormalities (nodules). 24-hour RAI uptake is elevated, usually > 35% (mean of 40%). Graves’ Disease Single Toxic Nodule Single hot nodule (independent of TSH or autonomous). Rest of thyroid gland is poorly visualized due to low TSH level (TSH dependant). 24-hour RAI uptake is slightly elevated, usually around 20%. Multi-nodular Goiter • Cut surface of one lobe of thyroid gland showing ill defined nodules. • Focus of cystic degeneration seen (blue arrow). • Some hemorrhage (red arrow) and some scarring. Multi-nodular Goiter Multi-nodular Goiter 6.75 X 3.16 CM 7.34 X 4.21 CM THYROID COMPUTED TOMOGRAPHY NORMAL 0.99 X 1.07 CM 3.75 X 1.16 CM NODULES Toxic Nodule Hot Nodule US images of thyroid nodule of varying parenchymal composition (solid to cystic). papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America US features of thyroid nodules there is some overlap between the US appearance of benign nodules and that of malignant nodules certain US features are helpful in differentiating between the two. These features include 1. 2. 3. 4. 5. micro-calcifications local invasion lymph node metastases a nodule that is taller than it is wide markedly reduced echogenicity. Other features, such as the absence of a halo, illdefined irregular margins, solid composition, and vascularity, are less specific but may be useful. US Features Associated with Thyroid Cancer Recommendations for Thyroid Nodules 1 cm or Larger in Maximum Diameter Society of Radiologists in Ultrasound Consensus Conference Statement Punctate echogenicities in thyroid nodules. papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America US images of thyroid nodules of varying parenchymal composition (solid to cystic). papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America US images of thyroid nodules of varying parenchymal composition (solid to cystic). proved to be benign at cytologic examination Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America US images of thyroid nodules of varying parenchymal composition (solid to cystic). proved to be benign at cytologic examination Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America US images of thyroid nodules of varying parenchymal composition (solid to cystic). proved to be benign at cytologic examination Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America Role of color Doppler US. (a) Transverse gray-scale image of predominantly solid thyroid nodule (calipers). papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America Role of color Doppler US. (a) Transverse gray-scale image of predominantly solid thyroid nodule (calipers). papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America Transverse US images of mostly cystic thyroid nodule with a mural component containing flow. The lesion was benign at cytologic examination Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America US-guided FNA Technique The needle may be introduced parallel or perpendicular to the transducer, and the needle tip should be carefully monitored during the procedure. US-guided FNA Technique Parallel positioning of the fine-gauge needle for thyroid nodule biopsy. Kim M J et al. Radiographics 2008;28:1869-1886 Thank you