Parameters 2 Flashcards

1
Q

Increasing TR will:

a) Decrease scan time
b) Increase T1 weighting
c) Increase scan time
d) Decrease SNR

A

c) Increase scan time

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2
Q

A short TE primarily enhances:

a) T2 weighting
b) Proton density weighting
c) SNR
d) Motion artifacts

A

b) Proton density weighting

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3
Q

What happens if TE is increased?

a) T1 contrast increases
b) Scan time decreases
c) SNR decreases
d) Image resolution improves

A

c) SNR decreases

Longer TE means waiting longer for the signal, which leads to more decay and lower signal-to-noise ratio (SNR)

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4
Q

Which TR and TE combination is best for T1-weighted imaging?

a) Long TR, long TE
b) Short TR, long TE
c) Long TR, short TE
d) Short TR, short TE

A

d) Short TR, short TE

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5
Q

What does a long TR help reduce?

a) T1 contrast
b) T2 contrast
c) Spatial resolution
d) Motion artifacts

A

a) T1 contrast

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6
Q

What happens if phase matrix is increased?

a) SNR increases
b) Scan time decreases
c) Spatial resolution increases
d) Motion artifacts increase

A

c) Spatial resolution increases

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6
Q

Increasing FOV will:

a) Increase spatial resolution
b) Increase SNR
c) Increase scan time
d) Decrease pixel size

A

b) Increase SNR

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7
Q

Decreasing pixel size will:

a) Improve spatial resolution
b) Decrease scan time
c) Increase SNR
d) Reduce T2 contrast

A

a) Improve spatial resolution

Smaller pixels mean finer image details, improving resolution

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7
Q

Increasing FOV but keeping matrix constant will:

a) Decrease spatial resolution
b) Increase scan time
c) Increase contrast
d) Reduce blurring

A

a) Decrease spatial resolution

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8
Q

Increasing phase matrix affects scan time by:

a) Increasing it
b) Decreasing it
c) Keeping it unchanged
d) Reducing blurring

A

a) Increasing it

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9
Q

Increasing NSA/NEX will:

a) Reduce motion artifacts
b) Decrease SNR
c) Decrease scan time
d) Improve spatial resolution

A

a) Reduce motion artifacts

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10
Q

What is a disadvantage of increasing NSA/NEX?

a) Increased blurring
b) Increased scan time
c) Increased chemical shift
d) Reduced SNR

A

b) Increased scan time

More averages (NSA/NEX) reduce noise but take longer to scan

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11
Q

Reducing NSA/NEX will primarily affect:

a) Spatial resolution
b) Motion artifacts
c) T1 contrast
d) Scan time

A

b) Motion artifacts

Fewer averages mean less correction for motion, so motion artifacts increase

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12
Q

Why does increasing NSA/NEX help reduce noise?

a) It improves spatial resolution
b) It averages out random noise
c) It shortens TE
d) It increases pixel size

A

a) It improves spatial resolution

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13
Q

How does reducing NSA/NEX affect motion artifacts?

a) Increases them
b) Decreases them
c) No effect
d) Improves resolution

A

a) Increases them

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14
Q

Decreasing receive bandwidth has what effect?

a) Reduces noise
b) Increases SNR
c) Reduces chemical shift artifacts
d) Decreases scan time

A

b) Increases SNR

A lower bandwidth allows more signal collection time, increasing SNR but also increasing chemical shift artifacts

14
Q

What does increasing receive bandwidth (rBW) do?

a) Increases SNR
b) Reduces chemical shift artifacts
c) Increases scan time
d) Increases motion artifacts

A

b) Reduces chemical shift artifacts

Higher bandwidth captures signals faster, reducing the misalignment that causes chemical shift artifacts

15
Q

A lower rBW leads to:

a) Higher SNR
b) Shorter scan time
c) Less chemical shift
d) Lower resolution

A

a) Higher SNR

Less bandwidth means less noise, leading to a better SNR

16
Q

Which artifact is most affected by rBW?

a) Motion artifact
b) Chemical shift
c) Truncation artifact
d) Gibbs ringing

A

b) Chemical shift

17
Q

If metal artifacts are a concern, how should rBW be adjusted?

a) Increased
b) Decreased
c) Unchanged
d) Reduced NSA/NEX

A

a) Increased

Higher bandwidth helps reduce distortion from metal because it captures signals faster

18
Q

Increasing ETL will:

a) Increase scan time
b) Reduce scan time
c) Improve SNR
d) Reduce blurring

A

b) Reduce scan time

19
Q

What is a drawback of a long ETL?

a) Increased blurring
b) Higher SNR
c) Reduced scan time
d) Reduced motion artifacts

A

a) Increased blurring

More echoes in one sequence mean less time for accurate signal recovery, leading to blurring

20
Q

What does a short ETL do?

a) Increases scan time
b) Reduces blurring
c) Decreases SNR
d) Increases T2 contrast

A

a) Increases scan time

Fewer echoes per repetition mean more repetitions are needed, increasing scan time

21
Q

A long ETL is beneficial for:

a) Reducing motion artifacts
b) Enhancing T1 contrast
c) Increasing T2 contrast
d) Decreasing chemical shift

A

c) Increasing T2 contrast

More echoes allow better visualization of T2-weighted structures

22
Increasing ETL too much can result in: a) Increased resolution b) Image blurring c) Shorter scan time d) Higher SNR
b) Image blurring
23
Which factor increases Specific Absorption Rate (SAR)? a) Increasing FOV b) Increasing flip angle c) Increasing TR d) Decreasing ETL
b) Increasing flip angle A larger flip angle uses more energy, increasing SAR (which is heat absorbed by the body)
24
Reducing SAR exposure can be done by: a) Increasing TR b) Increasing flip angle c) Decreasing FOV d) Increasing NSA/NEX
a) Increasing TR Longer TR means more time between pulses, allowing the body to cool down
25
Higher SAR is a concern with: a) Low field MRI b) High flip angles c) Low TR values d) Long TE values
b) High flip angles
26
If a patient is overheating during an MRI, which adjustment can help reduce SAR? a) Increase TR b) Increase flip angle c) Decrease FOV d) Increase ETL
a) Increase TR Giving more time between pulses helps reduce heat buildup in the patient
27
What parameter has the least impact on SAR? a) TR b) TE c) Flip angle d) NSA/NEX
d) NSA/NEX Averaging scans (NSA/NEX) mainly affects noise and motion but has little effect on heating (SAR)