|
Magnetic
Resonance -
Technology
Information
Portal |
Friday, 20 November 2009 •• |
|
|
|
Info Sheets
|
|
| | | | | | | | | | | | | | | | | | | |
|
Out- side
|
| |
|
|
|
|
|
|
|
ADVERTISEMENT |
 |
|
ADVERTISEMENT |
|
ADVERTISEMENT |
 |
|
ADVERTISEMENT |
|
ADVERTISEMENT |
 |
|
ADVERTISEMENT |
|
| | | | |
Result : Searchterm 'Phase Encoding' found in 7 terms [ ] and 67 definitions [ ]
| 1 - 5 (of 74) nextResult Pages : [1 2] [3 4 5 6 7 8 9 10 11 12 13 14 15] | |  | |
 |
Searchterm 'Phase Encoding'
was also found in the following service of MR-TIP.com: |
|
| | | |  |  |
| |
|
The process of locating a MR signal by altering the phase of spins in one dimension with a pulsed magnetic field gradient along that dimension prior to the acquisition of the signal.
If a gradient field is briefly switched on and then off again at the beginning of the pulse sequence right after the radio frequency pulse, the magnetization of the external voxels will either precess faster or slower relative to those of the central voxels.
During readout of the signal, the phase of the xy-magnetization vector in different columns will thus systematically differ. When the x- or y- component of the signal is plotted as a function of the phase encoding step number n and thus of time n TR, it varies sinusoidally, fast at the left and right edges and slow at the center of the image. Voxels at the image edges along the phase encoding direction are thus characterized by a higher 'frequency' of rotation of their magnetization vectors than those towards the center.
As each signal component has experienced a different phase encoding gradient pulse, its exact spatial reconstruction can be specifically and precisely located by the Fourier transformation analysis. Spatial resolution is directly related to the number of phase encoding levels (gradients) used.
The phase encoding direction can be chosen, e.g. whenever oblique MR images are acquired or when exchanging frequency and phase encoding directions to control wrap around artifacts. |
| | |
Further Reading: |
Basics:
|
|
News & More:
| | | | |
|  |
 |
MRI Resources |
|
| | | |  |  |  |
| |
|
| The temporal order in which the phase encoding gradient pulses are applied. The order can be sequential, centric, reverse centric, random, etc. |
| | | | |
|  |
 |
Searchterm 'Phase Encoding'
was also found in the following service of MR-TIP.com: |
|
| | | |
|
 |  |
| |
|
| | |
Further Reading: |
Basics:
|
|
News & More:
| | | |
|  |
 |
MRI Resources |
|
| | | |  |  |  |
| |
|
| | |
Further Reading: |
News & More:
|
| | |
|  |
 |
Searchterm 'Phase Encoding'
was also found in the following service of MR-TIP.com: |
|
| | | |
|
 |  |
| Phase Encoding Artifact Reduction |  |
| |
|
| (PEAR) Each phase of the respiratory cycle coincides with the collection of phase encoded data. The low order phase encoded data, with is highly sensitive to motion, is collected towards the end of exhalation and beginning of inspiration. The high order data, which is less sensitive, is collected over the remaining part of each respiratory cycle. |
| | |
Further Reading: |
Basics:
|
| | |
|  |
|
 |
MRI Resources |
|
| | | |  |  | | |
|
| |
|
Look Ups
|
 |
Latest
News |
|
|
ADVERTISEMENT |
|
|
|
ADVERTISEMENT |
| |
|
|
| [last update: 2009-11-16 01:58:13] |
|
|