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

High acceleration factors in parallel imaging introduce a geometry (g-factor) penalty that reduces SNR, especially in the center of the image where coil sensitivity overlap is less distinct.

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

Placing phase encoding in the right-left direction directs respiratory ghosting away from critical abdominal structures, reducing diagnostic interference.

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

Longer ETL fills k-space faster (reducing scan time) but each echo has progressively more T2 decay, causing blurring particularly of edges and fine detail.

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

CNR is the SNR difference between adjacent tissues; high CNR is essential for detecting lesions because it reflects how well two tissues can be discriminated from each other.

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

Increasing receiver bandwidth reduces the frequency difference between fat and water in pixel units, shrinking the spatial shift of fat signal relative to water signal.

MRI - Magnetic Resonance Imaging Practice Test

MRI - Magnetic Resonance Imaging Practice Test

MRI MRI Image Quality and Optimization 3