L7: Imaging Anatomy Flashcards

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1
Q

What does imaging modalities refer to ?

A

Different techniques & technologies used in medical & biological science to capture images of the body

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2
Q

Examples of imaging modalities

A

1) X-ray
2) Ultrasound
3) Computerised Tomography (CT, CAT scan)
4) MRI scan

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3
Q

Define ‘invasive’ in medical terms

A

A medical procedure that ‘invades’ (enters) the body, usually by cutting/ puncturing the skin

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4
Q

Give 1 example of minimally invasive and 1 example of invasive procedure

A

Minimally invasive: Injection
Invasive: Abdominal surgery

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5
Q

Techniques in invasive imaging

A
  • Contrast is introduced
  • Injection of radioactive isotopes (PET)
  • A probe is inserted

Barium contrast

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6
Q

What are X-Rays a form of?

A

High-energy electromagnetic radiation

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7
Q

Why was X-Ray called X in 1895?

A

At the time it represented ‘unknown’ radiation emitted by discharged tubes

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8
Q

When was X-Ray discovered?

A

In 1895

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9
Q

What did discharge tubes in X-ray developed into?

A

Development of vacuum tube that converts electrical input power into X-rays

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10
Q

Explain what happens as X-Rays penetrate the body

A

Some of the energy is absorbed or scattered according to the different tissue densities

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11
Q

Describe the relationship between density of the tissue and radiation

A

Denser the tissue, the more radiation is absorbed

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12
Q

2 common uses of X-Ray technology

A

1) Chest X-Rays
2) Mammograms (breast screening)

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13
Q

Advantages of clinical X-Rays

A

Cheap and quick
Painless & non-invasive

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14
Q

Disadvantages of clinical X-Rays

A

Limited due to harmful radiation

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15
Q

What does PA & AP X-Ray stand for?

A

PA: Chest Posterior Anterior
AP: Anterior Posterior

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16
Q

Why is positioning of the film very important?

A

Proper assessment of organ dimensions

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17
Q

What does AP X-Ray show?

A

Magnification of the heart & widening of the mediastinum

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18
Q

Whats the most common use in mammograms?

A

Screen for tumours & main vessels around the heart during lateral chest X-Rays

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19
Q

What does a contrast X-Ray show?

A

Show soft tissues more clearly

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20
Q

How does contrast X-Ray work?

A

Radiopaque material (barium) is introduced into the body to coat the wall of the lumen

21
Q

What is the technique that combines the use of radiopaque material across time by studying moving body functions?

A

Fluoroscopy

22
Q

How does a computed tomography (CT) scan work?

A

Sending a narrow beam of X-Rays at the subject while the machine quickly rotates around the body, then the computer combines all these cross-sectional images to produce a 3D rendition

23
Q

Advantages of a CT scan

A

Basic structures, tumours more easily identified

24
Q

Disadvantages of a CT scan

A

More expensive, more training and takes longer to process

25
Q

What does PET stand for?

A

Positron Emission Tomography

26
Q

How does a PET scan work?

A
  • Radioactive isotope attached to a drug (e.g injected), when the isotope collides with an electron in the tissue, it releases energy in the form of GAMMA RAYS
  • This is picked up by gamma cameras to produce a 3D image
27
Q

Why is a PET scan called a ‘functional’ imagine technique?

A

Uses a radioactive isotope

28
Q

Advantages of a PET scan

A

Able to detect changes with time

29
Q

Disadvantages of a PET scan

A

Minimally invasive (injection), costly, may need to combine with CT

30
Q

Why does cancer show up as bright spots in a PET scan?

A

Cells have a higher metabolic rate compared to normal, requires more sugar

31
Q

Why are CT & PET scans combined?

A

To explore the higher resolution of CT with the time-lapse of PET, to allow tumours to be precisely localised

32
Q

What does MRI stand for ?

A

Magnetic Resonance Imagery

33
Q

What is MRI based on ?

A

NMR (nuclear magnetic resonance)

34
Q

How does a MRI scan work?

A
  • Most tissues contain water, which contains H+ atoms at the centre, which is the proton
  • These protons spin around an axis, this produces a magnetic field
35
Q

What needs to happen for an equilibrium to exist in MRI ?

A

No. of high energy electrons must be less than the low energy, the ‘excess’ protons are what produces the MRI signal

36
Q

What shows the image in MRI?

A

Pulse is emitted so all protons move in phase, when the pulse is stopped, the protons return to their original equilibrium and this produces a signal

37
Q

Name 2 equilibriums that take place in MRI

A

1) Out of phase (T2)
2) Lower energy state (T1)

38
Q

Advantages of MRI

A

Non-invasive, best resolution

39
Q

Disadvantages of MRI

A

Needs training, expensive

40
Q

Uses of a ultrasound

A

Monitor an unborn baby, diagnose condition, guide surgeon during certain procedures

41
Q

Advantages of ultrasound

A

Simple, portable, affordable

42
Q

How does a ultrasound work?

A
  • Sound travels through tissues and sends echos which will differ in intensity/delay according to densities
  • Transducer will pick up the echoes & relay to a computer that converts each signals into a colour to build an image
43
Q

What does the colours in ultrasound scan mean?

A

Dark: Fluid & air
Bright: Bony surfaces

44
Q

What do you see through a angiography scan?

A

Luminal structures (blood vessels/hollow organs)

45
Q

What does angiography need to access ?

A

Large vessel, minimally invasive

46
Q

How does a angiography work?

A

Contrast is injected which shows up as it absorbs X-Rays

47
Q

Define digital subtraction angiography

A

Subtracts bone & other organs so only vessels filled with contrast agent stays

48
Q
A