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Assessment of motion gating strategies for mouse magnetic resonance at high magnetic fields
Paul J Cassidy1, Jürgen E Schneider, Stuart M Grieve
1Oxford Cardiac Research Group Magnetic Resonance Unit, University Laboratory of Physiology, University of Oxford, Oxford, UK. paul.cassidy@physiol.ox.ac.uk
Purpose:
To assess the performance of motion gating strategies for mouse cardiac magnetic resonance (MR) at high magnetic fields by quantifying the levels of motion artifact observed in images and spectra in vivo.
Materials And Methods:
MR imaging (MRI) of the heart, diaphragm, and liver; MR angiography of the aortic arch; and slice-selective 1H-spectroscopy of the heart were performed on anesthetized C57Bl/6 mice at 11.75 T. Gating signals were derived using a custom-built physiological motion gating device, and the gating strategies considered were no gating, cardiac gating, conventional gating (i.e., blanking during respiration), automatic gating, and user-defined gating. Both automatic and user-defined modes used cardiac and respiratory gating with steady-state maintenance during respiration. Gating performance was assessed by quantifying the levels of motion artifact observed in images and the degree of amplitude and phase stability in spectra.
Results:
User-defined gating with steady-state maintenance during respiration gave the best performance for mouse cardiac imaging, angiography, and spectroscopy, with a threefold increase in signal intensity and a sixfold reduction in noise intensity compared to cardiac gating only.
Conclusion:
Physiological gating with steady-state maintenance during respiration is essential for mouse cardiac MR at high magnetic fields.
Insights
User-defined physiological gating significantly improves mouse cardiac magnetic resonance (MR) imaging and spectroscopy at high magnetic fields. This method enhances signal intensity and reduces noise for better in vivo results.
Area of Science:
- Biomedical Engineering
- Magnetic Resonance Imaging
- Cardiovascular Research
Background:
- High magnetic fields in mouse cardiac MRI offer enhanced resolution but are susceptible to motion artifacts.
- Effective motion gating is crucial for acquiring high-quality in vivo cardiac images and spectra in small animal models.
Purpose of the Study:
- To evaluate the efficacy of various motion gating strategies for mouse cardiac magnetic resonance (MR) at 11.75 T.
- To quantify motion artifact levels in cardiac MR images and spectra using different gating techniques.
Main Methods:
- Performed MR imaging, angiography, and 1H-spectroscopy on anesthetized C57Bl/6 mice at 11.75 T.
- Utilized a custom physiological motion gating device to compare no gating, cardiac gating, conventional gating, automatic gating, and user-defined gating.
- Assessed gating performance by quantifying image motion artifacts and spectral amplitude/phase stability.
Main Results:
- User-defined gating with steady-state maintenance during respiration demonstrated superior performance.
- Achieved a threefold increase in signal intensity and a sixfold reduction in noise intensity compared to cardiac gating alone.
- User-defined gating optimized cardiac imaging, angiography, and spectroscopy.
Conclusions:
- Physiological gating incorporating steady-state maintenance during respiration is essential for high-field mouse cardiac MR.
- This optimized gating strategy significantly improves image and spectral quality in vivo.
- The findings are critical for advancing small animal cardiovascular research using high-field MRI.
