Review Final

What does a moving magnetic field induce in a conductor?

Increase magnetic field strength

Electrical current

Stronger magnetic field

Angular momentum

What parameters would you use to minimize T1 effects on a T2WI in a GRE?

short TR

long TR

short TE

long TE

short FA

long FA

Longitudinal magnetization occurs when protons align with which direction of the magnetic field?

X

Y

Z

XY

The main reason why fat and water would be out of phase with each other at some point and time in the transverse plane is the result of:

Magnetic susceptibility

Chemical shift

Magnetic field inhomogeneities

Spin-spin interaction

Fe2O3 is a _____________ particle.

Diamagnetic

Paramagnetic

Superparamagnetic

Ferromagnetic

Once the net magnetization vector (NMV) has started to move away from equilibrium, the following will occur:

The longitudinal component start to increase.

The transverse component start to decrease.

The longitudinal component will stay the same.

The transverse component start to increase.

Which of the following is the primary MR signal resulting from a 90-degree excitation RF pulse?

Gradient echo rephasing

Spin echo generation

Free Induction Decay

Net Magnetization Vector

Match the columns

slice selection gradient :
perpendicular to the slice

frequency encoding gradient :
long axis of the anatomy

phase encoding gradient
short axis of the anatomy

What better describes vector M right after a 90 degree flip angle

Rotating magnetic field in the B1 plane

Located at a right angle from the longitudinal axis

Protons precessing in phase

All answers are correct

What parameter combination would you select to produce a T2WI? select more than one answer

short TE

long TE

short TR

long TR

Materials with which of the following components have the highest degree of magnetic susceptibility

Diamagnetic

Paramagnetic

Superparamagnetic

Ferromagnetic

Which of the following conditions are necessary for resonance to occur?

Correct temperature and humidity

Matching chemical bonds

Equal number of protons and electrons

Energy applied at the precise frequency

Which of the following characteristics determines if an atom is suitable for use in MRI?

High atomic number

Full electron shell

Even mass number

Odd mass number

The direction perpendicular to the main magnetic field is designated as which direction?

X

Y

Z

XY

In MRI, substances respond to a specific radio frequency which is known as:

Magnetic frequency.

Radio frequency.

Gyro-magnetic frequency.

Resonance frequency.

What would be the effect of combining a very short TR (50 ms) with a long FA (90)? select more than one answer

Increase T1 effects

Increase T2 effects

Maximize saturation effects

Minimize T1 effects

What is the approximate precessional frequency of hydrogen in a 3.0 T magnet?

21 MHz/T

43 MHz/T

64 MHz/T

128 MHz/T

Which of the following conditions is necessary for energy to be the most efficiently transferred from one system to another?

Resonance

Precession

Alignment

Relaxation

In a gradient echo pulse sequence, what parameter combination would you use to produce a T1WI?

short TR

long TE

short TE

long FA

long TR

short FA

The magnetic field created by the nuclear alignment of hydrogen is known as which of the following?

Magnetic moment

Static magnetic field

Gradient magnetic field

Net Magnetization Vector

Which of the following provides the greatest Signal to Noise Ratio?

Reverse gradient slopes

High speed gradient slopes

Steep gradients slopes

Shallow gradients slopes

In a 3D volumetric acquisition: What would be the scan time utilizing the following parameters?
TR 50 ms, PES 192, Slice 20, TE 25 ms, FES 256, ETL 1, FA 10, NEX 1, RBW 21 mHz

2.1 min

4.2 min

3.2 min

6.4 min

What TOF technique is more affected by the presence of slow flow in the blood vessels?

2D-TOF-MRA

3D-TOF-MRA

CE-MRA

PC-MRA

What parameters would you use to calculate the scan time in an FSE

FES

TE

NEX

PES

TR

ETL

In a 2D acquisition: What would be the scan time using the following parameters?
TR 4000 ms, PES 192, Slice 20, TE 25 ms, FES 256, ETL 6, FA 90, NEX 2, RBW 21 mHz

2.1 min

4.2 min

6.6 min

8.4 min

Image construction in MRI is accomplished through which of the following mathematical processes?

Fast Fourier Transformation

Gradient reversal

Reverse Radio-Frequency Encoding

Pulse Sequence Manipulation

What imaging parameter affect the entry slice phenomenon?

TE

TR

TI

All answers are correct

What can be the artifact resulting from using a narrow receive bandwidth?

Aliasing

Truncation

Susceptibility

Chemical shift

To prevent in-plane flow saturation on a TOF-MRA, the slices should be positioned __________ to the blood vessels

Parallel

At 45 degrees

Perpendicular

The position of the slices does not prevent in-plane flow effects.

The steady state is the phenomenon that result from ____ shorter that the ___ relaxation times of the tissues?

TR / T1 & T2

TE / T1 & T2*

TI / TE & TR

TR / TE & T1

What technique is more effective to reduce intra-voxel dephasing?

Long TE

Short TR

Gradient moment nulling

No-phase wrap

What pulse sequence would be the most susceptible to in-homogeneities of the magnetic field?

SE

FSE

IR-FSE

GRE

What combination will reduce the most the effects of magnetic susceptibility?

FSE 24 ETL/Matrix 512/RBW 64 Hz

FSE 24 ETL/Matrix 512/RBW 32 Hz

FSE 12 ETL/Matrix 512/RBW 64 Hz

FSE 24 ETL/Matrix 256/RBW 64 Hz

To maintain the entry slice in a TOF-MRA, how should the slice be acquired?

with a very short TR

with a very short TE

co-current

counter -current

In an axial image, slice encoding is achieved through which of the following?

X gradient

RF receiver

Z gradient

Shim coil

If FOV is increased from 20 to 40, SNR will increases by a factor of

1

2

3

4

Using narrow receive bandwidth can result in an:

Increase SNR

Increase chemical shift artifacts

Increase of the minimum TE

All of the above

When increasing the FOV: (Select best two)

Increase scan time

Increase the chances of chemical shift

Increase spatial resolution

Increase SNR