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13 Cards in this Set
- Front
- Back
MRI stands for?
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Magnetic
Resonance Imaging |
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What is being imaged in MRI?
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-Proton density
-T1 and T2 relaxation times |
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What is being imaged in SPECT, PET?
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Distribution of introduced radioisotopes.
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What is being imaged in classical radiography?
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Distribution of linear attenuation coefficient.
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What is being imaged in ultrasonography?
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-Distribution of acoustic impedance.
-Velocity of flow |
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Name 6 advantages of MRI over other, "classical" imaging techniques.
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-Neglibile side-effects
-True multiplanar imaging -High, unique contrasting of soft tissues -Ability of flow imaging w/o contrast agents -Simultaneous information about both anatomical and physiological information. -Less severe artefacts. |
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What tissue properties determine the MRI image?
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-Proton density
-T1 and T2 relaxation times -Macroscopic motion (flow of liquids) -Microscopic liquids (diffusion) |
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What do T1 and T2 relaxation times depend on?
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-Water content
-Mobility of molecules -Presence of large molecules -Presence of paramagnetic molecules -Temperature and magnetic field intensity |
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What does echo 1 depend on?
What does echo 2 depend on? |
-Only on T2 and TR
-T1, T2, TR and TE |
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The intensity of a tissue signal (brightness of an image) is?
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-Proportional to proton density
-Proportional to T2 -Inversely proportional to T1 |
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T1 relaxation does what?
T2 relaxation does what? |
-Restores NMR signal intensity
-Reduces NMR signal intensity |
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FONAR?
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Field fOcused Nuclear mAgnetic Resonance
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Contrasting agents
Are what type of molecules? What effects to they have? How do areas of accumulated contrasting agents appear on T1 and T2 images? |
-Highly paramagnetic molecules
-Shorten relaxation times and enhance contrast -Brighter on T1 imgages -Darker on T2 images |