Magnetic resonance microscopy for submillimeter samples in a horizontal MR scanner

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Imaging (MRI)
• Microscopy

Background:

• Spatial resolution in MRI is limited by signal-to-noise ratio (SNR), necessitating long scan times or specialized hardware.
• Achieving single-digit micron resolution in MRI is challenging due to particle diffusion effects and gradient strength limitations.
• Existing microscopy inserts for MRI often require dedicated NMR spectrometers with field drift compensation.

Purpose of the Study:

• To develop a microscopy insert for preclinical MRI systems enabling single-digit micron spatial resolution.
• To enhance SNR and overcome diffusion limitations for ultra-high-resolution imaging.
• To leverage existing preclinical imaging system capabilities for advanced microscopy applications.

Main Methods:

• Designed a microscopy insert with a dedicated gradient system (0.135 T/(m∙A) efficiency, max 27 T/m).
• Integrated a low-noise amplifier in the RF-path to boost SNR for small samples.
• Implemented a modified constant time imaging sequence for ultra-high-resolution capabilities.

Main Results:

• Achieved a three-fold SNR improvement for small samples.
• Demonstrated ultra-high-resolution imaging with (9 µm)³ resolution.
• Successfully imaged zebrafish embryos at various developmental stages with the developed system.

Conclusions:

• The novel microscopy insert enables single-digit micron resolution MRI on standard preclinical systems.
• The enhanced SNR and modified imaging sequence significantly improve ultra-high-resolution capabilities.
• This technology offers a powerful tool for detailed morphological studies in preclinical research.