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Endocrine Scan - Coggle Diagram

- - - - iodine-131 (Na131I)
        
        reactor product
        
        abundant and cheap
        
        high internal radiation exposures
        
        gamma energy: 364 keV
        
        high energy collimator required
        
        theranostic agent
        
        allow prolonged delay phase scan
        
        better tumor-to-bkg contrast
        
        half life: 8 days (biological 12 days)
      - iodine-123 (Na123I)
        
        13 hours
        
        159 keV (LEAP collimator)
        
        better resolution
        
        cyclotron product
    - - released along time after uptake
      - thyroid + salivary gland seen
      - transported into thyroid by NIS (1-5%), X organification
      - preferred for patienets with thyroid-blocking agents
  - - - clincial index of thyroid function
      - suggest to treatment dose
    - - 4-6 hours
        
        normal: 5-15%
        
        early turnover: differentiate Graves' Disease
      - 24 hours
        
        normal: 10-30%
        
        radioiodine therapy
    - - neck phantom with capsule (as bkg)
      - thyorid uptake (%) = (neck counts-thigh counts)/ corrected capsule counts *100%
      - measurement done twice @ 1-min and 20min, avg
      - ~5-10 uCi of 141I-sodium/
        50-100 uCi 123I-sodium
    - - increased uptake
        
        • Hyperthyroidism (diffuse or nodular goiter)
        
        • Early Hashimoto thyroiditis
        
        • Recovery from subacute thyroiditis
        
        • Rebound after abrupt withdrawal of
        
        antithyroid medication
        
        • Enzyme defects
        
        • Iodine deficiency or starvation
        
        • Hypoalbuminemia
        
        • Thyroid-stimulating hormone
        
        • Tumor-secreted stimulators
        
        • Pregnancy
      - decreased uptake
        
        • Hypothyroidism (primary or secondary)
        
        • Iodine overload (especially radiographic contrast)
        
        • Medications
        
        • Subacute or autoimmune thyroiditis
        
        • Thyroid hormone therapy
        
        • Ectopic secretion of thyroid hormone from tumors
        
        • Renal failure
  - - - functional disorders
        
        overactive or underactive
        
        hot or cold spots
      - structural disorders
        
        morphological changes
        
        anatomical changes e.g. nodules
    - - determine functional status of a thyroid nodule
      - determine whether a cervical or mediastinal mass in thyrodi tissue
      - differentiate '/. hyperthyroidism and other causes of thyrotoxicosis
      - locate ectopic tissue e.g. lingual thyroid
      - differentiate among causes of hyperthyroidism
        
        Graves disease from toxic nodular goiter
      - assist in evaulate of congenital hypothyroidism or organification defects
    - - screen of recent drug list & iodine contrast administrartion
      - palpation of thyrodi gland with patient sitting upright
    - - 200-400 uCi (7.4-14.8 MBq) oral
      - image '/. 4-24 hrs
      - image acquisition
        
        100,000 counts
        
        7-10 mins (~200 cps)
        
        pinhole collimator
        
        3 views: ant + bilateral oblique
        
        anterior marker on sternal notch
        
        supine with neck extended
    - - less affected by drug/ food occupancies
      - 2-10 mCi (74-370 MBq) i.v.
      - image 5-30 mins after
      - image acquisition
        
        100,000-250,000 counts
        
        5 mins (~500 cps)
        
        ant + bilateral oblique views
        
        pinhole collimator (parallel hole collimator
        
        supine with neck extended
        
        anterior marker on sternal notch
    - - height of image/distance(image->pinhole) *distance(thyroid->pinhole)
      - usually 4-5 cm for each lobe
- - - - regulate calcium and phosphorus metabolism
  - - - 99mTc-sestamibi
      - 99mTc-pertechnetate
    - - 99mTcO4 (4-6 mCi) + 99mTc-MIBI (20-25 mCi)
      - image of MIBI (Thyroid+parathyroid) - TcO4 (thyroid)
    - - 99mTc-MIBI (20-25 mCi)
      - immediate image + 2-hrs delay image
      - wait for washout of thyroid gland
- - - - mesoderm (75% of adrenal gland)
      - Golmerular (ext.) + Fascicular (inter.) + Reticular (int.)
      - Aldosterone, Glucocorticoids & adrenal androgens (androstenedione)
    - - 1 mC (37 MBq)
      - Thyroid blockade for at least 3 days
      - 2, 4, 7th -> day image
      - 500,000 - 1,000,000 counts (20-30 mins)
    - - ~0.2 mCi (6-8 MBq)
      - 2,4, 7th -> image
      - T1/2: 119.78 days
      - 265 keV (59.8%)
    - - ACTH-dependent
        
        only 1 adrenal gland overactive
      - ACTH-independent
        
        both (mostly)
    - - 99mTc-colloid for liver substraction image
  - - - analog of catecholamine norepinephrine
      - active amine uptake on cell membrane of symapthomedullary tissues
      - diagnosis oh pheochromocytoma
      - discontinue tricyclic antidepressants, antipsychotics, beta-blockers, reserpine, calcium channel blockers, cocaine, sympathomimetics
      - 123I-MIBG
        
        400 MBq
        
        20-24 hours
      - 131I-MIBG
        
        40-80 MBq
        
        1-3 days
      - kidney substraction: 99mTc-DSMA
    - - analog of somatostatin
      - via expression of octreotide binding by somatostatin receptors on most nneuroendocrine cells
      - 171 keV (90%)
      - diagnosis of pheochromocytoma & neuroendocrine tumors
      - T1/2: 2.83 days