Sequences and Image Contrasts

Question 1

the time between two 90 RF excitation pulses

Answer 1

repetition time (TR)

Question 2

the time between the 90 RF pulse and the peak of the signal in the receiver coil

Answer 2

echo time (TE)

Question 3

T1’s use __ TRs and ___ TEs

Answer 3

T1= short TR and short TE

Question 4

What is the normal TR range for T1 images?

Answer 4

350-700 MS

Question 5

The ___ the TR the more T1 weighted it will be.

Shorter/longer

Answer 5

shorter TR = more T1

Question 6

What is the normal range for TE on a T1 image?

Answer 6

10-30 (think SHORT TE for T1)

Question 7

ON a T1 image

Water is ___

dark or bright?

Answer 7

dark

Question 8

On a T1 image

Fat is ___

dark or bright?

Answer 8

bright

Question 9

What are another name for a T1 image?

Answer 9

spin lattice

Question 10

Is T1 better for ANATOMY or PATHOLOGY?

Answer 10

ANATOMY!! think A comes first in the alphabet…A for T1

Question 11

PD stands for proton density. These sequences will have a ____ TR and a ___ TE?

short / long

Answer 11

PD= Long TR and Short TE

Question 12

What is the normal TR range for a PD image?

Answer 12

1600-4000

Question 13

What is the normal range for TE on a PD image

Answer 13

10-30

Question 14

a proton density image is basically canceling out both T1 and T2 properties.

Answer 14

True. We want to minimize both T1 and T2. PD is neither T1 or T2.

Question 15

T2s use a ___ TR and a ___ TE.

Answer 15

Long TR + Long TE = T2

Question 16

What is the normal TR for T2 images?

Answer 16

2000-6000

Question 17

WHat is the normal TE of a t2?

Answer 17

80-120

Question 18

Does the TE or the TR control T2 weighting?

Answer 18

TE controls T2

Question 19

Increasing the T2 weighting of an image can be done by increasing the ___

TR or TE?

Answer 19

TE

Question 20

On T2s, fluid is ___

bright or dark?

Answer 20

t2= BRIGHT fluids

Question 21

On T2s, fat is typically ___

dark or bright?

Answer 21

T2- fat is dark

Question 22

When we are scanning an inversion recovery sequence, what is the contrast controlled by?

The TR the TE or the TI?

Answer 22

All three! Inversion recovery is controlled by TE TR and TI (inversion time)

Question 23

The T1 of adipose tissue is shorter than the T1 of water

True or False

Answer 23

True

Question 24

What does STIR stand for?

Answer 24

Short TI inversion recovery

Question 25

STIRs use specific timing to suppress the signal from fat. True or False?

Answer 25

TRUE, that's why they are so dark.

Question 26

a spin echo pulse sequence preceded by a 180 RF pulse is what type of sequence??

Answer 26

STIR

Question 27

Why with a STIR do we do the 180 RF Pulse?

Answer 27

it inverts the starting magnetization which then returns to its equilibrium according to T1 relaxation.

Question 28

During a STIR, Fat will reach its null point faster than white matter, grey matter, water or edema, and so an image of these structures can be generated

Answer 28

True

Question 29

make the TI long and you have the FLAIR pulse sequence, which suppresses signal from fluid True or False

Answer 29

True

Question 30

Enabling Driven Equilibrium (DRIVE: Philips) will enable the operator to increase TR and preserve contrast

Answer 30

FALSE Enabling Driven Equilibrium (DRIVE: Philips) will ENABLE the operator to reduce TR and preserve contras

Question 31

When does the presaturation pulse typically occur? prior to excitation or after the excitation pulse?

Answer 31

prior

Question 32

Fat suppression techniques suppress based on the precessional frequency of ___

Answer 32

Fat

Question 33

90 RF followed by 180 RF is what type of pulse sequence? Spin echo, fast spin echo, inversion recovery or a gradient echo.

Answer 33

Spin Echo

Question 34

90 RF followed by a train of 180 RF pulses is what type of pulse sequence? Spin echo, fast spin echo, inversion recovery or a gradient echo.

Answer 34

fast spin echo.

Question 35

a 180 RF followed by a 90 RF is what type of pulse sequence? Spin echo, fast spin echo, inversion recovery or a gradient echo.

Answer 35

inversion recovery

Question 36

variable RF followed by gradient to produce echo this is what type of pulse sequence?? Spin echo, fast spin echo, inversion recovery or a gradient echo.

Answer 36

gradient echo.

Question 37

What are examples of extrinsic contrast parameters ( ones that MR techs can adjust to alter image)

Answer 37

TR, TE, flip angle, TI and ETL

Question 38

What are examples of intrinsic paramters ( specific to tissue and cannot be changed by MR tech)

Answer 38

ADC, T1 AND T2 times, specific proton density, and flow

Question 39

What are some structures that will ALWAYS appear black on an MRI image?

Answer 39

air, tendons, ligaments, metallic susceptibility and cortical bone.