Mri Arrt Review 2013

Front 1

How many NEX are needed to maintain the SNR at 100% if the matrix is changed from 256 x 256 to 512 x 512?

Back 1

16

Front 2

On two dimensional acquisition the k-space is filled:

Back 2

All k-spaces are filled at the same time

Front 3

What would be the correct action to take if you realize that the patient inside the magnet has a ferromagnetic aneurism clip?

Back 3

Call the radiologist and emergency services and then slowly move the patient out of the magnet

Front 4

From the following parameters combination, which one will result in square pixels?

Back 4

256 x 512 matrix, 12 x 24 FOV

Front 5

Gradient recall echo is caracterized by:

Back 5

Using a gradient to rephase the protons

Front 6

In MRI, thin slices are achieved by applying a ______ gradient slope or a _____ bandwidth.

Back 6

Steep, Narrow

Front 7

Which of the following intrinsic contrast parameters is responsible for the contrast in a MR image?

Back 7

T1 relaxation

Front 8

Artifacts can cause:

Back 8

Unreadable images
Poor quality images
Readable images, but mimicking or masking pathology

Front 9

Isotopes are atoms that gain or loose:

Back 9

Neutrons

Front 10

Image data along both the phase and frequency axis with the lowest signal amplitude is stored in which area of the K space?

Back 10

Outer lines

Front 11

The process that uses mathematical conversions to calculate the amplitude of individual frequencies is known as ______

Back 11

Fast fourier transformation

Front 12

Which method is the most accurate when trying to rule out metal foreing bodies in the patient eyes?

Back 12

CT

Front 13

As the slice thickness increases the TOF phenomenon:

Back 13

Decreases

Front 14

Which gradients could be used for phase encoding in sagital image?

Back 14

Y or Z

Front 15

Gradient recall echo technique rephases the transverse magnetization ______ than the spin echo.

Back 15

faster

Front 16

What is the Farday's cage?

Back 16

used to prevent external RF to enter the MR suite

Front 17

Halving the receive bandwidth increases the SNR by:

Back 17

40%

Front 18

Which is the precessional frequency of hydrogen protons when are under a .2T magnet?

Back 18

8.6 MHz

Front 19

In a dual echo pulse sequence two different echoes are obtained. The early echo will produce an image with _______ contrast, and the late echo will produce an image with ______ contrast.

Back 19

PD, T2

Front 20

Cross talk and cross excitation can be reduce by:

Back 20

Using gaps between the slices

Front 21

FLAIR sequences are used to saturate:

Back 21

Free fluid

Front 22

What will be the effect of increasing the TR in the SNR?

Back 22

Increase

Front 23

Some of the advantages of the SE technique include:

Back 23

Good image quality
Very versatile
True T2 weighting

Front 24

RF shielding is achieved by:

Back 24

Lining the MR suite with cooper

Front 25

Gradient amplitude is:

Back 25

Strength of the gradient.

Front 26

What parameter combination will be the best to increase saturation effects (T1) in gradient echo pulse sequences?

Back 26

Decrease TR and increase flip angle

Front 27

acquires data from an entire volume of tissue, then uses a method called slice encoding to separate the images

Back 27

3D volumetric

Front 28

The frequency encoding gradient is also known as the ______ because it is turned on during the sampling of signal.

Back 28

Readout gradient

Front 29

pulse sequences will produce an image with higher SNR

Back 29

SE

Front 30

The main Source of magnetic field inhomogeneities are:

Back 30

Eddy currents

Front 31

In order to maximize T1 differences in GRE pulse sequences the best flip angle will be?

Back 31

90

Front 32

The gradient that is turned on just before the 180 degree rephasing pulse is known as the ______

Back 32

Phase encoding gradient

Front 33

The horizontal axis of K space represents which axis of the image?

Back 33

Frequency encoding

Front 34

Flow produced by a stenosis or stricture of the blood vessel is known as:

Back 34

Vortex flow

Front 35

The phase encoding gradient is turn on:

Back 35

Depending on the pulse sequence some time between the 90 RF and the collection of the echo

Front 36

How increasing the TE will affect the effects magnetic susceptibility on the image?

Back 36

Increase

Front 37

When the phase encoding gradient is activated, steep slopes produce what type of signal amplitude?

Back 37

Low

Front 38

What is the name of the equipment used to measure the strength of the magnetic field?

Back 38

Gauss meter

Front 39

STIR sequences are characterized by using:

Back 39

Short TI

Front 40

The gradient use for slice selection is the one that:

Back 40

Runs perpendicular to the slice

Front 41

In T2 weighted images free fluid appears _______ compared to fat tissues.

Back 41

Hiperintense

Front 42

The top portion of the k-space is a mirror of:

Back 42

Bottom

Front 43

Which of the following coil is used to improve the magnetic field homogeneity?

Back 43

Shim coil

Front 44

The process of filling only a percentage of K space with acquired data and filling the rest with zeros is known as _______

Back 44

Partial averaging

Front 45

In a 2DFT technique, the phase encoding gradient is used to change the phase along the:

Back 45

Short axis of the anatomy

Front 46

In what type of FOV and matrix combination is intravoxel dephasing is more prominent?

Back 46

Large FOV and low matrix

Front 47

During the acquisition of axial images of the body with the phase direction AP, frequency encoding is performed by which physical gradient?

Back 47

X gradient

Front 48

During half Fourier Technique:

Back 48

Only half of the k-space is fill

Front 49

Which is the carotid artery that arises straight from the aortic arch?

Back 49

LT common carotid artery

Front 50

The main source of degrading fat sat sequences is:

Back 50

Eddy currents

Front 51

EPI fills the k-space by rapidly switching the:

Back 51

Readout gradient from positive to negative

Front 52

Aliasing in the slice selection direction is seen in:

Back 52

3D acquisition

Front 53

GRE pulse sequences will allow to obtain bright signal from flowing protons. This is because:

Back 53

The rephasing gradient is not slice selected

Front 54

The time varying magnetic field is produce by:

Back 54

Gradients coils

Front 55

The magnitude of the phase shifts between two points within a patient is determined by which factor?

Back 55

Slope of the phase encoding gradient

Front 56

Compare to narrow transmitter bandwidth, a broader transmitter bandwidth will produce:

Back 56

Thicker slices

Front 57

Keeping all other parameters constant. Decreasing the slice thickness will ________ SNR.

Back 57

Decrease

Front 58

When the phase encoding gradient is activated, steep slopes produce data with what type of spatial resolution?

Back 58

High

Front 59

The degree of the net magnetization vector inversion is called:

Back 59

Flip angle

Front 60

Gradient slew rate is measured in:

Back 60

mT/m/s

Front 61

What will be the best choice in order to maximize T2 contrast on an image?

Back 61

Long TE

Front 62

The MR signal is recorded in:

Back 62

Transverse plane

Front 63

In MRS no images are obtained, the main reason for this is:

Back 63

Low number of hydrogens present on the aminoacids

Front 64

Possible conductors of Eddy currents include:

Back 64

Cryoshields
RF coils
Shim coils
Patient

Front 65

To minimize differences in T2 relaxation the best parameter selection will be:

Back 65

Short TE

Front 66

Doubling the NEX will increase SNR by:

Back 66

1.41

Front 67

Ernst angle

Back 67

The flip angle which produces the best SNR, for a given TR and tissue type

Front 68

The type of Shielding that uses metal isolation is call:

Back 68

Passive

Front 69

When imaging the wrist, the optimal plane in which to visualize the carpal tunnel is the:

Back 69

Axial

Front 70

Intra-voxel dephasing decreases as the TE :

Back 70

Decreases

Front 71

The range of frequencies that is sampled during frequency encoding is known as the ______

Back 71

Receive bandwidth

Front 72

Some characteristics of superconductive magnets include:

Back 72

High field homogeneity

Front 73

B1 is another name for:

Back 73

Radio frequency field

Front 74

The FDA allows the manufacturer to either maintain the SAR level less than or equal to:

Back 74

4 W/Kg

Front 75

The main purpose of reducing the fringe field is:

Back 75

Ancillary electronic equipment, credit cards and computer disks can be brought closer to the magnet

Front 76

Tissues that return faster to the longitudinal plane are said to have:

Back 76

Short T1 relaxation time

Front 77

T1 relaxation is a process characterized by:

Back 77

Energy been released

Front 78

When evaluating the female pelvis, the plane that best demonstrates the uterine anatomy is the:

Back 78

Sagittal

Front 79

used to cool down the superconductive magnets

Back 79

Helium

Front 80

In order to produce a T2* weighted images. What parameters combination will you select?

Back 80

Long TR, long TE, and small flip angle

Front 81

There are two ways of achieving homogeneity of the main magnetic field. What is the name for the one that uses electricity?

Back 81

Active

Front 82

The theorem that states that a frequency must be sampled at least twice in order to reproduce it reliably is known as the _______

Back 82

Nyquist theorem

Front 83

Intrinsic contrast parameters are those:

Back 83

Can not be manipulated by the MR technologist

Front 84

Quadrature coil can provide a __ % improvement in signal to noise ratio (SNR) when used to receive the MR signal.

Back 84

40

Front 85

As the strength of the main magnetic field increases the T1 relaxation time of the tissues:

Back 85

Increases

Front 86

What is the best way of reducing chemical shift artifact?

Back 86

Increasing receiver band width

Front 87

What will be the sequence of choice to detect Multiple Sclerosis?

Back 87

FLAIR

Front 88

Flow that is faster in the center of the blood vessel is known as:

Back 88

Laminar flow

Front 89

increasing the sampling time will force to:

Back 89

Increase the minimum TE

Front 90

The sequence of choice in order to detect small hemorrhages will be:

Back 90

GRE (gradient echo sequence)

Front 91

The best option to increase SNR and not affect other factors that influence image quality will be:

Back 91

Use the smallest possible coil that covers the anatomy of interest.

Front 92

SNR

Back 92

(signal-to-noise ratio)

Front 93

In MR, small electrical potentials have been observed in:

Back 93

Large blood vessels that flow perpendicular to the static magnetic filed

Front 94

Compare to narrow transmitter bandwidth, a broader transmitter bandwidth will produce:

Back 94

Thicker slices

Front 95

Between T1 and T2 relaxation. Which one happens faster?

Back 95

T2

Front 96

During T1 relaxation:

Back 96

Protons return to longitudinal magnetization

Front 97

If the slice thickness is increase from 5 to 10 mm:
Signal will?

Back 97

increase

Front 98

The islets of Langerhans are found in:

Back 98

Pancreas

Front 99

Fast gradient echoes pulse sequence have the advantage of:

Back 99

Reduce motion on the image
Acquire images where temporal resolution is required
Scan faster

Front 100

Increasing the FOV from 10 to 20 will increase SNR by:

Back 100

4

Front 101

The coil selected for a procedure will have a direct impact in the SNR of the image. The coil that will provide better SNR is:

Back 101

- The one that have more channels
- The one with the smallest size that covers the area of interest
- The one that is closer to the anatomy

Front 102

The sampling rate can be calculated with:

Back 102

Nyquist theorem

Front 103

The optimal plane to use when evaluating patients for cruciate ligament tears of the knee is the:

Back 103

Sagittal

Front 104

In Gradient Echo Pulse sequence which parameter combination will produce a T2* weighted image?

Back 104

Long TR, Long TE, 10 Flip Angle

Front 105

Gradient slew rate is:

Back 105

Strength of the gradient over distance

Front 106

In SE pulse sequence which parameter combination will produce a PD weighted image?

Back 106

2500 TR, 20 TE, 90 Flip Angle

Front 107

Tissues with short T2 relaxation time will appear__________ on T2 weighted images.

Back 107

Dark

Front 108

Keeping all other parameters constant, decreasing the slice thickness will ________ SNR.

Back 108

Decrease

Front 109

The conus medularis and the cauda equina in adult patients are best demonstrated by a:

Back 109

Sagittal image of the lumbar spine

Front 110

In a T2* image of the abdomen the liver will show ________ compared to the spleen.

Back 110

Hipointense

Front 111

The strength of the signal depends on:

Back 111

The degree of magnetization in the transverse plane

Front 112

The FDA limits the acoustic noise to a maximum of:

Back 112

140dB/dt

Front 113

Some of the major concerns with EPI (Echo-planar Imaging) pulse sequences are:

Back 113

Increase acoustic noise
Increase peripheral nerve stimulation
Increase image artifacts

Front 114

The FDA limits the effect of RF absorption to an increase in core body temperature of:

Back 114

1°C

Front 115

Chemical saturation can be used to saturate signal from:

Back 115

Fat
Water
Silicone

Front 116

Chemical saturation technique is achieved by applying:

Back 116

A 90° RF pulse at the beginning of the sequence to the tissues being saturated.

Front 117

The line of the k-space to be filled with data in a given TR is determined by:

Back 117

The polarity and slope of the phase gradient

Front 118

Balance gradient echo are utilize to reduce

Back 118

Phase dephasing due to flow

Front 119

Another name for Torque force is:

Back 119

Alignment force

Front 120

If the slice thickness is reduce by half, how many times do we need to increase the NEX to maintain the original SNR?

Back 120

4

Front 121

The slice thickness can be determine by:

Back 121

Transmitter bandwidth and slope of slice select gradient

Front 122

How many NEX are needed to maintain the SNR at 100% if the matrix is changed from 256 x 256 to 256 x 512?

Back 122

4

Front 123

Which method of image acquisition fills one line of K space for each slice in the sequence before it moves to the second line of K space?

Back 123

2D volumetric

Front 124

Which of the following pulse sequences will you select in order to reduce susceptibility artifact in patient that has a metallic implanted device in the area of interest?

Back 124

FSE (Fast Spin Echo)

Front 125

The renal arteries drain to:

Back 125

IVC (Inferior vena cava)

Front 126

The term used to describe a picture element is known as a ____

Back 126

Pixel

Front 127

What tissue will transfer energy faster?

Back 127

The one were molecules are closely pack

Front 128

Halfling the receive bandwidth increases the SNR by:

Back 128

40%

Front 129

In a spin echo pulse sequence which parameter combination will produce a T1 weighted image?

Back 129

500 TR, 10 TE, 90 Flip Angle

Front 130

T2 relaxation time is defined as when:

Back 130

63% of the transverse magnetization has decayed

Front 131

The MR signal is recorded in:

Back 131

Transverse plane

Front 132

Possible conductors of Eddy currents include:

Back 132

Patient
Shim coils
RF coils
Cryoshields

Front 133

the limit of the static magnetic field strength of clinical images

Back 133

80 000 G for children and adults = 8 teslas

Front 134

Proper patient screening should include which of the following?

Back 134

- The elimination of any loose metal objects and personal items
- The identification of any possible contraindications
- The identification of any biomedical implants

Front 135

For optimum operation of the MR system, the ambient temperature should be between:

Back 135

65° to 75°F

Front 136

The coil that will provide the best image quality is the one:

Back 136

More number of receiver channels
Closer to the anatomy of interest

Front 137

Hydrogen protons in high energy state are oriented in:

Back 137

Anti-parallel orientation

Front 138

When protons recieve a 90 RF pulse they are located:

Back 138

In the transverse plane in phase

Front 139

High field magnets are consider to be in a range of:

Back 139

1.5 to 3.0 T

Front 140

will increase Chemical shift effects

Back 140

Increasing the strength of the magnetic field

Front 141

Array coils:

Back 141

Use more than one coil to gather imaging data simultaneously

Front 142

In a horizontal magnet the X axis is located:

Back 142

Left to Right

Front 143

The main Source of magnetic field inhomogeneities are:

Back 143

Eddy currents

Front 144

an induced spurious electrical current produced by time-varying magnetic fields. Eddy currents can cause artifacts in images and may seriously degrade overall magnet performance.

Back 144

Eddy currents

Front 145

Which of the following coil is used to improve the magnetic field homogeneity?

Back 145

Shim coil

Front 146

B1 is another name for:

Back 146

Radio frequency field

Front 147

the ratio of signal intensity differences between two regions, scaled to image noise. Improving CNR increases perception of the distinct differences between two clinical areas of interest.

Back 147

CONTRAST-TO-NOISE RATIO (CNR

Front 148

an artifact introduced into images by interference between adjacent slices of a scan. This artifact can be eliminated by limiting the minimum spacing between slices.

Back 148

CROSSTALK

Front 149

a series of 180° RF rephasing pulses and their corresponding echoes for a Fast Spin Echo (FSE) pulse sequence.

Back 149

ECHO TRAIN

Front 150

a cooling agent, typically liquid helium or liquid nitrogen used to reduce the temperature of the magnet windings in a superconducting magnet.

Back 150

CRYOGEN

Front 151

the utilization of rapid gradient reversal pulses of the readout gradient resulting in a series of gradient echo signals to reduce fast dephasing or signal loss.

Back 151

ECHO PLANAR IMAGING (EPI)

Front 152

an electrically conductive screen or shield that reduces or eliminates interference between outside radio waves and those from the MRI unit.

Back 152

FARADAY SHIELD (Faraday Cage)

Front 153

Fluid Attenuated Inversion Recovery

Back 153

FLAIR

Front 154

Fast Low-Angle Recalled Echoes

Back 154

FLARE

Front 155

a mathematical procedure used in MRI scanners to analyze and separate amplitude and phases of the individual frequency components of the complex time varying signal.

Back 155

FOURIER TRANSFORM (FT)

Front 156

the process of locating an MR signal in one dimension by applying a magnetic field gradient along that dimension during the period when the signal is being received.

Back 156

FREQUENCY ENCODING

Front 157

a term usually relating to the extents of the magnetic field surrounding the magnet.

Back 157

FRINGE FIELD

Front 158

is a non-toxic paramagnetic contrast enhancement agent utilized in MR imaging.

Back 158

GADOLINIUM

Front 159

three paired orthogonal current-carrying coils located within the magnet which are designed to produce desired gradient magnetic fields which collectively and sequentially are superimposed on the main magnetic field (Bo) so that selective spatial excitation of the imaging volume can occur.

Back 159

GRADIENT COILS

Front 160

a constant for any given nucleus that relates the nuclear MR frequency and the strength of the external magnetic field.

Back 160

GYROMAGNETIC RATIO (g)

Front 161

uniformity of the main magnetic field.

Back 161

HOMOGENEITY

Front 162

an equation that states that the frequency of precession of the nuclear magnetic moment is directly proportional to the product of the magnetic field strength (Bo) and the gyromagnetic ratio (g).

Back 162

LARMOR EQUATION

Front 163

the frequency at which magnetic resonance in a nucleus can be excited and detected. The frequency varies directly with magnetic field strength, and is normally in the radio frequency (RF) range.

Back 163

LARMOR FREQUENCY

Front 164

number of excitations.

Back 164

NEX

Front 165

a loss of resolution due to excessively large voxels, typically caused by slices that are too thick.

Back 165

PARTIAL VOLUMING

Front 166

a term describing the degree to which precessing nuclear spins are synchronous.

Back 166

PHASE COHERENCE

Front 167

acronym for a picture element, the smallest discrete two-dimensional part of a digital image display.

Back 167

PIXEL

Front 168

a method of scanning in which the data is collected simultaneously from an entire layer.

Back 168

PLANAR IMAGING

Front 169

a positively charged particle located in the nucleus of an atom

Back 169

PROTON

Front 170

the concentration of mobile Hydrogen atoms within a sample of tissue.

Back 170

PROTON DENSITY

Front 171

magnetic field gradient applied during the period when the receiver components are on. The application of this gradient, which is active during the period when the echo is being formed, results in the frequency encoding of the object being imaged.

Back 171

READOUT GRADIENT

Front 172

a signal-to-noise improvement method that is accomplished by taking the average of several FIDs made under similar conditions. This is also referred to as the number of excitations (NEX) or the number of acquisitions.

Back 172

SIGNAL AVERAGING

Front 173

relates to the addition of phase encoding steps for 3D volumetric imaging.

Back 173

SLICE ENCODING

Front 174

the ability to define minute adjacent objects/points in an image, generally measured in line pairs per mm (lp/mm).

Back 174

SPATIAL RESOLUTION

Front 175

SPIN-LATTICE RELAXATION TIME

Back 175

T1 or Longitudinal Relaxation Time.

Front 176

SPIN-SPIN RELAXATION TIMe

Back 176

T2 and Transverse Relaxation Time.

Front 177

an image created typically by using short TE and TR times whose contrast and brightness are predominately determined by T1 signals.

Back 177

T1 WEIGHTED

Front 178

spin-spin or transverse relaxation time. The time constant for loss of phase coherence among spins oriented at an angle to the static magnetic field due to interactions between the spins. Results in a loss of transverse magnetization and the MRI signal.

Back 178

T2

Front 179

the time constant for loss of phase coherence among spins oriented at an angle to the static magnetic field due to a combination of magnetic field inhomogeneities and the spin-spin relaxation.

Back 179

T2* ("T-two-star")

Front 180

an image created typically by using longer TE and TR times

Back 180

T2 WEIGHTED

Front 181

a specialized imaging technique that uses computer processing to combine individual slice acquisitions together to produce an image that represents length, width and height. TI (Inversion Time) - the time between the initial (inverting) 180° pulse and the 90° pulse used in inversion recovery pulse sequences.

Back 181

THREE DIMENSIONAL IMAGING (3DFT)

Front 182

and MRA technique relying solely on the flow of unsaturated blood into a magnetized presaturated slice.

Back 182

TIME OF FLIGHT (TOF)

Front 183

an MRI surface coil that acts as both transmitter and receiver

Back 183

TRANSCEIVER COI

Front 184

the Fourier transformation process reconstructs the detected frequency and phase encoded image information (which are rotated 90° from each other) into a usable image.

Back 184

TWO-DIMENSIONAL IMAGING (2DFT)

Front 185

volume element; the element of the three-dimensional space corresponding to a pixel, for a given slice thickness.

Back 185

VOXEL

Front 186

the phenomenon resulting from digitizing fewer than two samples per period in a periodic function.

Back 186

ALIASING (WRAP AROUND ARTIFACT)

Front 187

the signal height.

Back 187

AMPLITUDE

Front 188

an all-inclusive term referring to the preselected band or range of frequencies which can govern both slice select and signal sampling.

Back 188

BANDWIDTH (BW)

Front 189

a series of rapidly recorded multiple images taken at sequential cycles of time and displayed on a monitor in a dynamic movie display format. This technique can be used to show true range of motion studies of joints and parts of the spine.

Back 189

CINE

Front 190

a large network of interconnecting blood vessels at the base of the brain that when visualized resembles a circle.

Back 190

CIRCLE OF WILLIS

Front 191

Magnetic suceptibility is:

Back 191

Ability of a substance to become magnetized

Front 192

Between T1 and T2 relaxation. Which one happens faster?

Back 192

T2

Front 193

During thermal equilibrium the magnetization is located in:

Back 193

In the longitudinal orientation

Front 194

Which pulse sequence increases the RF deposition the most?

Back 194

Fast Spin Echo

Front 195

In MRI Vector M is used to indicate

Back 195

Patient magnetization

Front 196

advantage of Spin Echo

Back 196

Reduce magnetic suceptibility

Front 197

What is used to prevent external RF to enter the MR suite

Back 197

Farday's cage

Front 198

T1 relaxation time is defined as when:

Back 198

63% of the longitudinal magnetization has regrow

Front 199

One of the advantages of the transmit-receive coil is:

Back 199

Decrease SAR (RF deposition on the patient)

Front 200

Bo is used in MRI to indicate:

Back 200

Main Magnetic Field

Front 201

Which of the followings is a characteristic of a magnet?

Back 201

Attract ferromagnetic material
Has a north and a south pole
Has magnetic lines

Front 202

The strenght of the signal depends on:

Back 202

The degree of magnetization in the transverse plane

Front 203

The T wave of the ECG represents which phase of the cardiac cycle?

Back 203

Ventricular diastole

Front 204

Gradient echo pulse sequences that eliminate leftover transverse magnetization are said to be what?

Back 204

Incoherent

Front 205

Noise that degrades image quality in a specific location within an MRI image is known as what?

Back 205

Discrete noise interference

Front 206

At a field strength of 1.0 tesla, the approximate T2 relaxation time for water is what?

Back 206

2500 ms

Front 207

Image data along both the phase and frequency axis with the highest signal amplitude is stored in which area of K space?

Back 207

Central lines

Front 208

The effects of time of flight and entry slice phenomena can be minimized by which method?

Back 208

Pre-saturation RF pulse

Front 209

At a field strength of 1.0 tesla, the approximate T2 relaxation time for CSF is what?

Back 209

300 ms

Front 210

Noise that generally degrades overall quality of an MRI image is known as what?

Back 210

Random noise interference

Front 211

During the sampling of signal, the sampling rate is directly proportional to what?

Back 211

Receive bandwidth

Front 212

The type of MRA that produces image contrast based on the differences in phase shifts between blood flow and stationary tissue is known as what?

Back 212

PC MRA

Front 213

The pulse sequence that performs a series of 180 degree rephasing pulses and echoes is known as what?

Back 213

Fast spin echo

Front 214

When image matrix increases, acquisition time ________

Back 214

Increases

Front 215

On a T1 weighted image of the brain, white matter appears________ to grey matter.

Back 215

Hyperintense

Front 216

The vascular imaging method that maximizes vascular contrast while also suppressing stationary tissue is known as what?

Back 216

Magnetic resonance angiography

Front 217

On a T1 weighted image of the knee, cortical bone appears to all other tissues.

Back 217

Hypointense

Front 218

When the number of excitations is increased, spatial resolution _______

Back 218

Stays the same

Front 219

Gradient moment nulling is most effective on which type of flow?

Back 219

Slow laminar flow Correct

Front 220

In a proton density weighted image, tissues with a high number of hydrogen nuclei appear _______

Back 220

Hyperintense

Front 221

At a field strength of 1.0 tesla, the approximate T2 relaxation time of fat is

Back 221

40 ms

Front 222

In a T2 weighted image, tissues with long T2 relaxation times appear ______

Back 222

Hyperintense

Front 223

The horizontal axis of K space represents which axis of the image?

Back 223

Frequency encoding

Front 224

Image data with high spatial resolution is stored in which area of K space?

Back 224

Outer lines

Front 225

As the echo time increases, the effects of time of flight phenomenon _______

Back 225

Increase

Front 226

The number of 180 degree rephasing pulses performed in a fast spin echo pulse sequence is known as its what?

Back 226

Turbo factor
Echo train length

Front 227

The number of picture elements used to make up an image is known as ______

Back 227

Matrix

Front 228

During the acquisition of axial images of the body with the frequency direction L/R, phase encoding is performed by which physical gradient?

Back 228

Y gradient

Front 229

When slice thickness is decreased, the effects of entry slice phenomenon _____

Back 229

Increase

Front 230

The depth of a volume element is determined by what parameter?

Back 230

Slice thickness

Front 231

The magnitude of intra-voxel dephasing is dependent upon which factor(s)?

Back 231

Degree of disruption in the flow

Front 232

Three characteristics commonly used to define the quality of an MRI image are ______

Back 232

Resolution, Contrast, Signal to noise

Front 233

When voxel size decreases, signal to noise ratio________

Back 233

Decreases

Front 234

The P wave of the ECG represents which phase of the cardiac cycle?

Back 234

Atrial systole

Front 235

In a T1 weighted image, tissues with long T1 relaxation times produce what type of signal?

Back 235

Low

Front 236

At a field strength of 1.0 Tesla, the approximate T2 relaxation time for blood is what?

Back 236

180 ms

Front 237

During cardiac gating, which of the following is the formula used to calculate available imaging time?

Back 237

Time = R-R interval - (trigger window + trigger delay)

Front 238

During cardiac gating, the waiting time between the R wave and the start of the data acquisition is known as what?

Back 238

Trigger delay

Front 239

At a field strength of 1.0 tesla, the approximate T1 relaxation time for spleen tissue is what?

Back 239

480 ms

Front 240

The gradient echo pulse sequence that is characterized by an echo time that is longer than its repetition time is known as what?

Back 240

Steady state free precession

Front 241

When the amplitude of the phase encoding gradient increases, the amount of phase shift along the gradient _________

Back 241

Increases

Front 242

The T wave of the ECG represents which phase of the cardiac cycle?

Back 242

Ventricular diastole

Front 243

Blood flow that has consistent velocities within a vessel is known as what type of flow?

Back 243

Laminar flow

Front 244

The area within the array processor where spatially located information is stored is known as _______

Back 244

K space

Front 245

In MRI, thick slices are achieved by applying a ______ gradient slope or a _____ bandwidth.

Back 245

Shallow, Broad

Front 246

During cardiac gating, one R-R interval and a short TE is used to produce what type of image?

Back 246

T1 weighting

Front 247

When the direction of blood flow is opposite the direction in which slices are acquired, the effects of entry slice phenomenon

Back 247

Increase

Front 248

The condition that occurs in a gradient echo pulse sequence when the TR is shorter than the T1 and T2 relaxation times of tissue is known as what?

Back 248

Steady state

Front 249

The type of signal that is created after a gradient is used to refocus the dephasing net vector is known as what?

Back 249

Gradient echo signal

Front 250

The theorem that states that a frequency must be sampled at least twice in order to reproduce it reliably is known as the _______

Back 250

Nyquist theorem

Front 251

the conventional technique used to produce a black appearance in vascular structures

Back 251

Short TE, Short TR, Pre-saturation pulse

Front 252

The effects of entry slice phenomenon are dependent upon which factor(s)?

Back 252

Repetition time
Slice thickness
Velocity of flow

Front 253

As blood flow velocity increases, the effects of time of flight phenomenon _____

Back 253

Increase

Front 254

The smaller the net magnetic vector in the transverse plane the ____the signal that is produced.

Back 254

Weaker

Front 255

The area of K space filled with the shallowest phase encoding slopes is known as ______

Back 255

Central lines

Front 256

Blood flow that receives a 90 degree excitation pulse but not a 180 degree rephasing pulse produces what type of signal?

Back 256

No signal

Front 257

The letters FID in an FID signal stand for what?

Back 257

Free induction decay

Front 258

Which of the following type of MRA uses a bipolar gradient to enhance vascular structures?

Back 258

Phase contrast MRA

Front 259

The method of acquiring more than one echo that are multiples of each other to reduce intra-voxel dephasing is known as what?

Back 259

Even echo rephasing

Front 260

Gradient echo pulse sequences that have incoherent residual transverse magnetization are primarily used to create what type of image weighting?

Back 260

T1 weighting
Proton density weighting

Front 261

As blood flow velocity decreases, the effects of time of flight phenomenon _____

Back 261

Decrease

Front 262

When field of view is increased, signal to noise ratio________

Back 262

Increases

Front 263

In TOF MRA, which method is used to suppress signal from stationary tissue?

Back 263

Saturation

Front 264

The type of pulse sequence that fills all lines of K space per TR is known as what?

Back 264

Echo planar

Front 265

The height and width of a picture element is determined by what parameter(s)?

Back 265

Number of phase encoding steps
Size of the FOV
Number of frequency encoding steps

Front 266

Which of the following is the formula for determining scan time for a 3D FT pulse sequence?

Back 266

TR x NEX x phase steps x number of slices

Front 267

On a T2 weighted image of the brain, CSF appears _______ to grey matter.

Back 267

Hyperintense

Front 268

The gradient that is turned on just before the 180 degree rephasing pulse is known as the ______

Back 268

Phase encoding gradient

Front 269

Typical peak velocities of the vertebral and basilar arteries are usually within what range?

Back 269

30-50 cm/sec

Front 270

Blood flow velocity is measured in what type of unit?

Back 270

cm/sec

Front 271

Which of the following is a parameter that directly affects signal to noise ratio?

Back 271

Voxel size
Number of excitations
Repetition time

Front 272

The type of MRA that uses gradient echo pulse sequences and gradient moment nulling to enhance flow is known as

Back 272

TOF MRA

Front 273

During the sampling of signal, the sampling time is inversely proportional to what?

Back 273

Sampling rate
Receive bandwidth

Front 274

In a T2 weighted image, fat has a _______ T2 relaxation time and therefore appears_______

Back 274

Short, Dark

Front 275

The number of times each signal is sampled with the same value of the phase encoding gradient is known as ______

Back 275

Number of signal averages
Number of excitations
Number of signal quotients

Front 276

During a fast spin echo pulse sequence, which lines of k space are filled by the gradients performed closest to the effective TE?

Back 276

Central lines

Front 277

When TR is increased, acquisition time ________

Back 277

Increases

Front 278

Which Parameter(s) effect total scan time?

Back 278

Repetition time
Number of phase encoding steps
Number of excitations

Front 279

At a field strength of 1.0 tesla, the approximate T1 relaxation time for CSF is what?

Back 279

2000 ms

Front 280

The X gradient alters the magnetic field strength along which axis?

Back 280

Horizontal axis

Front 281

Which of the following is a method used in MRA to increase signal from vascular structures?

Back 281

Gradient moment nulling
Bipolar gradient

Front 282

In a gradient echo pulse sequence, blood flow that receives the initial RF pulse produces what type of signal?

Back 282

High

Front 283

At a field strength of 1.0 tesla, the approximate T1 relaxation time for water is what?

Back 283

2500 ms

Front 284

MRI images that are based on the differences in the amount of hydrogen nuclei in tissues are known as what?

Back 284

Proton density weighted images

Front 285

On a T2 weighted image of the brain, grey matter appears _______ to white matter.

Back 285

Hyperintense

Front 286

Which of the following is an advantage of TOF MRA?

Back 286

Increased sensitivity to flow
Relatively short scan times
Decreased sensitivity to intra-voxel dephasing

Front 287

The type of spin echo pulse sequence that begins with a 180 degree inversion RF pulse and is followed by a 90 degree excitation pulse is known as what?

Back 287

Inversion recovery

Front 288

In a RARE pulse sequence, the multiple number of echo times that create image weighting are averaged together to produce what is known as the what?

Back 288

Effective TE

Front 289

During the acquisition of axial images of the brain with the phase direction L/R, frequency encoding is performed by which physical gradient?

Back 289

Y gradient

Front 290

The ability to distinguish one structure from another on an image is known as ______

Back 290

Spatial resolution

Front 291

Which of the following is the formula that is used to calculate blood flow velocity?

Back 291

Flow volume + vessel area

Front 292

At a field strength of 1.0 tesla, the approximate T2 relaxation time of liver tissue is what?

Back 292

50 ms

Front 293

Typical peak velocities of the distal aorta and iliac vessels are usually within what range?

Back 293

100 - 160 cm/sec

Front 294

The spin echo pulse sequence that performs more than one phase encoding step per TR is known as what?

Back 294

Fast spin echo
RARE

Front 295

The series of 180 degree rephasing pulses in a fast spin echo pulse sequence is known as what?

Back 295

Echo train

Front 296

The signal produced after the 180 degree RF pulse is applied is known as what?

Back 296

Spin echo signal

Front 297

Bright pixels on an MRI image represent what type of signal?

Back 297

High

Front 298

The center of the magnet where the magnetic field strength remains unchanged even during the application of gradient magnetic fields is known as the_______.

Back 298

Isocenter

Front 299

The use of an additional gradient to correct the effects of intra-voxel dephasing is a technique known as what?

Back 299

Gradient moment rephasing
Gradient moment nulling

Front 300

With the parameters given, which protocol gives the highest spatial resolution?

Back 300

Thin slice/Small FOV/High matrix

Front 301

Which of the following is a disadvantage of fast spin echo pulse sequences?

Back 301

Increased effects of flow motion
Bright fat on T2 weighted images

Front 302

Which of the following is a method used in MRA to suppress stationary tissue?

Back 302

Tissue subtraction
Tissue saturation

Front 303

Which of the following logical gradients is known as the phase encoding gradient?

Back 303

Y gradient

Front 304

the conventional technique used to produce a bright appearance in vascular structures

Back 304

Gradient moment nulling

Front 305

When slice thickness is increased, the effects of entry slice phenomenon _____

Back 305

Decrease

Front 306

The image parameter that primarily affects T1 weighting is known as what?

Back 306

Repetition time

Front 307

Which method of image acquisition fills one line of K space for each slice in the sequence before it moves to the second line of K space?

Back 307

2D volumetric

Front 308

The gradient that is turned on during signal sampling is known as the ______

Back 308

Frequency encoding gradient

Front 309

The clarity with which different areas of an image are distinguished is known as _______

Back 309

Spatial resolution

Front 310

When TE is decreased, the spatial resolution.

Back 310

Stays the same

Front 311

Volume averaging artifact can be reduced by

Back 311

Decreasing slice thickness

Front 312

The method of MRI field containment that uses additional magnets outside the cryogenic area of the magnet is known as what?

Back 312

Active shielding

Front 313

In MR imaging, the inter slice gap is determined by which factor(s)?

Back 313

Slice selection gradient slope
Slice thickness

Front 314

The artifact that is produced when anatomy that is outside the FOV is mapped within the FOV is known as what?

Back 314

Aliasing

Front 315

The time it takes for a tissue's bulk longitudinal magnetization to return to 63% of its original value is known as what?

Back 315

T1 relaxation time

Front 316

The type of signal that is created after a gradient is used to refocus the dephasing net vector is known as what?

Back 316

Gradient echo signal

Front 317

The wire used in the main magnetic field of a superconducting magnet has its resistance removed by cooling it to a temperature of what?

Back 317

-452 degrees Fahrenheit

Front 318

Dephasing of the net vector in the transverse plane is caused by two factors, imperfections in the external magnetic field and what?

Back 318

Interaction between surrounding nuclei

Front 319

The proportion of signal actually used to construct an image relative to the amount of background noise is known as what?

Back 319

Signal to noise ratio

Front 320

Which of the following is an advantage of using a resistive magnet for clinical MRI?

Back 320

Low capital cost

Front 321

With the exception of hydrogen, all matter is composed of three components. They are what?

Back 321

Neutrons, Electrons, Protons

Front 322

At a field strength of 1.0 tesla, the approximate T1 relaxation time of fat is what?

Back 322

180ms

Front 323

During the acquisition of coronal images with the frequency direction S/I phase encoding is conducted by which physical gradient?

Back 323

X gradient

Front 324

The RF pulse used to move nuclei into a higher energy state is at a frequency known as what?

Back 324

Resonance frequency

Front 325

Which of the following three characteristics are commonly used to define the quality of an MRI image?

Back 325

Resolution, Contrast, Signal to noise

Front 326

There are how many pairs of gradient coils in a standard MRI system?

Back 326

3 pairs

Front 327

To decrease the chances of cross excitation there should be at least what percentage of interslice gap?

Back 327

30%

Front 328

Image data with high spatial resolution is stored in which area of K space?

Back 328

Outer lines

Front 329

In biological tissue, which type of relaxation occurs the quickest?

Back 329

T2* relaxation

Front 330

Which method of image acquisition acquires all of the data from one slice before acquiring data from the next slice?

Back 330

Sequential

Front 331

Another name for T1 relaxation is what?

Back 331

Longitudinal relaxation

Front 332

The difference in brightness between two regions of an image is known as what?

Back 332

Image contrast

Front 333

Magnetic susceptibility artifact can be used to help diagnose what pathology?

Back 333

Hemorrhage

Front 334

After being placed in an external magnetic field, low energy hydrogen nuclei point in which direction?

Back 334

Parallel

Front 335

When the phase encoding gradient is activated, steep slopes produce data with what type of spatial resolution?

Back 335

High

Front 336

Which imaging parameter affects the amount of chemical misregistration that will be seen on an image?

Back 336

TE

Front 337

At a field strength of 1.0 tesla, the approximate T1 relaxation time for white matter is what?

Back 337

390 ms

Front 338

The vertical axis of K space represents which axis of the image?

Back 338

Phase encoding

Front 339

The process during prescan that fine tunes the resonant frequency is known as what?

Back 339

Center frequency adjustment

Front 340

A 180 degree RF pulse is used to ______ the dephasing net vector in the transverse plane.

Back 340

Refocus

Front 341

The smaller the net magnetic vector in the transverse plane, the ____ the signal that is produced.

Back 341

Weaker

Front 342

Material that is slightly repelled from a magnetic field is said to be what?

Back 342

Diamagnetic

Front 343

What type of molecule makes up 50% to 90% of a person's total body weight?

Back 343

Water

Front 344

The thickness of an MRI image can be changed by which of the following methods?

Back 344

Altering the gradient slope
Altering the RF bandwidth

Front 345

In a T2 weighted image, tissues with short T2 relaxation times appear_______.

Back 345

Hypointense

Front 346

Chemical misregistration artifact is most likely to affect which type of pulse sequence?

Back 346

Gradient echo pulse sequences

Front 347

The process during the prescan that determines the amount of signal that is received is known as what?

Back 347

Receive attenuation adjustment

Front 348

In a T2 weighted image, CSF has a ________ T2 relaxation time and therefore appears _______.

Back 348

Long, Bright

Front 349

Image data with low spatial resolution is stored in which area of K space?

Back 349

Central lines

Front 350

The area of K space that is filled with the steepest phase encoding gradient slopes is known as what?

Back 350

Outer lines

Front 351

The image parameter that primarily affects T1 weighting is known as what?

Back 351

Repetition time

Front 352

The artifact that is caused due to the difference in precessional frequencies between fat and water is called what?

Back 352

Chemical shift

Front 353

The device used to store and transport cryogenic liquids is known as a what?

Back 353

Dewar

Front 354

A volume element that has the same height, width, and depth is known as what?

Back 354

Isotropic

Front 355

An artifact caused by faulty receiver attenuation settings during prescan is known as what?

Back 355

Data clipping

Front 356

The time that both fat and water are in phase with each other is known as what?

Back 356

Periodicity

Front 357

The center of the magnet where the magnetic field strength remains unchanged even during the application of gradient magnetic fields is known as what?

Back 357

Isocenter

Front 358

An image artifact caused by anatomical motion along a gradient is known as what type of artifact?

Back 358

Phase mismapping

Front 359

Materials reach their highest magnetic potential when their atoms are grouped in areas known as what?

Back 359

Domains

Front 360

Chemical shift artifact occurs in which direction of the MR image?

Back 360

Frequency encoding direction

Front 361

At a field strength of 1.0 tesla, the approximate T1 relaxation time for muscle tissue is what?

Back 361

600 ms

Front 362

The number of times each signal is sampled with the same value of the phase encoding gradient is known as what?

Back 362

Number of signal averages
Number of excitations
Number of signal quotients

Front 363

This materials is most commonly used to produce a permanent magnet

Back 363

Aluminum-Nickel-Cobalt alloy

Front 364

The signal produced after the 180 degree RF pulse is applied is known as what?

Back 364

Spin echo signal

Front 365

Cross excitation artifact can be eliminated by which of the following methods?

Back 365

Increasing interslice gap
Using a digital RF pulse
Interleaving

Front 366

The type of magnet that is produced by permanently magnetizing a ferromagnetic substance is known as a what?

Back 366

Permanent magnet

Front 367

Coils used to imperfections in the magnetic field are known as what?

Back 367

Shim coils

Front 368

A voxel that is unequal in height, width, and depth is known as what?

Back 368

Anisotropic

Front 369

The ability to distinguish one structure from another on an image is known as what?

Back 369

Spatial resolution

Front 370

Another name for aliasing artifact is what?

Back 370

Foldover artifact
Wraparound artifact

Front 371

Wraparound artifact caused by undersampling of frequencies in the readout direction is known as what?

Back 371

Frequency wrap

Front 372

During the acquisition of axial images of the brain with the frequency direction A/P, phase encoding is performed by which physical gradient?

Back 372

X gradient

Front 373

The law that is used in MRI to describe how a magnetic field is induced by flowing current is known as what?

Back 373

Faraday's Law

Front 374

During slice selection, the Y gradient is used to select slices in which plane?

Back 374

Coronal

Front 375

The computer that performs the complex calculations necessary to reconstruct MRI images is known as the what?

Back 375

Array processor

Front 376

At a field strength of 1.0 tesla, the approximate T2 relaxation time for grey matter is what?

Back 376

100 ms

Front 377

The height and width of a picture element is determined by what parameter(s)?

Back 377

Size of the FOV
Number of phase encoding stepsw~
Number of frequency encoding steps

Front 378

The time it takes for a gradient coil to reach its peak strength is known as its what?

Back 378

Rise time

Front 379

Which of the following logical gradients is known as the slice selection gradient?

Back 379

Z gradient

Front 380

MRI images that are based on the differences in the transverse relaxation characteristics of tissues are known as what?

Back 380

T2 weighted images

Front 381

The ratio that describes the constant at which any magnetic nucleus will precess in a 1 tesla magnet is known as what?

Back 381

Precessional ratio
Gyromagnetic ratio

Front 382

When a patient is placed in an external magnetic field, the number of unmatched hydrogen protons usually equals how many?

Back 382

Few per million

Front 383

During the acquisition of axial images of the brain with the phase direction L/R, frequency encoding is performed by which physical gradient?

Back 383

Y gradient

Front 384

The stronger the magnetic field the ________ the precessional frequency.

Back 384

Higher

Front 385

At a field strength of 1.0 tesla, the approximate T1 relaxation time for renal cortex tissue is what?

Back 385

360 ms

Front 386

Three types of ferromagnetic material are include which of the following?

Back 386

Iron, Cobalt, Nickel

Front 387

The equation that is used to determine the precessional frequency of magnetic nuclei is known as what?

Back 387

Larmor equation

Front 388

Coils that are used to transmit and receive radio frequencies are known as what?

Back 388

RF coils

Front 389

The homogeneity of the external magnetic field is measured in what type of unit?

Back 389

Parts per million

Front 390

At a field strength of 1.0 tesla, the approximate T2 relaxation time for spleen tissue is what?

Back 390

80 ms

Front 391

The process of filling only a percentage of K space with acquired data and filling the rest with zeros is known as what?

Back 391

Partial averaging

Front 392

When the radio frequency is turned off, precessing nuclei begin to display what type of behavior?

Back 392

Relax
Lose energy
Dephase

Front 393

Gradient moment nulling is most effective in reducing flow related motion in which type of flow?

Back 393

Slow flow
Inplane flow

Front 394

In an inversion recovery pulse sequence, the time between the 180 degree RF pulse and the 90 degree RF pulse is known as what?

Back 394

Inversion time

Front 395

A spin echo image with a long TR and a long TE is known as what type of image?

Back 395

T2 weighted image

Front 396

The wire used to create the main magnetic field in a superconducting magnet is known as what?

Back 396

Niobium-Titanium

Front 397

The precessional frequency of magnetic nuclei is determined by which of the following?

Back 397

The strength of the external magnetic field
The gyromagnetic ratio of the specific nuclei

Front 398

Which of the following is an example of phase mismapping artifact?

Back 398

Cardiac motion
Flow motion
Respiratory motion

Front 399

When the proper radio frequency is applied, the precessing hydrogen nuclei begin to display which type of behavior?

Back 399

Resonate

Front 400

In plane pixel size can be determined by which of the following methods?

Back 400

Dividing the FOV by the number phase and frequency steps

Front 401

The depth of a volume element is determined by what parameter?

Back 401

Slice thickness

Front 402

Dephasing of the net vector in the transverse plane is known as what?

Back 402

Spin-Spin relaxation

Front 403

The rule that is used to determine the direction of the magnetic field in an electromagnet is known as what?

Back 403

Right hand thumb rule

Front 404

The range of frequencies that is sampled during frequency encoding is known as what?

Back 404

Receive bandwidth

Front 405

How many milliseconds are there in a minute?

Back 405

60,000

Front 406

The technique used to eliminate cross excitation artifact that acquires data in two separate acquisitions from alternating slices is known as what?

Back 406

Interleaving

Front 407

Gradient strength is measured in what form of unit?

Back 407

Gauss per centimeter
Millitesla per meter

Front 408

The time it takes for transverse magnetization to decay to 37% of its original value is known as what?

Back 408

T2 relaxation time

Front 409

At a field strength of 1.0 tesla, the approximate T1 relaxation time for CSF is what?

Back 409

2000 ms

Front 410

Magnetization in the transverse plane can also be known as what?

Back 410

Mxy
Mo

Front 411

In clinical MRI, the homogeneity of the magnet should be at least what?

Back 411

10 parts per million

Front 412

Alignment of the net magnetic vector in the direction of the external magnetic field is known as what?

Back 412

Longitudinal magnetization
Equilibrium

Front 413

In an MR image, the degree of chemical shift artifact depends upon which parameter?

Back 413

Receive bandwidth
Size of the FOV
Magnetic field strength

Front 414

The amplitude of the phase and frequency encoding gradients determines the dimension of what parameter?

Back 414

FOV

Front 415

In a proton density weighted image, tissues with a high number of hydrogen nuclei appear _______.

Back 415

Hyperintense

Front 416

Which Parameter(s) effect total scan time?

Back 416

Repetition time
Number of phase encoding steps
Number of excitations

Front 417

The area within the array processor where spatially located information is stored is known as what?

Back 417

K space

Front 418

15,000 gauss is equal to what?

Back 418

1.5 tesla

Front 419

Which of the following logical gradients is known as the phase encoding gradient?

Back 419

Y gradient

Front 420

In fat, the hydrogen atom is bound with what other type of atom?

Back 420

Carbon

Front 421

Prior to each scan, the process of prescanning performs which type of calibration?

Back 421

Adjusts the transmit gain
Adjusts the receive attenuation
Sets the center frequency

Front 422

During the acquisition of sagittal images with the frequency direction S/I, phase encoding is conducted by which physical gradient?

Back 422

Y gradient

Front 423

The Z gradient alters the magnetic field strength along which axis?

Back 423

Long axis

Front 424

When the phase encoding gradient is activated, shallow slopes produce what type of signal amplitude?

Back 424

High

Front 425

On a T1 weighted image of the knee, bone marrow appears to meniscal tissues.

Back 425

Hyperintense

Front 426

A saturation pulse is a technique used to reduce what type of motion artifact?

Back 426

Blood flow motion
Respiratory motion
Swallowing motion

Front 427

Which method of image acquisition acquires data from an entire volume of tissue, then uses a method called slice encoding to separate the images?

Back 427

3D volumetric

Front 428

The time between the 90 degree RF pulse and the spin echo signal in a spin echo pulse sequence is known as what?

Back 428

Echo time

Front 429

The area of K space filled with the shallowest phase encoding slopes is known as what?

Back 429

Central lines

Front 430

The precessional frequency of hydrogen nuclei that experience increased magnetic field strength due to gradient coils ________.

Back 430

Increases

Front 431

The type of coils used to change the strength of the magnetic field inside the bore of the magnet are known as what?

Back 431

Gradient coils

Front 432

Another name for a proton density weighted image is what?

Back 432

Spin density
Intermediate

Front 433

The process of filling K space by sampling only half of the echo and interpolating the rest is known as what?

Back 433

Fractional echo
Partial echo

Front 434

Data loss due to gradient instability, excessive noise, or tuning errors can cause an artifact with what type of appearance?

Back 434

Herringbone

Front 435

The strength of a magnet is measured by its what?

Back 435

Flux density

Front 436

The range of frequencies that is transmitted by the RF pulse is known as what?

Back 436

Transmit bandwidth

Front 437

The gradient that is turned on during signal sampling is known as what?

Back 437

Frequency encoding gradient

Front 438

The sum of all of the unmatched parallel protons in an external magnetic field makes up what is called the what?

Back 438

Net magnetic vector

Front 439

The device in the MRI system that supplies power to the gradient coils is known as the what?

Back 439

Gradient amplifier

Front 440

Isolating the RF transmitter from the RF receiver is known as what?

Back 440

Decoupling

Front 441

The term used to describe a volume element is known as what?

Back 441

Voxel

Front 442

Another name for phase mismapping artifact is what?

Back 442

Ghosting

Front 443

Chemical misregistration artifact most commonly occurs in which direction of the MR image?

Back 443

Phase encoding direction

Front 444

the movement of molecules in the extra-cellular space due to random thermal motion.

Back 444

Diffusion

Front 445

an imaging technique that displays a frequency spectrum of differences between various elements within tissues. This techniques is commonly utilized to measure the amount of a specific element that is within the tissue.

Back 445

Spectroscopy

Front 446

In diffusion weighted imaging, tissues with a low apparent diffusion coefficient have what type of signal intensity?

Back 446

Hyperintense

Front 447

The term _____________ is defined as the volume of blood that flows into one gram of tissue.

Back 447

Perfusion

Front 448

While ligaments, membranes, and macromolecules are all common boundaries that restrict motion within the extra-cellular space, _________ is not one of these boundaries.

Back 448

Microfibers

Front 449

In diffusion weighted imaging, tissues with a high apparent diffusion coefficient have what type of signal intensity?

Back 449

Hypointense

Front 450

Which of the following terms is used to describe the net displacement of molecules diffusing across an area of tissue per second?

Back 450

Apparent Diffusion Coefficient

Front 451

Which MR imaging techniques creates image contrast by enhancing magnetic susceptibility differences between various tissues?

Back 451

Susceptibility Weighted Imaging

Front 452

In MR spectroscopy, which of the following is an element commonly found in the proton spectra of human tissue?

Back 452

Creatine
Glutamine
Choline

Front 453

Which MR imaging techniques is utilized to image activity within the brain caused by stimulus?

Back 453

Functional

Front 454

Which of the following is a method utilized in MR spectroscopy to locate a spectrum of elements?

Back 454

Multi-Voxel
Single Voxel

Front 455

Which is a diffusion weighted imaging technique that is utilized to map the white matter tracks within the brain?

Back 455

Diffusion Tensor Imaging

Front 456

In diffusion weighted imaging, the b-value is expressed in what unit of measurement?

Back 456

s/mm2 ( seconds per millimeters squared)

Front 457

In functional MRI, which physiological effects is utilized to measure variations in signal intensity between areas of the brain experiencing stimuli versus areas at rest?

Back 457

Blood Oxygenation Level Dependent or (BOLD)

Front 458

During the acquisition of sagittal images with the phase direction A/P, frequency encoding is performed by which physical gradient?

Back 458

Z gradient

Front 459

Typical peak velocities of the ascending aorta are usually within what range?

Back 459

150-175 cm/sec

Front 460

The speed at which blood flows through an excited slice and only receives one RF pulse is known as what type of phenomenon?

Back 460

Time of flight phenomenon

Front 461

When TR is decreased, the effects of entry slice phenomenon ______

Back 461

Decrease

Front 462

In a T2 weighted image, a long TE is used to do what?

Back 462

Maximize T2 effects

Front 463

The process of filling K space by sampling only half of the echo and interpolating the rest is known as _______

Back 463

Fractional echo
Partial echo

Front 464

MRI images that are based on the differences in the transverse relaxation characteristics of tissues are known as what?

Back 464

T2 weighted images

Front 465

A 180 degree RF pulse is used to ______ the dephasing net vector in the transverse plane.

Back 465

Refocus

Front 466

In a gradient echo pulse sequence, the process of eliminating residual transverse magnetization is known as what?

Back 466

Spoiling

Front 467

In which of the following types of flow can intra-voxel dephasing be compensated for?

Back 467

Laminar flow

Front 468

The area of K space that is filled with the steepest phase encoding gradient slopes is known as _______

Back 468

Outer lines

Front 469

Which of the following methods can reduce blurring in a fast spin echo pulse sequence?

Back 469

Reduce echo train length

Front 470

At a field strength of 1.0 tesla, the approximate T2 relaxation time for renal cortex tissue is _______

Back 470

70 ms

Front 471

The flow phenomenon that is characterized by phase differences between flowing and stationary nuclei within a voxel is known as ______

Back 471

Intra-voxel dephasing

Front 472

TOF MRA is most sensitive to blood flow that flows in what direction in relation to the slice?

Back 472

Perpendicular

Front 473

In conventional spin echo pulse sequences, how many phase encoding steps are achieved per TR?

Back 473

1

Front 474

When the number of excitations is decreased, acquisition time________

Back 474

Decreases

Front 475

At a field strength of 1.0 tesla, the approximate T1 relaxation time for muscle tissue is what?

Back 475

600 ms

Front 476

During slice selection, the X gradient is used to select slices in which plane?

Back 476

Sagittal

Front 477

In conventional spin echo pulse sequences, how many lines of K space are filled per TR?

Back 477

1

Front 478

The time between the 90 degree RF pulse and the spin echo signal in a spin echo pulse sequence is known as what?

Back 478

Echo time

Front 479

The signal created after applying a 90 degree RF pulse is known as what?

Back 479

FID Signal

Front 480

In an echo planar pulse sequence, proton density weighting can be produced by which of the following techniques?

Back 480

Using a short TE

Front 481

The three primary functions that gradients perform during MR scanning are known as what?

Back 481

Slice selection, Phase encoding, Frequency encoding

Front 482

A spin echo image with a long TR and a long TE is known as what type of image?

Back 482

T2 weighted image

Front 483

At a field strength of 1.0 Tesla, the approximate T1 relaxation time for blood is what?

Back 483

800 ms

Front 484

The time between two successive 90 degree RF pulses is known as what?

Back 484

Repetition time

Front 485

Entry slice phenomenon is most prominent in what slice of the area scanned?

Back 485

Affects all the same

Front 486

Advantages of phase contrast MRA

Back 486

Increased stationary tissue suppression
Sensitive to flow in all directions
Sensitive to flow with various velocities

Front 487

In MRI, thin slices are achieved by applying a ______ gradient slope or a _____ bandwidth.

Back 487

Steep, Narrow

Front 488

Blood flow velocity at a given point is dependent upon which factor?

Back 488

Phase of patient's cardiac cycle

Front 489

Blood flow that has high velocities in the center of the vessel but spirals near walls of a vessel due to a stricture is known as what type of flow?

Back 489

Vortex flow

Front 490

As bandwidth increases, sampling time ______

Back 490

Decreases

Front 491

Which method of image acquisition acquires all of the data from one slice before acquiring data from the next slice?

Back 491

Sequential

Front 492

In MR imaging, the inter slice gap is determined by which factor(s)?

Back 492

Slice selection gradient slope
Slice thickness

Front 493

In conventional spin echo sequences, how many phase encoding steps must be selected to fill 256 lines of K space?

Back 493

256

Front 494

Which method of image acquisition acquires data from an entire volume of tissue, then uses a method called slice encoding to separate the images?

Back 494

3D volumetric

Front 495

Image data along both the phase and frequency axis with the lowest signal amplitude is stored in which area of the K space?

Back 495

Outer lines

Front 496

At a field strength of 1.0 tesla, the approximate T2 relaxation time for renal medulla tissue is what?

Back 496

140ms

Front 497

Another name for a proton density weighted image is ______

Back 497

Spin density
Intermediate

Front 498

The Y gradient alters the magnetic field strength along which axis?

Back 498

Vertical axis

Front 499

The magnitude of time of flight phenomenon effects is dependent upon which factor(s)?

Back 499

Velocity of flow
TE
Slice thickness

Front 500

Which of the following TOF MRA sequences is most likely to saturate slow flow?

Back 500

3D TOF

Front 501

Which of the following is a disadvantage of phase contrast MRA?

Back 501

Long scan times
Increased sensitivity to turbulence

Front 502

At a field strength of 1.0 tesla, the approximate T1 relaxation time of liver tissue is what?

Back 502

390 ms

Front 503

When image matrix is decreased, spatial resolution _______

Back 503

Decreases

Front 504

The type of pulse sequence that uses only 90 degree RF pulses is known as what?

Back 504

Partial saturation pulse sequence
Gradient echo pulse sequence

Front 505

During cardiac gating, the time between two consecutive R waves is known as what?

Back 505

R-R interval

Front 506

The amplitude of the phase and frequency encoding gradients determines the dimension of what parameter?

Back 506

FOV

Front 507

On a T1 weighted image of the spine, the intervertebral disk appears to spinal cord.

Back 507

Hypointense

Front 508

During an inversion recovery pulse sequence, the time between the 180 degree inversion pulse and the 90 degree excitation pulse is known as what?

Back 508

Inversion time

Front 509

As slice thickness increases, the effects of time of flight phenomenon _______

Back 509

Decrease

Front 510

Image data with low spatial resolution is stored in which area of K space?

Back 510

Central lines

Front 511

The precessional frequency of hydrogen nuclei that experience decreased magnetic field strength due to gradient coils_______

Back 511

Decreases

Front 512

During slice selection, the Y gradient is used to select slices in which plane?

Back 512

Coronal

Front 513

The vertical axis of K space represents which axis of the image?

Back 513

Phase encoding

Front 514

In plane pixel size can be determined by which of the following methods?

Back 514

Dividing the FOV by the number phase and frequency steps

Front 515

The Z gradient alters the magnetic field strength along which axis

Back 515

Long axis

Front 516

SSFP

Back 516

Steady-state free precession

Front 517

FFE

Back 517

Fast Field Echo

Front 518

A spin echo image with a long TR and a short TE is known as what type of image?

Back 518

Proton density weighted image

Front 519

At a field strength of 1.0 tesla, the approximate T2 relaxation time for white matter is what?

Back 519

90 ms

Front 520

In a proton density weighted image, tissues with a low number of hydrogen nuclei appear ______

Back 520

Hypointense

Front 521

When the velocity of flow increases, the effects of entry slice phenomenon _____

Back 521

Increase

Front 522

The inversion recovery pulse sequence that is used to suppress CSF in proton density and T2 weighted images is known as what?

Back 522

FLAIR

Front 523

At a field strength of 1.0 tesla, the approximate T2 relaxation time for muscle tissue is what?

Back 523

40 ms

Front 524

In MR imaging, slice thickness is determined by which factor(s)?

Back 524

Gradient slope slice select
Transmit bandwidth

Front 525

used to describe parameters that affect each other inversely.

Back 525

Trade-off parameters

Front 526

At a field strength of 1.0 tesla, the approximate T1 relaxation time of fat is what?

Back 526

180ms

Front 527

Which of the following conventional MRI techniques can be used to produce contrast differences between vascular structures and stationary structures?

Back 527

Gradient moment nulling
Pre-saturation pulse

Front 528

In an echo planar pulse sequence, pre-inverting tissue with a 180 degree RF pulse before excitation produces what type of image weighting?

Back 528

T1 weighting

Front 529

When the phase encoding gradient is activated, steep slopes produce data with what type of spatial resolution?

Back 529

High

Front 530

The frequency encoding gradient is also known as the ______ because it is turned on during the sampling of signal.

Back 530

Readout gradient

Front 531

At a field strength of 1.0 tesla, the approximate T2 relaxation time for spleen tissue is ________

Back 531

80 ms

Front 532

When the direction of blood, flow is the same as the direction in which slices are acquired, the effects of entry slice phenomenon _______

Back 532

Decrease

Front 533

The difference in brightness between two regions of an image is known as______

Back 533

Image contrast

Front 534

Spatial resolution

Back 534

determines how "sharp" the image looks.

Front 535

Blood flow that has randomly different velocities is known as what type of flow?

Back 535

Turbulent flow

Front 536

In a gradient echo pulse sequence, the use of an RF pulse to eliminate residual transverse magnetization is known as what?

Back 536

Digital RF spoiling

Front 537

The magnitude of the phase shifts between two points within a patient is determined by which factor?

Back 537

Slope of the phase encoding gradient

Front 538

During cardiac gating, the waiting time before each R wave is known as what?

Back 538

Trigger window

Front 539

The term used to describe a volume element is known as ______

Back 539

Voxel

Front 540

When pixel size increases, signal to noise ratio________

Back 540

Increases

Front 541

Gradient echo pulse sequences that preserve left over transverse magnetization are said to be what?

Back 541

Coherent

Front 542

As bandwidth decreases, sampling time ______

Back 542

Increases

Front 543

During cardiac gating, TR is dependent upon which factor(s)?

Back 543

The patient's heart rate
The R- R interval

Front 544

When the phase encoding gradient is activated, steep slopes produce what type of signal amplitude?

Back 544

Low

Front 545

A spin echo pulse sequence is characterized by which of the following?

Back 545

90 degree excitation pulse followed by a 180 degree rephasing pulse

Front 546

The method that is most commonly used to reduce artifact produced by cardiac motion when scanning the chest is known as ______

Back 546

Cardiac gating

Front 547

When image matrix is increased, spatial resolution______

Back 547

Increases

Front 548

Gradient echo pulse sequences that eliminate leftover transverse magnetization are said to be what?

Back 548

Incoherent

Front 549

In an echo planar pulse sequence, using a long TE produces what type of weighting?

Back 549

T2 weighting

Front 550

In a T2 weighted image, CSF has a ________ T2 relaxation time and therefore appears _______

Back 550

Long, Bright

Front 551

Which of the following logical gradients is known as the frequency encoding gradient?

Back 551

X gradient

Front 552

The proportion of signal actually used to construct an image relative to the amount of background noise is known as ______

Back 552

Signal to noise ratio

Front 553

Noise that degrades image quality in a specific location within an MRI image is known as what?

Back 553

Discrete noise interference

Front 554

Blood flow that travels in the same direction in which the slices are acquired is known as what type of flow?

Back 554

Co-current flow

Front 555

When TR is increased, the effects of entry slice phenomenon _______

Back 555

Increase

Front 556

The range of frequencies that is transmitted by the RF pulse is known as the

Back 556

Transmit bandwidth Correct

Front 557

The precessional frequency of hydrogen nuclei that experience increased magnetic field strength due to gradient coils ________

Back 557

Increases

Front 558

The inversion recovery pulse sequence that is used to suppress fat in a T1 weighted image is known as what?

Back 558

STIR

Front 559

During the acquisition of sagittal images with the frequency direction S/I, phase encoding is conducted by which physical gradient?

Back 559

Y gradient

Front 560

As slice thickness decreases, the effects of time of flight phenomenon ______

Back 560

Increase

Front 561

The type of cardiac gating that detects the increase in blood volume in the capillary bed during systole is known as what?

Back 561

Peripheral gating

Front 562

MRI images that are based on the differences in longitudinal relaxation characteristics of tissues are known as what?

Back 562

T1 weighted images

Front 563

When the phase encoding gradient is activated, shallow slopes produce what type of signal amplitude?

Back 563

High

Front 564

In a T1 weighted image, a short TR is used to do what?

Back 564

Maximize T1 effects

Front 565

In a gradient echo pulse sequence, transverse magnetization that is leftover from a previous excitation pulse is known as what?

Back 565

Residual transverse magnetization

Front 566

Typical peak velocities of the middle and anterior cerebral arteries are usually within what range?

Back 566

40-70 cm/sec

Front 567

The gradient that is turned on during the application of the 90 degree excitation pulse and the 180 degree RF pulse is known as ______

Back 567

Slice selection gradient

Front 568

The spatial location of signal according to its precessional frequency is known as ______

Back 568

Frequency encoding

Front 569

The ECG wave with the highest electrical amplitude is known as the what?

Back 569

R wave

Front 570

Because the nucleus of the hydrogen atom acts much like a bar magnet it is said to have what?

Back 570

Magnetic moment

Front 571

An example of aperiodic motion is what?

Back 571

Peristalsis motion

Front 572

Material that is strongly attracted to a magnetic field is said to be what?

Back 572

Ferromagnetic

Front 573

paramagnets

Back 573

Unlike ferromagnets, paramagnets do not retain any magnetization in the absence of an externally applied magnetic field because thermal motion randomizes the spin orientations.

Front 574

Which of the following is the equation that is used to determine precessional frequencies?

Back 574

Wo=yBo
F=Boy

Front 575

Another name for transverse relaxation is what?

Back 575

Spin-Spin relaxation

Front 576

The X gradient alters the magnetic field strength along which axis?

Back 576

Horizontal axis

Front 577

During the acquisition of axial images of the body with the frequency direction L/R, phase encoding is performed by which physical gradient?

Back 577

Y gradient

Front 578

Chemical shift artifact can be minimized by which of the following methods?

Back 578

Minimizing the FOV
Increasing the receive bandwidth
Utilizing chemical saturation

Front 579

After being placed in an external magnetic field, high energy hydrogen nuclei point in which direction?

Back 579

Anti-parallel

Front 580

The return of longitudinal magnetization to equilibrium is known as what?

Back 580

T1 relaxation
Spin-Lattice relaxation
Longitudinal relaxation

Front 581

The gradient that is turned on during the application of the 90 degree excitation pulse and the 180 degree RF pulse is known as what?

Back 581

Slice selection gradient

Front 582

The artifact that is produced when many structures with different signal intensities are averaged together within a pixel is known as what?

Back 582

Partial volume averaging

Front 583

The spatial location of signal according to its precessional phase is known as what?

Back 583

Phase encoding

Front 584

Wraparound artifact occurs in which direction of an MR image?

Back 584

Phase direction
Frequency direction

Front 585

During slice selection, the Z gradient is used to select slices in which plane?

Back 585

Axial

Front 586

Gibbs artifact can be decreased by ______ the number of phase encoding steps.

Back 586

Increasing

Front 587

The number of picture elements used to make up an image is known as what?

Back 587

Matrix

Front 588

In MRI, thin slices are achieved by applying a ______ gradient slope or a _____ bandwidth.

Back 588

Steep, Narrow

Front 589

Image data along both the phase and frequency axis with the lowest signal amplitude is stored in which area of the K space?

Back 589

Outer lines

Front 590

Another name for truncation artifact is what?

Back 590

Gibbs artifact
Ringing artifact

Front 591

Peripheral gating is a technique used to decrease what type of motion artifact?

Back 591

CSF pulsation motion

Front 592

The type of RF coil configuration that uses a series of independent coils to create one image is known as a what?

Back 592

Phased array coil

Front 593

The spin of the proton of the hydrogen atom is known as what?

Back 593

Hydraulic spin

Front 594

The magnitude of the phase shifts between two points within a patient is determined by which factor?

Back 594

Slope of the phase encoding gradient

Front 595

During the sampling of signal, the sampling rate is directly proportional to which of the following?

Back 595

Receive bandwidth

Front 596

The image parameter that primarily affects T2 weighting is known as what?

Back 596

Echo time

Front 597

The nucleus of the hydrogen atom carries what type of charge?

Back 597

Positive

Front 598

On a T1 weighted image of the knee, cortical bone appears __________ to all other tissues.

Back 598

Hypointense

Front 599

The clarity with which different areas of an image are distinguished is known as what?

Back 599

Spatial resolution

Front 600

The larger the net magnetic vector in the transverse plane the _____ the signal that is produced.

Back 600

Stronger

Front 601

The artifact produced by the transfer of spin lattice energy from one slice to its adjacent slice is known as what?

Back 601

Cross talk artifact

Front 602

The artifact that is characterized by a loss of signal intensity in one area of an image is known as what?

Back 602

Shading artifact

Front 603

An artifact that is caused by an external radio frequency leak is known as what?

Back 603

Zipper artifact

Front 604

Image data along both the phase and frequency axis with the highest signal amplitude is stored in which area of K space?

Back 604

Central lines

Front 605

At a field strength of 1.0 tesla, the approximate T2 relaxation time for water is what?

Back 605

2500 ms

Front 606

Hydrogen nuclei begin to precess in phase when which of the following occurs?

Back 606

The proper RF is turned on

Front 607

During the acquisition of coronal images with the phase direction L/R, frequency encoding is conducted by which physical gradient?

Back 607

Z gradient

Front 608

On a T1 weighted image of the brain, fat appears ________ to white matter.

Back 608

Hyperintense

Front 609

When placed in an external magnetic field, the hydrogen nuclei that are of clinical interest are known as what?

Back 609

Parallel unpaired

Front 610

In a T1 weighted image, a short TR is used to do what?

Back 610

Maximize T1 effects

Front 611

The time between two successive 90 degree RF pulses is known as what?

Back 611

Repetition time

Front 612

The external magnetic field in a superconducting magnet is said to be what type of magnetic field?

Back 612

Static

Front 613

Metal in the patient, in the area that is being scanned, will most likely create what type of artifact?

Back 613

Magnetic susceptibility

Front 614

The frequency encoding gradient is also known as the ______ because it is turned on during the sampling of signal.

Back 614

Readout gradient

Front 615

When the phase encoding gradient is activated, medium slopes produce what type of signal amplitudes?

Back 615

Medium

Front 616

The type of secondary rotation that is displayed by hydrogen nuclei in an external magnetic field is known as what?

Back 616

Precession

Front 617

In a T1 weighted image, tissues with short T1 relaxation times produce what type of signal?

Back 617

High

Front 618

When the amplitude of the phase encoding gradient increases, the amount of phase shift along the gradient _________.

Back 618

Increases

Front 619

The nucleus of the hydrogen atom is made up of one ______.

Back 619

Proton

Front 620

The type of RF coil that encompasses the entire anatomy to be scanned is known as what?

Back 620

Volume coil

Front 621

A spin echo image with a short TR and a short TE is known as what type of image?

Back 621

T1 weighted image

Front 622

The calibration of transmit gain during the prescan process determines which factor?

Back 622

RF output necessary to produce a 90 degree flip angle

Front 623

The artifact that is produced by overlapping radio frequency pulses in adjacent slices is known as what?

Back 623

Cross excitation artifact

Front 624

The image parameter that primarily affects T2 weighting is known as what?

Back 624

Echo time

Front 625

When slice spacing increases, signal to noise ratio________

Back 625

Increases

Front 626

When repetition time is increased, signal to noise ratio ________

Back 626

Increases

Front 627

When the velocity of flow decreases, the effects of entry slice phenomenon ____

Back 627

Decrease

Front 628

The vertical axis of K space represents which axis of the image?

Back 628

Phase encoding

Front 629

the following terms is defined as the volume of blood that flows into one gram of tissue

Back 629

Perfusion

Front 630

the following MRI imaging techniques displays a frequency spectrum of differences between various elements within tissues

Back 630

Spectroscopy

Front 631

There are two image types associate with diffusion weighted imaging

Back 631

Trace Images
and
ADC Maps

Front 632

In MR spectroscopy, the following is an element commonly found in the proton spectra of human tissue

Back 632

Creatine, choline, and glutamine are all common elements found in the proton spectra of human tissue.

Front 633

A diffusion weighted imaging technique that utilizes multi-directional gradients to map the anatomy of white matter tracks within the brain.

Back 633

Diffusion Tensor Imaging

Front 634

Used to describe the movement of molecules in the extra-cellular space due to random thermal motion.

Back 634

Diffusion

Front 635

In diffusion weighted imaging, which parameter controls the amount of a tissue’s apparent diffusion coefficient (ADC) that is utilized to weight the image?

Back 635

b-Value - The b value controls the amount of a tissue's apparent diffusion coefficient (ADC) that is utilized to weight an image. Image weighting on images with a b value of 0 are controlled by other timing parameters such as TR and TE.

Front 636

Specific absorption rate is expressed in units of what?

Back 636

Watts/kg

Front 637

The rate at which a patient can safely dissipate excess heat caused by RF energy is known as what?

Back 637

Specific absorption rate

Front 638

The chemical compounds used to bind the metallic ion in MRI contrast agents are known as what?

Back 638

Chelates

Front 639

The recommended SAR limit for safely imaging the head is what?

Back 639

3.2 Watts/kg.

Front 640

The recommended whole body SAR limit for MR imaging is what?

Back 640

4.0 Watts/kg

Front 641

The first use of a paramagnetic agent on a human subject was in what year?

Back 641

1981

Front 642

The term used to describe freedom from infection or infectious material is known as what?

Back 642

Asepsis

Front 643

Contrast agents most commonly used in MRI today have what type of effect on tissue?

Back 643

Decrease T1 relaxation times

Front 644

The effect of MRI contrast media on tissue relaxation rates is known as what?

Back 644

Relaxivity

Front 645

The amount of a drug required to cause death in half of a sample of laboratory mice is known as what?

Back 645

LD50
and
Median lethal dose

Front 646

Which of the following is a biological effect unique to echo planar imaging?

Back 646

Muscular twitches in face and back

Front 647

Heating that is directly associated with the RF pulse sequence should not increase the core body temperature greater than what?

Back 647

1 degree Celsius

Front 648

The first material used by Felix Bloch to change magnetic relaxation times was known as what?

Back 648

Ferric Nitrate

Front 649

Substances that adhere to and transmit infectious material are known as what?

Back 649

Fomites - A fomite is defined as an inanimate object or substance that is capable of transmitting infectious organisms from one individual to another.

Front 650

The first oral MRI contrast agent used in a human subject was known as what?

Back 650

Ferric Chloride

Front 651

To minimize MRI contrast agent's toxicity, the agent should be what?

Back 651

Excreted intact by the kidneys
and
Excreted intact by the gallbladder and intestines

Front 652

Which of the following describes the two major types of asepsis?

Back 652

Medical and Surgical

Front 653

The first intravenous MRI contrast agent that was used on a human subject was known as what?

Back 653

Gadopentetate dimeglumine

Front 654

Infections that originate within the healthcare setting are known as what?

Back 654

Nosocomial infections, healthcare associated infections, and HAI's are all terms that describe infections that originate within the healthcare setting.

Front 655

The recommended SAR limit for safely imaging small volumes is what?

Back 655

8.0 Watts/kg

Front 656

Which of the following is the median lethal dose of Gadopentetate dimeglumine?

Back 656

10-20 mmol/kg

Front 657

The image parameter that primarily affects T2 weighting is known as what?

Back 657

Echo time

Front 658

On a T2 weighted image of the brain, grey matter appears _______ to white matter.

Back 658

Hyperintense

Front 659

On a proton density weighted image of the brain, CSF appears_______ to grey matter.

Back 659

Hypointense

Front 660

When slice thickness is increased, signal to noise ratio________

Back 660

Increases

Front 661

The T wave of the ECG represents which phase of the cardiac cycle?

Back 661

Ventricular diastole

Front 662

When TR is decreased, the effects of entry slice phenomenon ______

Back 662

Decrease

Front 663

The QRS wave of the ECG represents which phase of the cardiac cycle?

Back 663

Ventricular systole

Front 664

When image matrix is increased, spatial resolution______

Back 664

Increases

Front 665

Which of the following type of MRA uses a bipolar gradient to enhance vascular structures?

Back 665

Phase contrast MRA

Front 666

Gradient echo pulse sequences that preserve left over transverse magnetization are said to be what?

Back 666

Coherent

Front 667

When the number of excitations is decreased, acquisition time________

Back 667

Decreases

Front 668

the volume of blood that flows into one gram of tissue

Back 668

Perfusion

Front 669

term used to describe the net displacement of molecules diffusing across an area of tissue per second.

Back 669

Apparent Diffusion Coefficient

Front 670

artifact specifically associated with diffusion weighted imaging

Back 670

T2 Shine Through

Front 671

In diffusion weighted imaging, the b-value is expressed in what unit of measurement?

Back 671

s/mm2

Front 672

controls the amount of a tissue's apparent diffusion coefficient (ADC) that is utilized to weight an image.

Back 672

b-Value

Front 673

In diffusion weighted imaging, tissues with a low apparent diffusion coefficient have what type of signal intensity

Back 673

Hyperintense

Front 674

In diffusion weighted imaging, tissues with a high apparent diffusion coefficient have what type of signal intensity?

Back 674

Hypointense

Front 675

Which of the following is an image type associated with diffusion weight imaging?

Back 675

trace images and ADC maps

Front 676

Creatine, choline, and glutamine are all common elements found in the

Back 676

proton spectra of human tissue.

Front 677

________________ is a term describing the containment of the static magnetic fringe field through the use of secondary coils attached around the MRI scanner

Back 677

Active shielding

Front 678

_______________ is a term used to describe the adjustment of the current within the shim coils on a per/patient or per/sequence basis, for the purposes of achieving uniform fat suppression or optimal prescan calibrations.

Back 678

Active shimming

Front 679

__________images are reconstructed from diffusion weighted images with multiple b-values, and correspond to the spatially distributed diffusion coefficients of the target tissues

Back 679

ADC

Front 680

________ artifact occurs when tissue outside the Field of View is undersampled, causing a misregistration of anatomical location, in the phase direction, but on the opposite side of the anatomical location, also known as wrap-around artifact

Back 680

Aliasing

Front 681

_________ – equates to signal height or strength; the larger the amplitude, the larger the number of protons

Back 681

Amplitude

Front 682

________ – being continuous, or having a continuous range of values

Back 682

Analog

Front 683

The ____________ converter (ADC) is part of the computer system that converts the analog acquired MR signal into a digital signal

Back 683

Analog-to-digital

Front 684

An ________ voxel is a voxel with uneven measurements, with regards to the phase, frequency and slice thickness dimensions

Back 684

anisotropic

Front 685

An ______ processor comprises a multiprocessor that is switched in sequence and in parallel while simultaneously performing a computing task

Back 685

array

Front 686

_________ are signal misrepresentations that do not correspond to the spatial location of the specific tissue imaged

Back 686

Artifacts

Front 687

_________ is defined as the range or spectrum of frequencies (minimum to maximum processed frequency) of a pulse sequence acquired by an RF system

Back 687

Bandwidth

Front 688

The _____ coil is an integrated part of the magnet design that acts as its own transceiver coil, with large FOV capabilities, but lacking the high SNR of localized coils

Back 688

body

Front 689

The ______ is defined as a factor in diffusion weighted imaging; the higher the factor, the stronger the diffusion weighting

Back 689

b-value

Front 690

The ____ field is defined as the static main magnetic field of an MR system

Back 690

B0

Front 691

_____________ prevents or reduces motion artifacts in the MR image caused by the heartbeat or pulsating blood flow and enables the images to be acquired synchronized to cardiac movement

Back 691

Cardiac triggering

Front 692

________________ artifact is due to the difference in resonant frequencies between fat and water, causing a phase shift in voxels containing fat and water.

Back 692

Chemical shift

Front 693

____ function scrolls through the entire sequence's images, giving the appearance of CSF flowing or cardiac movement, from the cycling of the images acquired; a “movie” function of scrolling images

Back 693

Cine

Front 694

_________ – maintaining a constant state of “in-phase” relationships between protons; located at the same phase cycle simultaneously

Back 694

Coherent

Front 695

________ can be defined as the signal strength differences between two adjacent tissue types

Back 695

Contrast

Front 696

__________________ utilizes the reduced T1 relaxation time of blood through the use of an intravenously injected Gadolinium contrast agent

Back 696

CE MRA (Contrast-enhanced MR angiography)

Front 697

_________ – Circularly polarized transmission or receiver coil with two orthogonal transmission and/or receiver channels, also known as a quadrature coil. This yields better signal-to-noise than a linear coil

Back 697

CP coil

Front 698

_______ artifact occurs when slices are positioned too close together, causing signals from adjacent slices to affect one another. This affects T1 contrast, and is remedied by utilizing an interleaved slice profile or by increasing slice gap

Back 698

Cross-talk

Front 699

______ – Formula for the temporal change of the magnetic field, especially important with regards to patient safety in relation to gradients.

Back 699

dB/dt

Front 700

__________ occurs after initial RF application, causing phase differences to appear between precessing spins, resulting in decay of transverse magnetization

Back 700

Dephasing

Front 701

____________ is an effect resulting in a slightly weakened magnetic field when a substance is introduced into it. This material is considered to have a negative magnetic susceptibility

Back 701

Diamagnetism

Front 702

_______ – the movement of atoms or molecules from an area of higher concentration to an area of lower concentration. (Brownian motion)

Back 702

Diffusion

Front 703

______________ – displays the mobility of water molecules in all three coordinates

Back 703

Diffusion tensor

Front 704

_________ – A technique utilizing the differences in resonant frequencies of fat and water separating the two tissues, acquiring each separately, then adding the two to yield a water-only image (fat suppression), then subtracting the two to yield a fat-only image

Back 704

Dixon

Front 705

_________ – A spin echo sequence with two echoes, two generated images per slice location

Back 705

Double Echo

Front 706

_________ – The time which the gradient system can be run at maximum power

Back 706

Duty cycle

Front 707

______________________________ refers to DCE, or Basic T1 perfusion imaging (pituitary or prostate dynamic sequences, longer acquisition times/dynamic compared to DSC)

Back 707

Dynamic Contrast Enhancement

Front 708

___________________ -- refers to DSC, or better known as T2* gradient echo Perfusion imaging, utilized in Brain Perfusion studies

Back 708

Dynamic Susceptibility Contrast

Front 709

_____ – The MR signal generated by an RF or a gradient pulse

Back 709

Echo

Front 710

_______________ – Very fast MR imaging technique where the complete image is acquired using a single selective excitation pulse, field gradients are periodically switched to generate a series of gradient echoes

Back 710

Echo Planar Imaging

Front 711

____________ – Distance between two echoes, as in Fast Spin Echo or EPI sequences. The shorter the echo spacing, the more compact the sequence timing and few artifacts result

Back 711

Echo Spacing

Front 712

___________ – The time between the excitation pulse of a sequence and the resulting echo used as the MR signal

Back 712

Echo Time (TE)

Front 713

___________– Multiple echoes in sequence, each obtaining rows of k-space, shortening overall scan time, also reducing SNR with each additional echo train

Back 713

Echo Train

Front 714

_________ – In a pulse sequence, the contrast and overall SNR of an image is determined by the position of the echo when the phase encoding gradient has the smallest amplitude.

Back 714

Effective TE

Front 715

__________ – referring to prospective cardiac triggering techniques, the patient’s heart rate controls the TR, or termed the effective or available TR (TReff), according to the beats per minute (BPM) factor

Back 715

Effective TR

Front 716

_________________ – The electrical voltage created in a receiver coil as a result of a temporal change in the magnetic field

Back 716

Electromagnetic Induction

Front 717

________ –the medical term used to describe vomiting

Back 717

Emesis

Front 718

_________– Number of gradient echoes in an Echo Planar sequence acquired after the initial excitation pulse; equating to the scan time acceleration factor

Back 718

EPI factor

Front 719

______________ – The radiofrequency (RF) pulse used to disturb the equilibrium of the Net Magnetization Vector; the higher the energy of excitation, the greater the flipped angle of magnetization

Back 719

Excitation pulse

Front 720

________ – the cause or origin of a disease

Back 720

Etiology

Front 721

____________ – An MR technique used to suppress signal from fat protons, yielding a “water-only” image, utilizing a chemically selective presaturation pulse

Back 721

Fat Saturation

Front 722

________ – the process of utilizing specific sequence parameters to null signal from fat in the MR sequence, as in STIR, for example

Back 722

Fat Suppression

Front 723

_____________ – the property of being strongly attracted to either pole of a magnet.

Back 723

Ferromagnetism

Front 724

________________ – A technique used to suppress fluids, utilizing a long echo time (TE) coupled with a long Inversion Time (TI)

Back 724

FLAIR – FLuid Attenuated Inversion Recovery

Front 725

_________ – the angle to which the longitudinal magnetization is tipped into the transverse plane, following the initial RF excitation pulse

Back 725

Flip Angle

Front 726

______________ – an MR technique used to reduce artifacts from spin phase effects through the use of additional gradient pulses. Also known as Gradient Moment Nulling

Back 726

Flow Compensation

Front 727

_______ – the invisible lines of force that extend around a magnetic field, with the greatest strength/force being at the two poles/ends of the magnet

Back 727

Flux

Front 728

_______________ – the mathematical process of converting raw data into an image suitable for display

Back 728

Fourier Transform

Front 729

__________ -- a time-based electrical signal that is detected in a nuclear magnetic resonance spectrometer, that is produced by induction from the motion of the magnetic moments of nuclei, that decays with time (T2*), that can be converted to a more conventional frequency-based signal using analysis by Fourier transforms;

Back 729

Free Induction Decay

Front 730

________ – the number of times that a periodic function or vibration repeats itself in a specified time. It is usually measured in hertz (Hz),

Back 730

Frequency

Front 731

_________ – the process of locating an MR signal in one dimension by applying a magnetic field gradient along that dimension during the period when the signal is being received, utilizing differences in frequencies along the same row in order to spatially differentiate one location from another

Back 731

Frequency Encoding

Front 732

_________ – A non-toxic paramagnetic contrast agent used in MR imaging. The infusion of gadolinium based paramagnetic contrast agents (GBCA’s) shortens the T1 (and T2) times of tissue, dependent upon concentration

Back 732

Gadolinium

Front 733

_________ – Due to the symmetry of the matrix to be sampled, a little more than half of the raw data is necessary to be acquired, reconstructing the remaining data to complete the image, greatly reducing scan time

Back 733

Half-Fourier

Front 734

___________ – Mathematical computation converting the collected raw data signals into images using Fourier Transform

Back 734

Image Reconstruction

Front 735

_______________ – MR sequence that begins with 180º RF inverting pulse followed by 90º RF excitation pulse, then 180º RF refocusing pulse

Back 735

Inversion Recovery

Front 736

_________ – The time between the initial 180º RF and the 90º RF excitation pulse in an Inversion Recovery sequence

Back 736

Inversion time (TI)

Front 737

______ – Atomic nuclei that contain the same number of protons but differ in the number of neutrons in the nucleus of the atom

Back 737

Isotope

Front 738

_________– data acquisition matrix containing raw image data prior to image processing.

Back 738

k-space

Front 739

_______– the magnetic and thermal environment through which nuclei exchange energy in longitudinal (T1) relaxation

Back 739

Lattice

Front 740

____________ – MR technique utilized to image flowing blood and specific vasculature structures

Back 740

Magnetic resonance angiography (MRA)

Front 741

_______________________ – MR technique which quantitatively assesses the mechanical properties of tissues, based on the propagation of shear waves

Back 741

Magnetic resonance elastography (MRE)

Front 742

_____________ – MR technique generating a spectrum of metabolites in a specific volume of interest

Back 742

Magnetic resonance spectroscopy (MRS)

Front 743

____________ – an MR technique using a series of echoes following a single excitation pulse, usually in the form of 180º RF pulses that generate images

Back 743

Multi-echo imaging

Front 744

________ how many times each line of k-space data is acquired during the scan, or how many times each slice is repeated to gain signal and reduce noise, improving SNR

Back 744

NEX

Front 745

____________ – A scan time acceleration technique which requires the use of a phased array coil to reconstruct an image in less time than conventional imaging

Back 745

Parallel Imaging

Front 746

_________ – property of magnetism signifying weak magnetic properties due to its unpaired electrons. IV Gadolinium contrast is an example of a paramagnetic substance

Back 746

Paramagnetic

Front 747

____________ – a loss of resolution due to excessively large voxels, typically caused by slices that are too thick

Back 747

Partial volume averaging

Front 748

__________ – a term describing the degree to which precessing nuclear spins are synchronous

Back 748

Phase coherence

Front 749

_______ – an MRA technique based on the speed of the vessels of interest, utilizing velocity encoding (VENC)

Back 749

Phase contrast

Front 750

_____________ – the process of locating an MR signal along the phase axis, directly correlating spatial resolution and scan time with the number of phase encodings in an MR image

Back 750

Phase encoding

Front 751

_______________ – an image minimizing T1 and T2 effects, with contrast primarily dependent upon the density of protons in the imaging volume

Back 751

Proton Density weighting

Front 752

__________ – magnetic field gradient applied during the moment when the echo is formed, and is responsible for frequency encoding in the image

Back 752

Readout gradient

Front 753

_______ – the process of returning out-of-phase magnetic moments to phase coherence, instigated by applying a 180º RF pulse (spin echo) or reversing a magnetic gradient (gradient echo)

Back 753

Rephasing

Front 754

_________ – is the speed rate of ascent or descent of a gradient from zero to its maximum amplitude, either positive or negative

Back 754

Slew rate

Front 755

_____________– the ability to define adjacent points in an image

Back 755

Spatial resolution

Front 756

________ – An MRI pulse sequence whose signal is an echo resulting from the refocusing of magnetization after the application of 90º and 180º RF pulses

Back 756

Spin echo

Front 757

_____________________ – A gradient echo sequence in which a non-zero steady state develops for both transverse and longitudinal components of magnetization

Back 757

Steady-state free precession

Front 758

_______– Short TI Inversion Recovery: a version of the Inversion Recovery pulse sequence where the inversion time (TI) is set to 0.69 times the T1 of fat, nulling the signal from fat at the specific field strength in which it’s being acquired

Back 758

STIR

Front 759

_________ – the medical term for fainting, is precisely defined as a transient loss of consciousness and postural tone

Back 759

Syncope

Front 760

________________ – MRA technique relying on flow related enhancement to distinguish between stationary spins and flowing spins

Back 760

Time of Flight (TOF)

Front 761

_____________ – MRA technique used for encoding flow velocities

Back 761

Velocity Encoding (VENC)