MRI Knowledge 2

Question 1

What does the term 'repetition time' (TR) refer to in MRI pulse sequences?

Accepted Answer

The time between successive RF excitation pulses applied to the same slice

Answer

TR is the interval between the beginning of one RF excitation pulse and the beginning of the next for the same slice, controlling T1 contrast.

Question 2

Which MRI artifact is caused by periodic patient motion such as cardiac or respiratory movement?

Accepted Answer

Ghosting (motion) artifact

Answer

Ghosting artifacts appear as repeated copies of moving structures along the phase-encoding direction due to periodic physiologic motion.

Question 3

The flip angle in an MRI sequence refers to which of the following?

Accepted Answer

The degree to which the net magnetization vector is rotated from B0 by the RF pulse

Answer

The flip angle is how far the net magnetization vector is tipped away from the longitudinal axis by the RF pulse.

Question 4

Which type of MRI coil surrounds the entire body and is used to transmit RF energy uniformly?

Accepted Answer

Body (volume) coil

Answer

The body (volume) coil is built into the bore and provides uniform RF transmission across the entire patient.

Question 5

In MRI, what is k-space?

Accepted Answer

The raw data space containing spatial frequency information used to reconstruct images

Answer

K-space is the mathematical domain that stores the raw MRI signal as spatial frequencies; a Fourier transform converts it into an image.

MRI - Magnetic Resonance Imaging Practice Test