Brainscape's Knowledge GenomeTM

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


See full index

MRI > Chapter 5 > Flashcards

Chapter 5 Flashcards

1
Q

An MRI protocol is defined as

A

A set of rules or variety of parameters that are selected by the operator

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

What are these parameters that can be selected by the operator?

A

Extrinsic contrast parameter
Geometric parameters
Variety of imaging options

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

Way of examining certain area or pathology

A

Protocol

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

What are the pulse sequence?

A

TR /TE

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

When choosing pulse sequence, it will determine what

A

Weight of the image
Quality of the image
Sensitivity to pathology

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

TR determine the amount of

A

T1 and proton density

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

Flip angle will control the amount of

A

T1 and proton density

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

Four main consideration determine the MR image quality

A

Signal to noise ratio
Contrast to noise ratio
Spatial resolution
Scan time

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

Amplitude of the signal received to the average amplitude of the noise

A

Signal to noise ratio

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

It is the voltage in used in the receiver coil by the precession of the net magnetisation vector in the transverse plane

A

Signal

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

Predicted by Lamar frequency law

A

Signal

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

Frequency that exist randomly in space and time

A

Noise

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

Unpredictable cannot be controlled and have an unknown value

A

Noise

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

Noise is generated by

A

The presence of the patient in magnet
Background electrical noise of the system

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

Noise is constant and depend on

A

The build of the patient
Area under examination
Inherent noise of the system

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

True or false?
Any factor that affect the signal amplitude will affect the SNR

A

True

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

What are the factors that effect SNR

A

Magnetic field strength of the system
Proton density of the area under examination
Voxel volume
TR,TE and flip angle
Number of excitation or number of signal
Receive bandwidth
Coil type and position

18
Q

Results in more available magnetisation to image the patient

A

Field strength

19
Q

Pelvis have

A

Higher signal to noise ratio because it has more proton density

20
Q

Number of a proton or hydrogen under the area to be examined will determine the amplitude of the signal received

A

True

21
Q

3-D representation of pixel

A

Voxel

22
Q

Represent a volume of tissue within the patient and is determined by pixel area and slice thickness

A

Voxel

23
Q

Pixel area is determined by

A

size of FOV
number of pixel in matrix

24
Q

SNR is ….. to the Voxel

A

Proportional

25
Q

Explain each of the three parameters that alter the size of voxel

A

Slice thickness: if you increase the slice thickness, we will have better SNR ratio
Matrix : image matrix is defined as the number of pixel in image if we double the matrix and the field of view remain the same the SNR will be half because if you have larger matrix mean that you will have larger pixel and large pixel mean larger voxel means better sSNR
Field of view decreasing the field of view will decrease the pixel dimension therefore the Voxel and SNR are reduced

26
Q

If double the metrix while the FOV remain on change SNR well

A

Be half

27
Q

A flip angle of 120°
Or a flip angle with 50°
Which one has better SNR?

A

An angle of 120° is better because increasing the angle will result in increasing the SNR

28
Q

A 500 TR or 200 TR
Which one has lower SNR

A

200 TR has lower SNR
Because the amount of net magnetisation Victor on the longitude plane would be higher therefore it will have a higher signal or a had higher signal when it was in the transverse plane

29
Q

If you increase TE SNR well

A

Decrease

30
Q

Why is long TE images have lower SNR?

A

Because we wait too long for it to decay, therefore we will have less signal collected

31
Q

200 TE or 500 TE which one has better SNR

A

The 200 TE

32
Q

Number of times data collected with the same amplitude of phase

A

Number of signal average or number of excitation

33
Q

Increasing the number of excitation and the ScanTime by four will

A

Double SNR

34
Q

Range of frequencies that are sample during the application of the readout gradient

A

Receive bandwidth

35
Q

Which one has better SNR the narrow bandwidth or the wide one?

A

Narrow because the number of signals ratio to the noise is better or higher

36
Q

Increase the SNR because two coins are used to receive signal

A

Quadrature coils

37
Q

Collect data from several coils added together

A

Phase array coil

38
Q

Please close to the area under examination

A

Surface coils

39
Q

Size and position of coils important role in affecting the SNR

A

True

40
Q

The coin must be positioned in the transverse plane…….. toB0

A

Perpendicular

MRI (1 decks)

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