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Assessing effects of scanner upgrades for clinical studies
Kathryn E Keenan1, Zydrunas Gimbutas2, Andrew Dienstfrey2
1Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado, USA.
Journal of Magnetic Resonance Imaging : JMRI
|May 22, 2019
Summary
Scanner upgrades can impact MRI studies. Post-upgrade T1 relaxation time measurements showed increased errors, highlighting the need for robust quality assurance (QA) protocols to ensure data integrity.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Quantitative MRI Techniques
Background:
- Scanner upgrades, encompassing both hardware and software, are common in MRI research.
- Inadequate quality assurance (QA) protocols following upgrades can compromise study validity.
Purpose of the Study:
- To assess changes in T1 relaxation time measurements using inversion recovery (IR) and variable flip angle (VFA) techniques.
- To evaluate these changes on a 3T MRI system after a comprehensive upgrade.
Main Methods:
- Utilized an ISMRM/NIST phantom for repeated T1 measurements over multiple days.
- Compared T1 IR and VFA measurements with known nuclear magnetic resonance (NMR) values to quantify error.
- Performed measurements on the system before and after the upgrade.
Main Results:
- T1 VFA errors shifted from centered around zero pre-upgrade (-15% to +10%) to positive post-upgrade (+5% to 30%).
- T1 IR errors increased significantly post-upgrade (±5% to ±20%) until signal saturation was addressed.
- After accounting for signal saturation, T1 IR errors reduced to ±10% post-upgrade.
Conclusions:
- T1 VFA measurement discrepancies are attributable to B1 field variations.
- T1 IR results underscore the necessity of quantitative QA processes.
- Existing QA protocols failed to detect increased T1 errors and signal saturation, emphasizing the need for more frequent and systematic measurements.
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