In Vivo Meso-Scale Whole-Brain Quantitative Imaging With Tailored MRF on the NexGen 7T Scanner.

Area of Science:

• Neuroimaging
• Quantitative MRI
• Biophysics

Background:

• Quantitative magnetic resonance imaging (qMRI) is crucial for assessing brain tissue properties.
• Current methods face limitations in speed and resolution for detailed in vivo analysis.
• Mesoscale quantitative mapping of subtle brain structures remains challenging.

Purpose of the Study:

• To enhance the speed and resolution limits of in vivo quantitative imaging.
• To enable accurate estimation of quantitative tissue parameters in subtle brain structures.
• To develop an efficient quantitative imaging approach for advanced brain analysis.

Main Methods:

• Implementation of an efficient 3D-Simultaneous Multi-Slice Parallel Imaging (3D-SPI) MR Fingerprinting (MRF) on a NexGen 7T scanner.
• Development of acquisition and reconstruction mitigation strategies including flip-angle-aware dictionary fitting, gradient imperfection corrections, and rapid B1+/B0 mapping.
• Incorporation of high-temporal motion navigation for improved data quality.

Main Results:

• Achieved whole-brain T1 and T2 maps at 560-μm isotropic resolution in under 4 minutes.
• Demonstrated the necessity of implemented mitigation methods for artifact and bias removal.
• Acquired data at 360-μm isotropic resolution for mesoscale multi-parameter quantitative mapping in vivo.
• Showcased a ~3x reduction in scan time compared to state-of-the-art methods with improved accuracy.

Conclusions:

• Developed tailored 3D MRF acquisition and reconstruction for fast, accurate whole-brain T1 and T2 mapping.
• Enabled mesoscale quantitative mapping in vivo on a high-performance 7T scanner.
• Pushed the boundaries of speed and resolution in quantitative neuroimaging.