A new study by Duke University researchers has led to the discovery of a new class of molecular tags that can enhance MRI signals by 10,000 times and create detectable signals that last more than an hour.
The finding is a step towards a new type of MRI that can record the biochemical reactions that take place in the body in real time.
"This represents a completely new class of molecules that doesn't look anything at all like what people thought could be made into MRI tags," said Warren S. Warren, senior author of the study. "We envision it could provide a whole new way to use MRI to learn about the biochemistry of disease."
MRIs are used in clinical settings to create detailed images of organs, blood vessels and tumors by applying a strong magnetic field to the body, followed by a series of radio waves. This causes the nuclei in hydrogen atoms - which act as tiny magnets due to a property called spin - to broadcast their locations and give scientists a view of their structure. However, the new study reveals that this technique has the potential to show body chemistry as well.
"With magnetic resonance in general, you have this unique sensitivity to chemical transformation," said Thomas Theis, co-lead author on the paper. "You can see them and track them in real time."
In order to achieve this, Theis and his team worked on something that scientists have been attempting to do for years: hyperpolarize biologically important molecules in order to turn them into "lightbulbs," allowing smaller molecules to possess a resonance that gives them a stronger signal.
"Hyperpolarization gives them 10,000 times more signal than they would normally have if they had just been magnetized in an ordinary magnetic field," Warren said.
Jerry Ortiz, co-lead author of the paper, synthesized a series of diazarine-containing molecules. Diazirines were deemed a promising target for screening due to their geometry, which traps hyperpolarization in a "hidden state" and prevents it from relaxing quickly.
Using a simple, cheap approach called SABRE-SHEATH, the team mixed molecular tags with a spin-polarized form of hydrogen and a catalyst, allowing them to rapidly hyperpolarize one of the diazirine-containing molecules and increase the magnetic resonance signals over the course of an hour.
"It can be tagged on small molecules, macro molecules, amino acids, without changing the intrinsic properties of the original compound," said Qui Wang, co-author of the paper. "We are really interested to see if it would be possible to use it as a general imaging tag."
The team believes that the technique can be used to hyperpolarize numerous chemical structures and increase the clarity and effectiveness of future MRI techniques.
The findings were published in the March 25 issue of Science Advances.
