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Thyroid

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Thyroid

  1. 1. Thyroid Scan รศ . พญ . มลฤดี เอกมหาชัย หน่วยเวชศาสตร์นิวเคลียร์ ภาควิชารังสีวิทยา คณะแพทยศาสตร์ มหาวิทยาลัยเชียงใหม่
  2. 2. Normal and Aberrant Locations of Thyroid Tissues
  3. 3. Hypothalamus- Pituitary- Thyroid Axis
  4. 4. Iodide M etabolisms <ul><li>1. Trapping </li></ul><ul><li>2. Organification </li></ul><ul><li>3. Couplings </li></ul><ul><li>4. Hormonal release </li></ul>
  5. 5. Iodide M etabolisms <ul><li>1. Trapping : Active transport </li></ul><ul><li>2. Organification : </li></ul><ul><li> Iodide ----------> Neutral Iodine </li></ul><ul><li> Iodine + Tg -----> MIT, DIT </li></ul><ul><ul><li>MIT = Mono-iodinated tyrosine </li></ul></ul><ul><ul><li>DIT = Di-iodinated tyrosine </li></ul></ul>Peroxidase
  6. 6. Iodide M etabolisms <ul><li>3. Couplings : </li></ul><ul><ul><li>MIT + DIT = Triiodothyronine (T3) </li></ul></ul><ul><ul><li>DIT + DIT = Thyroxine (T4) </li></ul></ul><ul><li>4. Hormonal release : T3 & T4 </li></ul><ul><li>- Free form </li></ul><ul><li>- Bound form </li></ul>
  7. 7. Radiopharmaceuticals <ul><li>1. Iodine-125 : In vitro TFT </li></ul><ul><ul><ul><li>T1/2 = 60 days </li></ul></ul></ul><ul><ul><ul><li>r-energy 29-35 keV </li></ul></ul></ul><ul><li>2. Iodine-123 : Ideal isotope </li></ul><ul><ul><ul><li>T1/2 = 13 hours </li></ul></ul></ul><ul><ul><ul><li>r-energy 159 keV </li></ul></ul></ul><ul><ul><ul><li>Cyclotron produced isotope </li></ul></ul></ul>
  8. 8. Radiopharmaceuticals <ul><li>3. Iodine-131 : Oral </li></ul><ul><ul><ul><li>T1/2 = 8.06 days </li></ul></ul></ul><ul><ul><ul><li>r-energy 364 keV </li></ul></ul></ul><ul><ul><ul><li>B-energy 192 keV </li></ul></ul></ul><ul><li>4. Tc-99m pertechnatate : IV </li></ul><ul><ul><ul><li>T1/2 = 6 hours </li></ul></ul></ul><ul><ul><ul><li>r-energy 140 keV </li></ul></ul></ul>
  9. 9. <ul><li>1. Iodine uptake test (Thyroid uptake test) </li></ul><ul><li>2. Perchlorate washout test </li></ul><ul><li>3. T3 suppression test </li></ul><ul><li>4. TSH stimulation test </li></ul>Thyroid Function Studies
  10. 10. <ul><li>1. Clinical hyperthyroidism, but with equivocal thyroid function tests </li></ul><ul><li>2. R/O subacute thyroiditis </li></ul><ul><li>3. Known case of hyperthyroidism with plan to give low dose Iodine-131 treatment </li></ul>Indications for Iodine-131 Uptake
  11. 11. <ul><li>Methods : </li></ul><ul><ul><li>Oral iodine-131 dose 20 uCi </li></ul></ul><ul><ul><li>Serial thyroid uptake at 2, 24 & 48 hrs </li></ul></ul><ul><li>% Iodine uptake </li></ul><ul><ul><li>Net thyroid counts X 100 % Net counts of standard dose </li></ul></ul>Iodine Uptake Test
  12. 12. <ul><li>2 hours = 10-30 % </li></ul><ul><li>24 hours = 20-60 % </li></ul><ul><li>48 hours = 20-60 % </li></ul>Normal Iodine Uptake
  13. 13. <ul><li>1. Hyperthyroidism </li></ul><ul><li>2. Rebound effect </li></ul><ul><li>3. Iodine deficiency </li></ul><ul><li>4. Recovery phase of subacute thyroiditis </li></ul><ul><li>5. Compensatory dyshormogenesis </li></ul>Factors Affecting Increased 131-I Uptake
  14. 14. <ul><li>1. Hypothyroidism </li></ul><ul><li>2. Medications : ATD, Thyroid hormones </li></ul><ul><li>3. Iodine overload : Diet, Contrast media etc. </li></ul><ul><li>4. Goitrogens </li></ul><ul><li>5. Subacute thyroiditis, early phase </li></ul>Factors Affecting Decreased 131-I Uptake
  15. 15. Indications for Thyroid Scan <ul><li>1. Thyroid nodule(s) </li></ul><ul><li>2. Diffuse or multinodular goiter </li></ul><ul><li>3. Clinical hyper- or hypothyroidism </li></ul><ul><li>4. Evaluation of substernal mass </li></ul><ul><li>5. R/O Ectopic thyroid tissue </li></ul><ul><li>6. Subacute thyroiditis, early phase </li></ul><ul><li>7. Patient with previous Hx of H & N RT </li></ul>
  16. 16. Normal Thyroid Scan
  17. 17. Normal Thyroid Scan
  18. 18. Thyroid Nodule <ul><li>1. Cold nodule </li></ul><ul><li>2. Hot nodule </li></ul><ul><li>3. Warm nodule </li></ul>
  19. 19. Single Cold Nodule
  20. 20. Single Cold Nodule
  21. 21. Causes of Cold Nodule <ul><li>Colloidal cyst </li></ul><ul><li>Hypofunctioning adenoma </li></ul><ul><li>Thyroid carcinoma 15-25 % </li></ul><ul><li>Others : focal thyroiditis, abscess, hematoma, lymphoma, metastasis, parathyroid adenoma, lymph node enlargement (rare) </li></ul>70-75 %
  22. 22. Hot Nodule Ant RAO
  23. 23. Hot Nodule
  24. 24. Causes of Hot Nodule <ul><li>Hyperfunctioning adenoma(s) </li></ul><ul><li>Anatomical variant </li></ul><ul><li>Thyroid carcinoma 2 % </li></ul><ul><li>Compensatory hypertrophy </li></ul>
  25. 25. Warm Nodule
  26. 26. Causes of Warm Nodule <ul><li>Functioning adenoma </li></ul><ul><li>Anatomical variant </li></ul><ul><li>Thyroid carcinoma 4 % </li></ul><ul><li>Deep seated cold nodule </li></ul>
  27. 27. Diffuse Goiter <ul><li>Euthyroid </li></ul><ul><ul><ul><li>Simple goiter or </li></ul></ul></ul><ul><ul><ul><li>Adolescent goiter </li></ul></ul></ul><ul><li>Hyperthyroidism </li></ul><ul><ul><ul><li>Diffuse toxic goiter (Graves’ disease) </li></ul></ul></ul>
  28. 28. Simple Goiter
  29. 29. Simple Goiter
  30. 30. Graves’ Disease
  31. 31. Graves’ Disease
  32. 32. Graves’ Disease
  33. 33. Nodular Goiter <ul><li>Euthyroid </li></ul><ul><ul><ul><li>Multinodular goiter </li></ul></ul></ul><ul><li>Hyperthyroidism </li></ul><ul><ul><ul><li>Single : Nodular toxic goiter </li></ul></ul></ul><ul><ul><ul><li>Multiple : Plummer’s disease </li></ul></ul></ul><ul><li>Hypothyroidism </li></ul><ul><ul><ul><li>Hashimoto’s thyroiditis </li></ul></ul></ul>
  34. 34. Multinodular Goiter
  35. 35. Multinodular Goiter
  36. 36. Multinodular Goiter
  37. 37. Nodular Toxic Goiter
  38. 38. Nodular Toxic Goiter
  39. 39. Plummer’s Disease
  40. 40. Substernal Goiter
  41. 41. Subacute Thyroiditis
  42. 42. Subacute Thyroiditis
  43. 43. Normal Thyroid Scan
  44. 44. Congenital Hypothyroidism <ul><li>Thyroid agenesis </li></ul><ul><li>Ectopic thyroid </li></ul><ul><li>Congenital organification defect </li></ul><ul><li>Normal location of thyroid gland with diffuse decreased uptake </li></ul>
  45. 45. Thyroid Agenesis
  46. 46. Thyroid Agenesis
  47. 47. Ectopic Thyroid Ant Rt.lateral
  48. 48. Ectopic Thyroid
  49. 49. Ectopic Thyroid
  50. 50. Ectopic Thyroid
  51. 51. Congenital Organification Defect
  52. 52. Congenital Organification Defect
  53. 53. Diffuse Decreased Uptake
  54. 54. Whole Body Scan with Iodine-131
  55. 55. Indications for I-131 WBS <ul><li>1. Post-operative evaluation for thyroid remnant or functioning metastasis </li></ul><ul><li>2. Follow up patients after I-131 ablation or I-131 treatment </li></ul><ul><li>3. Serum Tg rising </li></ul><ul><li>4. Suspected tumor recurrence </li></ul><ul><li>5. Suspected functioning metastases, either local or distant metastases </li></ul>
  56. 56. Well differentiated thyroid CA Total or neartotal thyroidectomy Whole body scan with Iodine-131 Residual thyroid tissue Distant metastases Iodine-131 Rx + Thyroid hormone Rx 4-6 weeks
  57. 57. Residual thyroid tissue Tumor size > 1.5 cm or Papillary CA + < 1.5 cm + multifocal Tumor size < 1.5 cm < 1.5 cm + capsular invasion < 1.5 cm + vascular invasion Thyroid hormone Follicular CA Rx only Iodine-131 ablation + Thyroid hormone Rx
  58. 58. Ant- Head & Neck Chest Abdomen Post- Chest Abdomen Pelvis & Thigh
  59. 59. Ant- Head & Neck Chest Abdomen Post- Chest Abdomen Pelvis & Thigh
  60. 60. Ant- Head & Neck Chest Abdomen Post- Chest Abdomen Pelvis & Thigh
  61. 61. Ant- Head & Neck Chest Abdomen Post- Chest Abdomen Pelvis & Thigh
  62. 62. Ant- Head & Neck Chest Abdomen Post- Chest Abdomen Abdomen

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