MRI is a powerful diagnostic tool, but the size and cost of the machinery limits where it can be used. Scientists at the University of Hong Kong (HKU) have now developed a more compact and affordable MRI system, which uses a much smaller magnetic field and doesn’t require shielding, while still being able to diagnose brain disorders in patients.
Magnetic resonance imaging is the technique of choice for scanning soft tissues in the body, and it’s particularly effective at diagnosing problems in the brain, such as tumors, injuries or stroke. Risks are also much lower than other imaging techniques like X-rays or CT scans.
But this power doesn’t come easy. MRI machines can cost millions initially, followed by tens of thousands of dollars per month to run and maintain. They can chew through a lot of power, and require bulky magnetic and radiofrequency shielding. All up, this makes MRI technology prohibitive to use in many places, particularly developing countries.
A smaller, cheaper, portable MRI machine could greatly expand the use of the technology, and that’s what the HKU team has detailed in a new study. Conventional MRI uses magnetic fields with strengths of up to 3 tesla (T), but the new machine works using an ultra-low field of just 0.055 T.
Because of the smaller magnetic field, the device does away with the need for the magnetic shielding cage of traditional MRI machines. Radiofrequency shielding is usually needed to prevent external electromagnetic signals from interfering with the magnets, but for the new machine the team developed deep learning algorithms to cancel out this interference. Removing the need for both types of shielding helps keep the new machine compact.
The simplicity and smaller size also reduces the cost and power requirements. The team says that the machine can be run from a standard AC power outlet, and they estimate the cost at under US$20,000. Its footprint measures about 2 m2 (21.5 ft2) and it weighs 750 kg (1,653 lb), though the researchers say optimization could bring it down to under 500 kg (1,100 lb).
Importantly, the smaller machine was still effective at diagnosing brain disorders. The team tested the device on 25 patients, including 13 with brain tumors, eight with ischemic stroke, and four with intracerebral hemorrhage. The images weren’t as stark as those scanned with a 3-T MRI, but most of the key pathologies were still picked up in all patients.
The team says that these portable, ultra-low field MRI machines could have a range of advantages. Being cheaper and smaller, more hospitals should be able to afford them, including those in developing countries. And even within a hospital, the machine can be brought to a patient’s bedside, which can help in ICU or COVID-19 wards where it’s not always practical to move a patient. It’s more comfortable for a patient to use too, since it’s much quieter in operation and patients don’t need to lie in a claustrophobic tube. And the lower magnetic field strength makes it safer for patients with metallic implants, and reduces image artifacts these can create.
There’s still plenty of work to be done to improve the ultra-low field MRI machines before they can be used clinically. In the meantime, the FDA has already approved a similar system by Hyperfine, with a slightly higher power of 0.064 T.
The research was published in the journal Nature Communications.
Source: University of Hong Kong via Asia Research News
