9/12 Introduction To Medical Imaging - Brauer (Completed) Flashcards

1
Q

What are the contrasts that can be used with X-ray? How are they administered? 2

A

Barium sulfate - orally & rectally

Iodine compounds - intravascularly, orally, rectally, vaginally

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2
Q

What is the role of barium sulfate as a contrast in X-rays? 2

A

To study hollow organs (Hernias)

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3
Q

What is the role of iodine compounds as a contrast in X-rays? 2

A

To Study vessels (angiography)

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4
Q

What’s happening during Fluoroscopy? Where is the source? 5

A

Continuous stream of x-rays using a tracer or contrast medium

Source is below the patient

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5
Q

How many frames per second is used for coronary artery study using fluoroscopy? 5

A

15 - 30 frames/second

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6
Q

How many frames per second is used for peripheral vascular studies? 5

A

2 - 3 frames/second

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7
Q

What is MDCT? 6

A

Multi-detector computed tomography

Patient moves through a rotating tube and then a computer can make 3-D renderings

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8
Q

What does the Hounsfield Scale measure? 7

A

Measures the density of a CT

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9
Q

What does CT stand for? 7

A

CT - computed tomography

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10
Q

What are the different values for the density of water, air, compact bone, and soft tissue in reference to the Hounsfield Scale? 7

A

Water –> 0

Air (of the lungs) –> (-1000)

Compact bone –> +3095

Soft tissue –> -100 - +100

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11
Q

What is a wide window good for in CT imaging? 7

A

Good for imaging bone

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12
Q

What is a narrow window width good for in CT imaging? 7

A

Good for soft tissue imaging

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13
Q

What are the benefits of CT? 8

A

Fast imaging

Some motion ok

Good resolution, gray scale can be adjusted on viewing screen

Widely available and cheap

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14
Q

What are the disadvantages to using CT? 8

A

Uses ionizing radiation

Contrast requires renal function eval

Iodine allergies w/ some patients

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15
Q

How does MRI work? 9

A

Patient is put in a magnetic field to align the spins of their atoms within all their tissue

A radio pulse is sent into the body which momentarily knocks the spins out of alignment

The atoms immediately re-align themselves and emit an energy as they do so

The energy changes for different tissue types that contain different varieties and concentrations of atoms

Imaging is received on a coil and sent to a computer

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16
Q

What are the contrast agents used in MRI? 9

A

Intravenous gadolinium

Oral Agents (juice, water)

17
Q

What will appear Dark and Bright on a T1-weighted image? 10

A

Dark:
Tumor, inflammation,
infection,hemorrhage

Bright:
Fat, melanin, subacute hemorrhage, protein-rich fluid

18
Q

What will appear dark and bright on a T2-weighted image? 10

A

Dark:
Calcification, fibrous tissue, protein-rich fluid

Bright:
Tumor, inflammation, infection, subdue all collection, edema (water)

19
Q

What are the advantages of MRI? 11

A

No ionizing radiation

Better for soft tissue than CT

Very versatile (can view everything or nothing)

20
Q

What are the disadvantages of MRI? 11

A

Data collection takes a long time

More costly than with CT

Only specific data is collected (wide range collected with CT)

Loud/hot/claustrophobic

No metal

21
Q

Quiz yourself on CT vs MRI. What is the contrast that was used? 12

A

Open lecture

22
Q

How is nuclear medicine chiefly different from CT and MRI? 13

A

Measures physiological process instead of anatomy

23
Q

What is Digital Subtraction (DS) Angriography? 16

A

X-rays viewed in realtime

X-rays taken before contrast then with contrast and then bone and other tissue as are digitally subtracted out

24
Q

What is a downside of DS? 16

A

You have to inject contrast using an IV

25
Why would you use volume-rendering algorithms for CT? 17
To get better depth perception within an image
26
During an Angiography using MRI how is a 3D perspective achieved 17
Using an MRI this can only be achieved by rotating the view
27
What is Functional Magnetic Resonance Imaging (fMRI) used for? 18
Detects changes in blood oxygenation and flow Used to produce activation maps of the brain
28
How is it possible to use fMRI on hemoglobin? 18
Hemoglobin is: diamagnetic when oxygenated Paramagnetic when deoxygenated
29
Which methods use X-ray for image production?
Flouroscopy CT Nuclear medicine can be used in addition to CT
30
What's the difference between AP and PA film radiograph?
PA (posterioranterior) Film>front>back> xray tube 6ft distance Pt. stands ``` AP (anteriorposterior) Film>back>front>xray tube 3 ft distance pt supine enlarged heart and mediastinum (NOT PREFERRED) ```
31
What's the difference between flouroscopy and X-ray?
Both use X-rays, but X-ray alone is a single image w/ pt. sitting or standing. Fluoroscopy usually has the pt. lying and numerous images are taken each second
32
When would fluoroscopy be preferred over X-ray?
for vascular or coronary artery studies
33
How does CT build on plain film? How is a CT usually read? 6
CT's builds a bunch of slices starting from the superior aspect of the pt. The computer allows for sagital or coronal views to be constructed CTs are usually read transversely from cephalic to caudal
34
How does the Hounsfield Scale utilize Grey Scale? 7
Hounsfield scale uses series of greys, monitors only show 256 levels of grey therefore the "window" is adjusted to see different tissue