Cooldown and Ramp Test of a Low-Cryogen, Lightweight, Head-Only 7T MRI Magnet

Area of Science:

• Medical Imaging
• Biophysics
• Superconducting Magnet Technology

Background:

• High-field Magnetic Resonance Imaging (MRI) offers superior image quality for neurological applications.
• Existing 7.0 T MRI systems are often large, complex, and have limited accessibility.
• A need exists for more compact and easily installable high-field MRI systems.

Purpose of the Study:

• To report the successful construction and energization of a compact 7.0 T MRI system (C7T).
• To evaluate the performance of the C7T magnet, including its cryogenic system and field homogeneity.
• To demonstrate the feasibility of a 7T MRI with a size comparable to clinical 3T systems.

Main Methods:

• Construction of a compact 7.0 T superconducting magnet.
• Implementation of a closed-loop cryogenic system using 12 liters of liquid helium.
• Testing of the magnet's ramp-up to 7.01 T and assessment of field homogeneity (<1.0 ppm over 26 cm).
• Evaluation of quench protection and stray magnetic field characteristics.

Main Results:

• The compact 7.0 T MRI system (C7T) was successfully constructed, cooled, and ramped to 7.01 T.
• The system achieved a B0-field homogeneity of <1.0 ppm over a 26-cm field-of-view.
• The cryogenic system utilizes a minimal amount of liquid helium (12 liters) in a sealed, closed-loop design.
• The C7T magnet exhibits comparable size and stray magnetic field to a clinical 3.0 T MRI magnet.

Conclusions:

• The developed compact 7.0 T MRI system is a viable advancement for high-performance brain imaging.
• Its compact design and compatibility with 3T scanner bays significantly enhance accessibility for patients.
• The successful energization and performance metrics demonstrate the potential of this technology for wider clinical adoption.