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FunMed Week 6 > Medical Imaging > Flashcards

Medical Imaging Flashcards

1
Q

what is X-ray useful for visualisng?

what does the picture show?

what are they?

A

visualise: skeletal system and some diseases in soft tissue

what are?: a picture of the parts of the patients that absorb or block the x-rays

picture: based on density and composition of the structure a proportion of the x-rays will be absorbed (more dense: more absorb - looks whiter, less dense: black- e.g. fat / air)

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2
Q

advantages v disadvantae of plan radiographs / x-rays?

A

advantage:

  • cheap
  • readily avail.

disadvantage:

  • ionising radiation (damaging e.g. for foetus / genetilia: DNA damage)
  • limited range of densities: shades of grey
  • 2D representation of 3D object: some tissues obscure view
  • soft tissue doesnt show up well
  • Not very sensisitve
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3
Q

* chest x-rays *

know this !

how can you take chest x-rays? - which one is standard and why?

A

antierior -> posterior (AP) view

posterior -> anterior (PA) view. standard x-ray

in AP view: x-rays get distorted and shadowed when going through = get heart shadows

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4
Q

which chest x-ray is this?

how do u know?

A

PA

  • clavicle is in lung field
  • ribs are more slanted / curved
  • posterior ribs more in show
  • smaller heart shadow
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5
Q

which chest x-ray is this?

how can u tell?

A

AP

  • clavicle at top of lung view
  • scapula is in lung field
  • ribs more horizontal - can see anterior ones more
  • heart shadow larger
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6
Q

what is difference between left hemidiaphragm compared to right?

A
  • left hemi-diaphragm is lower slightly c.f. the right (right side is pushed up by liver)
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7
Q

which view for X-ray is used for appendicular skeleton?

A

AP and lateral views

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8
Q

how are images displayed?

A

presented as if you in front of the indivudual (face on): left side = right side

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9
Q

what does this show?

A

situs inversus totalis :s a condition in which the arrangement of the internal organs is a mirror image of normal anatomy.

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10
Q

what does this show?

A

normal:

carpals havent occified yet in baby’s hand. currently cartilage (just cant see bc not as dense)

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11
Q

what can you see with this/?

A

line: shows that left side is more dense (whiter)
- heart is further to the left

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12
Q

what are DEXA scans?

used for?

A
  • two different, low energy x-ray sources; more precise and accurate calculation of density
    a) the denser the bone the fewer the x-rays get to detector
    b) used for diagnosis of osteoperosis (health condition that weakens bones)
    c) can measure BMI and fat (more precise soft tissue measurements)
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13
Q

what are the different types of x-ray contrast media how work?

A

contrast media

  • use air to reduce density of hollow organ soft tissue (esp. GI system): creates negative contrast
  • e.g. can see large intestine more

OR
- can make tissue denser: liquid contrast media used are barium and iodine. non-toxic substances that contain elements of high atomic number - increased atomic number

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14
Q

what is method and what does barium sulphate and iodine highlight when used as contrast media?

A

1. barium sulphate:

- highlight: GI system

- method: swallow barium meal / enema

2. iodine - angiography

highlights: blood vessels

method: injection of iodine

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15
Q

what is a CT scan?

A

= computerised tomography

  • multiple x-ray at different angle to build up cross section of bodies tissues and organs
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16
Q

advan and disadvan of CT scans?

A

Advantages:

  • cross sectional images and other planes can be reconstructed afterwards
  • readily available
  • well tolerated (not claustrophobic / noisy)
  • high contrast bone detail

Disadvantages:

  • ionisng radiation higher than x-ray
  • metallic artefacts cause loss of detail
  • soft tissue surrounded closely by bone difficult to image
  • resp. movement artefact
17
Q

when you see an axial view of CT scan - what is this angle of?

A

standing at foot of bed and looking up into head

18
Q

label where you find the diferent chambers of heart from CT scan?

A
19
Q

whats wrong with this CT?

A

sinusitis: full of snot lol in a synouse

20
Q

whats wrong with this?

A

no right common iliac artery

21
Q

describe MRI imaging

A
  • non-ionising radiation
  • v high soft tissue contrast
  • images acquired in transverse plane (patients lies through)
  • structural and functional information
  • does not image bone directly - but good for showing inside bone
  • get two views: T1: normal anatomical structure and T2: good for pathology - can see water in bone (oedema)
  • noisy and claustrophobic
  • people can be in room bc isnt ionising
  • no metal objects in room -> esp. ferrous.
22
Q

what is MRI brill for?

A

soft tissue imaging

23
Q

explain difference between T1 and T2 MRI scans

occur at same time or different?

what does white scan show in each?

A
  • occur at same time
  • T1: normal anatomy

a) in brain: good gray/white matter contrast (fat: white = myelin, yellow = bone marrow etc)

b) white is fat
- T2: pathology.

a) white is fluid (water)

24
Q
A
25
Q

which imaging method can be used for embryos?

A

MRI

26
Q

what is the contrast medium for MRI?

which scan does it give more detail in?

A

gadolinium contrast

  • changes relaxation time of H ion spin
  • gives more detail in T2

- gadolinium highlights breakdowns of blood brain barrier (normally cant go through them)

27
Q

describe ultrasound

A
  • uses soundwaves (1-18 megahertz)
  • safe during fetal development
  • cheap
  • readily available: real time imaging
  • becoming more common for both diagnostic and therapetutic imagine
  • difficult to interpret what is going on, cant say what things are without knowing where are
28
Q
A
29
Q

main use of ultrasound?

A

diagnostic and therapeutic injections, nerve blocks: can visualise at same time as injection

30
Q

what is doppler ultrsound?

A

shows blood flow direction:

  • red = towards transducer
  • blue = away from transducer

can measure blood flow

FunMed Week 6 (7 decks)

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