MRI constitutes one of the most important examination methods used to show anatomical regions and answer physiology- and function-related questions. It employs very-high–magnetic fields and doesn’t use ionising radiation, rendering it non-toxic. However, since its development in the 1970s, MRI exhibits problems associated with low sensitivity and spatial resolution of the image. These issues are typically addressed by increasing the magnetic field of the MRI scanner. This solution is not possible in portable MRI scanners, where different inter- and intramolecular phenomena result in very low image resolution and contrast.
Towards a portable MRI scanner
With the support of the Marie Skłodowska-Curie programme, the RF-MAFS project designed and developed a novel portable MRI scanner that addresses these issues. “The RF-MAFS technology reduces the molecular interactions and improves the resolution of MRI images obtained with portable MRI scanners,” explains the Marie Skłodowska-Curie fellow Javier Alonso-Valdesueiro. This is achieved by implementing the magic angle spinning technique using RF signals instead of mechanical rotation. The sample is subjected to a rotating and a static magnetic field, which produce a total magnetic field positioned at an angle of exactly 54.7 degrees with respect to the sample. This reduces the impact of nuclear interactions on MRI image contrast and NMR spectral resolution. By combining engineering skills, magnetic resonance knowledge and medical imaging insight, researchers optimised magnet design and constructed the RF-MAFS prototype. The electromagnets that produce the rotating and static magnetic field utilise double helix dipole and Helmholtz coils and are controlled with specialised software. The generated magnetic field was measured with ad hoc instrumentation designed and built during the project.
Advantages of the RF-MAFS scanner
The new RF-MAFS scanner boasts low weight, low maintenance and low consumption, rendering it suitable as an early diagnosis tool. In addition, its low cost and accessibility mean it can be deployed in emergency rooms to ensure that patient needs are promptly addressed and facilitate first medical decisions when an ambulance arrives at the scene of an accident. “However, the RF-MAFS technology is not intended to replace the strong and powerful hospital MRI scanners as we know them. Traditional scanners will still be used on a regular basis for precise diagnosis,” emphasises Alonso-Valdesueiro. Importantly, the RF-MAFS scanner is compatible with other diagnostic tools thanks to the lower strength of its magnetic field. Further technological improvement can make the scanner useful in different situations such as surgeries or in combination with other scanners, including computed tomography and ultrasound.
According to Alonso-Valdesueiro, “the RF-MAFS project presented an opportunity to develop a new technology based on an untested concept in MRI.” The resultant magnet fulfils the requirements of reduced size and limited magnetic field strength that guarantee low cost and portability. The future plans of RF-MAFS scientists include the study of material interfaces, paramagnetic impurities and object movements with the RF-MAFS magnet to demonstrate image improvement in MRI scanning experiments. Ongoing efforts to build an NMR spectrometer will further assess the use of the magnet in NMR molecular spectroscopy.
RF-MAFS, MRI, scanner, magnetic field, diagnosis, NMR, magnetic resonance imaging, magic angle spinning, nuclear magnetic resonance