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Subintern 백민관

Subintern 백민관. Introduction . Thyroid scintigraphy : important tool for guiding clinical and surgical decisions. The most common indications nodular or enlarged thyroid gland thyrotoxicosis Neonatal hypothyroidism characterization of ectopic tissue or mediastinal masses.

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Subintern 백민관

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  1. Subintern 백민관

  2. Introduction • Thyroid scintigraphy : • important tool for guiding clinical and surgical decisions. • The most common indications • nodular or enlarged thyroid gland • thyrotoxicosis • Neonatal hypothyroidism • characterization of ectopic tissue or mediastinal masses

  3. PRINCIPLES OF THYROID SCINTIGRAPHY • Thyroid Embryology • gland develops from the ventral wall of the pharynx • grows the base of tongue ~ level of the cricoid cartilage • thyroglossal duct usually obliterates during fetal development • Anatomy • isthmus , 2 lobes(5 X 2 Cm, 15 to 30 g) • pyramidal lobe : cephalad from the isthmus or the medial portion of lobes superiorly

  4. Physiology

  5. Thyroid Imaging

  6. PATTERN: NORMAL LOCALIZATION • “Trapping” • in salivary gland = Tc99m < I-123 Asymetric size : normal variaton

  7. DIFFUSELY INCREASEDLOCALIZATION • Graves’ disease(diffuse toxic goiter) • homogeneously enlarged gland • Pearl: In Graves’ disease, the pattern could be heterogeneous.

  8. Graves’ disease • Isthmus, pyramidal lobe : • visible in Graves’ disease • but, seen other conditions causing enlargement.

  9. DIFFUSELY DECREASEDLOCALIZATION • Subacute, silent thyroiditis • Quantified RAIU of 1% • Faint salivary activity is present (arrowhead) • silent thyroiditis occurred after withdrawal of corticosteroids, with extreme hyperthyroidism biochemically, followed 1month later by profound hypothyroidism and markedly elevated antibodies

  10. DIFFUSELY HETEROGENEOUSLOCALIZATION • A) mild heteogenesity Pt. • B) marked heterogenesity Pt. • Both normal TFTs • Dx. : Euthyroid multinodular goiter • Multinodular goiter goitrogen, iodine deficiency, thyroditis

  11. Heterogenous uptake • A Pt.) Rt.Lobe • B) Lt.Lobe dominant • Both Pt. TFTs : thyrotoxic • Dx. : toxic multinodular goiter

  12. FOCALLY INCREASEDLOCALIZATION • Solitary “hot” nodule Dx. : autonomous adenoma • “Hot” nodules are almost always benign • adenoma :homogeneous, but, necrosis or undergo cystic degeneration, central photopenia (a “cold” center)

  13. “discordant” nodule (“warm” on Tc-99m, “cold” on I-123) could be malignant and warrants fine needle aspiration (FNA) biopsy

  14. FOCALLY DECREASEDLOCALIZATION • Approximately 90% of solitary “cold” nodules are benign • nonfunctioning adenomas • colloid cysts • abscess in acute thyroiditis • Hashimoto’s disease • 5% to 10% chance of malignancy  fine needle aspiration (FNA) biopsy

  15. Dx. : papillary carcinoma with pul. Meta • A malignant palpable nodule can appear “warm” on Tc-99m imaging,secondary to overlying/underlying normal thyroid tissue FNA biopsy or I-123 imaging

  16. Papillary carcinoma in a multinodular goiter Biopsy-proven benign dominant adenoma in a multinodular goiter

  17. PATTERN: ‘EXTRATHYROIDAL’ ACTIVITY • Esophageal Activity • Ectopic Thyroid Tissue • Thyroglossal Duct Cyst • Substernal Goiter

  18. Esophageal activity before and after drinking water clearing of swallowed saliva ectopic embryological thyroid tissue postoperative thyroid tissue salivary activity

  19. Substernal Goiter Large mediastinal mass Heterogenous uptake Left lobe substernally Mass ant.mediastinum

  20. PATTERN: NEONATAL HYPOTHYROIDISM 3 typical abnormal scintigraphic patterns Agenesis m/c Lingual thyroid Dyshormonogenesis Normal location

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