Expanding Access to Advanced Imaging Tech

Researchers have embarked on a new advanced imaging (MRI) Technology. This advanced technology enables clear visualisation of soft tissues like the brain, muscles, and ligaments, as well as the ability to detect tumours, facilitating the diagnosis of numerous diseases and conditions.

However, traditional MRI machines are expensive and bulky due to their powerful magnets, limiting their usage primarily to hospitals and extensive facilities.

To overcome these limitations, companies are developing portable versions of MRI machines with lower-strength magnetic fields. These innovative models have the potential to revolutionise the applications of MRI.

For example, low-field MRI systems could be utilised in ambulances and other mobile settings, expanding access to timely diagnoses. Moreover, these portable machines are expected to be more affordable, making MRI more accessible to underserved communities and developing nations.

Further investigation is required to fully exploit the capabilities of low-field MRI scanners, particularly in comprehending the correlation between low-field images and the corresponding properties of the underlying tissue.

The National Institute of Standards and Technology (NIST) has been actively engaged in various research endeavours to advance low-field MRI technology and establish reliable techniques for generating images using weaker magnetic fields.

Kalina Jordanova, an Electrical Engineer at NIST, explained that the magnetic strength employed in MRI directly affects the characteristics of tissue images. With low-field MRI systems, the image contrast varies, necessitating a comprehensive understanding of how human tissue appears at these lower magnetic field strengths.

The researchers utilised a commercially available portable MRI machine to conduct brain imaging on five male and female volunteers. The imaging process involved employing a magnetic field strength of 64 millitesla, at least 20 times weaker than the magnetic field used in conventional MRI scanners.

During the imaging sessions, they captured comprehensive brain images and gathered data on three distinct components:

• Grey matter (which contains a high concentration of nerve cells)
• White matter (the deeper brain tissues housing nerve fibres)
• Cerebrospinal fluid (the clear fluid surrounding the brain and spinal cord)

The low magnetic field affected these three constituents of the brain differently, generating distinct signals that reflected their unique properties. As a result, the MRI system produced images that contained quantitative information about each component.

Katy Keenan, a Biomedical Engineer at NIST, emphasised that understanding the quantitative properties of the tissue allows the development of novel image collection strategies for this particular MRI system.

Separately, NIST researchers are also exploring various potential materials that can significantly enhance image quality in low-field MRI scans. MRI contrast agents, which are magnetic materials injected into patients to enhance image contrast, are crucial in helping radiologists identify anatomical features and signs of diseases.

These agents are commonly used in MRI scans with conventional magnetic field strengths. However, their usage with the new low-field MRI scanners is still being explored by researchers. At lower magnetic field strengths, the behaviour of contrast agents may differ from that at higher field strengths, presenting opportunities to utilise new magnetic materials for image enhancement.

Scientists from NIST and their collaborators conducted a study comparing the sensitivity of various magnetic contrast agents in low magnetic fields. The results indicated that iron oxide nanoparticles outperformed traditional contrast agents of gadolinium, a rare-earth metal. Remarkably, the nanoparticles provided satisfactory contrast at a concentration approximately one-ninth that of gadolinium particles.

An additional advantage of iron oxide nanoparticles is that they are broken down by the human body, eliminating the potential risk of accumulating in tissues. Samuel Oberdick, a Researcher at NIST, highlighted that, in contrast, gadolinium may accumulate in tissues, which could complicate the interpretation of future MRI scans if not considered carefully.