Smaller, Less Expensive Portable MRI Systems to Expand Applications in Various Health Care Settings

Magnetic Resonance Imaging (MRI) machines offer detailed views of the body's non-bony structures like the brain, muscles, and ligaments, and are instrumental in identifying tumors and diagnosing various ailments. Nonetheless, their high cost, bulkiness, and dependency on powerful magnets limit their availability, primarily to large healthcare facilities. In response to this, companies are designing portable MRI machines that rely on lower-strength magnetic fields. These innovative models hold the potential to extend MRI applications, possibly being incorporated in mobile environments like ambulances. Their reduced cost could also enable greater accessibility, especially in underprivileged communities and developing nations. However, further research is crucial to comprehend the connection between low-field images and the underlying tissue properties they represent.

Researchers at the National Institute of Standards and Technology (NIST, Gaithersburg, MD, USA) have been exploring ways to advance and validate the use of low-field MRI technology for creating images with weaker magnetic fields. In a recent study, the team employed a portable MRI machine available in the market to examine brain tissue characteristics at low magnetic field strength. They used a 64 millitesla magnetic field, significantly lower than traditional MRI machines, to image the brain tissue of ten volunteers. The MRI system was able to produce distinctive images of the entire brain, including its gray matter, white matter, and cerebrospinal fluid. Each of these brain constituents responds uniquely to low magnetic fields, generating distinct signals that offer quantitative information about each component.

Separately, NIST researchers are also investigating materials that could dramatically improve the image quality of low-field MRI scans. MRI contrast agents, which enhance image contrast, making it easier for radiologists to identify anatomical features or evidence of disease, are generally used in MRI at conventional magnetic field strengths but are relatively new in the area of low-field MRI scanners. Researchers have discovered that contrast agents behave differently at lower field strengths, indicating a potential to explore new types of magnetic materials for image enhancement.

The team at NIST tested several magnetic contrast agents' sensitivity at low magnetic fields. The findings revealed that iron oxide nanoparticles were more effective than conventional contrast agents made from gadolinium, a rare-earth metal. At low magnetic field strength, the nanoparticles yielded sufficient contrast utilizing only about one-ninth of the concentration of the gadolinium particles. Moreover, the human body can break down iron oxide nanoparticles, thereby preventing potential accumulation in tissue, unlike gadolinium, which could affect the interpretation of future MRI scans if not accounted for.

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