MRI

Question 1

the patient is asked to perform certain activities to help the neurosurgeons map the functional areas of the brain before surgery takes place.

Answer 1

fMRI

Question 2

types of MRI exams

Answer 2

fMRI
Breast Scans
MRA
MRV

Question 3

s a non-invasive technique that is used to examine our patients at high risk for breast cancer. Breast MRI can catch areas of concern earlier and in ways not possible with other breast imaging techniques, giving our experts the ability to best diagnosis and treat breast cancers.

Answer 3

Breast Scans

Question 4

is a non-invasive diagnostic procedure that uses a combination of magnetic resonance technology (MRI) and intravenous (IV) contrast dye to visualize blood vessels. An MRA is often used to examine the heart and other soft tissues and to assess blood flow.

Answer 4

Magnetic Resonance Angiography (MRA)

Question 5

diagnostic procedure that uses a combination of a large magnet, radio frequencies, and a computer to produce detailed images of organs and structures within the body. An MRV uses magnetic resonance technology and intravenous (IV) contrast dye to visualize the veins.

Answer 5

Magnetic Resonance Venography (MRV)

Question 6

is measured frequently by calculating the difference in signal intensity between the area of interest and the background (usually chosen from the air surrounding the object).

Answer 6

signal-to-noise ratio

Question 7

Used to describe the relative contributions to a detected signal of the true signal and random superimposed noise

Answer 7

Signal to Noise Ratio (SNR)

Question 8

is proportional to the volume of the voxel and to the square root of the number of averages and phase steps (assuming constant-sized voxels).

Answer 8

Signal-to-noise ratio

Question 9

On MRI, the signal-to-noise ratio can be improved by:

Answer 9

volume acquisition as compared to 2D imaging, but imaging time is increased
spin-echo sequences as compared to gradient echo
decreasing the noise by reducing the bandwidth, using surface coils, and increasing the number of excitations
increasing the signal by decreasing the TE (time to echo) and increasing the TR (time to repeat), slice thickness, or field of view

Question 10

Additionally, SNR can be improved by tweaking scan parameters. Assuming all other factors remain the same, SNR can be improved by:

Answer 10

increasing the field of view (FOV)
decreasing the matrix size
increasing the slice thickness

Question 11

is energy delivered to the spins via excitation.

Answer 11

Relaxation Time

Question 12

The NMV in the transverse plane decreases due to:

Answer 12

relaxation processes;
field in homogeneities and susceptibility effects.

Question 13

The amplitude of the voltage induced in the receiver coil therefore gradually decreases. This is called

Answer 13

free induction decay or FID

Question 14

The magnetization in each tissue relaxes at different rates. This is one of the factors that create image contrast.

Answer 14

Relaxation processes

Question 15

Spins emit energy absorbed from the RF pulse through a process known as

Answer 15

spin lattice energy transfer

Question 16

Spins emit energy absorbed from the RF pulse through a process known as spin lattice energy transfer and shift their magnetic moments from the high‐energy state to the low‐energy state. The NMV recovers and realigns to B0. This relaxation process is called ___

Answer 16

T1 recovery

Question 17

The magnetic moments of the spins lose precessional coherence or dephase and the NMV decays in the transverse plane. The dephasing relaxation process is called__

Answer 17

T2 decay.

Question 18

is also called the longitudinal or spin-lattice relaxation time. The term longitudinal refers to events occurring along the axis of the net magnetization vector, which is parallel to B0. T1 relaxation describes the growth and decay of MZ; therefore it is longitudinal in nature.

Answer 18

T1

Question 19

is called the transverse relaxation time. Because T2 relaxation represents a loss of net XY magnetization, it represents the loss of phase coherence in a plane perpendicular to or transverse to M0. M0 lies along the Z-axis.

Answer 19

T2

Question 20

concentration of nuclei in tissue processing at theLarmor frequency in a given region; one of the principal determinants of the strength of theNMR signal from the region.

Answer 20

Spin Density

Question 21

are very fast bursts of radio waves, provided that the radio waves and nuclear precession are of the same frequency.

Answer 21

RF pulse

Question 22

The grouping of two or more RF pulses is called a __

Answer 22

pulse sequence.

Question 23

is the time between the delivery of the RF pulse and the receipt of the echo signal.

Answer 23

Time to Echo (TE)

Question 24

is the amount of time between successive pulse sequences applied to the same slice.

Answer 24

Repetition Time (TR)

Question 25

are wave forms of the gradients and RF pulses applied in MR image acquisition

Answer 25

Pulse sequences

Question 26

is a schema of the timing of instructions sent to the RF generator and gradient amplifiers.

Answer 26

pulse sequence diagram

Question 27

There are only two fundamental types of MR pulse sequences: __

Answer 27

SE and GRE

Question 28

MR pulse sequences can be either

Answer 28

2D w/ one section acquired at a time or 3D w/ volume of multiple sections obtained in a single acquision

Question 29

If a 180° RF pulse follows the 90° RF pulse at some later time, an __ of the FID can be generated.

Answer 29

echo signal

Question 29

does not follow the 180° RF pulse immediately. The spin echo sequence is the most commonly used two-pulse MRI sequence.

Answer 29

spin echo (SE)

Question 30

pulse sequence using three RF pulses is the __

Answer 30

inversion recovery (IR).

Question 31

RF pulse sequence uses a 180° RF pulse before the 90° RF pulse.

Answer 31

inversion recovery (IR)

Question 32

When three RF pulses are used and if the time between the pulses is less than T2, then a different kind of echo signal, called the

Answer 32

stimulated echo (STE)

Question 33

is designed to detect the random movements of water protons.

Answer 33

Diffusion weighted imaging (DWI)

Question 34

is a non-toxic paramagnetic contrast enhancement agent.

Answer 34

Gadolinium (Gad).