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61 Cards in this Set
- Front
- Back
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Does a CT or MRI have good bone imaging?
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CT
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Does a CT or MRI have good soft-tissue imaging?
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MRI
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Which one can detect blood flow (CT or MRI)
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MRI
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Which one uses Xrays to make cross-sectional axial images?
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CT (right is left and left is right like the feet are coming out toward you)
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On a CT the object colors are based on what?
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density
white - hyperdense gray - isodense black - hypodense |
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Which one is optimal test for acute blood?
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CT but MRI is getting better
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Which one has iodine-based contrast that is nephrotoxic?
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CT
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Which one is better to visualize the inferior temporal lobes and posterior fossa (brainstem, cerebellum)?
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an MRI because a CT has bone artifact interference
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Out of hypodense, isodense, and hyperdense on CT:
ocular lense |
hyperdense
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Out of hypodense, isodense, and hyperdense CT:
calcifications |
hyperdense
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Out of hypodense, isodense, and hyperdense on CT:
bone |
hyperdense
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Out of hypodense, isodense, and hyperdense on CT:
acute blood |
hyperdense
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Out of hypodense, isodense, and hyperdense on CT:
metal/bullets |
hyperdense
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Out of hypodense, isodense, and hyperdense on CT:
contrast |
hyperdense
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Out of hypodense, isodense, and hyperdense on CT:
fat |
hypodense
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Out of hypodense, isodense, and hyperdense on CT:
air |
hypodense
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Out of hypodense, isodense, and hyperdense on CT:
CSF/Water |
hypodense
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Out of hypodense, isodense, and hyperdense on CT:
gray matter & white matter |
isodense
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Which is darker on a CT, gray matter or white matter
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white matter
gray matter is more dense, so it is whiter |
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What does a CT show after an ischemic stroke?
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In first few hours to day CT usually normal (though it may show blurring of gray-white jxn and sulcal effacement)
By day 2, CT shows dark area w/ mas effect (compression of surrounding structures) |
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What kind of infarction (acute, subacute or chronic) is dark/hypodense on CT
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subacute
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What are watershed territories and why are they significant?
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watershed territories are the margins of the sprinklers/ blood supply
infarctions in these ares are usually from hypotension |
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What is a ring enhancing lesion?
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A lesion in the brain that after adding contract a ring forms around it, usually an abscess or tumor due to leakage of dye around the lesion from a blood brain barrier disruption
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What causes vasogenic edema and what are features of it?
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causes: due to mass lesions-abscesses, tumor
represents blood-brain barrier disruption involves only white matter |
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On a CT you see layers concave to the brain like a crescent that is gray w/ sulcal effacement and a buckled cerebral cortex that does not extend to the skull. What is wrong?
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a subacute subdural hematoma
note: chronic blood (wks to mos) is black |
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What does an MRI use to create cross-sectional images?
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magnet and pulses of radio waves
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what are the colors in an MRI based on?
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intensity of signal
hyperintense - white hypointense - black |
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Which one uses IV gaolinium for contrast?
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MRI
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In a T1 MRI what color is CSF?
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black
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In a T1 MRI what color are lesions (edema, water, acute infarction, gliosis)?
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Dark
poorly seen w/o IV contrast, best used for pre & post gadolinium comparisons |
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On a T1 MRI what color is calcium and bone?
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black
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On a T1 MRI, what is black?
What is white? |
CSF, Lesions, Ca+ and bone
white- fat |
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In a T2 MRI what color is the CSF?
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white
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In a T2 MRI what color are the lesions?
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white
lesions are well seen!!! |
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ON a T2 MRI what is black?
What is white? |
white: CSF, lesions (hard to distinguish)
black: Ca and bone |
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Can you distinguish new and old lesions on a T2 MRI?
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No
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On a Flair MRI what color is the CSF?
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black
standing water is black, including old lacunes |
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On a Flair MRI what colors are the lesions?
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white (edema, acute infarction, gliosis)
VERY WELL SEEN |
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What are the drawbacks of Flair MRIs?
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Does not visualize very new infarctions
cannot distinguish new and old lesions |
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On a DWI MR what color is CSF?
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black
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On a DWI what is white?
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New infarctions (30 min to few wks)
old lesions are NOT seen |
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What do you compare a DWI MR with to distinguish new and old lesions?
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compare to a T2 or Flair
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What do you compare a DWI MR with to ensure infarction is real?
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compare to ADC
DWI may show lesions due to other conditions such as seizure or T2 shine through phenom |
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What's characteristic of the DWI image?
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it's fuzzy
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What color is CSF on a ADC map MRI
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white
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What color are new infarctions on ADC map MRI?
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black
hemorrhages may also be black, so must compare to other MR images |
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Are ADC map MRIs picture clear or fuzzy?
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fuzzy
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What MRI is the most senstive technique for detecting intraparenchymal blood and what color is it?
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black
T2*GRE |
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A Spin Echo involves T1, T2 and FLAIR. What color are normal vessels on an SE?
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black
no or low flow gray and white |
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A Gradient Recall Echo uses GRE images. What color is normal flow on this image?
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normal flow is white
no or low flow black |
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Does MR Angiography use contrast?
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no, its MRI w/ software changes/GR technology
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Can a MRA differentiate between low flow vs. occlusion?
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no
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Can a MRA differentiate between veins vs arteries?
What about anterior circuation vs posterior circulation? |
yes and yes
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What color is normal flow on a MRA?
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normal = white
no or low flow is black |
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What type of MRI is acute heme gray?
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only T1, the rest it is black (T2, Flair, DWI)
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What type of MRI is subacute heme white?
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all (T1, T2, Falir, DWI)
chronic blood is all black on these too |
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What color is vasogenic edema on a DWI?
What color is cytogenic edema? |
vasogenic- gray
cytogenic - white |
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What kind of technology does MRV use?
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GRE technology
saturation of arterial flow eliminates arteries |
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In MRV what relationship should there be with blood flow?
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perpendicular - coronal acquisition
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What kind of technology does MRV use?
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GRE technology
saturation of arterial flow eliminates arteries |
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In MRV what relationship should there be with blood flow?
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perpendicular - coronal acquisition
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