MRI Could Eventually Produce Images in Living Color

Current MRI technology produces black and white images that are often blurred. The problem with black-and-white images is they are often too difficult to interpret--even by experienced physicians. In an effort to add some color to imaging techniques, Li Sun, an associate professor in the Cullen College of Engineering's department of mechanical engineering at the University of Houston, is developing a contrasting agent that is designed to add color to MRI images. His goal is to make such images easier to read.

Sun's contrasting agent is based on iron nanostructures. While most currently available nanostructures are shaped like spheres or rods, the new nanostructures are available in such uncommon shapes as dumbbells and tubes. Such shapes, Sun says, make each type of nanostructure respond only to a specific magnetic frequency.

"Currently, MRIs are in black and white. If you use one of the existing contrasting agents, you only adjust the grayscale, which makes the bright parts of the image brighter and the dark parts darker," Sun explains. "These nanostructures will allow you to use different colors to identify each type of tissue."

Creating unusually shaped nanostructures currently requires the use of lithography, an expensive stencil-based fabrication technique that can create these shapes only at the micron level instead of the necessary nanolevel. To produce nanostructures, Sun is developing a fabrication method that combines nanotemplates, or nanoparticle molds, with electrochemical synthesis, which introduces a small electrical current into a chemical solution to generate a reaction. After these nanostructures are produced, they are coated with proteins that bond only with certain types of cells, such as those that make up a ligament or a specific internal organ.

Before undergoing MRI, the patient will be injected with the new contrasting agents. Programmed to scan at the magnetic frequencies assigned to the different nanostructures injected into the patient, the MRI machine will assign a particular color to each type of nanostructure it senses. For example, nanostructures that bond with a ligament will appear red, while those that bond with bone will appear blue. All the scans will then be combined into a single color-coded image.

"Inside your body you can use frequency information to separate these particles," Sun comments. "That's what gives you a colored picture."

For more information about this technology, see "Professor Creating Color-Coded MRIs" at the University of Houston Cullen School of Engineering news site.