MRI Registry Review (Scan Principles) –Questions With Fully Explained Solutions

MRI Registry Review (Scan Principles) –
Questions With Fully Explained Solutions
A set of specifically timed instructions to the magnet is known as:
A. A recipe
B. A pulse sequence
C. Gyromagnetic instructor
D. Fourier transformation Correct Answer - B. A pulse
sequence

A pulse sequence is a set of specifically timed instructions to the
magnet telling it how images should look with regards to the tissue
being sampled.

Decreasing the TR will:
A. Lower SNR
B. Reduce scan time
C. Increase SNR
D. Both A and B Correct Answer - D. Both A and B

A reduction in FOV will result in:
A. Decrease in spatial resolution
B. Increase in SNR
C. Decrease in SNR
D. None of the above
E. A and C only Correct Answer - C. Decrease in SNR

A reduction in FOV will result in a decrease in SNR, but will increase
the spatial resolution in the image by lowering the pixel size.

Assuming all other parameters are the same, a ___________ ms TR
provides the best signal-to-noise ratio.
A. 30

,B. 200
C. 500
D. 800 Correct Answer - D. 800

If a sequence with a matrix of 256 x 512 is adjusted to 512 x 512,
A. The SNR will stay the same
B. The scan time will decrease
C. The SNR will increase and the scan time will decrease
D. The SNR will decrease and the scan time will increase Correct
Answer - D. The SNR will decrease and the scan time will
increase

As the number of excitations (NEX) is increased from 1 to 3, which
of the following does NOT occur?
A. The scan time triples
B. The pixel size is increased
C. The image resolution remains the same
D. The signal-to-noise ratio is increased Correct Answer - B.
The pixel size is increased

A method of reducing MRI scan time by not filling as many lines of k-
space in the phase direction, while maintaining spatial resolution, is
known as:
A. Halfscan
B. Rectangular FOV
C. Partial fourier
D. Fast spin echo Correct Answer - B. Rectangular FOV

The smallest object that can be resolved in an image acquired with a
20cm FOV and a 224 x 224 matrix is _________ mm.
A. 0.54
B. 0.89
C. 1.12
D. 1.89 Correct Answer - B. 0.89

,Calculate the pixel area for the following sequence: TR 450, TE 12,
FOV 18cm, 224 x 256 matrix, 4 NEX.
A. 0.56 mm2
B. 0.70 mm2
C. 0.80 mm2
D. 1.50 mm2 Correct Answer - A. 0.56 mm2

FOV/matrix x FOV/matrix = pixel area. 180/224 x 180/256 = 0.56
mm2

SNR increases with all the following adjustments, EXCEPT:
A. Increasing FOV
B. Decreasing pixel size
C. Increasing NEX/NSA
D. Decreasing phase matrix Correct Answer - B. Decreasing
pixel size

Smaller pixel size (higher phase matrix) leads to improved
resolution, but decreased SNR.

Increasing NSA will:
A. Improve SNR
B. Degrade SNR
C. Shorten scan time
D. Have no effect on SNR Correct Answer - A. Improve SNR

As the number of phase encodings is increased from 256 to 512,
SNR (signal to noise ratio):
A. Increases
B. Decreases
C. Doubles
D. Is unchanged Correct Answer - B. Decreases

, Assuming all other parameters are the same, an echo time of
___________ ms provides the best Signal-to-Noise Ratio.
A. 15
B. 30
C. 80
D. 110 Correct Answer - A. 15

K-space is typically filled:
A. With a funnel
B. One line at a time
C. From back to front
D. From right to left Correct Answer - B. One line at a time

Another name for a picture element is a:
A. Voxel
B. Pixel
C. Cubicle
D. Filament Correct Answer - B. Pixel

Which of the following is NOT affected by changing the slice
thickness?
A. The signal-to-noise ratio of the image
B. The T1 contrast
C. The image resolution
D. The anatomical coverage Correct Answer - B. The T1
contrast

With a recFOV that is twice as tall as it is wide, and the phase
direction oriented along the smaller "width" dimension of the FOV,
which of the following relationships between the frequency and
phase steps yields square pixels?
A. Frequency steps must be half the phase encoding steps
B. Phase steps must equal the number of frequency steps
C. Phase steps must be half the number of frequency steps