Nuclear medicine

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Nuclear medicine
2015-06-07 09:16:46
Nuclear Medicine

Review of Nuclear medicine
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  1. What function that is common to the liver and spleen is used in nuclear medicine for imaging those organs?
  2. What is the most commonly used agent for liver/spleen nuclear imaging?
    99 - Tc sulfur colloid
  3. What cells take up sulfur colloid particles in the liver?
    Kupffer cells
  4. How long does it take for the liver to take up adequate sulfur colloid in patients with normal versus abnormal hepatic function?
    5 - 10 minutes in normal patients

    20 - 30 minutes in patients with compromised hepatic function
  5. What type of collimator is used for liver/spleen scans?
    Low energy

    Parallel hole
  6. What is the most common right liver lobe shape variant?
    Long, thin right lobe (Riedel's lobe)
  7. What are the most common liver lobe variant shapes?
    Riedel's lobe

    Prominent quadrate lobe
  8. What size defects can be detected on gamma camera?
    8 mm
  9. How much radiotracer usually accumulates in liver vs spleen?
    90% liver

    10% spleen
  10. What uptake pattern is seen in pelvic insufficiency fractures?
    Honda sign
  11. What effect do vertebral compression fractures have on the measurement of bone mineral density?
    More bone in smaller volume > overestimation of bone mineral density
  12. How does gamma x-ray emission occur?
    The positron reacts with the electron causing annhilation

    Release of two 511 keV photons
  13. How much demineralization needs to occur for a lytic lesion to be visualized on radiographs?
    30-50% is needed to be visualized on plain film
  14. What type of malignancy is much more likely to produce a false-negative bone scan?
    Multiple myeloma

    Skeletal survey is test of choice for these patients
  15. What tumors have a propensity to metastasize to bone?


  16. When is a single focus of increased activity associated with metastatic disease?
    Single sternal lesion in patient with breast cancer

    80% are metastatic lesions
  17. What is the expected response on bone scan after initiation of successful chemotherapy?
    Flare phenomenon

    Increased uptake by focal bone metastases
  18. What is the differential diagnosis of diffuse symmetric increased uptake in bone with diminished activity in the kidneys?
    Metastatic disease (prostate)

    Metabolic disease (hyperparathyroidism)
  19. What is the typical appearance of malignant versus benign bone lesions on initial and early blood pool images?
    Malignant tumors > hyperemic

    Benign tumors > Little radiopharmaceutical uptake
  20. What types of fracture location may not show any activity on bone scan even by 14 days?
    Skull fractures
  21. Which types of fracture show delayed increase in activity?
    Pelvis fractures

    Spine fractures

    By 3 days, only 30% of these fratures have increased activity
  22. What are the findings in shin splints?
    Normal angiographic phase

    Normal blood pool phase

    Increased linear activity along posteromedial tibial cortex on delayed phase
  23. What is the half life of Technetium 99?
    6 hours
  24. What is the half life of Thallium 201?
    73 hours
  25. What are the two main methods by which radioisotopes are produced?
    Mother daughter system - longer half life mother decays into shorter half life daughter

  26. What is the photon energy emitted from Technetium-99?
    140 KeV
  27. What are the energy peaks for Thallium?
    69 to 81 KeV
  28. What is the difference in physical vs biologic half lives of Xenon-133?
    Physical half life - 5 days

    Biologic half life - Seconds to minutes
  29. What is the energy peak for Xenon?
    80 KeV
  30. What are the energy peaks seen in Gallium citrate?
    100/200/300 KeV
  31. What is the half life of Gallium citrate?
    78 hour half life
  32. What types of collimators are useful for tracking small targets?
    Pinhole collimators


    Pediatric patients
  33. What types of foods/drinks can interfere with coronary vasodilator agents?
    Caffeine (xanthine compounds)

  34. How does one identify sentinel node(s) on lymphoscintigraphy?
    These nodes are the first to be visualized on this study
  35. What is the most common perfusion defect seen in patients with left bundle branch block?
    Reversible defect in Septum
  36. Prior to Yttrium 90 microsphere treatment, what type of nuclear medicine study needs to be performed?
    • Intra-arterial Injection of Tc-99 MAA particles into hepatic artery branch
    •               Lung or GI tract shunting

    >20% lung shunting - contraindication to treatment

    GI tract shunting > may need to embolize
  37. What types of 24 hour iodine uptake values are seen in patients with hyperthyroidism due to Graves disease versus toxic multinodular goiter?
    Graves disease - very high iodine uptake (>60%)

    Multinodular goiter - mildly elevated (20-30%)
  38. What is the difference in thyroid gland processing of Tc-99-pertechnetate versus I-123 or I-131?
    I-123 and I-131 are taken up by the thyroid gland (trapping), and then are bound to tyrosine moieties (organification) to eventually form T3 and T4

    Tc-99-pertechnetate - undergoes TRAPPING but no organification.
  39. How does I-131 decay versus I-123?
    Beta emission for I-131

    Electon capture for I-123
  40. What is the half life of I-131 versus I-123?
    8 days for I-131

    13 hours for I-123
  41. What is the principle energy emission of Iodine-131 vs I-123?
    364 keV for I-131

    159 keV for I-123
  42. What is the difference between physical half life and biological half life?
    Physical half life - amount of time required for half of the material to decay via radioactive decay

    Biological half life -amount of time for half of the material to be removed by body clearance mechanisms.
  43. How does one distinguish Alzheimer's from Lewy body disease on PET?
    Both - Decreased uptake in parietal and temporal lobes

    Lewy body disease - Occipital lobe involvement (+/- hallucinationss)
  44. What is the most common inherited cause of neonatal cholestasis?
    Alpha-1 antitrypsin deficiency
  45. What are the mechanisms by which gallium accumulates in inflammatory tissues?
    • 1) Iron compounds (Lactoferrin, Transferrin)
    • 2) Taken up by bacteria
  46. What type of nuclear medicine study to initially evaluate for fever of unknown origin?
    Labeled leukocyte study - 1/3 of infections are in the abdomen and gallium has lots interfering bowel activity
  47. In an immunocompromised patient with a mass on CXR, what does a normal gallium scan suggest?
    Kaposi's sarcoma
  48. In an immunocompromised patient, what does bilateral diffuse uptake of gallium suggest?
    Pneumocystis carinii pneumonia (PCP)
  49. What does increased nodal uptake suggest in a patient with AIDS suggest?

    Mycobacterium infection
  50. Sarcoidoisis -

    Lambda sign in chest

    Panda sign in parotid/salivary/lacrimal glands
  51. What type of metastases can have increased uptake on a bone scan?
    Mucin producing adenocarcinomas

    Bone/cartilage tumors
  52. Alzheimer's disease 

    Decreased parietal / temporal metabolism
  53. Focal nodular hyperplasia

    Disorganized hepatocytes have Kupffer cells that take up sulfur colloid
    • "Hot nose sign" 
    • Decreases perfusion to internal carotid arteries, increased perfusion to the external carotid arteries
  54. What are radionuclides?
    Isotopes attempting to reach stability by emitting radiation
  55. What occurs in alpha decay?
    Emission of helium nucleus (two protons and two neutrons)
  56. Describe beta minus decay
    To achieve more optimal stability of number of neutrons vs protons, an electron (B-) is emitted from the nucleus along with an an anti-neutrino. A neutron is converted into a proton.
  57. Describe beta plus decay
    Because of an excess of protons, a beta plus particle is emitted consisting of a positron and neutrino. A proton is converted into a neutron.
  58. Describe electron capture
    Neutron deficient nuclide - capture of one of the inner orbital electrons by proton in the nucleus > formation of neutron and neutrino

    Always accompanied by gamma emission
  59. How do generator systems work versus cyclotrons?
    Generator - radionuclide parent (ex. 99 Mo) with long half life is fixed to ion exchange column. Parent isotope decays to radioactive daughter (ex. 99 Tc) with shorter half life. Daughter is periodically washed off and used clinically.

    Cyclotron - Irradiation of target elements with neutrons or charged particles to produce an unstable isotope
  60. What is the physical half life of fluorine-18 (F-18)?
    2 hours (110 minutes)
  61. What are the photopeaks for Indium-111?
    173 keV

    247 keV
  62. What is the half life for Indium-111?
    67 hours
  63. What are the half lives of Strontium 89 vs other treatment radionuclides (Samarium-153 and Yttrium-90)?
    Strontium 89 - Very long (50.5 days, 14 days in bone)

    • Samarium-153 - 46 hours
    • Yttrium-90 - 64 hours