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Thyroid disease By Dr Fahad Anatomy of the Thyroid Gland.

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Presentation on theme: "Thyroid disease By Dr Fahad Anatomy of the Thyroid Gland."— Presentation transcript:

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2 Thyroid disease By Dr Fahad

3 Anatomy of the Thyroid Gland

4 Location: ant neck at C5-T1, overlays 2 nd – 4 th tracheal rings Average width: 12-15 mm (each lobe) Average height: 50-60 mm long

5 Thyroid Diseases Thyrotoxicosis Hypothyroidism Thyroid nodules

6 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.

7 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

8 Thyroiditis and exogenous thyroid hormone intake Early phase sub-acute thyroiditis: inflammation of thyroid gland that leads to release of stored thyroid hormone due to follicular cell destruction. In acute stage, the patient is thyrotoxic. Exogenous thyroid hormone intake: 1- By mistake 2- with weight loss pills

9 Thyrotoxicosis and TFT TSH is always suppressed in thyrotoxicosis. TSH is the most sensitive test for thyroid function and it is the screening test for thyroid dysfunction. If TSH is abnormal, T3 and T4 levels can be obtained in order to determine the severity of the disease. T3 and T4 are usually elevated in thyrotoxicosis.

10 TFT and Thyroid scan Thyrotoxicosis= suppressed TSH and elevated T3/T4. Based on TFT, the exact cause of thyrotoxicosis can not be determined. Thyroid scan is a very helpful tool in differentiating between various causes of thyrotoxicosis.

11 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.

12 Imaging findings Symmetric or asymmetric lobes. Homogeneous or inhomogeneous uptake Nodules; cold or hot

13 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%

14 Thyroid Uptake Probe

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16 Increase uptake Hyperthyroidism Iodine starvation Thyroiditis Hypoalbominemia lithium

17 decrease uptake Hypothyroidism Thyroid hormon therapy, PTU,Lugol’s solution Medication(contrast, multivitamins ) Thyroiditis

18 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%).

19 Graves’ Disease

20 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%.

21 Toxic Nodule

22 Hot Nodule

23 Toxic Multi-Nodular Goiter Mild inhomogeneous uptake in thyroid gland. Multiple cold and hot nodules in both thyroid lobes. 24-hour uptake is mildly elevated, usually between 20%-30%.

24 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.

25 Multi-nodular Goiter

26 Early Phase Sub-acute Thyroiditis Inhomogeneous uptake could be mild or severe. In some cases thyroid gland is not visualized. No significant focal abnormalities (nodules). 24-hour RAI uptake is low, usually < 5%.

27 Sub-acute Thyroiditis

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29 Hypothyroidism The main cause is chronic thyroiditis (Hashimoto’s thyroiditis). TSH is elevated. Thyroid scan does not have significant diagnostic value in this entity. However, if there is nodule/nodules confirmed by physical examination and ultrasound, thyroid scan may be helpful.

30 Thyroid Nodules thyroid nodules are common, perhaps existing in almost half the population Nodules are usually found by physical examination or by ultrasound. US is the first modality used to investigate a palpable thyroid nodule scintigraphy is reserved for characterizing functioning nodules and for staging follicular and papillary carcinomas. The patient is usually euthyroid.

31 If the patient is hyperthyroid do nuclear scan otherwise do FNA. FNA is the most accurate and cost- effective method for diagnostic evaluation of thyroid nodules. FNA have a sensitivity of 76%–98%, specificity of 71%–100%

32 Frequency of Occurrence of Thyroid Malignancies

33 Risk factors for thyroid cancer family history of thyroid cancer, a history of head and neck irradiation, male sex, age of less than 30 years or more than 60 years, previous diagnosis of type 2 multiple endocrine neoplasia

34 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.micro-calcifications 2.local invasion 3.lymph node metastases 4.a nodule that is taller than it is wide 5.markedly reduced echogenicity. Other features, such as the absence of a halo, ill- defined irregular margins, solid composition, and vascularity, are less specific but may be useful.

35 US Features Associated with Thyroid Cancer

36 Thyroid microcalcifications They are psammoma bodies, which are 10–100- μ m round laminar crystalline calcific deposits. They are one of the most specific features of thyroid malignancy, with a specificity of 85.8%–95% and a positive predictive value of 41.8%–94.2%

37 Figure 2a. Papillary thyroid carcinoma in a 42-year-old man. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

38 Figure 2b. Papillary thyroid carcinoma in a 42-year-old man. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

39 Local Invasion and Lymph Node Metastases US features that should arouse suspicion about lymph node metastases include a rounded bulging shape, increased size, replaced fatty hilum, irregular margins, heterogeneous echotexture, calcifications, cystic areas and vascularity throughout the lymph node instead of normal central hilar vessels at Doppler imaging

40 Figure 5a. Anaplastic thyroid carcinoma in an 84-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

41 Figure 5b. Anaplastic thyroid carcinoma in an 84-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

42 Figure 7b. Papillary carcinoma and cystic lymph node metastasis in a 28-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

43 Margins, Contour, and Shape A completely uniform halo around a nodule is highly suggestive of benignity, with a specificity of 95%

44 Figure 9. Follicular adenoma in a 30-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

45 Vascularity Chan et al (18) reported that all papillary thyroid carcinomas in their study had some intrinsic blood flow, and they concluded that a completely avascular nodule is very unlikely to be malignant.18

46 Figure 11a. Renal cell carcinoma metastases to the thyroid in a 69-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

47 Figure 11b. Renal cell carcinoma metastases to the thyroid in a 69-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

48 Figure 12. Follicular adenoma in a 36-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

49 Hypoechoic Solid Nodule Marked hypoechogenicity is very suggestive of malignancy.

50 Figure 13. B cell lymphoma of the thyroid in a 73-year-old woman with Hashimoto thyroiditis. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

51 Nonspecific US Features The size of a nodule is not helpful for predicting or excluding malignancy. There is a common but mistaken practice of selecting the largest nodule in a multinodular thyroid for FNA.

52 Number of Nodules Although most patients with nodular hyperplasia have multiple thyroid nodules and some patients with thyroid carcinoma have solitary nodules, the presence of multiple nodules should never be dismissed as a sign of benignity.

53 Interval Growth of a Nodule In general, interval growth of a thyroid nodule is a poor indicator of malignancy. Benign thyroid nodules may change in size and appearance over time. The exception is clinically detectable rapid interval growth, which most commonly occurs in anaplastic thyroid carcinoma but also may occur in lymphoma, sarcoma, and, occasionally, high-grade carcinoma.

54 Recommendations for Thyroid Nodules 1 cm or Larger in Maximum Diameter Society of Radiologists in Ultrasound Consensus Conference Statement

55 Punctate echogenicities in thyroid nodules. papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America

56 Figure 4. Benign thyroid nodule in a 51-year-old woman. Hoang J K et al. Radiographics 2007;27:847-860 ©2007 by Radiological Society of North America

57 Punctate echogenicities in thyroid nodules. colloid crystals in a benign nodule Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America

58 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

59 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

60 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

61 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

62 US images of thyroid nodules of varying parenchymal composition (solid to cystic). FNA of this presumed benign lesion was not performed because the nodule appears entirely cystic Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America

63 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

64 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

65 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

66 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

67 US features of malignant lymph node rounded bulging shape increased size, replaced fatty hilum irregular margins heterogeneous echotexture calcifications cystic areas vascularity throughout the lymph node instead of normal central hilar vessels at Doppler imaging

68 Abnormal cervical lymph nodes. metastatic papillary carcinoma Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America

69 Abnormal cervical lymph nodes. metastatic papillary carcinoma. Frates M C et al. Radiology 2005;237:794-800 ©2005 by Radiological Society of North America

70 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.

71 Figure 7a. Parallel positioning of the fine-gauge needle for thyroid nodule biopsy. Kim M J et al. Radiographics 2008;28:1869-1886 ©2008 by Radiological Society of North America

72 Figure 7b. Parallel positioning of the fine-gauge needle for thyroid nodule biopsy. Kim M J et al. Radiographics 2008;28:1869-1886 ©2008 by Radiological Society of North America

73 Figure 8a. Perpendicular positioning of the fine-gauge needle for thyroid nodule biopsy. Kim M J et al. Radiographics 2008;28:1869-1886 ©2008 by Radiological Society of North America

74 Figure 8b. Perpendicular positioning of the fine-gauge needle for thyroid nodule biopsy. Kim M J et al. Radiographics 2008;28:1869-1886 ©2008 by Radiological Society of North America

75 Radiopharmaceuticals Radioactive Iodine 131 (scan and uptake) used for therapy Radioactive Iodine 123 (scan and uptake) is the radioisotope of choice. The 13.3-hour half-life, the 159-keV principal photon, and the absence of particulate emission allow for good imaging with modest patient exposure. However, this isotope is cyclotron produced and relatively expensive, and the short half- life necessitates frequent shipments from the producer. Free Tc 99m (scan only)

76 Ablation of Benign Thyroid diseases with I131 Graves’ disease is ablated with 10-15 mCi of I131. Toxic nodular goiter (single nodule or multinodular) is ablated with 25-30 mCi of I131

77 Ablation of Thyroid cancer with I131 This is effective in differentiated thyroid cancer only(papillary and follicular thyroid cancers). Both are originated from follicular cell which is the functional cell in thyroid tissue (build thyroid hormone by utilizing iodine).

78 Thyroid Cancer Ablation Once follicular cell (benign or malignant) takes up radioactive iodine I131, beta particles will be emitted causing serious damage to cell components. These cells become nonfunctional and then die. Ablation is not helpful in medullary thyroid cancer and anaplastic carcinoma.

79 Protocol Total thyroidectomy is required before ablation. 100-200 mCi of I131 is needed for ablation of remnant thyroid tissue post total thyroidectomy.

80 Radiation Protection Cancer patients should be isolated in special room (leaded walls) to prevent others from radiation coming from the patient. Isolation is usually for 2-3 days. Once the residual iodine is coming down to 30 mCi and less, the patient can be discharged. Patient is followed up with thyroglobulin to detect recurrence and if needed nuclear scan

81 Remnant thyroid tissue

82 Remnant thyroid tissue with metastatic cervical adenopathy

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84 Thank you

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