The portable mini MRIs on wheels widening access to MRI
By: Sarah Morris, University of British Columbia
Since the first scan in 1977, MRI has revolutionised clinical care. MRI produces beautiful, high-resolution images of soft tissue used to diagnose and monitor a wide range of diseases and accurately detect tumours.
Over the last 40 years, research has hugely improved the acquisition speed and image quality. However, if you have ever had an MRI, you will know that the scanners are very large, intimidating, and loud. The main component of an MRI scanner is an expensive, powerful magnet which requires a lot of electrical power, and must be housed in a copper-shielded room. For this reason, MRI scanners cost over a million USD to install, with high running and upkeep costs and consequently a large percentage of the world’s population has no access to MRI. Twenty-four countries, the majority in Africa, have no MRI scanners at all. Even in economically developed countries, rural communities have less access and wait times can be long.
As MRI scans became more and more vital for high-quality healthcare, the race was on for researchers to develop a lower cost, portable, practical MRI scanner. In August 2020, the Hyperfine SwoopTM scanner was approved by the FDA for neuroimaging of patients of all ages. The scanner is small and can plug into a normal outlet. The imaging is controlled by a tablet, and the whole scanner rolls on wheels to be brought to the patient’s bedside. Previously, a patient had to be transported to the MRI scanner, often in a different wing of the hospital or even a different building, which was dangerous for intensive care patients on ventilators or in time-critical emergency situations such as after a stroke. The Hyperfine SwoopTM also costs a fraction of the price of a standard MRI scanner.
The main reason that this scanner can be so small, cheap, and mobile is the strength of the magnet. Conventional MRI scanners use a superconducting magnet kept below -260ºC, which provides a magnet strength of 1.5 Tesla. The Hyperfine scanner on the other hand uses a permanent magnet which produces only 0.064 Tesla. This is the same type of magnet as those keeping photos on your fridge and only about 60x stronger. Using a weaker magnet reduces magnet safety risks, meaning the scanner can be used in a room containing metal objects and on patients with metal implants. The scanner can be used during operations to monitor the brain in real time or to monitor patients in a critical condition on life-support.
The Hyperfine scanner’s minimalist design has other benefits. It is less noisy than a regular MRI scanner, which regularly produce over 100 decibels (comparable to a loud motorcycle!) and is small which can be more comfortable for claustrophobic patients.
You might wonder, why was this not developed more quickly? The main drawback to using a weaker magnet is that the useful signal in the images is reduced, and the noise is increased. The Hyperfine scanner tries to solve this using cutting-edge deep-learning computer algorithms to improve the noisy scans after they are taken. Research is ongoing into exactly how sensitive the Hyperfine scans are for detecting issues in the brain including strokes, concussions, and brain tumors. The data looks promising, but careful comparison with standard MRI is vital to insure small abnormalities are not missed in the noisier scans. A currently very important application for these scanners has been neuroimaging for COVID-19 patients in the ICU who are often too sick to be safely transported to the standard scanner.
Portable MRI is still a very new technology, and more research is needed to analyse its efficacy in different diseases. However, the recent advances are an exciting step forward towards widening access to MRI and bringing these life-saving scans to more people across the world.