Conventional spin echo pulse sequences are rarely used for acquiring the anatomical volume data used for NPR because

Excessive time required with long TR of spin echo sequences are used in volume imaging. 2 Gaps from crosstalk in 2D the spin echo imaging. 3. Low SNR ratios result when acquiring thin slices in 2D the spin echo imaging

The formula for calculating scan time for a 3-D acquisition is:

Measurement time= (TR) * (PHASE LINES IN MATRIX) * (#SLICES) * (NSA) / Echo train length

In a 3-D volume pulse sequence with a 256 x 256 matrix and 16 transverse slices,_________ unique phases must be generated by the Z gradient, assuming one acquisition:

As many fees and coding steps are required along the slice direction as the number of slices: 16

In a 3D volume pulse sequence with a 256 x 256 matrix, 16 transverse slices, and the Y-gradient responsible for in plain phase encoding,_____unique phases must be generated by the Y-gradient assuming one acquisition and no RFOV or parallel imaging:

The in-plane special encoding of the traverse slices are accomplished by the Y-and-X gradients. The X- gradient is used as the slice select gradient. 256

In a 3-D volume pulse sequence with a 256 x 256 matrix, 16 transverse slices, and the Y-gradient responsible for in-plain phase encoding,_____ unique phases must be generated by the X-gradient, assuming 1 acquisition:

NO. In-plane special encoding of the transverse slices are accomplish by the Y-and-X gradients. Therefore, the X-gradient is used for frequency encoding and it's not used to generate phase information in the sequence.

Which of the following is TRUE of the specific absorption rate of a 3D spoiled gradient echo sequence with 16 slices VS a 2D spoiled gradient echo sequence with 16 slices, assuming all other parameters are identical:

The SAR is the same on both sequences. Total number of RF pulses = (phase matrix) * ( number of signal averages) * (number of slices)

Scan Time of a 3D pulse sequence with 205 phase steps in the image matrix, a TR of 40 ms, a FOV of 28 cm, 20 slices, 2 signal averages, and echo train length of 1 and no parallel imaging is_______ minutes:

Therefore, the scan time = (TR) * (phase matrix) * ( NSA) * (#of slices) * (echo train length). =0.04sec * 205 * 2 * 20 / 1 = 328sec =5.5 minutes

Help

Options

focusNode

Didn't know it?
click below

Knew it?
click below

Don't Know

Remaining cards (0)

Know

retry

shuffle

restart

0:00

Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

Normal Size Small Size show me how

7 Volume imaging

Review

Question	Answer
Conventional spin echo pulse sequences are rarely used for acquiring the anatomical volume data used for NPR because	Excessive time required with long TR of spin echo sequences are used in volume imaging. 2 Gaps from crosstalk in 2D the spin echo imaging. 3. Low SNR ratios result when acquiring thin slices in 2D the spin echo imaging
The formula for calculating scan time for a 3-D acquisition is:	Measurement time= (TR) * (PHASE LINES IN MATRIX) * (#SLICES) * (NSA) / Echo train length
In a 3-D volume pulse sequence with a 256 x 256 matrix and 16 transverse slices,_________ unique phases must be generated by the Z gradient, assuming one acquisition:	As many fees and coding steps are required along the slice direction as the number of slices: 16
In a 3D volume pulse sequence with a 256 x 256 matrix, 16 transverse slices, and the Y-gradient responsible for in plain phase encoding,_____unique phases must be generated by the Y-gradient assuming one acquisition and no RFOV or parallel imaging:	The in-plane special encoding of the traverse slices are accomplished by the Y-and-X gradients. The X- gradient is used as the slice select gradient. 256
In a 3-D volume pulse sequence with a 256 x 256 matrix, 16 transverse slices, and the Y-gradient responsible for in-plain phase encoding,_____ unique phases must be generated by the X-gradient, assuming 1 acquisition:	NO. In-plane special encoding of the transverse slices are accomplish by the Y-and-X gradients. Therefore, the X-gradient is used for frequency encoding and it's not used to generate phase information in the sequence.
In a 3D spoiled gradient echo sequence,_________contributes to the image contrast: Spin spin interactions magnetic susceptibility effects magnetic inhomogeneities	ALL
Which of the following is TRUE of the specific absorption rate of a 3D spoiled gradient echo sequence with 16 slices VS a 2D spoiled gradient echo sequence with 16 slices, assuming all other parameters are identical:	The SAR is the same on both sequences. Total number of RF pulses = (phase matrix) * ( number of signal averages) * (number of slices)
Scan Time of a 3D pulse sequence with 205 phase steps in the image matrix, a TR of 40 ms, a FOV of 28 cm, 20 slices, 2 signal averages, and echo train length of 1 and no parallel imaging is_______ minutes:	Therefore, the scan time = (TR) * (phase matrix) * ( NSA) * (#of slices) * (echo train length). =0.04sec * 205 * 2 * 20 / 1 = 328sec =5.5 minutes
In a set of volume images, emotion artifact may be seen along the: 1) in-plane phase direction. 2) Slice direction, from one image to another. 3) frequency direction.	1&2

Created by: tomvilla21

"Know" box contains:
Time elapsed:
Retries: