Ultra-low-field MRI: a David versus Goliath challenge in modern imaging

Area of Science:

• Medical Imaging
• Biophysics
• Biomedical Engineering

Background:

• Ultra-low-field magnetic resonance imaging (ULF-MRI), operating below 0.2 Tesla, is experiencing a resurgence.
• Traditional limitations of ULF-MRI, including low signal and contrast-to-noise ratios, are being overcome by technological advancements.
• High- and ultra-high-field MRI systems currently dominate the diagnostic landscape.

Purpose of the Study:

• To review the physical principles, technological progress, and clinical applications of ULF-MRI.
• To analyze the unique advantages and niche of ULF-MRI compared to other imaging modalities.
• To discuss future directions and challenges for the clinical translation of ULF-MRI.

Main Methods:

• A narrative review synthesizing existing literature on ULF-MRI.
• A focused literature search was conducted across major scientific databases (PubMed, Scopus, IEEE Xplore, Google Scholar) up to August 11, 2025.
• Keywords combined hardware, software, and clinical aspects of ULF-MRI, with inclusion based on scientific rigor and relevance.

Main Results:

• Recent advances in magnet design, RF coils, pulse sequences, and AI-based reconstruction have significantly improved ULF-MRI image quality.
• ULF-MRI offers advantages such as reduced susceptibility artifacts, safe imaging with metallic implants, low power consumption, and portability.
• Comparative analysis highlights ULF-MRI's distinct role in accessible diagnostic imaging.

Conclusions:

• ULF-MRI presents a sustainable and democratizing force in medical imaging, expanding access to MRI.
• The technology has the potential for point-of-care applications, addressing the need for accessible imaging solutions.
• Further research and development are crucial for overcoming challenges in clinical translation.