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Flashcards in MRI Physics 3 Deck (100)
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1

Why is EPI the sequence of choice for functional MRI
a. High SNR
b. high resolution
c. ultra fast sequence
d. all of the above

c. ultra fast sequence

2

In Gradient Recalled Echo (GRE) the main reason for using partial flip angles is to
a. lower TE
b. Lower TR
c. increase SNR
d. b and c

b. lower TR

3

the Flow Related Enhancement Effect (FRE) is associated with which pulse sequence
a. GRE
b. EPI
c. SE
d. FSE

a. GRE

4

In an FSE sequence as the echo train length of turbo factor increases, the number of slices per TR
a. decreases
b. increases
c. stays the same
d. depends on the flip angle

a. decreases

5

Magnetization Transger (MR) suppresses signal from
a. protein bound water
b. protein bound fat
c. free water
d. free fat

a. protein bound water

6

MRI signal data placed in outer edges of K space has a greater effect on
a. image contrast
b. image spatial resolution
c. image SNR
d. b and c

b. image spatial resolution

7

Which kind of scan uses the B parameter with units [s/mm^2]
a. diffusion
b. perfusion
c. a and b
d. none of the above

a. diffusion

8

A short TE time in a GRE sequence is typically
a. less than 10 ms
b. 15-25 ms
c. 30-40 ms
d. none of the above

a. less than 10ms

9

The TI required to null the signal from a tissue in an IR sequence is given by
a. .37T1
b. .63T1
c. .69 T1
d. T1

c. .69 T1

10

T1 weighted images are generally useful for demonstrating anatomy in MRI because they have a high SNR. T2 weighted images are generally useful for demonstrating pathology because
a. they have a low SNR
b. the TR is long
c. diseased tissue is accompanied by edema
d. none of the above

c. diseased tissue is accompanied by edema

11

If the spacing between the echoes (ESP) in the FSE echo train is reduced from a time of 15ms to 10ms, then the contrast blurring will be
a. decreased
b. the same
c. increased
d. b or c

a. decreased

12

The TE time in a GRE sequence is measured from the start of the RF pulse to
a. the starting time of the dephasing gradient
b. the midpoint time of the dephasing gradient
c. the starting time of the rephasing gradient
d. the midpoint time of the rephasing gradient

d. the midpoint time of the rephasing gradient

13

For balanced gradient lobes, what must be equal
a. gradient amplitude
b. gradient time
c. (gradient amplitude) x (gradient time)
d. all of the above

c. (gradient amplitude) x (gradient time)

14

If Gmax is the maximum gradient and Tr is the rise time, then the slew rate SR is given by
a. SR=Gmax x Tr
b. SR=Gmax/Tr
c. SR=Tr/Gmax
d. none of the above

b. SR = Gmax / Tr

15

reversing the phase encoding gradient after readout in a coherent gradient echo is a process known as
a. spoiling
b. rewinding
c. blipping
d. fractional echo

b. rewinding

16

If the ETL or TF for a FSE sequence is 4, how much faster would the FSE sequence be compared to a similar CSE sequence
a. 2
b. 4
c. 16
d. none of the above

b. 4

17

In a dual echo FSE scan with ETL = 8, using the first four echoes for a PD image and the last four echoes for a T2W image would be an example of what method
a. Full Echo Train
b. Split Echo Train
c. Shared Echo
d. none of the above

b. Split Echo Train

18

Which of the following statements about EPI are true
I. EPI uses gradient blipping to fill K space
II. the weighting of EPI images is given by an effective TE
III. EPI imaging is often used for fMRI

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

d. I II and III

19

A SE produced by 2 90deg RF pulses is called
a. CSE
b. Hahn Echo
c. stimulated Echo
d. b and c

d. b and c

20

Incoherent GRE sequences can use
a. RF spoiling
b. gradient spoiling
c. a and b
d. none of the above

c. a and b

21

In a dual SE sequence, the weighting of the image associated with the first echo is
a. PD weighting
b. T1W
c. T2W
d. a or c

a. PD Weighting

22

To achieve full recovery of the longitudinal magnetization in a FLAIR sequence, the TR should be
a. 400-800ms
b. 2000+ms
c. 6000+ms
d. none of the above

c. 6000+ms

23

fMRI uses a rechnique knows as
a. FLAIR
b. STIR
c. BOLD
d. SSFSE

c. BOLD

24

The central park of K space conrols ____, while the peripheral part of K space controls ____.
a. image contrast, spatial resoluion
b. spatial resolution, image contrast
c. image window, image level
d. image level, image window

a. image contrast, spatial resolution

25

In order to rewind a gradient, what factor must be balanced between positive and negative gradient lobes
a. amplitude * rise time
b. amplitude * gradient time
c. slew rate * rise time
d. slew rate * gradient time

b. amplitude * gradient time

26

The percentage of time during a TR period that a gradient is at maximum amplitude is known as
a. rise time
b. slew rate
c. gradient balance
d. duty cycle

d. duty cycle

27

A typical rise time for gradients on high field MRI systems is several hundred
a. picoseconds
b. microseconds
c.milliseconds
d. seconds

b. microseconds

28

The gradient coils are powered by the
a. RF amplifiers
b. RF coils
c. gradient amplifiers
d. none of the above

c. Gradient amplifiers

29

SSFSE is an acquisition that
a. fills multiple lines of K space in one TR
b. is acquired in one TR
c. can fill half of K space and transpose the other half
d. all of the above

d. all of the above

30

In IR pulse sequences, what is the proper ordering of the initial two RF pulses
a. 90, 90
b. 90, 180
c. 180, 90
d. 180, 180

c. 180, 90