ARMRIT

Question 1

Which parameter in a pulse sequence helps prevent “crosstalk” between two adjacent images

Answer 1

Slive Interval

Question 2

When selecting only one slice at a time during a pulse sequence, which method for providing spatial localization is employed?

Answer 2

2DFT

Question 3

In spatial localization, which factor most affects slice thickness and position?

Answer 3

Bandwidth and strength of the G’s

Question 4

Determine Scan Time
TR 550 ms
NEX 4
Matrix 256 x 192

Answer 4

7 minutes

Question 5

Which is a normally enhancing structure after the administration of gadolinium

Answer 5

Choroid plexus

Question 6

Inverstion time, in an Inversion pulse sequence, is the time interval between the:

Answer 6

180 and 90 degree pulses

Question 7

Decreasing slice thickness will

Answer 7

Decrease SNR

Question 8

A gradient is employed exposing the patients body to a series of increasing or decreasing magnetic field strengths for slice selection, in what relation to the slice is this gradient?

Answer 8

Perpendicular

Question 9

What year was the first MRI enhancement agent approved for clinical use?

Answer 9

1988

Question 10

In a pulse sequence employing 2DFT, the time can be calclulated using which formula

Answer 10

TRxNEXxMatrixw

Question 10

In an Inversion recovery pulse sequence, what TI will produce a STIR fat suppressed pulse sequence?

Answer 10

80 - 120

Question 11

Residual, undesirable gradient magnetic fields that persist for a variable time duration after the pulse of electricity from the gradient power supply is terminated are known as

Answer 11

Eddy Currents

Question 12

Tissues that have low (short) relaxation times

Answer 12

Have higher relaxation rates

Question 13

The two types of enhancement media described by Lauffer, the mechanisms of T1 agents is:

Answer 13

To decrease T1 relaxation time, thus emitting high signal

Question 14

which parameters describe a PD image

Answer 14

Long TR
Short TE

Question 15

Scan time
TR 2000
NEX 1
Matrix 256x128

Answer 15

4 Minutes

Question 16

Combining a metal lon with a ligand reduces their tendency to bind to proteins, enzymes, or membranes. The degree to which they disassociate is a measure of their

Answer 16

Toxicity

Question 17

In a horizontal Field magnet what is the primary G’s for a sagittal slice

Answer 17

Gx

Question 18

when matrix goes up

Answer 18

the pixel goes down

Question 19

In spatial localization, the “logical” slice selection gradient is symbolized

Answer 19

Gz

Question 20

Information acquired when you increase or decrease the frequency of the RF pulse of the G’s, causing the center of the excited plane to change with the center of the G’s RF pulse is

Answer 20

Slice Position

Question 21

Decreasing the NEX

Answer 21

Decrease SNR and Resolution

Question 22

In a horizontal field magnet, what is the primary Gs for a Coronal slice

Answer 22

Gy

Question 23

In General, parameters for a T1 and T2 weighted images are as follows:

Answer 23

T1
TR 100-1000 ms
TE 20-30 ms

T2
TR 1600-3000 ms
TE 70-100 ms

Question 24

When selecting a volume of slices, which method for providing spatial encoding is employed

Answer 24

3DFT

Question 25

Who described the mathematical method for converting a time-varying signal into it's frequency components, which are used to obtain positional information from the MR signal

Answer 25

Jean Baptiste Joseph Fourier

Question 26

Decreasing matrix does what to pixel

Answer 26

Increases pixel

Question 27

The maximum exposure to the head and trunk from the main magnetic field (B0) is:

Answer 27

3T

Question 28

Patients with a pacemaker are contraindicated for an MRI scan in MR magnets with field strength of:

Answer 28

Any Strength

Question 29

Maximum exposure to the extremities from the main magnetic field (Bo) is:

Answer 29

5T

Question 30

Hazzards associated with ferromagnetic objects such as O2 tanks are contraindicated in MR magnets with field strengths of

Answer 30

Any Strength

Question 31

Passed through a strong magnetic field; aneurysm clips, sutures, and surgical clips can experience the force of:

Answer 31

Torque

Question 32

Painful peripheral nerve stimulation can be caused by

Answer 32

GMF

Question 33

Side effects of associated with the main magnetic field (Bo) are

Answer 33

Tissue heating and cataract formation.

Question 34

Acoustic noise is experienced during an MRI study and is caused by

Answer 34

GMF

Question 34

SAR is decided by coupling what type of electromagnetic energy employed in MRI to body tissue

Answer 34

RF

Question 34

an explosive boiling off of liquid helium and/or liquid nitrogen and a sudden loss of superconductivity is known as a

Answer 34

Quench

Question 34

Guidelines which exclude pregnant individuals from exposures to MRI are mainly to protect the individual from

Answer 34

Radio Frequency

Question 34

Maximum exposure to RF frequency averaged over the whole body is

Answer 34

no more than 0.4 w/kg

Question 34

Magnetically sensitive objects such as credit cards etc should be kept behind the ____ Gauss line

Answer 34

5

Question 35

Maximum exposure to RF in one gram of tissue is

Answer 35

a maximum spatial peak of 8 w/kg

Question 36

Side effects associated with gradient magnetic fields are

Answer 36

cardiac fibrillation, magnetophosphenes

Question 37

the factor which determines the calculated SAR average is

Answer 37

the patients weight in kilograms

Question 38

Conductive material in the MRI environment can be affected by electrical currents from

Answer 38

GMF and/or RF

Question 39

the safety rate index for MRI Gadollinium enhancement agent is

Answer 39

50

Question 40

the effects of main magnetic field inhomogeneites on the FID signal are corrected for in a spin-echo sequence by applying a second RF pulse. The flip angle of this RF pulse is

Answer 40

180 degrees

Question 41

an equation dervied to predict the MR signal intensity of a particular tissue as the result of a spin-echo pulse sequence is the

Answer 41

Bloch equation

Question 42

a 90 degree RF pulse will alter the NMV, a secondary effect is

Answer 42

the hydrogen protons will have phase coherence.

Question 43

the main magnetic field of MRI systems in clinical use must meet an acceptable specification of

Answer 43

20-30 PPM

Question 44

what type of electromagnetic coils correct inhomogeneites in the main magnetic field

Answer 44

shim coils

Question 45

the larmor frequency of hydrogen protons in a 1.5 Tesla magnetic field is

Answer 45

63.9MHz/Tesla

Question 45

T1 process is also known as

Answer 45

Spin Lattice

Question 46

the purpose of a magnetic resonance angiography is to image the

Answer 46

Blood flow

Question 47

Which type of MRI magnet requires a steady current of electricity in coils of conductor wrapped around an air or iron core?

Answer 47

resistive

Question 48

Magnetic susceptibility is defined as

Answer 48

tendency of a substance to attract or repel magnetic lines of force which is decided by the magnetic properties of its electrons

Question 49

in comparison to CT a disadvantage of MRI is that

Answer 49

special and costly site planning and shielding

Question 50

Fast transition phenomenon and entry phenomenon are theories that explain which of the following tissue characteristics

Answer 50

Velocity effects

Question 51

which type of electromagnetic coils can be found both inside and outside of the housing of the MRI magnet

Answer 51

RF coils

Question 52

In the USA, MRI systems in clinical use have main magnetic field strengths that range from

Answer 52

0.06 to 3 Tesla

Question 53

which type of receiver radio frequency coil is placed close to a patients body for the purpose of imaging superficial anatomic strucures

Answer 53

surface coils

Question 54

at any one time, human body tissue is made up primarily 50-90% of what tissue

Answer 54

H2O

Question 55

On a PD image two types of tissue that that contain very low concentrations of hydrogen and appear very hypointense are

Answer 55

cortical bone and lung

Question 56

the introduction of Gado based contrast enhancement agents by IV injection can involve passing through an abnormal BBB, the tissue compartments involved are

Answer 56

intravascular to interstitial space

Question 57

Once the NMV has moved away from equillibrium, the following will occur

Answer 57

the transverse component will increase

Question 58

The transmit radio frequency coil generates a second electromagnetic field to the hydrogen protons. this field is designated

Answer 58

B1

Question 59

which type of electromagnetic coils produce smaller magnetic field which allow spatial localization to be performed.

Answer 59

gradient coils

Question 60

the tissue characteristic that depends heavily on the relative content of fat molecules and free water is

Answer 60

T1 effects

Question 61

T2 process is also known as

Answer 61

Spin Spin

Question 62

which type of MRI magnet requires a special cooling system to dissipate heat produced by very large currents?

Answer 62

resistive

Question 63

In MR imaging for a chemical substance to be affected by the main magnetic field and the radio wave it must contain an

Answer 63

odd number of total protons and neutrons

Question 64

Magnetism can be defined as the ability of certain substances to attract

Answer 64

iron cobalt nicke

Question 65

a sinewave is a symbol used to measure electromagnetic energy. A sinewaves two components of measurements are

Answer 65

Wavelength and frequency

Question 66

The component Mz is most associated with

Answer 66

Parallel to Bo, T1 relaxation, longitudinal magnetization

Question 67

of the following RF flip angles which is the smallest that will produce the maximum signal.

Answer 67

90 degrees

Question 68

to describe the uniformity of the MRI systems main magnetic field, the term employed is

Answer 68

Homogeneity.