Mid Term Exam Flashcards by Laura Kirwan

T/F: All contrast media is potentially harmful and should be used knowledgeably.

True

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T/F: Intravascular contrast media administration is performed under the supervision of a licensed physician.

True

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T/F: Technical and nursing personnel injecting contrast media must be knowledgeable in the recognition of, and able to assist in the treatment of any adverse reaction.

True

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T/F: Literature in the MRI community and manufacturer recommendations lists the dosage of intravenous gadolinium chelate contrast to be 0.1 mmol/kg of body weight.

True

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T/F: Any and all adverse events, incidents or “near incidents” that occur pertaining to MR safety are to be reported to the MRI Medical Director, the MRI Department Supervisor or the Radiology Administrator immediately.

True

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T/F: A student may review and sign the MRI screening sheet prior to an individual entering the scan room.

False

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T/F: The Medical Director will be involved with the introduction of new policies and procedures as needed with the advancement of technologies and procedures in the MRI environment.

True

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T/F: Zone III – This area is synonymous with the MR scanner room itself.

False

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T/F: Lenz’s Law is an important consideration with non-ferromagnetic objects.

True

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T/F: Having undergone a previous MRI successfully with an implanted device indicates that the device is MRI safe.

False

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T/F: The potential for translational forces (“projectile forces”) exists at any field strength.

True

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T/F: After a quench the patient and personnel should evacuate the area immediately.

True

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Which of the following describe T1 Recovery? (Choose all that apply)

Spin lattice relaxation

The time it takes 63% of transverse magnetization to decay in the tissue.

Caused by the nuclei giving up their energy to the surrounding environment or lattice.

Spin-spin relaxation that results in decay or loss of coherent transverse magnetization.

Spin lattice relaxation

Caused by the nuclei giving up their energy to the surrounding environment or lattice.

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What MUST be done prior to anyone entering the scan room? (Select the BEST answer)

Pat the patient down for metal objects.

A screening sheet must be filled out and in the patient’s chart.

The patient must be scanned with the metal detector.

The completed screening sheet must be signed by a level II staff member and the patient must be scanned with the metal detector, prior to admittance to the MRI scan room.

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What happens to the alignment of hydrogen protons when placed in an external magnetic field? (Check all that apply)

Nothing until an RF pulse is applied.

The magnetic moments of the nuclei align with or against the main magnetic field.

More nuclei oppose the main magnetic field than line up with the main magnetic field.

Slightly more nuclei line up with the main magnetic field than against it.

The magnetic moments of the nuclei align with or against the main magnetic field.

Slightly more nuclei line up with the main magnetic field than against it.

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Where do we look up the safety of an implanted device? (Check all that apply)

www.MRISafety.com

Shellock’s reference manual

The manufacturer’s website

If we remember that it is a safe implant, there is no need to look it up again.

www.MRISafety.com

Shellock’s reference manual

The manufacturer’s website

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What effect does the magneto-hemodynamic effect have? Is this a permanent effect? (Check all that apply)

Increase in the amplitude of the “R” wave on EKG gating.

Increase in the amplitude of the “T” wave on EKG gating.

Reversible effect– EKG tracing returns to normal when the patient is removed from the static magnetic field.

Permanent effect– EKG tracing continues to show an elevated wave form after the patient has had an MRI exam.

Increase in the amplitude of the “T” wave on EKG gating.

Reversible effect– EKG tracing returns to normal when the patient is removed from the static magnetic field.

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What is the gyromagnetic ratio of hydrogen?

28 MHz/T
8 MHz/T
57 MHz/T
57 MHz/G

42.57 MHz/T

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Select the three components of the magnetic field from those listed below.

Static Magnetic Field

Faraday’s Field

Radiofrequency Fields

Time Varying Magnetic Fields

Precessional Frequency Field

Static Magnetic Field

Radiofrequency Fields

Time Varying Magnetic Fields

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What are the guidelines for pregnant employees? (Choose all that apply)

No changes to pregnant employees work environment in MRI. Everyone knows that MRI doesn’t use radiation.

Pregnant employees may enter the scan room, but should leave before scanning begins.

Pregnant employees are exempt from scanning and may only do paperwork.

Pregnant employees MUST transfer to x-ray once they’ve announced their pregnancy to the MRI department.

Pregnant employees may enter the scan room, but should leave before scanning begins.

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T/F: The gyromagnetic ratio expresses the relationship between the angular momentum and the magnetic moment of each MR active nucleus.

True

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Identify which of the following describe a “fringe field.” (Select all that apply)

The stray magnetic field outside the bore of the magnet.

An area on the outskirts of the magnet– generally two feet long by three feet wide.

Active or passive shielding is used to reduce the size of the fringe field.

The fringe field is not confined by walls, floors, or ceilings.

The stray magnetic field outside the bore of the magnet.

Active or passive shielding is used to reduce the size of the fringe field.

The fringe field is not confined by walls, floors, or ceilings.

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What would you do in the event of a CODE BLUE in MRI? (Select all that apply)

Stay with the patient in the scan room until help arrives.

Begin CPR.

Activate the Code Blue response process (push the Code Blue button)

Get the patient out of the scanner and into Zone III; locking the scan room door and monitoring it when other Code Team members arrive

Begin CPR.

Activate the Code Blue response process (push the Code Blue button)

Get the patient out of the scanner and into Zone III; locking the scan room door and monitoring it when other Code Team members arrive

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What are the two results of resonance? (Choose from the list below)

The NMV moves out of alignment and away from B0.

The NMV moves into a repeating pattern of /- 100 MHZ.

The magnetic momements of hydrogen nuclei move out of phase with each other.

The magnetic moments of hydrogen nuclei move into phase with each other.

The NMV moves out of alignment and away from B0.

The magnetic moments of hydrogen nuclei move into phase with each other.

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T/F: The "warm zone" in MRI is the scan room itself.

False

Which of the following best describe spin-lattice relaxation? (Choose all that apply) T2 Decay T1 Recovery Time it takes 88% of the longitudinal magnetization to recover in tissue. Nuclei give up energy to the surrounding environment, resulting in longitudinal recovery.

T1 Recovery Nuclei give up energy to the surrounding environment, resulting in longitudinal recovery.

What makes a nucleus an MR active nucleus? (Select all that apply) Odd mass numbers Atoms with a balanced mass number Nuclei with a net spin or angular momentum None of the above

Odd mass numbers Nuclei with a net spin or angular momentum

T/F: We ALWAYS scan pregnant patients with contrast.

False

T/F: For resonance of hydrogen to occur, RF at EXACTLY the Larmor frequency of hydrogen must be applied.

True

What are the three types of motion present in an atom? (Select all that apply) Electrons spinning on their own axis. Nuclei spinning around each other. Electrons orbiting the nucleus. The nucleus itself spinning about its own axis.

Electrons spinning on their own axis. Electrons orbiting the nucleus. The nucleus itself spinning about its own axis.

Identify the two factors that determine which hydrogen nuclei align parallel and which align anti-parallel with the main magnetic field. The strength of the external magnetic field How many nuclei there are in each patient's body The thermal energy level of the nuclei The orientation of the patient in the scanner (head first vs. feet first)

The strength of the external magnetic field The thermal energy level of the nuclei

Which way does the main magnetic field run in permanent magnets? Horizontally Vertically Side to Side Down the bore of the magnet

Vertically

What is the terminal velocity of a paperclip at 1.5T? 64 mph 55mph 40mph None- not attracted

40mph

Which of the following describe the purpose of gradients in MRI? (Choose all that apply) Alter the main magnetic field in a linear fashion Change thermal equilibrium Spatially encode data Cause electrons to spin on their own axis

Alter the main magnetic field in a linear fashion Spatially encode data

What does SAR stand for? Special Atomic Rate Start Atoms Rolling Specific Absorption Rate Specific Atomic Rate

Specific Absorption Rate

What does the net magnetization vector (NMV) represent? The type of MR active nuclei present The relative number of electrons to protons The atomic number of the nuclei present The relative balance of spin-up to spin-down nuclei

The relative balance of spin-up to spin-down nuclei

Which way does the main magnetic field run in superconducting magnets? Along the bore of the magnet (horizontal) Along the Y-axis Vertically Side to side

Along the bore of the magnet (horizontal)

What is the best device to use when monitoring a patient's status in MRI? Blood pressure cuff Pulse ox EKG Auditory monitoring

Pulse ox

What does the Larmor Equation calculate? The NMV The precessional frequency The gyromagnetic ratio The atomic mass

The precessional frequency

What is the T2 relaxation time of tissue? [Hint: Think about which axis T2 relaxation is occurring in (longitudinal vs. transverse) and whether T2 relaxation indicates recovery vs. decay.] The time it takes 43% of the longitudinal magnetization to recover in the tissue. The time it takes 63% of the transverse magnetization to recover in the tissue. The time it takes 63% of the longitudinal magnetization to decay in the tissue. The time it takes 63% of the transverse magnetization to decay in the tissue.

The time it takes 63% of the transverse magnetization to decay in the tissue.

What is another term for T2 Decay? Spin-lattice relaxation Spin-spin relaxation T1 recovery NMV

Spin-spin relaxation

How do gradients affect the main magnetic field? (Select all that apply) They add to the main magnetic field They subtract from the main magnetic field They alter the main magnetic field in a linear fashion They give the image its shades of gray

They add to the main magnetic field They subtract from the main magnetic field They alter the main magnetic field in a linear fashion

T/F: Rewinders are gradients that rephase.

True

Which of the following controls T2* weighting in gradient echo? TE TR Flip angle TR and flip angle

What controls the polarity of a gradient? The steepness of the slice select gradient The sharpness of the frequency readout The direction of the current through the gradient coil The strength of the main magnetic field

The direction of the current through the gradient coil

T/F: TR controls T2 weighting.

False

Which of the following is known as the basic MRI contrast? T1 weighting T2 weighting Gray imaging Proton density weighting

Proton density weighting

# Choose extrinsic contrast parameters from the list below. ``` T1 Recovery Time TR Proton Density Flip Angle Flow TE b Value ```

TR Flip Angle TE b Value

What are the two extremes of contrast in MRI? T1 Recovery Fat Air Water

Fat | Water

T/F: The TE is twice the TAU.

True

T2* decay is faster than T2 decay since it is a combination of which two of the following effects? T1 decay with spin echo T2 decay itself Dephasing due to magnetic field inhomogeneities *weighting

T2 decay itself Dephasing due to magnetic field inhomogeneities

Which of the following best describes a T1 weighted image? (Select all that apply) Bright water Bright fat Dark Water Dark Fat

Bright fat Dark Water

Which of the following statements is true: Spin-spin interactions drive T1 contrast Slow tumbling molecules lead to decreased spin-spin dephasing Fast tumbling molecules lead to increased spin-spin dephasing Spin-spin interactions drive T2 contrast

Spin-spin interactions drive T2 contrast

What is the approximate T1 relaxation time of water at 1T? 200 ms 500 ms 2000 ms 2500 ms

2500 ms

Which of the following items are T1 and T2 relaxation times dependent on? (hint: there are three) How well the molecular tumbling rate matches the Larmor frequency of hydrogen Spin-spin interactions of oxygen atoms How closely packed the molecules are The inherent energy of the tissue The number of electrons orbiting the nucleus

How well the molecular tumbling rate matches the Larmor frequency of hydrogen How closely packed the molecules are The inherent energy of the tissue

T/F: Intrinsic parameters are those that cannot be changed because they are inherent to the body's tissues.

True

To achieve T1 weighting in gradient echo sequences, the flip angle should be ______. Large Small No flip angle should be used

Large

T/F: Spin echo sequences do not compensate for magnetic field inhomogeneities, while gradient echo sequences do compensate for magnetic field inhomogeneities.

False

___ controls the amount of T1 weighting. TR TE TI PD

For PD weighting, the TR must be ______. Long Short Intermediate T1

Long

T/F: Generally speaking, gradient echo sequences are faster than spin echo sequences.

True

For T2 weighting, the TE must be _____. short long intermediate PD

long

Gradients that dephase are called __________. rewinders weighted spoilers variable flip angles

spoilers

The spin echo is created by: The application of a long TE The application of a rewinding gradient A 180 degree RF pulse A rapid TI

A 180 degree RF pulse

Gradients are used to rephase spins in gradient echo sequences because: The resulting images have less artifact than spin echo images They are faster to apply than an RF pulse They rephase spins more completely than an RF pulse They result in images with better contrast resolution

They are faster to apply than an RF pulse

Which of the following controls T1 weighting in gradient echo? TI TE Gradient amplitude TR and flip angle

TR and flip angle

Saturation results in T1 weighting because: The flip angle used was small so vectors are not pushed beyond the transverse plane Only occurs when the TR is long as this allows for full recovery Vectors are pushed beyond the transverse plane because they were completely recovered before the RF excitation pulse Vectors are pushed beyond the transverse plane as they were incompletely recovered before the RF excitation pulse

Vectors are pushed beyond the transverse plane as they were incompletely recovered before the RF excitation pulse

T/F: nhomogeneities are areas within the magnetic field that do not exactly match the external magnetic field strength.

True

What does the phase encoding gradient do? Encode data along the LONG axis of the anatomy Encode data along the DIAGONAL axis of the anatomy Encode data along the SHORT axis of the anatomy Both the DIAGONAL and SHORT axes

Encode data along the SHORT axis of the anatomy

Which gradient performs slice selection for coronal slices? X gradient Y gradient Z gradient Any combination of gradients

Y gradient

Which gradient performs phase encoding for coronal slices? X gradient Y gradient Z gradient Any combination of gradients

X gradient

When is the slice select gradient switched on during a spin echo pulse sequence? During the rephasing pulse only During the 90 and 180 degree pulses During the excitation pulse only It is always on during the scan

During the 90 and 180 degree pulses

To achieve thin slices, do we need a STEEP or SHALLOW slice select slope? STEEP SHALLOW

STEEP

To achieve THIN slices would we use a narrow or broad transmit bandwidth? Narrow Broad

Narrow

When is the phase encoding gradient switched on in a pulse sequence? Before the 90 degree excitation pulse Usually just before the application of the 180 degree rephasing pulse Between TRs During the spin echo

Usually just before the application of the 180 degree rephasing pulse

What does the slope of the frequency encoding gradient determine? (Select all that apply) The size of the anatomy covered along the frequency encoding axis The 180 degree rephasing pulse The FOV The size of the phase matrix

The size of the anatomy covered along the frequency encoding axis The FOV

What is another term for the duration of the readout gradient? X gradient Sampling time Z gradient Window of opportunity

Sampling time

How often must we sample frequencies, according to the Nyquist Theorem? Once per cycle Twice per cycle Three times per cycle Less than once per cycle

Twice per cycle

What artifact occurs if we sample frequencies less than once per cycle? Zipper Cross talk Cross excitation Aliasing

Aliasing

What is the unit of K space? Inches Radians per meter Radians per centimeter Degrees

Radians per centimeter

T/F: The phase axis of K space is vertical and is centered in the middle of K space perpendicular to the frequency axis.

True

Which part of K space do steep phase gradients fill? Outer lines of K space, positive only Outer lines of K space, both positive and negative Central lines of K space, positive only Central lines of K space, both positive and negative

Outer lines of K space, both positive and negative

Which part of K space do shallow phase gradients fill? Outer lines of K space, positive only Outer lines of K space, both positive and negative Central lines of K space, positive only Central lines of K space, both positive and negative

Central lines of K space, both positive and negative

T/F: K space is not the image

True

Which gradient locates signal along the LONG axis of the anatomy? Phase encoding gradient Frequency encoding gradient Slice select gradient Isocenter gradient

Frequency encoding gradient

T/F: The scan time is the time to fill K space.

True

T/F: Data in K space are symmetrical.

True

What kind of information is contributed by data collected in the central lines of K space? (Select all that apply) Resolution Signal Contrast *weighting

Signal | Contrast

What kind of information is contributed by data collected in the outer lines of K space? Resolution Signal Contrast *weighting

Resolution

The direction of the current through the gradient coil

T/F: Phase encoding gradient positive fills the bottom half of K space.

False

Which gradient performs slice selection for sagital slices? X gradient Y gradient Z gradient Any combination of gradients

X gradient

What is another name for the frequency encoding gradient? Phase encoding gradient Short gradient Readout gradient Rephasing gradient

Readout gradient

Where are the data points collected by the system stored? FFT K space Frequency domain 42.57 MHz

K space

During a typical spin echo sequence, there are three gradient applications. In chronological order they are: Phase encoding, Slice select, Frequency encoding Slice select, Phase encoding, Frequency encoding Frequency encoding, Phase encoding, Slice select Slice select, Frequency encoding, Phase encoding

Slice select, Phase encoding, Frequency encoding

Which gradient lies along the horizontal axis of a typical superconducting MRI system? X gradient Y gradient Z gradient W gradient

X gradient

If a 512 phase matrix is selected, which k-space lines are likely to be filled in a normal acquisition? 0 to 512 256 to -256 0 to -512 256, 0 to -255

256 to -256

Which of the following statements is true? A data point contains frequency encoding information only A data point contains phase encoding information only A data point contains both phase and frequency information A data point represents a specific pixel on the image

A data point contains both phase and frequency information

T/F: A thicker slice has a better SNR than a thinner slice.

True

Decreasing receive bandwidth by half increases the SNR by how much? 60% 40% 1/2 .22

40%

T/F: A fine matrix is one with a low number of frequency encodings and/or phase encodings, and results in a small number of pixels in the FOV.

False

# Choose three factors that affect the SNR from the list below (there are three factors). Magnetic field strength of the system Proton density of the area under examination The patient's height and weight Receive bandwidth

Magnetic field strength of the system Proton density of the area under examination Receive bandwidth

T/F: A long TE increases SNR and a short TE decreases SNR.

False

T/F: TR controls the amount of T2 weighting.

False

# Choose the term that best describes "a unit volume of patient tissue" from the list below. Pixel Grayscale value Voxel Slice thickness

Voxel

Which of the following factors affect scan time during a sequential acquisition? (choose all that apply) ``` TR TE Phase Matrix NEX Frequency Matrix ```

TR Phase Matrix NEX

Which of the following factors affect voxel size (choose all that apply)? Slice thickness Number of pixels or matrix Size of the flip angle FOV

Slice thickness Number of pixels or matrix FOV

T/F: Square pixels ALWAYS provide better spatial resolution than rectangular pixels.

True

If we double the NEX, what does that do to our scan time? Reduces the scan time by 1/2 Doubles the scan time Reduces the scan time by 1.4 Increases the scan time by 1.4

Doubles the scan time

Decreasing the phase matrix does which of the following? Decreases SNR Increases spatial resolution Makes the scan shorter Has no effect on scanning

Makes the scan shorter

Of the following parameters, which would give the best spatial resolution? 256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX 256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX 512 × 256, 6 mm slice thickness, 14 cm FOV, 2 NEX None of the above would give good spatial resolution.

256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX

Of the following parameters, which would give the highest SNR? 256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX 256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX 512 × 256, 6 mm slice thickness, 14 cm FOV, 2 NEX None of the above.

256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX

Increasing the field strength increases SNR because: The flip angle increases The NMV increases in size because the high energy population of spins increases The precessional frequency increases The NMV increases in size because the low energy population of spins increases

The NMV increases in size because the low energy population of spins increases

Halving a square FOV reduces the SNR by: 1/2 1/4 3/4 1/8

3/4

Which of the following does NOT occur when the receive bandwidth is reduced? SNR increases Chemical shift artifact improves Number of slices available decreases TE increases

Chemical shift artifact improves

Doubling the number of signal averages changes the SNR by how much? × 2 1/2 22 √2

√2

Which of these is a consequence of decreasing the TR from 2500 ms to 500 ms? Scan time decreases T1 weighting decreases Spatial resolution decreases Slice number available increases

Scan time decreases

Do we achieve greater SNR with a long or a short TR? long short

long

Pixel area = __ / matrix size. SNR Resolution FOV GNR

FOV

Which sequence is considered the gold standard for MR imaging? SSFP Spin Echo Gradient Echo Coherent Gradient Echo

Spin Echo

What is the approximate T1 relaxation time of CSF at 1T? 2000 ms 150 ms 500 ms 3000 ms

2000 ms

What is the approximate T1 relaxation time of fat at 1T? 2000 ms 200 ms 500 ms 3000 ms

200 ms

What do T1 images typically best demonstrate? Anatomy Pathology Bright fluid Everything

Anatomy

What does STIR stand for? Short ___ Inversion Recovery.

Tau tau TAU

When would we be most likely to use a STIR sequence? CSF flow studies MSK studies (i.e. knee, wrist) Head or Spine studies (to look for periventricular lesions) All studies must include a STIR sequence

MSK studies (i.e. knee, wrist)

T/F: FLAIR stands for Fluid Low Attenuation Inversion Recovery

False

When would we be most likely to use a FLAIR sequence? MSK studies (i.e. knee, wrist) Head or spine studies (to look for periventricular lesions) All studies must include a FLAIR sequence To image the great vessels

Head or spine studies (to look for periventricular lesions)

How is time reduced in fast spin echo? (Choose all that apply) The operator must prescribe fewer slices Use a turbo factor Use thinner slices Use an echo train

Use a turbo factor Use an echo train

What artifact can occur as a result of using long echo trains? Cross talk Truncation Image Blurring Aliasing

Image Blurring

An inversion recovery pulse sequence begins with which of the following? 90 degree RF pulse 180 degree inverting pulse 180 rephasing pulse Gradient pulse (variable flip angle)

180 degree inverting pulse

Which Fast Inversion Recovery sequence(s) do we often use? STIR SSFP FLAIR Incoherent Gradient Echo

STIR | FLAIR

What is Double IR prep used to accomplish? Used to null blood for cardiac imaging Flips the NMV back to zero Imaging large patients FSE sequences

Used to null blood for cardiac imaging

A coherent gradient echo sequence samples which of the following? FID Only Stimulated Echo Only Both the FID and Stimulated Echo T2 Information Only

Both the FID and Stimulated Echo

T/F: During EPI all the lines of K space are filled during one repetition.

True

How is K space filled in Fast Gradient Echo Sequences? (choose all that apply) Elliptical filling Centric filling Keyhole filling Outside to inside

Centric filling | Keyhole filling

In which of the following sequences is all the transverse magnetization rewound at the end of each TR period? Coherent gradient echo Incoherent gradient echo EPI

Coherent gradient echo

Which of the following statements is true in an incoherent gradient echo sequence? Residual transverse magnetization has the same phase as the magnetization most recently created The flip angle is always 10° The system discriminates between residual and the most recently created transverse magnetization because it has a different phase value It is not a steady state sequence

The system discriminates between residual and the most recently created transverse magnetization because it has a different phase value

What type of echoes are sampled during SS-FSE? Spin echoes Gradient echoes Incoherent Gradient echoes

Spin echoes

What are the advantages of propeller K Space filling? Better detail Low SNR but high resolution Bright signal Rapid imaging, increased SNR and CNR, reduced motion artifact.

Rapid imaging, increased SNR and CNR, reduced motion artifact.

T/F: Using a long echo train decreases the SAR.

False

T/F: STIR sequences should NOT be used in conjunction with contrast enhancement.

True

T/F: Spin echo pulse sequences are classified according to whether the residual transverse magnetization is in phase (coherent) or out of phase (incoherent).

False

SSFP sequences usually produce images that are ___ weighted. T1 T2 T2* T1 or T2*

T/F: Parallel imaging is usually used to increase resolution or decrease scan time.

True

Which artifact is produced as a result of motion of flowing nuclei? Zipper effect Aliasing Phase ghosting Truncation

Phase ghosting

Which type of motion can we compensate for in MRI? First order laminar flow Second order motion acceleration Third order motion jerk All of those listed can be compensated for

First order laminar flow

T/F: TOF phenomenon results in a dark vessel.

True

Which of the following effects does TOF depend on? (Select all that apply) Velocity of flow TE Slice Thickness TR

Velocity of flow TE Slice Thickness

# Choose the two main uses of spatial pre-saturation from the list below. (Select all that apply) Chemical Pre-saturation STIR FLAIR SPIR

Chemical Pre-saturation | SPIR

T/F: Counter current flow occurs when flowing nuclei are traveling in the same direction as slice selection.

False

Which of the following is/are result(s) of time of flight? (Select all that apply) Flow-related enhancement Entry slice phenomenon High velocity signal void Zipper effect

Flow-related enhancement High velocity signal void

In a dual echo sequence, which of the following combinations would result in reduced flow artifact in the second echo? TE 20 and 50 ms TE 20 and 70 ms TE 40 and 80 ms TE 40 and 95 ms

TE 40 and 80 ms

What is the chemical shift at 1.5 T? 2.2 Hz 22 Hz 220 Hz 220KHz

220Hz

T/F: STIR is most useful in post contrast imaging.

False

T/F: Even echo rephasing reduces intra-voxel dephasing.

True

T/F: Intra-voxel dephasing results in an increase in total signal amplitude from the voxel.

False

Stationary nuclei always receive both excitation and rephasing pulses, but flowing nuclei present in the slice for the excitation may have exited the slice before rephasing. This is called ______________. Time of Flight Phenomenon Entry Slice Phenomenon Intra-Voxel Dephasing Turbulent Flow Effects

Time of Flight Phenomenon

T/F: As velocity of flow decreases, the time of flight effect decreases.

True

T/F: Another term for time of flight is inflow effect.

False

Determine which of the following parameters would result in the most entry slice phenomenon (i.e. entry slice phenomenon would increase compared to the other options). Slice 1 of 20, 3000 TR, .7 mm slice thickness Slice 1 out of 20, 400 TR, 1.2 mm slice thickness Slice 10 out of 20, 3000 TR, 1.2 mm slice thickness Slice 10 out of 20, 400 TR, .7 mm slice thickness

Slice 1 of 20, 3000 TR, .7 mm slice thickness

T/F: Flow affects image quality.

True

The frequency difference between fat and water is called ___________ and can be used to specifically null the signal from either fat or water. Chemical Pre-Saturation Chemical Shift Precessional Frequency Even Echo Rephasing

Chemical Shift

T/F: Any tissue can be nulled as long as an RF pulse matching its precessional frequency is applied to the imaging volume before excitation.

True

T/F: Pre-saturation techniques increase the RF deposition to the patient.

True

What is another term for phase ghosting? Phase wrap Phase mismapping Chemical misregistraion Aliasing

Phase mismapping

What is another term for phase ghosting? Phase wrap Phase mismapping Chemical misregistraion Aliasing

Phase mismapping

In which direction does phase ghosting occur? (Choose all applicable) Phase Axis Frequency Axis Slice Select Axis Anterior to Posterior

Phase Axis

Which of the following are methods of reducing phase ghosting? (Choose all that apply) Using respiratory compensation techniques Decrease the TE Carefully explain the procedure to the patient Swap phase and frequency Use pre-saturation pulses Use "no phase wrap" software

Using respiratory compensation techniques Carefully explain the procedure to the patient Swap phase and frequency Use pre-saturation pulses

In which direction does aliasing occur? (Choose all that apply) Phase Axis Frequency Axis Slice Select Axis Anterior to Posterior

Phase Axis Frequency Axis

Which of the following is a remedy for aliasing? Decreasing the slice thickness Decreasing the size of the FOV Decreasing the TE Using "no phase wrap" software

Using "no phase wrap" software

Which of the following best describes the appearance of chemical shift artifact on an image? Extra information wraps into the image The cancellation of fat and water signals when they are out of phase. Banding artifact at the interfaces of high and low signal. Produces a dark edge at the interface between fat and water.

Produces a dark edge at the interface between fat and water.

In which direction does chemical shift artifact occur? (Choose all that apply) Phase Axis Frequency Axis Slice Select Axis Anterior to Posterior

Frequency Axis

What unit is used to express the amount of chemical shift? MHz Hz ppm gyromagnetic ratio

ppm

What is another name for a truncation artifact in a sagital cervical spine? Truncation Gyromagnetic Artifact Gibbs Faraday

Gibbs

How can we reduce truncation? Increase the TE Increase the TR Increase the number of phase encoding steps Increase the number of frequency encoding steps

Increase the number of phase encoding steps

In which direction does truncation occur? (Choose all that apply) Phase Axis Frequency Axis Slice Select Axis Anterior to Posterior

Phase Axis

Which best describes the appearance of a zipper artifact? Distortion of the image together with large signal voids. Anatomy folded into the FOV A dense line on the image at a specific point. Tissues return a high signal intensity

A dense line on the image at a specific point.

Which of the following is a possible cause of shading artifact? A hemorrhage A leak in the RF shielding of the scan room Spin echo sequences Inhomogeneities in the main magnetic field

Inhomogeneities in the main magnetic field

Which of the following best describes Moire artifact? Black and white banding artifact on the edge of the FOV Fat and water are out of phase and their signals cancel each other out. Different chemical environments of fat and water produce a dark edge at the interface between fat and water. Anatomy from outside the FOV are wrapped into the image.

Black and white banding artifact on the edge of the FOV

T/F: To reduce chemical shift artifact, ALWAYS use the widest receive bandwidth in keeping with good SNR and the smallest FOV possible.

True

T/F: To reduce chemical shift artifact, ALWAYS use the widest receive bandwidth in keeping with good SNR and the smallest FOV possible.

True

In spin echo sequences using a pre-saturation pulse, what would persistent bright signal within the vessel indicate? Slow Flowing Blood Fast Flowing Blood Blood Clot Vascular Occlusion

Slow Flowing Blood Blood Clot Vascular Occlusion

Which of the following best describes what the "P" wave represents? Atrial Systole (Contraction) Ventricular Systole Ventricular Diastole None of the above

Atrial Systole (Contraction)

Which of the following best describes what the "QRS" complex represents? Atrial Systole (Contraction) Ventricular Systole Ventricular Diastole (Relaxation) None of the above

Ventricular Systole

Which of the following best describes what the "T" wave represents? Atrial Systole (Contraction) Ventricular Systole Ventricular Diastole (Relaxation) None of the above

Ventricular Diastole (Relaxation)

Which of the following sequence(s)/technique(s) can be used to make vessels appear bright? Gradient Echo Imaging Gradient Moment Rephasing Contrast Enhancement All of the above

All of the above

Which of the following is used to trigger each pulse sequence when using ECG gating? P wave Q wave R wave S wave

R wave

How much does a typical patient's heart rate vary during an exam? 10- 20 % 20- 30% 40- 50% 60- 70%

10- 20 %

If the R to R interval is 500 ms, the trigger window is 10%, and the trigger delay is 50 ms, what is the time available to acquire data? 310 ms 400 ms 460 ms 500 ms

400 ms

If the R to R interval is 500 ms, the trigger window is 10%, and the trigger delay is 50 ms, what is the time available to acquire data? 310 ms 400 ms 460 ms 500 ms

400 ms

What determines the length of the R to R interval? The technologist performing the exam The radiologist who establishes the protocol The patient's heart rate The type of sequence

The patient's heart rate

What is the waiting period before each R wave called? Trigger Window Trigger Delay R to R Interval Available Imaging Time

Trigger Window

T/F: ECG gating is prospective.

True

When using MRA to evaluate intracranial vascularity, flow within smaller vessels can best be demonstrated by: 2D Time of Flight MRA 3D Time of Flight MRA 3D Phase Contrast MRA All of the Above

3D Time of Flight MRA

When using MRA to evaluate intracranial vascularity, flow within smaller vessels can best be demonstrated by: 2D Time of Flight MRA 3D Time of Flight MRA 3D Phase Contrast MRA All of the Above

3D Time of Flight MRA

MRA techniques include all of the following EXCEPT: TOF-MRA PC-MRA CE-MRA CT-MRA

CT-MRA

Which of the following does NOT reduce flow motion artifact? SAT ECG gating GMN Subtraction

Subtraction

Which of the following can be used to improve coverage and at the same time maintain the signal from blood flowing within the larger volume? MC-TOF PC-MRA MOTSA Phase images

MOTSA

The vascular signal, produced on time of flight MRA (TOF-MRA), relies on: MOTA PC Flow related enhancement Velocity-induced phase shifts

Flow related enhancement

The vascular signal, produced on PC-MRA, relies on: MOTA PC Flow related enhancement Velocity-induced phase shifts

Velocity-induced phase shifts

Contrast enhanced MRAs are acquired with all of the following EXCEPT: Test bolus Bolus tracking VENC settings Fluoro triggering

VENC settings

Contrast enhanced MRAs are acquired with all of the following EXCEPT: Test bolus Bolus tracking VENC settings Fluoro triggering

VENC settings

Multiphase images, acquired with additional modulation of magnetization, are known as: TOF-MRA PC-MRA VENC SPAMM

SPAMM

What is the available imaging time using these parameters? R to R 800 ms, trigger window 10%, delay after trigger 4 ms. 688 ms 700 ms 716 ms 800 ms

716 ms

When using MRA to evaluate peripheral vascular flow, such as that within the arteries of the legs, saturation pulses are: Placed superior to the acquired slices Placed in the acquired slices Placed inferior to the acquired slices Not necessary

Placed inferior to the acquired slices

When using MRA to evaluate extracranial vascular flow, such as that within common carotid arteries, a recommended technique is: 2D time of flight MRA 3D time of flight MRA 3D phase contrast MRA All of the above

2D time of flight MRA

Magnetic field strength can be expressed in units of Tesla (T) or gauss (G), where: 1 T = 1 G 1. 5 T = 1500 G 3. 0 T = 0.3 G 1 T = 10 000 G

1 T = 10 000 G

The homogeneity of a magnetic field is expressed in units of: ppm (parts per million) T (Tesla) G (gauss) MHz (megaHertz)

ppm (parts per million)

The homogeneity of a magnetic field is expressed in units of: ppm (parts per million) T (Tesla) G (gauss) MHz (megaHertz)

ppm (parts per million)

Gradient strength is expressed in units of all of the following EXCEPT: w/kg mT/m G/cm T/m/s

w/kg

Gradient strength is expressed in units of all of the following EXCEPT: w/kg mT/m G/cm T/m/s

w/kg

Passive magnetic shielding can be accomplished by lining the scan room walls with: Copper Lead Steel Shim plates

Steel

Fourier transform (FT) is a mathematical process that is used to convert MR signal from a FID into a spectrum. FT occurs in the: Image processor Array processor RF coil Gradient amplifier

Array processor

What rule determines the direction of current flow through a coil, and the direction of the magnetic field that the current produces? The size of the magnetic field Right hand thumb rule MRI Fringe Field Rule Whether you are using an open or closed configuration

Right hand thumb rule

What is the maximum field strength allowed for clinical imaging of adults in the USA? 3 T 4 T 8 T 10 T

8 T

T/F: The purpose of magnetic field shimming is to reduce the size of the fringe field.

False

What is the most common material used to make permanent magnets? Titanium Helium Iron Alnico

Alnico

Ohm's law states: B = k (l) V = I (R) B = H (1 x) 1 T = 10 kG

V = I (R)

T/F: The law of electromagnetic induction indicates that whenever a charge particle such as an electron exhibits motion, a corresponding magnetic field is induced.

True

Which cryogen is commonly used to super cool wires in MRI? Liquid helium Niobium Alnico Hydrogen

Liquid helium

Which material is most commonly used to make superconducting wires? Liquid helium Niobium-titanium alloy Alnico Hydrogen

Niobium-titanium alloy

Why do we use shimming? To apply a magnetic field To make the field even or homogenous To make the magnetic field smaller To induce a current

To make the field even or homogenous

Select all of the following that determine the strength of an electromagnet: The amount of current passed through the windings The number of windings in the coil The distance or spacing between the windings The diameter of the wire used in the windings

All of the above

In a typical superconducting magnet, the direction of the magnetic field is: Vertical Horizontal Around the flux lines Hard to measure

Horizontal

T/F: The SNR is enhanced when using local coils.

True

T/F: The SNR is enhanced when using local coils.

True

What does BOLD stand for? Blood oxygenation level dependent Blood oxygen line developed Body oriented level dependent Type of CT scanning

Blood oxygenation level dependent

Functional imaging techniques include which of the following (check all that apply)? DWI fMRI Spectroscopy Perfusion imaging

All of the above

T/F: Functional imaging techniques allow MRI to be used to assess function and physiology as opposed to merely conventional structural imaging.

True

What term is used to describe the net displacement of diffusion spins across a tissue? SWI fMRI ADC MRS

ADC

What is the extrinsic parameter that controls the amount of diffusion seen in an image? TR TE flip angle b factor

b factor

What signal intensity is an area of abnormality likely to have on an ADC map? Hypointense Hyperintense Isointense

Hypointense

What signal intensity is an area of abnormality likely to have on a trace image? Hypointense Hyperintense Isointense

Hyperintense

T/F: Perfusion is the regional blood flow in tissues and is defined as the volume of blood that flows into one gram of tissue.

True

Which of the following best describes a use for MR Spectroscopy (MRS)? To show ankle anatomy To aid in brain tumor staging To demonstrate perfusion

To aid in brain tumor staging

T/F: Interventional MRI includes performing biopsies in the MR suite.

True

Chemical shift is measured in which of the following units? mm/s ppm T/m G/cm

ppm

T/F: Perfusion is measured using MRI by tagging the fat in arterial blood during image acquisition.

False

The anatomy of white matter tracts can be mapped using strong multi-directional gradients in which of the following? SWI diffusion tensor imaging (DTI) continuous arterial spin labeling (CASL) CBV

diffusion tensor imaging (DTI)

T/F: MR microscopy (MRM) is useful as a research tool when studying detail in a very small area of tissue.

True

T/F: MR microscopy (MRM) is useful as a research tool when studying detail in a very small area of tissue.

True

T/F: Gadolinium chelates are ferromagnetic.

False

After gadolinium administration, it is recommended that which images are acquired? One T1 weighted image One T2 weighted image Multiple T1 weighted images Multiple T2 weighted images

Multiple T1 weighted images

Enhanced MR images are evaluated for sensitivity and specificity, where sensitivity is ________ and specificity is ________. The ability to detect the lesion/the ability to classify the lesion The ability to classify the lesion/the ability to detect the lesion TE used to evaluate the lesion/TR used to evaluate the lesion TR used to evaluate the lesion/TE used to evaluate the lesion

The ability to detect the lesion/the ability to classify the lesion

T/F: All gadolinium contrast agents have the same ‘relaxivity’.

False

# Choose all of the following that enhancement agents can be useful in detecting. Infection Tumors Infarction Inflammation

All of the above

On a T1 weighted pre-contrast image, fat appears _____ and water appears _____. Bright, Dark Bright, Bright Dark, Bright Dark, Dark

Bright, Dark

T/F: Scar tissue enhances in the lumbar spine shortly after the injection of contrast.

True

T/F: Scar tissue enhances in the lumbar spine shortly after the injection of contrast.

True

Which sequence would be used to best visualize metastatic lesions in the bone? FLAIR with contrast Fat saturation techniques with contrast T2 weighted sequences Non-contrast imaging

Fat saturation techniques with contrast

T/F: Gadolinium cannot cross the intact blood-brain barrier (BBB).

True

Gadolinium element is ________ and gadolinium chelate contrast media is ________. Ferromagnetic/paramagnetic Ferromagnetic/ferromagnetic Paramagnetic/ferromagnetic Paramagnetic/paramagnetic

Ferromagnetic/paramagnetic

T/F: When using gadolinium, the T1 relaxation time of the water is reduced so enhancing lesions (such as tumors associated with free water) appear bright on a T1 weighted image.

True

Select all of the following that were discussed as possible MR contrast agents in the text. Gadolinium Blueberry juice Mango juice Dilute barium solutions

All of the above

Mid Term Exam Flashcards

(256 cards)