Portable MRI shines at ISMRM meeting in Glasgow

May 9, 2001

Imagine an MR scanner that could be carried from place to place. Engineers at Texas A&M went a step further-they built one.The handmade 0.2-tesla system has a magnet, gradients, and radio-frequency transmitter and receiver, just like its larger

Imagine an MR scanner that could be carried from place to place. Engineers at Texas A&M went a step further-they built one.

The handmade 0.2-tesla system has a magnet, gradients, and radio-frequency transmitter and receiver, just like its larger cousins. But development costs were a lot lower. Steven M. Wright, a professor in the A&M department of electrical engineering, and his colleagues built the prototype for less than $10,000.

The Texas team described the system and its construction at the annual meeting of the International Society for Magnetic Resonance in Medicine held in late April in Glasgow, Scotland.

The miniclamshell scanner is about the size of the tiny scale models some MRI vendors displayed at the meeting, but this one makes images. The prototype is better suited to mice than humans, however, according to Wright. The magnet gap is only four inches, and performance, specifically dynamic range and gradient linearity, is a bit under that of clinical scanners.

“But if all you need is a simple system to see if a tumor has grown to a particular size in a mouse, this will do it,” Wright said.

Future versions of the Lone Star MR need not be as small as the first one. The design could be expanded to fit people, or at least their extremities.

“In order to get MR scanners out there for broad use in physician offices, you need to look at lower-cost systems that don’t have all the bells and whistles but are still pretty good,” he said. “The idea of having a ‘push a button, out comes a Polaroid’ equivalent of an MRI scan is something we are interested in.”

The low cost of the prototype is due less to its size than its construction. The engineers bought all their components off the shelf. The gradient amplifier is based on a single chip from National Semiconductor; the RF amplifier was designed for a CB radio; the low-noise amplifier in the receiver came from a chain electronics store. The magnet was pieced together from a couple hundred blocks of permanent magnet material (total cost $3500). The computer is a Pentium II PC.

Initiative and imagination helped keep the cost of the unit under the $10,000 limit established at the start of the project. The MRI industry is not short on either of these, but the A&M development process had one ingredient MRI manufacturers have limited access to: graduate students.