Radiopharmaceuticals Flashcards

1
Q

What does SPECT stand for?

A

Single photon emission computed tomography; it is 3D gamma ray immaging

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2
Q

PET - how does it work?

A
  • Positron forms and annhylates with an electron - the mass gets converted to energy and 2 photons result at 180 degree angles
  • PET is a 3D imaging of photons given off when a positron annihilates with an electron
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3
Q

Why is PET better than SPECT and planar scintagraphy?

A
  1. immage gamma radiation of much higher energies
  2. Improved quantification of data and of counting statistics - making lesions more detectable and more reliable
  3. Radiopharmaceuticals used with PET have shorter half lives - meaning patients get to go home sooner
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4
Q

Radiopharmaceuticals have no pharmacologic effect. Why?

A

They are used in tracer quantities

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5
Q

Name 3 radionuclide production devices

A
  1. Nuclear reactors
  2. Charged particle accelererators
  3. Radionuclide generators
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6
Q

How is 99mTcO4- radiopharamceutical made?

A
  • Made using generator column chromatography
  • Parent isotope, Mycobonium-99, decays to Technetium-99
  • Tc-99 gets eluded with saline to become 99mTcO4- which is in solution
  • To make other RaPh that use Tc99m in label - use drug as a powder and add to the 99mTcO4- solution and it will combine to make RaPh
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7
Q

Which has the shorter half life:

  • Mycobonium - 99 (parent)
  • Technetium -99m (daughter)
A
  • Tc-99m
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8
Q

Two other names for the Gamma Camera

A
  • Scintillation camera
  • Anger camera
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9
Q

99mTcO4- ⇒Thyroid Scintigraphy

A
  • RaPh that acts like Iodine goes to the zygomatic salivary gland and the thyroid
  • Hyperthyroid, euthyroid, and hypothyroid is based on the thyroid/salivary ratio
  • Can also detect:
    • Hyperplasia - usually more one side than the other
    • Multinodular Adenoma - looks like string of pearls
    • Carcinoma - bilateral, metastasis can be seen
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10
Q

99mTc Sulfur Colloid - Liver Scintigraphy

A
  • Normal = well demarcated liver shape, sometimes more color on one side than the other
  • Liver metastasis - 4 hallmakrs of cancer:
    • Irregular borders
    • Abnormal morphology
    • Heterogenous uptake of pharmaceutical
    • Photopenic void = no radioactivity = lesions
  • Pseudotumor pattern of cirrhosis
    • Looks just like cancer - need to take a biopsy to confirm dx
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11
Q

Advantages of dynamic renal scintigraphy

A
  • can quantify individual kidney function
  • Can detect renal dysfunction before an increase in BUN can be detected
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12
Q

99mTc - DTPA Renal Scintigraphy

A
  • Provides a series of images of kidneys over a period of time to detect GFR - GFR scan
  • Normal GFR is >3.0 mL/min/kig
  • In renal failure, there is poor renal uptake of the RaPh and prolonged blood pool activity
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13
Q

99mTc - DMSA Renal Morphology Imaging

A
  • Used to evaluate size, shape, and location of kidneys
  • Used to evaluate for acute pyelonephritis
  • Used to determine the distribution of functional renal mass
  • Uptake of the RaPh by the renal cortex
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14
Q

99mTc - MDP (methylene diphosphate) Canine Bone Scan

A
  • bone is dynamic, constantly remodelling
  • Normally in equilirbium between osteoclastic and osteoblastic activity - cacner can disrupt this equilibrium
  • Normal to see action at the ends ofl ong bones
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15
Q

QuadraMetTM =

A

153Sm - EDTMP

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16
Q

Story of QuadraMetTM

A
  • 153Sm identified useful nuclide for radiotherapy by MU researches
  • Development began in early 1980s at MU in collaberation with teh Dow Chemical Company [phosphate ligand complexes; 153Sm - EDTMP
    • 153Sm - good agent for bone therapy because can track it in vivo
  • Clinical trials for human began in late 1980s with doses supplied by MURR for phase I staudes
    • 80% efficacy with ~25% obtaining full pain remission
  • Approved in US for pain palliation of metastatic bone cancer in March, 1997
17
Q

In 153Sm-EDTMP; what is EDTMP?

A

Phosphonate compound that targets bone cancer

18
Q

What is planar scintigraphy?

A

2D gamma ray imaging; whole body images are usually acquired with scintigraphy

19
Q

Why do you see photopenic voids in liver scintigraphy?

A

Tc-99m sulfur colloid images reticuloendothelial system (RES), of which the liver is a major organ. Liver tumors generally lack Kupffer cells, which mediate RES. Thus, liver tumors have defective RES function, they do not take up sulfur colloid, and the lesions are visible as cold spots

20
Q

Nuclear Reactors - Give Example

A
  • Nuclear reactors are a type of radionuclide prodcution device
  • Example is the MURR Reactor Core
  • Fast neutrons have a low probability of interaction with other nuclei. They are thermalized or slowed down to interact with other nuclei. Moderators (low MW materials like heavy water, beryllium, or graphite) are distributed in speces between fuel rods.
21
Q

Charged Particle Accelerators

A
  • Charged particle accelerators are a type of radionuclide production device
  • Example - positive ion cyclotron operation
    • Proton betwen two magnets
    • Magnets alternate in strength to cause the proton to move in a circular path. The proton eventually hits the deflection plate and goes out into the target.
22
Q

An example of a radionuclide generator

A

Mo-99/Tc-99m Generator Column Chromatography

23
Q

Fluorodeoxyglucose (FDG) metabolism

A
  • FDG is taken up by hypermetabolic cells
    • Physiologic hypermetabolic areas - brain, muscle, salivary glands, heart, large vessels, renal pelvis, bladder, liver
    • Neoplastic cells
  • FDG gets taken up by a glucose transporter and a negativley charged phopsphate gets added - this makes it unavailable for glucose metabolism and FDG is metabolically trapped inside the cell because negatively charged molecules can’t diffuse back through the negatively charged lipid membrane
24
Q

18F - FDG is used to treat _____

A

Neoplasms with hypermetabolic cells. Most neopastlic cells pick up a lot of glucose.

25
Q

18F - NaF is used in:

A
  • Detection of PRIMARY bone tumors
  • Detection of osseous metastases
  • Generally considered more sensitive than 99mTc - MDP bone scans
  • Often combined with 18F-FDG to show soft tissue and bone cancers
26
Q

What radiopharmaceutical is considered more sensitive in bone scans?

99mTc-MDP or 18F-NaF

A

18F-NaF

27
Q

Why would you do a combined PET/CT or PET/MRI?

A
  • aid in lesion localization
  • Functional information of a PET and spatial resolution of a CT
  • Helps to also distinguish spots on MRI that may seem concerning, but are NOT metaboically active as illustrated with the PET, and are therefore of no concern.
28
Q

Triamcinolone Acetonide

  • Synthesis
  • Treats?
  • Works best with what kind of administration?
A
  • Industrial process - dissolve triamcinolone in acetone, acid-catalysed reaction is rapid and complete
  • Treats asthma
  • Spacer (moutpiece to inhalers) works better - gets distribtuted throughout bronchi to the lungs
29
Q

Azmacort is a ____

A

triamcinolone inhaler

30
Q

What RaPh is used in thyroid scintigraphy?

A

99mTcO4- (acts like iodine and goes to thyroid and zyogmatic salivary glands)

31
Q

What RaPh is used in liver scintigraphy?

A

99mTc Sulfur Colloid

32
Q

What RaPh is used in renal scintigraphy that can measure GFR?

A

99mTc-DTPA

33
Q

Which RaPh is used in renal morphology imaging?

A

99mTc - DMSA

34
Q

What RaPh are used in bone scans?

A
  • 99mTc- MDP
  • 18F - NaF
35
Q

Which RaPh is used to treat pain of metastatic bone cancer?

A
  • 153Sm - EDTMP = QuadraMetTM
36
Q

Which RaPh is used to treat hypermetabolic neoplasms?

A

18F - FDG