A Versatile High Speed 250 MHz Pulse Imager for Biomedical Applications

Area of Science:

• Biomedical Engineering
• Magnetic Resonance Imaging
• Spectroscopy

Background:

• Electron Paramagnetic Resonance (EPR) is a sensitive technique for detecting paramagnetic species.
• Small animal imaging is crucial for preclinical research and drug development.
• Existing EPR imaging systems often face limitations in speed, sensitivity, or flexibility.

Purpose of the Study:

• To present a versatile 250 MHz pulse EPR instrument designed for small animal imaging.
• To demonstrate the instrument's capability for high-resolution 3D imaging using various pulse EPR modalities.
• To showcase the system's potential for precise physiological measurements, such as oxygen partial pressure.

Main Methods:

• Development of a flexible 250 MHz pulse EPR imager with a fast pulse generation and data acquisition system.
• Implementation of 3D electron spin echo (ESE) and single point imaging (SPI) protocols.
• Characterization of the instrument's performance using phantoms and homogeneous samples.

Main Results:

• Achieved 32-second acquisition time per 3D image using a fast 3D ESE imaging protocol in a phantom.
• Demonstrated a spatial resolution of 1.4 mm and a standard deviation of T(2e) of 8.5% with an 18-minute 3D T(2e) ESE imaging protocol.
• The achieved precision in T(2e) determination is equivalent to 2 torr resolution of oxygen partial pressure in tissues.

Conclusions:

• The developed 250 MHz pulse EPR instrument offers high versatility, sensitivity, and speed for small animal imaging.
• The system enables precise 3D imaging and quantitative physiological measurements, advancing preclinical research.
• This technology holds significant promise for non-invasive assessment of biological parameters in vivo.