MRI ‘glove’ captures clear images of hand anatomy

New York : In a first, scientists have developed a glove-shaped magnetic resonance imaging (MRI) detector that can capture high-quality images of moving joints.

The study, published in the journal Nature Biomedical Engineering, demonstrated that the glove-shaped detector could yield images of bones, cartilage, and muscles interacting as a hand 'plays piano.' Traditionally, MRI had required patients to remain strictly motionless, according to the researchers from the New York University School of Medicine in the US. 

The MRI glove prototype may become useful in the future diagnosis of repetitive strain injuries like carpal tunnel syndrome in office workers, athletes, and musicians, they said. 

As the invention shows how different tissue types impinge on each other as they move, the researchers say it could also enable the construction of a more versatile atlas of hand anatomy, guide surgery with hand images in more realistic positions, or aid in the design of better prosthetics. "Our results represent the first demonstration of an MRI technology that is both flexible and sensitive enough to capture the complexity of soft-tissue mechanics in the hand," said Bei Zhang, lead author of the study.

 Since its emergence in the 1970s, MRI has given physicians a better look inside tissues, helping to diagnose millions of maladies per year, from brain tumours to internal bleeding to torn ligaments. Despite this impact, the technology has long struggled with a basic limitation, researchers said. MRI works by immersing tissues in a magnetic field such that any hydrogen atoms present align to create an average magnetic force in one direction in each tissue slice. 

These "little magnets" can then be tipped out of equilibrium by waves of electromagnetic force (radio waves). Once tipped, they spin like tops and also emit radio signals, which reveal their positions and can be rebuilt into images. Also fundamental to MRI is the ability of radiofrequency coils to convert radio waves into a detectable electric current. However, this means that the captured ("spinning top") radio waves produce little currents inside receiver coils, which in turn create their own magnetic fields and prevent nearby coils from capturing clean signals. 

As all current MRI scanners measure signals that create currents in receiver coils (detectors), such coils have always been designed as "low impedance" structures that let the current flow easily. The new design has a "high impedance" structure that blocks current, and then measures how hard the force in magnetic waves "pushes" (the voltage) as it attempts to establish a current in the coil, researchers said.

 With no electric current created by the MR signal, the new receiver coils no longer create magnetic fields that interfere with neighbouring receivers, thus removing the need for rigid structures. The researchers found that their system, with the new coils stitched into a cotton glove, generated "exquisite" images of freely moving muscles, tendons and ligaments in a hand as it played piano and grabbed objects.