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Radiology > Alternate imaging modalities > Flashcards

Alternate imaging modalities Flashcards

1
Q

An imaging technique commonly used to obtain real-time moving radiographic images of the internal structures.

A

fluoroscopy

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2
Q

What kind of grey scale does fluoroscopy use?

A

inverted grey scale
High attenuation=Black
low attenuation=white

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3
Q

An imaging technique which has cross sectional imaging using a slice, has no superimposition and can create 3D images

A

CT

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4
Q

How does CT create and image?

A

X-ray tube spins around patient and the detectors determine amount of radiation absorbed by the patient, new spiral slicing allows for continuation of movement of the tube some, scanners even have multiple rows of detectors

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5
Q

A picture element and have only 2 dimensions.

A

pixel

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6
Q

A volume picture element and has three dimensions.

A

Voxel

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7
Q

In CT what constitutes to better resolution but a higher amount of radiation?

A

thickness of voxel slice (want thin slices)

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8
Q

All dimensions are equal and allows for multi-planar reconstructions and volume rendering without loss of resolution.

A

isotopic voxel

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9
Q

The range of HU represented on a specific image.

A

window

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10
Q

The central value of HU displayed.

A

level

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11
Q

hyper attenuating (CT)

A

white, highest HU (Bone, metal)

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12
Q

hypo attenuating (CT)

A

black, lowest HU values (Air)

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13
Q

What are some advantages of CT?

A

-more detailed view without superimposition
-faster and less expensive then MRI

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14
Q

what are some disadvantages of CT?

A

radiation exposure
more expensive than radiographs
poor soft tissue contrast

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15
Q

Which imaging techniques uses magnets?

A

MRI

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16
Q

What is the process of image formation for MRI?

A

Atoms with an odd number of protons possess a magnetic moment, hydrogen atoms have only 1 proton and act like tiny magnets, our protons will align with the magnetic field of the electromagnet some line up in the direction of the magnetic field while others will line up in the opposite direction some H atoms in opposite directions will cancel eachother out, a radiofrequency coil then applies energy which causes the non canceled out H atoms to flip direction, after a short period the pulse is stopped and the energy released from the H atoms are received by a coil
Weighting is then used to optimize the differences in relaxation rates of different tissues in order to provide contrast in the image

17
Q

The use of certain parameters to optimize the differences in relaxation rates of different tissues in order to provide contrast in the image.

A

Weighting

18
Q

hypointense (MRI)

A

less bright then the tissue you compare to

19
Q

hyperintesne

A

brighter than the tissue you compare to

20
Q

isointense

A

same brightness as the tissue you compare to

21
Q

T1 weighted

A

fluid is hypointense (Black)
fat is hyperintense (white)

22
Q

T2 weighted

A

fluid is hyperintense (white)
solid tissue is hypointese (black)

23
Q

What is an advantage of using MRI?

A

better soft tissue contrast and noninvasive

24
Q

Which imaging technique uses sound wave frequency higher than humans can hear?

A

US

25
Q

How is an US image formed?

A

US transducers transmit sounds waves into the tissues and then receivers measure the intensity and time of arrival of returning sound waves, an image is formed using the echoes returning from the tissues, differences in acoustic impedance in various tissues will alter the direction of the sound wave

26
Q

Lower frequency transducers penetrate _____ but have _____ resolution

A

farther, lower

27
Q

higher frequency transducers ______ penetrate ______, but have _____ resolution

A

do not, farther, higher

28
Q

Black no echos

A

anechoic

29
Q

darker than compared structure (dark grey, US)

A

hypoechoic

30
Q

the same echogenicity to compared structure (US)

A

isoechoic

31
Q

brighter than compared structure (US)

A

hyperechoic

32
Q

The perceived change in frequency that occurs as a result of the motion between the sound and source and the observer. Allows determination of velocity and direction of blood flow.

A

Doppler effect

Radiology (3 decks)

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