Test 2 Flashcards by Naomi Ngo

What is the readout gradient is also known as?
a. RF encoding gradient
b. Frequency encoding gradient
c. Phase encoding gradient
d. Slice select gradient

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What is the center of the bore in all planes is known as?
a. Claustrocenter
b. Hypercenter
c. Isocenter
d. Hypocenter

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When does the frequency encoding gradient turn on in a CSE pulse sequence?
a. Between the 90º and 180º pulses
b. During the 90º and 180º pulses
c. During the FID
d. During the spin echo

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What is the range of frequencies sampled during the read out gradient (sampling window) known as?
a. Spatial encoding
b. Spin echo
c. Transmit bandwidth
d. Receive bandwidth

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In general, what do small FOVs and thin slices require?
a. Steep gradients
b. Short TRs
c. Wide bandwidths
d. Long RF pulses

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During the scan, where is data stored?
a. Hard drive
b. k-Space
c. Chest of drawers
d. Spin echo

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What is the mathematical process that converts frequency amplitudes from the time domain to the frequency domain in order to locate them spatially?
a. FID
b. Fast Fourier Transform
c. Readout gradient
d. k-Space

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What determines which line of k-space get filled?
a. k-Space gradient
b. Slice select gradient
c. Readout gradient
d. Phase encoding gradient

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Data in the outer lines of k-space contribute to ________ information.
a. Signal and contrast
b. Distal pixels
c. Resolution
d. T1 or T2

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A single data point of k space contains information from the entire slice.
True
False

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FLAIR is a fast IR sequence that nulls signal from what tissue?
a. White matter
b. Water/CSF
c. Fat
d. Muscle

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In order to null the signal from a tissue using an IR sequence, the TI must be what?
a. at the larmor frequency
b. 0.69 times the T1 time of the tissue
c. 0.69 times the T2 time of the tissue
d. In steady state

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What pulse sequence is a 90º pulse followed by a 180º pulse?
a. FIESTA
b. SSFSE
c. CSE
d. FSE

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In a Fast/Turbo spin echo sequence, data from echoes farther away from the effective TE will be placed where?
a. In a shallow readout gradient
b. In noise
c. In the central lines of K space
d. In the outer lines of K space

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A sequence that uses a reverse flip angle at the end of the echo train to restore residual transverse magnetization into the longitudinal plane is known as what?
a. Single Shot Fast Spin Echo/SSFSE/HASTE
b. FIESTA/Balanced gradient echo
c. Incoherent Gradient Echo/SPGR
d. DRIVE/FR-FSE/Driven equilibrium Fourier transform

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Which inversion recovery sequence has the shortest TI?
a. FSE
b. FLAIR
c. STIR
d. SSFSE

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What is TI?
a. Time from 180º inversion pulse to the 90º excitation pulse
b. Time from the 90º excitation pulse to the 180º rephasing pulse
c. Time from 90º inversion pulse to the 90º excitation pulse
d. Time from 90º excitation pulse to the 180º inversion pulse

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What is Tau?
a. Time from 180º inversion pulse to the 90º excitation pulse
b. Time from the 90º excitation pulse to the 180º rephasing pulse
c. Time from 90º inversion pulse to the 90º excitation pulse
d. Time from 90º excitation pulse to the 180º inversion pulse

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What is TE?
a. Time from 180º inversion pulse to the 90º excitation pulse
b. Time from the 90º excitation pulse to the 180º rephasing pulse
c. Time from 90º inversion pulse to the 90º excitation pulse
d. Time from 90º excitation pulse to the peak of echo

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Increasing ETL will result in

    I. Increased T1 weighting

    II. Reduced scan time

    III. Increased heating

a. II and III
b. I and II
c. I and III
d. I, II, and III

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The technologist selects a TR of 600ms and a TE of 30ms for a CSE sequence. What weighting should they expect?
a. T1
b. T2
c. Diffusion
d. PD

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How does a CSE pulse sequence compensate for T2*?
a. Long TR
b. Two rephasing pulses
c. Short TR
d. 180º rephasing pulse

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What pulse sequence acquires all lines of k-space in one TR using FSE in combination with partial averaging?
a. CSE/FSE
b. SSFSE/HASTE
c. FRFSE/DRIVE
d. STIR/FLAIR

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What changes during every 180° rephasing echo in a Fast/Turbo spin echo?
a. Phase encoding gradient
b. Effective TE
c. Center frequency
d. Phase direction

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What occurs when a gradient is applied to B0? a. The precessional frequencies of H increases at one end and decreases at the other b. T2 weighting increases c. T2 weighting decreases d. Resonance occurs as long as it is at the Larmor frequency

GRE pulse sequences have more T2* than SE. True False

A pulse sequence with a TR of 50ms, a TE of 5ms, and a flip angle of 70 would result in what weighting? PD weighting T2* weighting T2 weighting T1 weighting

In general, GRE pulse sequences are faster than SE. True False

With a short TR, what determines the optimum flip angle to give the highest signal for a tissue? a. Larmor equation b. DRIVE c. Steady State d. Ernst angle

What processes affect weighting in GRE? a. All of the above b. Flip angle c. Steady State d. Residual transverse magnetization

What is the difference between SE and GRE I. GRE has a variable flip angle II. SE uses a 180º rephasing pulse III. GRE uses a rephasing gradient. a. I, II, and III b. I and III c. II only d. II and III

In incoherent gradient echo, the spoilers can be ____. a. Only RF pulses b. Only gradients c. Frequency modulation d. Gradient or RF pulses

Decreasing pixel size will increase resolution. True False

The technologist doubles the NEX. What happens to SNR? I. The SNR doubles II. The SNR increases by √2 III. The SNR increases by 1.4 a. II and III b.I only c. II only d. II and III

What results when slice thickness is increased? a. Decreased SNR b. Increased partial voluming c. Increased chemical shift d. Decreased coverage

Doubling NEX will double scan time. True False

Coil placement and selection is important for image quality True False

What results when FOV is increased? I. SNR increases II. Resolution decreases III. Coverage increases a. II and III b. I and III c. I, II, and III d. I and II

What results when receiving bandwidth increases? I. Resolution increases II. Minimum TE decreases III. SNR decreases a. II and III b. I, II, and III c. III only d. I and III

which of the following pulse sequences does not use a 180 refocusing RF pulse a. spin echo b. gradient echo c. inversion recovery d. fast spin echo

What does STIR stand for? a. sequence time in relaxation b. safe time in recovery c. short tau inversion recovery d. soft tune inversion RF

the highest signal amplitude is stored in which area of space a. central line b. outer line c. top half d. bottom half

what do data near periphery of kspace determine? a. contrast b. details and resolution c. weighting d. slice thickness

a long TI required for which pulse sequence a. STIR b. FLAIR c. CSE d. DRIVE

what determines the number of lines of k-space a. phase matrix b. phase encoding gradient c. frequency matrix d. frequency encoding gradient

What is the term for the number of times data is collected with the same phase encoding gradient slope? a. TR b. NEX/NSA c. frequency matrix d. Receive bandwidth

adjust which parameter will have smallest effect on scan time a. TR b. TE c. NEX/NSA d. slice thickness e. phase matrix

increasing what parameter will increase SNR? a. TR b. frequency matrix c. TE d. slice gap

increasing bandwidth will affect all of the following except: a. decrease chemical shift b. decrease SNR c. decrease resolution d. decrease minimum TE

decreasing slice thickness will result in all of the following except a. decrease SNR b. decrease coverage c. decrease resolution d. increase partial voluming

what GRE pulse sequence use oscillating readout gradient to produce a train of echo a. Fast GRE b. EPI c. FIESTA d. FSE

doubling NEX will double __ a. scan time b. SNR c. resolution d. T1-W

what is gradient amplitude

rate of change of mag field strength

___ gradient amplitude will have big differences in frequencies a. steep b. shallow

what is purpose of gradient axes

spatially locate signal along 3 gradients

what determine slice thickness ? (2)

slope of gradients range of frequencies (transmit bandwidth)

to achieve thin slice we need ___ & ___

steep slope and narrow transmit bandwidth

what is sampling window

amount of time the frequency encoding gradient is turned on

sampling interval has a ____ relationship with digital sampling frequency

inverse

sampling interval = ____/___

sampling window (s) sampling frequency (Hz)

incorrect frequency sampled is due to ____ which lead to artifact called ___

sampling frequency < Nyquist frequency aliasing

sampling frequency > Nyquist frequency = ____

more noise time insufficient

Receive bandwidth = ____ because both has 2 x Nyquist frequency

sampling frequency

to achieve small fFOV, we need ____

steep frequency encoding gradient

data in COLUMN determine ___ in ____ direction

size of FOV phase

data in ROW determine ___ in ____ direction

size of FOV frequency

duration of ____ affect minimum TE

sampling window

phase FOV expressed as ____

% of frequency FOV

what is frequency matrix

Number of pixels in frequency direction

phase FOV is used in ____ , ____, ____

rectangular FOV antialiasing parallel imaging

what determine frequency matrix

amount of time signal is sampled

duration of sampling window affect___

minimum TE

what happened when phase encoding gradient is ON

affect frequency of magnetic moments

what happened when phase encoding gradient is OFF

frequency back to normal & phase position remains

phase encoding gradient can be used to avoid ___

aliasing/wrap

what is phase matrix

number of time phase encoding is turned on

high amplitude signal = ____ which location in k-space

decrease resolution central

low amplitude signal = ___ which location in k-spce

increase resolution outer

2D scan time = _____ x ____ x_____

phase matrix TR NEX/NSA

what is needed to create a large change in phase

steep slope

small pixel = _____ phase encoding gradient

steep

steep phase encoding fill ___ lines

outer

shallow phase encoding fill ___ line

central

we can take advantage of which fact abt k-space to reduce scan time

conjugate symmetry

how pulse sequence fill k-space

1. Bss pick an area of k-space 2. phase encoding pick which line of k-space to fill 3. frequency encoding determine how each line is filled

what determine how each line of k-space is filled

frequency encoding

what are the options to fill k-space

1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

which options only fill half of k-space and has symmetrical top and bottom 1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

which option allow central line to get sample first 1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

which option fill many lines per TR and require special coil 1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

which option fill all data in k-space in a single TR with echo train 1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

which option has symmetrical echo that doesnt need to sample 1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

which option sample center every TR but has long scan time and reduce resolution 1. partial averaging 2. partial echo 3. parallel imaging 4 . single shot 5.spiral k-space 6. acquisition 7. propeller/BLADE

FFT converts ____ from the __ domain to the ____ domain

frequency amplitude time frequency

low amplitude signal generated ___

steep phase gradient + large phase change

For nyquist theorum, what must be sampled and how many times for accuracy

highest frequencies twice

each chest = ___

slice in the image

Number of chests = ___

Number of slice

each drawer = ____ of k-space

line

each sock = ___

data point

what determine what data to put in which line

frequency coding gradient

the number of data point is determined by ____

frequency matrix

Thru ADC, echo received at time ___ is digitized

amplitude is to figure out _____

if a pixel is bright or dark

frequency is to figure out ____

which pixel

what is spatial encoding

calculate how much signal from each voxel

SE use a ___ pulse to rephase echo

180

CSE give ____ weighting

True T2

pattern for CSE 1. 90-180 2. 90-180-180-180- 3. 180-90-180-180-

pattern for FSE 1. 90-180 2. 90-180-180-180- 3. 180-90-180-180-

FSE use ____ and has ____ while EPI use ___ & ___

ETL effective TE RF pulse and oscillating readout gradient

DRIVE use _____ pulse

reverse flip pulse

IR sequence use ____

pattern for IR 1. 90-180 2. 90-180-180-180- 3. 180-90-180-180-

what pulse sequence is 90-180

CSE

what pulse sequence is 180-90-180-180-

what pulse sequence is 90-180-180-180-

FSE

STIR has ____ TI

short

why STIR need a short TI

T1 time of fat is shorter than water

FLAIR has ____ TI

long

which pulse sequence null signal from fat 1. STIR 2. FLAIR 3. DIR 4. TIR

which pulse sequence null signal from BLOOD 1. STIR 2. FLAIR 3. DIR 4. TIR

which pulse sequence null signal from WATER 1. STIR 2. FLAIR 3. DIR 4. TIR

which pulse sequence add another inversion pulse to null signal from FAT AND BLOOD 1. STIR 2. FLAIR 3. DIR 4. TIR

what is the null point of fat

0.69 x T1 time

what is the definition of null point

time it takes a certain tissue to recover from full inversion to the transverse plane