MRI MRI Image Quality and Optimization 3

Question 1

What is the primary consequence of using a high acceleration factor in parallel imaging?

Accepted Answer

Reduced SNR due to the g-factor penalty

Answer

Increased spatial resolution

Answer

Improved T1 contrast

Answer

Reduced scan time with no image quality loss

Question 2

Which phase-encoding direction choice can help reduce motion artifact from breathing in abdominal MRI?

Accepted Answer

Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest

Answer

Orient phase encoding in the anterior-posterior direction to capture all motion

Answer

Use a larger FOV in the frequency direction

Answer

Increase the number of slices

Question 3

How does increasing the echo train length (ETL) in a fast spin echo (FSE) sequence affect image quality?

Accepted Answer

Scan time decreases but T2 blurring may increase

Answer

SNR improves proportional to ETL

Answer

Spatial resolution improves in all directions

Answer

T1 contrast increases significantly

Question 4

What is contrast-to-noise ratio (CNR) in MRI and why is it important?

Accepted Answer

The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue

Answer

The ratio of gadolinium dose to body weight

Answer

The ratio of TR to TE for optimal contrast

Answer

The number of phase encodes used to improve tissue differentiation

Question 5

A technologist wants to reduce chemical shift artifact at the fat-water interface. Which parameter change is most appropriate?

Accepted Answer

Increase the receiver bandwidth

Answer

Decrease the receiver bandwidth

Answer

Increase the FOV

Answer

Decrease the number of slices

Question 6

Which of the following best explains why a phased-array coil improves SNR compared to a body coil?

Accepted Answer

Multiple smaller coil elements are positioned close to the anatomy, maximizing signal pickup while limiting noise volume

Answer

Phased-array coils use higher magnetic field strength

Answer

They apply stronger RF pulses to excite more protons

Answer

They increase the repetition time automatically

Question 7

What is the effect of reducing the number of phase-encoding steps while keeping FOV and frequency steps constant?

Accepted Answer

Scan time decreases and phase-direction spatial resolution decreases

Answer

SNR improves and scan time increases

Answer

Through-plane resolution is affected

Answer

Frequency-direction resolution decreases