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MD 1 Anatomy (MCQ) > Anatomy 2 - Introduction to Medical Imaging > Flashcards

Anatomy 2 - Introduction to Medical Imaging Flashcards

1
Q

Characteristics of Radiography

A
  • Generate x-rays
  • Detect transmitted x-rays (on film or digitally)
  • Use radio-opaque contrast such as barium to help visualize structures
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2
Q

Characteristics of Fluoroscopy

A
  • Type of radiography
  • Real-time imaging, viewed on monitor
  • Used for interventional procedures
  • Higher doses of radiation
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3
Q

Production of X-Rays

A
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4
Q

How do bones, soft tissue, fat, and air look on an x-ray?

A
  • Bone = white (high density)
  • Soft tissue = gray
  • Fat = dark gray
  • Air = black
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5
Q

Radiography Benefits

A
  • Low dose and low risk
  • Simple, fast, and inexpensive
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6
Q

Radiography Drawbacks

A
  • Need 2 or more projections (usually)
  • Can’t see behind structures
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7
Q

Radiography Contraindications

A
  • Pregnancy
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8
Q

How does Computed Tomography work?

A
  • X-ray source (gantry) rotates around patient
  • Multple projections
    • Hundreds of “films”
    • Ability to see behind structures
    • Digital detector
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9
Q

CT Benefits

A
  • Fast scanning with good resolution
    • Good for traumas, post-op/unstable patients
  • Can see behind structures
  • Good bone contrast
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10
Q

CT Drawbacks

A
  • Limited soft tissue contrast
  • High patient radiation dose
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11
Q

CT Use in the United States

A
  • Rapid increase in use since 1970s
  • Sharp increse in use due to
    • improved CT technology
    • Fast scan times
    • Emergency room use
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12
Q

CT Characteristics

A
  • White - denser structures (bone, blood, clot, calcium)
  • Dark - less dense structures (air, fat, water)
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13
Q

Density on CT is measured in _____

A

Hounsfield Units (HU)

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14
Q

Air on CT: ___HU

A

-1000

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15
Q

Fat on CT: ___HU

A

-250

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16
Q

Water on CT: ___ HU

A

0

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17
Q

White matter on CT: ___HU

A

20-30

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18
Q

Gray matter on CT: ___HU

A

37-45

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19
Q

Blood (in vessel) on CT: ___HU

A

40

20
Q

Muscle on CT: ___HU

A

40

21
Q

Blood Clot on CT: ___HU

A

70

22
Q

Bone on CT: ___HU

A

1000

23
Q

CT Relative Contraindications

A
  • Pregnancy
  • Contrast:
    • Low glomerular filtration rate (GFR)
    • Metformin (glucophage)
    • Allergic reaction
    • No IV access
24
Q

Characteristics of Nuclear Medicine (Emission)

A
  • Medications attached to radioactive material (radioisotope)
  • Provides information about structure and function
  • Gamma camera captures emission image
25
Q

Iodine 123 is a radioisotope used to assess:

A

Thyroid function

26
Q

Thallium 201 is a radioisotope used to assess:

A

Cardiac function

27
Q

Gallium 67 is a radioisotope used to assess:

A

Infection

28
Q

Technetium-99m is a radioisotope used to assess:

A

Skeleton, heart, brain, lungs, liver, spleen, kidney, gall bladder, infection, parathyroid

29
Q

PET Imaging

A
  • Positron emitter: short half-life
  • Internal uptake (IV or oral)
  • Positron annihilates with electron to form 2 photons traveling in opposite directions
  • Photons interact in tissue and then a detector ring
30
Q

PET Benefits

A
  • More sensitive than transmission imaging
  • Functional imaging
31
Q

PET Drawbacks

A
  • Limited resolution
  • Requires CT for anatomy and attenuation correction
  • Patient dose
  • Radiotracers are expensive
32
Q

Magnetic Resonance Imaging

A
  • Uses non-ionizing radio frequency
  • Proton spins to align with external magnetic field
    • RF pulse tips proton spins by 90 degrees
33
Q

MRI T1,T2 sequence is used to assess:

A

Structural

34
Q

MRI Spectroscopy Sequence is used to assess:

A

Metabolites

35
Q

MRI Diffusion Weighted Sequence is used to assess:

A

Water Motion

36
Q

MRI Susceptibility Sequence is used to assess:

A

Iron deposition

37
Q

MRI Functional Sequence is used to assess:

A

Brain activity

38
Q

MRI Perfusion Sequence is used to assess:

A

Blood flow

39
Q

MRI Angiography Sequence is used to assess:

A

Vessels

40
Q

MRI Benefits

A
  • Good soft tissue detail
  • No ionizing radiation
41
Q

MRI Drawbacks

A
  • Expensive
  • Some patients may require sedation
  • Several contraindications
42
Q

MRI Contraindications

A
  • Older aneurysm clips
  • Pacemakers
  • Certain implants
  • First trimester of pregnancy
43
Q

How does Ultrasound (Sonography) work?

A
  • Most widely used imaging modality
  • Transducer produces high frequency mechanical pressure waves (sound)
    • Sound wave coupled to surface using gel
    • Sound is transmitted through tissue or reflected at interfaces
    • Reflected wave is detected by transducer
    • Time for reflection indicates depth of interface
44
Q

How does Doppler Ultrasound work?

A

Uses the Doppler effect to measure and visualize blood flow

45
Q

Ultrasound Benefits

A
  • Inexpensive and fast
  • No radiation dose
  • Extremely portable
46
Q

Ultrasound Drawbacks

A
  • Limited contrast
  • Difficult to see behind air-filled cavities and bone

MD 1 Anatomy (MCQ) (3 decks)

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