Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Radiography Year 1 Diagnostic Technology exam 2 RAD4046 > Magnetic Resonance Imaging > Flashcards

Magnetic Resonance Imaging Flashcards

1
Q

What EMR is used in MRI?

A

Radiowaves (and a Magnetic field is used)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

T1 Hypo intense is what colour

A

dark

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

T2 Hyper bright is what colour

A

White

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Ferro-magnetic

A

Strongest force of magnet

Stays magnet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

SAR

A

Specific adsorption rate

Heats up patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Homogeneity

A

All the same
All the magnets are in rows, that’s why it’s 50cm

Radio frequency
We want coils close cause inverse square law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Gradient coil

A

Pairs of the coils

On gradient axes to the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Paramagnetic

A

Slightly magnetic

Gadolinium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Didgeridoo

A

Vibration MRI

Same frequency of sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Super-conducting magnet

A

No resistance
Using liquid helium low temp
So it’s superconducting as there is no resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Pixel

A

A picture element
Pixels are bigger in MRI compared to CT
Poor signal to noise frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Matrix

A

Made up of pixels
You want a large matrix small pixel
But MRI has large pixel and small matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Larmour Frequency

A

Larmour frequency equation

Frequency is equal to magnetic field strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Voxel

A

Volume element to give pixel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

M0

A

Bodies magnetic field

Influence by the MRI to line up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

1 Tesla is what gauss

A

10000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Missile effect

A

If you bring metal into MRI room it will launch towards MRI machine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Deflection

A

Twist to follow the MRI scanner

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

MR safe

A

Safe for MRI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

MR conditional

A

You might be able to scan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

MR unsafe

A

Not safe for MRI

22
Q

In medical emergency

A

Take the patient out the room as the cardiac team may have metal equipment
Usually MRI have their own trolley for this reason

23
Q

5 guass

A

5 guass line is how far the metal field strength is

Always in the MRI room

24
Q

Implant effects the scan how

A

They are safe
But it makes area dark so you can’t see there

But if you don’t know it’s there smear the artefact across the image

25
Q

Uncontrolled quench

Controlled quench

A

Is to let the helium gas out safely, warm it up slowly

If it was to leak into the room it would cause dissipation of oxygen so you couldn’t breathe
Could explode

26
Q

How to deal with claustrophobia

A

Patients with bad claustrophobia will not be able to have MRI
Cognitive methods

reassurance

eye masks

mirrors on the head coil so the patient can see you at the scanner

mild oral medication such as low dose diazeplam

IV sedation is not safe for MRI because it can be magnetic the equipment

27
Q

Radio frequency burns

A

radio frequency waves raise the patient’s temp
different sequences in MRI have different SAR levels
changes can be made to the MRI protocol to limit the heating but it takes longer

radio frequency burns can be caused by skin-to-skin contact that can form a loop which leads to heating
ECG and overweight patients are also a risk
Sponge pads may be used to prevent skin to skin contact

28
Q

What is the most common element and why is it used for MRI

A

Hydrogen is chosen because:-

  1. It is very abundant in the body (approx
    10% of body mass is Hydrogen)
  2. It gives the strongest MRI signal
Hydrogen has a single spinning proton
(+ve)
• A moving (spinning) charge creates a
magnetic field
• This results in the nucleus acting like a
small bar magnet
29
Q

MRI involves 3 physical principles:-

A
  1. Nuclear - the nuclei of certain atoms
    behave like small bar magnets
  2. Magnetic – when placed in a strong
    magnetic field, these small bar
    magnets align with the field and
    precess
  3. Resonance - if a radio frequency pulse
    is applied to these nuclei, some
    resonate and absorb energy and re-
    emit the energy as an MRI signal
30
Q

Protons from M0 change to what

A

B0
some hydrogens may spin in the opposite direction
M0 perpendicular to B0 to measure it

31
Q

Advantages of MRI

A

No rad
Soft tissue contrast resolution
safer contrast, fewer contraindications
Multimodal- functional, anatomical angiographic in one exam

32
Q

Disadvantages of MRI

A 
longer time
Claustrophobic
metal devices, magnets
Noisy
Expensive to buy, 
and less staff, equipment for the MRI
33
Q

Pregnancy is a contraindication in what trimester

A

the first trimester

34
Q

Proton density
T1
T2
How long are the tr and te?

A

long tr short te its proton density
short tr and short te its T1
Long tr and long te its T2

35
Q

T1, what colour is water

A

Water is dark

36
Q

T2, what colour is water

A

Light

37
Q

TR means what

A

Time to repeat

38
Q

TE means what?

A

Time to echo

39
Q

Precessional frequency means what

A

How fast the hydrogen spins around B0
how fast it wobbles
RF pulse has to be the same frequency in order to flip the hydrogen from longitude to transverse plane (to take MRI picture)

40
Q

What is measured?

A

During excitation using the RF all the atoms are put on the same spin path at the same precession
We measure the point of the rotation as it causes a net magnetic field in the direction they are all pointing
Same transverse magnetism

41
Q

How do the spins depend on the tissues?

A

After the RF is stopped the atoms stay to go back to normal and stop spinning again
Different tissues return back at different rates
Spins recover at different rates depending on the type of tissue

42
Q

T1 recovery curve

A

Recovery of longitudinal magnetization

Rate of different tissues to go back to normal spin

43
Q

T2 relaxation curve

A

Transverse magnetization
Decay process
moving out of phase with each other once the RF is switched off

44
Q

Receiver coils do what?

A

Have to be close to the part measuring

collects the signal whilst recovery/relaxation takes place

45
Q

FLAIR meaning

A

Fluid Attenuated Inversion Recovery - Protons in tissue water

46
Q

What different coils are used in MRI?

A

Y coil
Z coil
X coil
Transceiver coil

47
Q

What does the information that is given on the screen with an MRI image represent?

A

What T1 or T2 it is

48
Q

Patient prep

A

Remove all the metal objects from the patient
Keys, coins, mobile phone, hair-grips, watch
Credit cards and travel cards will be wiped if taken into the room
Clothing with metal attached? Artificial limbs or callipers

49
Q

What contra-indications there are to MRI?

A 
Pregnant
Metal fragments in body e.g gunshot
Any metal implants
Cardiac pacemaker
Claustrophobia
(any contradictions to contrast)
50
Q

Explain how an MRI image is created.

A

Magnetic resonance imaging (MRI) uses the movement of protons within a magnetic field to generate an image.
The coils send different RFs to the tissues and depending on the coil will affect which way the atoms will face and spin.
Then you wait some time as the tissues start to go back to their original spin.
Then the Transceiver coil will measure the magnetic field given off the tissues (the tissues will give off different MF depending on which ones it is, some tissues go back to normal faster than others)

51
Q

What must you do if someone has a neurotransmitter device?

A

Check that its MRI compatible/safe

Will have to use a special low frequency to ensure that the MRI doesn’t affect the neurotransmitter device.

52
Q

Recognize the different sequences (T1 and T2) that may be used.

A

You can tell by what the colour of the water is

or the graphs in the PowerPoint.

Radiography Year 1 Diagnostic Technology exam 2 RAD4046 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions