Radiology and Endocrinology

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Radiology and Endocrinology

  1. 1. Radiology and Endocrinology <ul><li>ANATOMY </li></ul><ul><li>Radiography </li></ul><ul><li>Ultrasound </li></ul><ul><li>CT </li></ul><ul><li>MRI </li></ul><ul><li>FUNCTION </li></ul><ul><li>Radionuclide Imaging </li></ul><ul><li>- Scintigraphy </li></ul><ul><li>- PET </li></ul>
  2. 2. Radionuclide Imaging <ul><li>Images metabolic pathways </li></ul><ul><li>Pharmaceutical which mimics a component of a normal metabolic pathway is administered to the patient </li></ul><ul><li>Pharmaceutical radiolabelled so that its distribution in the patient can be visualised with a gamma camera </li></ul>
  3. 3. Ideal Radionuclide <ul><li>emits gamma radiation at suitable energy for detection with a gamma camera </li></ul><ul><li>(60 - 400 kev, ideal 150 kev) </li></ul><ul><li>should not emit alpha or beta radiation </li></ul><ul><li>half life similar to length of test </li></ul><ul><li>cheap </li></ul><ul><li>readily available </li></ul>
  4. 4. Ideal radiopharmaceutical <ul><li>cheap and readily available </li></ul><ul><li>radionuclide easily incorporated without altering biological behaviour </li></ul><ul><li>radiopharmaceutical easy to prepare </li></ul><ul><li>localises only in organ of interest </li></ul><ul><li>t 1/2 of elimination from body similar to duration of test </li></ul>
  5. 5. Thyroid - radiography <ul><li>Little role </li></ul><ul><li>Thyroid mass diagnosed incidentally on chest radiograph </li></ul><ul><li>Thoracic inlet views may demonstrate tracheal compression </li></ul>
  6. 6. Thyroid - ultrasound <ul><li>High resolution (5 - 10 MHz) </li></ul><ul><li>Confirms - mass is thyroid </li></ul><ul><li>cystic or solid </li></ul><ul><li>single or multiple </li></ul><ul><li>cannot distinguish solid carcinoma from solid dominant nodule </li></ul><ul><li>Not useful in hyperthyroidism </li></ul>
  7. 7. Thyroid - CT/MRI <ul><li>Not as good as US at resolving lesions within the thyroid </li></ul><ul><li>Best tests for assessing mediastinal disease </li></ul><ul><li>CT better than MRI for calcification </li></ul><ul><li>MRI better than CT for distinguishing between fibrosis and residual tumour </li></ul>
  8. 8. Thyroid - scintigraphy <ul><li>99m PERTECHNETATE </li></ul><ul><li>Trapped but not organified </li></ul><ul><li>Competes with iodide for uptake </li></ul><ul><li>Cheap and readily available </li></ul><ul><li>IODINE ( 123 I or 131 I) </li></ul><ul><li>Trapped and organified </li></ul><ul><li>Better for retrosternal goitres </li></ul><ul><li>Expensive, cyclotron generated </li></ul><ul><li>RECENT (10 days) IODINE CONTRAST BLOCKS UPTAKE </li></ul>
  9. 9. Thyroid scintigraphy <ul><li>99m Tc 123 NaI </li></ul><ul><li>ADMIN iv po/iv </li></ul><ul><li>PATIENT withdraw thyroid Rx </li></ul><ul><li>PREP avoid high Iodine foods </li></ul><ul><li>IMAGING 15 min pi 1-2hr pi </li></ul><ul><li>24 hr po </li></ul>
  10. 10. Hyperthyroidism <ul><li>RN uptake </li></ul><ul><li>1. Thyroid gland (>95%) </li></ul><ul><li>Toxic nodular goitre </li></ul><ul><li>Diffuse toxic goitre (Graves) </li></ul><ul><li>Thyroiditis </li></ul><ul><li>2. Exogenous T3/4/iodine </li></ul><ul><li>Iatrogenic </li></ul><ul><li>Iodine - induced </li></ul><ul><li>(XRay contrast, amiodarone) </li></ul>
  11. 11. Thyroid nodules <ul><li>Risk of malignancy </li></ul><ul><li>Overall 10% </li></ul><ul><li>US - cystic 0.3 - 10% </li></ul><ul><li>US - solid ???? </li></ul><ul><li>RNI - cold 16% </li></ul><ul><li>RNI - hot 4% </li></ul><ul><li>First line investigation: Cytology +/- US </li></ul>
  12. 12. RNI in thyroid disease <ul><li>Investigation of hyperthyroidism </li></ul><ul><li>Location of ectopic thyroid tissue (congenital hypothyroidism, retrosternal goitre) </li></ul><ul><li>Little role in thyroid nodules </li></ul>
  13. 13. 1 ry Hyperparathyroidism <ul><li>Type % </li></ul><ul><li>Adenomas Single 80 </li></ul><ul><li>Hyperplasia Chief cell 15 </li></ul><ul><li>Clear cell 1 </li></ul><ul><li>Carcinoma 4 </li></ul>
  14. 14. RN parathyroid imaging <ul><li>99m Tc / 201 Tl 99m Tc-MIBI </li></ul><ul><li>subtraction scans early/late scans </li></ul><ul><li>False positives: thyroid pathology </li></ul><ul><li>False negatives: parathyroid hyperplasia </li></ul><ul><li>Both good for ectopic parathyroids </li></ul>
  15. 15. Parathyroid imaging <ul><li>US not good at finding ectopic glands </li></ul><ul><li>CT Contrast </li></ul><ul><li>Surgical artifacts </li></ul><ul><li>MRI Good for localisation and ectopic glands </li></ul>
  16. 16. Imaging parathyroids <ul><li>Uncomplicated 1 ry hyperparathyroidsim </li></ul><ul><li>90 -95% surgical success rate without imaging </li></ul><ul><li>Recurrent/persistent hyperparathyroidism </li></ul><ul><li>surgical success rate without imaging -50% </li></ul><ul><li>with imaging - 90% </li></ul><ul><li>(combined RNI + MRI) </li></ul>
  17. 17. Adrenal glands <ul><li>Cortex aldosterone </li></ul><ul><li>cortisol </li></ul><ul><li>adrenal androgens </li></ul><ul><li>Medulla adrenalin </li></ul>
  18. 18. Adrenal glands <ul><li>AXR - may show calcification </li></ul><ul><li>US - large masses only (unless neonatal) </li></ul><ul><li>CT - can detect small lesions </li></ul><ul><li> - cannot distinguish metastases from non-functioning adenomas </li></ul><ul><li>MRI - small lesions </li></ul><ul><li> - may distinguish mets from </li></ul><ul><li>non-functioning adenomas </li></ul>
  19. 19. Adrenal cortical RNI <ul><li>Radiolabelled cholesterol esters </li></ul><ul><li>( 75 Seleno-methylnorcholesterol, </li></ul><ul><li>131 I - 6B iodomethyl-19-norcholesterol) </li></ul><ul><li>Image at 4 and 7 days </li></ul><ul><li>> 50% difference in activity between sides is abnormal </li></ul>
  20. 20. RNI in Cushings syndrome <ul><li>ACTH-dependent CS bilat </li></ul><ul><li>pituitary/ectopic </li></ul><ul><li>ACTH -independent CS </li></ul><ul><li>bilat nodular hyperplasia bilat </li></ul><ul><li>adrenocortical adenoma uni </li></ul><ul><li>Adrenocortical carcinoma bilat </li></ul>
  21. 21. Cushings syndrome <ul><li>Diagnosis - biochemistry </li></ul><ul><li>Localisation - CT/MRI </li></ul><ul><li>for </li></ul><ul><li>1. Pituitary ACTH-dependent </li></ul><ul><li>2. Ectopic ACTH-dependant </li></ul><ul><li>3. ACTH - independant </li></ul><ul><li>RNI not usually necessary </li></ul>
  22. 22. RNI and Cushings syndrome <ul><li>Used for </li></ul><ul><li>1. Finding residual functioning adrenal remnants if recurrent disease after prior bilateral adrenalectomy </li></ul><ul><li>2. Somatostatin receptor scanning for ectopic ACTH from small bronchial carcinoid tumours </li></ul>
  23. 23. Primary aldosteronism <ul><li>small tumours may not be seen with CT/MRI </li></ul><ul><li>RNI + dexamethasone suppression can find tumours < 1cm </li></ul><ul><li>Adrenal visualisation before 5 days is abnormal (bilateral/unilateral) </li></ul>
  24. 24. Adrenal medullary RNI <ul><li>Phaeochromocytoma </li></ul><ul><li>Paraganglioma </li></ul><ul><li>Neuroblastoma </li></ul><ul><li>Ganglioneuroblastoma </li></ul><ul><li>Ganglioneuroma </li></ul>
  25. 25. Adrenal medullary RNI <ul><li>Metaiodobenzylguanidine (MIBG) </li></ul><ul><li>- localises in catecholamine storage vesicles of adrenergic nerve endings </li></ul><ul><li>- 123 I or 131 I </li></ul><ul><li>somatostatin receptor imaging </li></ul><ul><li>111 In octreotide </li></ul>
  26. 26. MIBG <ul><li>phaeochromocytomas (95% sensitivity) </li></ul><ul><li>neuroblastoma (80 - 90% sens) </li></ul><ul><li>carcinoid </li></ul><ul><li>medullary thyroid carcinoma </li></ul><ul><li>(MEN syndromes) </li></ul>
  27. 27. Phaeochromocytomas <ul><li>10% malignant </li></ul><ul><li>bilateral </li></ul><ul><li>extra- adrenal </li></ul><ul><li>paediatric </li></ul>
  28. 28. Phaeochromocytomas <ul><li>Diagnosis - biochemistry </li></ul><ul><li>Localisation </li></ul><ul><li>CT if > 2cm </li></ul><ul><li>RNI to exclude - small tumours </li></ul><ul><li> - bilateral adrenal </li></ul><ul><li> - multifocal </li></ul><ul><li> - metastases </li></ul>
  29. 29. ‘ Incidentalomas’ <ul><li>Incidental adrenal mass in patients undergoing abdominal imaging (2%) </li></ul><ul><li>Q. Is it functioning? </li></ul><ul><li>Is it benign or malignant? </li></ul>
  30. 30. Functioning ‘incidentalomas’ <ul><li>Diagnosis </li></ul><ul><li>Clinical features </li></ul><ul><li>Biochmistry </li></ul><ul><li>Confirmation </li></ul><ul><li>RNI </li></ul>
  31. 31. Non-functioning <ul><li>Non-functioning adenoma vs. metastasis </li></ul><ul><li>CT using attenuation values </li></ul><ul><li>MRI - chemical shift imaging </li></ul>
  32. 32. Radiology and Endocrinology <ul><li>Localisation </li></ul><ul><li>not </li></ul><ul><li>Diagnosis </li></ul>
  33. 33. IMAGING and the ENDOCRINE SYSTEM

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