MRI Physics Ch 3 Spin Echo Imaging Take home Quiz

Spin echo or hahn echo is produced from a 90 to 180 degree rf pulse

A 90 degree RF pulse followed by a 180 degree RF pulse will produce a ___________echo.

K-space

A MRI sequence is built by filling____________ with slice, frequency and phase encoded data from a pulse sequence.

J-coupling

A T2 FSE sequence can yield hyper-intense signal from water AND fat. What term used to describe this?

Conventional Spin Echo

A _________sequence fills 1 line of data with the phase encoding gradient every TR period.

A 180-degree pulse that is added before the conventional 90-degree RF excitation pulse.

Define an inversion recovery pulse?

excitation pulses flip the NMV fully into the transverse plane, then the hydrogen nuclei start to dephase from the transverse plane at different rates. the 180 degree rephasing pulse flips the individual magnetic moments through the transverse plane so that the individual magnetic moments that "were behind" are now in front and this means that the magnetic moments that were dephasing faster catch up and you get maximum signal once they are all aligned. rephasing pulses also give more time to separate out fat and water. IR prep pulses are 180 degree inverting pulses used at the beginning of a sequence to get fat and water both aligned on the longitudinal plane giving them time to separate as the return back to the NMV.

Explain the difference between a excitation pulse, re-phasing pulse and an IR prep pulse.

After the excitation sequence, the moments start to become unaligned. Some moments spin faster and some slower depending on their location in the magnetic field.. Then a re-phasing pulse flips the moments like a pancake, which makes the faster moments go from first to last. Since the faster moments are in the back, they catch up to the slower moments as they all realign again.

Explain why a "spin echo" has symmetry (Use analogy if needed).

435 x 0.69 = 300 ms ish

Find the TI time of white matter when the T1 relaxation time is 435ms

All lines of K-space are acquired in one TR period. Used in conjunction with Partial Fourier technique (Half of the lines of K-space are interpolated)

How does a HASTE sequence differ from a fast spin echo sequence?

PD

In a TSE, what type of image contrast would be likely with a ETL of 5, TR of 3,000 ms and effective TE of 20 ms?

180 degree

In an Inversion recovery sequence a _________pulse is added before the conventional 90 degree RF pulse.

800 ms (medium)

Match the substance with it's TI Time: Blood

1700-2200 ms (long

Match the substance with it's TI time: CSF/Water

150-175 ms (short)

Match the substance with it's TI time: Fat

Increased T2 weighting Increased SAR Decreased Susceptibility Decreased signal Increased blurring Decreased scan time

Name at least 4 outcomes when increasing TF from 1 to 30

Inversion recovery

The diagram below is an example of what type of spin echo sequence?

TSE

The diagram below is an example of what type of spin echo sequence?

Middle lines

The effective TE used in a TSE will fill which lines in K-space?

TAU Time; 1/2 TE

The time between the 90 degree excitation pulse and the 180 degree re-phasing is equal to the time between 180 degree re-phasing pulse and peak of the MRI echo. This is referred to as the: (Check all that apply).

Tau

Time between the 900 flip and 1800 rephase and time between 180o flip and peak of signal. ( ½ TE time - Dephasing and the other ½ is Rephasing = total TE time)

0.69

To find the TI time of tissue, first find the T1 relaxation time and then multiply it by:

Less spin-spin interactions due to the multiple rephasing pulses in a TSE. The reason why fat remains bright on a T2 TSE image.

What causes J-coupling and what effect on image contrast will J-coupling cause?

Choose which line in k-space will be filled with data from the MRI signal

What does the phase encoding gradient do in a spin echo sequence?

Turbo factor/Echo Train Length

What extrinsic contrast parameter is unique to TSE/FSE?

Contrast enhancement may be suppressed

What is a possible consequence of running a IR sequence post contrast?

Hahn echo, A 90-degree excitation pulse followed by a 180 degree rephasing RF pulse.

What is another name for a spin echo and how is a spin echo produced?

TE

What is the time between 90 degree RF excitation pulse and the peak of the echo

TR

What is the time between 90 degree RF excitation pulses called

More T2 weighting, Increased SAR, Increased blurring

What outcomes occur when increasing the echo train length (ETL) for 8 to 32?

TI

What term denotes the time between the inversion pulse and the 90 degree excitation RF pulse?

PD weighting

What type of image contrast would these parameters produce? TR :5,000 ms ETL 5 FOV 20 cm 2 averages TE 20 ms

T2 FLAIR

What type of sequence was created on the image below (Be specific)?

Can be used to decrease TR; Can increase SAR

Which of the following is effected by using a restore (drive) pulse? Check all that apply.