MRI MRI Image Quality and Optimization 1

Question 1

Which parameter, when increased, will most directly improve the signal-to-noise ratio (SNR) in an MRI image?

Accepted Answer

Increasing the number of excitations (NEX/NSA)

Answer

Increasing NEX/NSA averages more signal acquisitions, which reduces noise and improves SNR proportional to the square root of the number of averages.

Question 2

What is the relationship between voxel size and SNR in MRI?

Accepted Answer

Larger voxels produce higher SNR

Answer

Larger voxels contain more protons contributing signal, increasing SNR, though at the cost of spatial resolution.

Question 3

Which of the following changes will increase spatial resolution without changing the FOV?

Accepted Answer

Increasing the matrix size

Answer

Increasing matrix size means more phase and frequency encoding steps, reducing voxel size and improving spatial resolution within the same FOV.

Question 4

A technologist wants to reduce scan time while maintaining similar SNR. Which strategy is most effective?

Accepted Answer

Use parallel imaging (SENSE/GRAPPA)

Answer

Parallel imaging techniques use multiple coil elements to under-sample k-space, reducing scan time while maintaining acceptable SNR through reconstruction algorithms.

Question 5

What happens to image contrast when the echo time (TE) is increased in a T2-weighted sequence?

Accepted Answer

T2 contrast increases as tissues with short T2 decay faster

Answer

Longer TE allows more T2 decay to occur, so tissues with short T2 lose signal faster and appear darker, enhancing T2 contrast between tissues.

MRI - Magnetic Resonance Imaging Practice Test

MRI - Magnetic Resonance Imaging Practice Test

MRI MRI Image Quality and Optimization 1