Unit 4 - Gradient Echo Sequences Flashcards

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1
Q

State how gradient echo sequences differ from spin echo sequences

A

-they use variable excitation pulse flip angle less than 90 degrees

-they use gradients to rephase magnetic moments

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2
Q

Describe how using different flip angles affect NMV

A

the excitation pulse flip angle is less than 90 degrees so the flip angle can be any angle

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3
Q

Identify the characteristics and the RF pulse flip angle for a gradient echo (GRE)

A

-FID occurs immediately after RF pulse

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4
Q

Discuss how the spins in the vector are caused to rephase in GRE sequence

A

a gradient is applied

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5
Q

Define spoilers

A

gradients that dephase magnetic moments

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6
Q

Define rewinders

A

gradients that rephase

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7
Q

Describe parameters in GRE T1 weighting

A

short TE, short TR, large flip angle

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8
Q

Describe parameters in GRE T2* weighting

A

long TE, long TR, small flip angle

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9
Q

Describe parameters in GRE PD weighting

A

short TE, long TR, small flip angle

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10
Q

Define steady state

A

energy in = energy out

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11
Q

Define residual transverse magnetization

A

leftover transverse magnetization is produced because of previous RF excitation pulses

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12
Q

Discuss coherent gradient echo

A

will use a reminder gradient to rephase, to then produce a gradient echo

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13
Q

Uses for coherent GRE sequences

A

typically are used to generate T2* weighted images in a very short scan time

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14
Q

Discuss incoherent gradient echo

A

aka as a spoiled gradient echo, residual magnetization is dephased or spoiled to minimize effect on image control

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15
Q

Uses for incoherent GRE sequences

A

used to produce T1 and PD weighted images

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