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Analysis of temperature dependence of background phase errors in phase-contrast cardiovascular magnetic resonance.

Busch J, Vannesjo SJ, Barmet C, Pruessmann KP, Kozerke S - J Cardiovasc Magn Reson (2014)

Bottom Line: The temperature of the gradient mount was found to increase by 20-30 K during PC-CMR measurements of 6-12 min duration.It is concluded that changes in gradient mount temperature significantly modify background phase errors during PC-CMR with high gradient duty cycle.Since temperature increases significantly during the first minutes of scanning the results presented are also of relevance for single-slice or multi-slice PC-CMR scans.

View Article: PubMed Central - PubMed

Affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland. kozerke@biomed.ee.ethz.ch.

ABSTRACT

Background: The accuracy of phase-contrast cardiovascular magnetic resonance (PC-CMR) can be compromised by background phase errors. It is the objective of the present work to provide an analysis of the temperature dependence of background phase errors in PC-CMR by means of gradient mount temperature sensing and magnetic field monitoring.

Methods: Background phase errors were measured for various temperatures of the gradient mount using magnetic field monitoring and validated in a static phantom. The effect of thermal changes during k-space acquisition was simulated and confirmed with measurements in a stationary phantom.

Results: The temperature of the gradient mount was found to increase by 20-30 K during PC-CMR measurements of 6-12 min duration. Associated changes in background phase errors of up to 11% or 0.35 radian were measured at 10 cm from the magnet's iso-center as a result of first order offsets. Zeroth order phase errors exhibited little thermal dependence.

Conclusions: It is concluded that changes in gradient mount temperature significantly modify background phase errors during PC-CMR with high gradient duty cycle. Since temperature increases significantly during the first minutes of scanning the results presented are also of relevance for single-slice or multi-slice PC-CMR scans. The findings prompt for further studies to investigate advanced correction methods taking into account gradient temperature and/or the use of concurrent field-monitoring to map gradient-induced fields throughout the scan.

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Related in: MedlinePlus

Gradient-impulse response functions. Self-term gradient-impulse response function for the x (A), y (B) and z (C) gradient coil measured at different temperatures of the gradient mount.
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Fig6: Gradient-impulse response functions. Self-term gradient-impulse response function for the x (A), y (B) and z (C) gradient coil measured at different temperatures of the gradient mount.

Mentions: FigureĀ 6 shows the self-term gradient impulse response functions for the x, y and z gradient coils measured under various thermal conditions of the gradient mount. The scale from light grey to black indicates increasing temperatures.Figure 6


Analysis of temperature dependence of background phase errors in phase-contrast cardiovascular magnetic resonance.

Busch J, Vannesjo SJ, Barmet C, Pruessmann KP, Kozerke S - J Cardiovasc Magn Reson (2014)

Gradient-impulse response functions. Self-term gradient-impulse response function for the x (A), y (B) and z (C) gradient coil measured at different temperatures of the gradient mount.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4263200&req=5

Fig6: Gradient-impulse response functions. Self-term gradient-impulse response function for the x (A), y (B) and z (C) gradient coil measured at different temperatures of the gradient mount.
Mentions: FigureĀ 6 shows the self-term gradient impulse response functions for the x, y and z gradient coils measured under various thermal conditions of the gradient mount. The scale from light grey to black indicates increasing temperatures.Figure 6

Bottom Line: The temperature of the gradient mount was found to increase by 20-30 K during PC-CMR measurements of 6-12 min duration.It is concluded that changes in gradient mount temperature significantly modify background phase errors during PC-CMR with high gradient duty cycle.Since temperature increases significantly during the first minutes of scanning the results presented are also of relevance for single-slice or multi-slice PC-CMR scans.

View Article: PubMed Central - PubMed

Affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland. kozerke@biomed.ee.ethz.ch.

ABSTRACT

Background: The accuracy of phase-contrast cardiovascular magnetic resonance (PC-CMR) can be compromised by background phase errors. It is the objective of the present work to provide an analysis of the temperature dependence of background phase errors in PC-CMR by means of gradient mount temperature sensing and magnetic field monitoring.

Methods: Background phase errors were measured for various temperatures of the gradient mount using magnetic field monitoring and validated in a static phantom. The effect of thermal changes during k-space acquisition was simulated and confirmed with measurements in a stationary phantom.

Results: The temperature of the gradient mount was found to increase by 20-30 K during PC-CMR measurements of 6-12 min duration. Associated changes in background phase errors of up to 11% or 0.35 radian were measured at 10 cm from the magnet's iso-center as a result of first order offsets. Zeroth order phase errors exhibited little thermal dependence.

Conclusions: It is concluded that changes in gradient mount temperature significantly modify background phase errors during PC-CMR with high gradient duty cycle. Since temperature increases significantly during the first minutes of scanning the results presented are also of relevance for single-slice or multi-slice PC-CMR scans. The findings prompt for further studies to investigate advanced correction methods taking into account gradient temperature and/or the use of concurrent field-monitoring to map gradient-induced fields throughout the scan.

Show MeSH
Related in: MedlinePlus