Abstract
The projection reconstruction (PR) trajectory was investigated for the effect of gradient timing delays between the actual and requested start time of each physical gradient. Radial trajectories constructed with delayed gradients miss the center of k-space in an angularly dependent manner, causing effective echo times to vary with projection angle. The gradient timing delays were measured in phantoms, revealing delays on the x, y, and z gradients which differed by as much as 5 μsec. Using this one-time calibration measurement, the trajectories were corrected for gradient delays by addition of compensatory gradient areas to the prephasers of the logical x and y readout gradients. Effective projection-to-projection echo time variability was reduced to less than 1 μsec for all imaging orientations. Using corrected trajectories, artifacts were reduced in phantom images and in volunteer studies. This correction should potentiate greater clinical use of the PR trajectory.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1-6 |
| Number of pages | 6 |
| Journal | Magnetic Resonance in Medicine |
| Volume | 50 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jul 1 2003 |
| Externally published | Yes |
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Keywords
- Compensation blips
- Echo-planar imaging
- Gradient delay
- Gradient errors
- Linear phase
- Magnitude back projection
- Projection reconstruction
- Radial imaging
- Reference scans
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology
Cite this
Centering the projection reconstruction trajectory : Reducing gradient delay errors. / Peters, Dana C.; Derbyshire, J. Andrew; McVeigh, Elliot R.
In: Magnetic Resonance in Medicine, Vol. 50, No. 1, 01.07.2003, p. 1-6.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Centering the projection reconstruction trajectory
T2 - Reducing gradient delay errors
AU - Peters, Dana C.
AU - Derbyshire, J. Andrew
AU - McVeigh, Elliot R.
PY - 2003/7/1
Y1 - 2003/7/1
N2 - The projection reconstruction (PR) trajectory was investigated for the effect of gradient timing delays between the actual and requested start time of each physical gradient. Radial trajectories constructed with delayed gradients miss the center of k-space in an angularly dependent manner, causing effective echo times to vary with projection angle. The gradient timing delays were measured in phantoms, revealing delays on the x, y, and z gradients which differed by as much as 5 μsec. Using this one-time calibration measurement, the trajectories were corrected for gradient delays by addition of compensatory gradient areas to the prephasers of the logical x and y readout gradients. Effective projection-to-projection echo time variability was reduced to less than 1 μsec for all imaging orientations. Using corrected trajectories, artifacts were reduced in phantom images and in volunteer studies. This correction should potentiate greater clinical use of the PR trajectory.
AB - The projection reconstruction (PR) trajectory was investigated for the effect of gradient timing delays between the actual and requested start time of each physical gradient. Radial trajectories constructed with delayed gradients miss the center of k-space in an angularly dependent manner, causing effective echo times to vary with projection angle. The gradient timing delays were measured in phantoms, revealing delays on the x, y, and z gradients which differed by as much as 5 μsec. Using this one-time calibration measurement, the trajectories were corrected for gradient delays by addition of compensatory gradient areas to the prephasers of the logical x and y readout gradients. Effective projection-to-projection echo time variability was reduced to less than 1 μsec for all imaging orientations. Using corrected trajectories, artifacts were reduced in phantom images and in volunteer studies. This correction should potentiate greater clinical use of the PR trajectory.
KW - Compensation blips
KW - Echo-planar imaging
KW - Gradient delay
KW - Gradient errors
KW - Linear phase
KW - Magnitude back projection
KW - Projection reconstruction
KW - Radial imaging
KW - Reference scans
UR - http://www.scopus.com/inward/record.url?scp=0037925300&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037925300&partnerID=8YFLogxK
U2 - 10.1002/mrm.10501
DO - 10.1002/mrm.10501
M3 - Article
C2 - 12815671
AN - SCOPUS:0037925300
VL - 50
SP - 1
EP - 6
JO - Magnetic Resonance in Medicine
JF - Magnetic Resonance in Medicine
SN - 0740-3194
IS - 1
ER -