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Variable velocity encoding in a three-dimensional, three-directional phase contrast sequence: Evaluation in phantom and volunteers.

Nilsson, Anders LU ; Markenroth Bloch, Karin LU ; Carlsson, Marcus LU ; Heiberg, Einar LU and Ståhlberg, Freddy LU (2012) In Journal of Magnetic Resonance Imaging
Abstract
PURPOSE: To evaluate accuracy and noise properties of a novel time-resolved, three-dimensional, three-directional phase contrast sequence with variable velocity encoding (denoted 4D-vPC) on a 3 Tesla MR system, and to investigate potential benefits and limitations of variable velocity encoding with respect to depicting blood flow patterns. MATERIALS AND METHODS: A 4D PC-MRI sequence was modified to allow variable velocity encoding (VENC) over the cardiac cycle in all three velocity directions independently. 4D-PC sequences with constant and variable VENC were compared in a rotating phantom with respect to measured velocities and noise levels. Additionally, comparison of flow patterns in the ascending aorta was performed in six healthy... (More)
PURPOSE: To evaluate accuracy and noise properties of a novel time-resolved, three-dimensional, three-directional phase contrast sequence with variable velocity encoding (denoted 4D-vPC) on a 3 Tesla MR system, and to investigate potential benefits and limitations of variable velocity encoding with respect to depicting blood flow patterns. MATERIALS AND METHODS: A 4D PC-MRI sequence was modified to allow variable velocity encoding (VENC) over the cardiac cycle in all three velocity directions independently. 4D-PC sequences with constant and variable VENC were compared in a rotating phantom with respect to measured velocities and noise levels. Additionally, comparison of flow patterns in the ascending aorta was performed in six healthy volunteers. RESULTS: Phantom measurements showed a linear relationship between velocity noise and velocity encoding. 4D-vPC MRI presented lower noise levels than 4D-PC both in phantom and in volunteer measurements, in agreement with theory. Volunteer comparisons revealed more consistent and detailed flow patterns in early diastole for the variable VENC sequences. CONCLUSION: Variable velocity encoding offers reduced noise levels compared with sequences with constant velocity encoding by optimizing the velocity-to-noise ratio (VNR) to the hemodynamic properties of the imaged area. Increased VNR ratios could be beneficial for blood flow visualizations of pathology in the cardiac cycle. J. Magn. Reson. Imaging 2012. © 2012 Wiley Periodicals, Inc. (Less)
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Contribution to journal
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published
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in
Journal of Magnetic Resonance Imaging
publisher
John Wiley & Sons
external identifiers
  • wos:000311381900020
  • pmid:23065951
  • scopus:84869381468
ISSN
1522-2586
DOI
10.1002/jmri.23778
language
English
LU publication?
yes
id
eb2b6d16-6bb3-4079-a26d-2aab3dee47a6 (old id 3160708)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/23065951?dopt=Abstract
date added to LUP
2012-11-01 13:31:43
date last changed
2017-06-18 04:41:00
@article{eb2b6d16-6bb3-4079-a26d-2aab3dee47a6,
  abstract     = {PURPOSE: To evaluate accuracy and noise properties of a novel time-resolved, three-dimensional, three-directional phase contrast sequence with variable velocity encoding (denoted 4D-vPC) on a 3 Tesla MR system, and to investigate potential benefits and limitations of variable velocity encoding with respect to depicting blood flow patterns. MATERIALS AND METHODS: A 4D PC-MRI sequence was modified to allow variable velocity encoding (VENC) over the cardiac cycle in all three velocity directions independently. 4D-PC sequences with constant and variable VENC were compared in a rotating phantom with respect to measured velocities and noise levels. Additionally, comparison of flow patterns in the ascending aorta was performed in six healthy volunteers. RESULTS: Phantom measurements showed a linear relationship between velocity noise and velocity encoding. 4D-vPC MRI presented lower noise levels than 4D-PC both in phantom and in volunteer measurements, in agreement with theory. Volunteer comparisons revealed more consistent and detailed flow patterns in early diastole for the variable VENC sequences. CONCLUSION: Variable velocity encoding offers reduced noise levels compared with sequences with constant velocity encoding by optimizing the velocity-to-noise ratio (VNR) to the hemodynamic properties of the imaged area. Increased VNR ratios could be beneficial for blood flow visualizations of pathology in the cardiac cycle. J. Magn. Reson. Imaging 2012. © 2012 Wiley Periodicals, Inc.},
  author       = {Nilsson, Anders and Markenroth Bloch, Karin and Carlsson, Marcus and Heiberg, Einar and Ståhlberg, Freddy},
  issn         = {1522-2586},
  language     = {eng},
  publisher    = {John Wiley & Sons},
  series       = {Journal of Magnetic Resonance Imaging},
  title        = {Variable velocity encoding in a three-dimensional, three-directional phase contrast sequence: Evaluation in phantom and volunteers.},
  url          = {http://dx.doi.org/10.1002/jmri.23778},
  year         = {2012},
}