December 07, 2004

New neuro-navigation system could save lives

by K.C. Jaehnig

(PRONOUNCER: Ajay Mahajan is "ah-JAY mah-HAH-jun)

CARBONDALE, Ill. - - A GPS-like system being developed at Southern Illinois University Carbondale could help surgeons navigate through the brain to find and remove everything from tumors to bullet fragments easily, cheaply and with hardly any "cutting" at all.

"This is a project I believe could save lives," said SIUC mechanical engineer Ajay Mahajan of an ultrasonic-based locational system devised in partnership with former Carbondale neurosurgeon Sumeer Lal.

Neuro-navigation is nothing new. More than a decade ago, surgeons began harnessing computers to cameras to create high-tech guides that could help them "see" what they were doing in the brain. Such precision allows them to make smaller incisions and remove only what needs to go, cutting the risk of complications and speeding healing.

But these vision-based systems are pricey and hard to maintain. The cameras take up a lot of space, and if someone moves into their sightlines or worse, bumps them, they can lose track of where they are or shut down altogether. "When they stop working, calibrating them again is very difficult," Mahajan said.

"It only takes about five to 10 minutes, but you have the patient's head open at that point.

Everything is covered in surgical drapes, so the fiducials (small markers, attached to the patient's head, that serve as pre-operative calibration aids) are no longer accessible."

Mahajan's system, adapted from one he developed some years ago at Tulane University to track robots, gets rid of the cameras. It replaces them with a head restraint from which ultrasonic sensors branch off like tree limbs and adds a couple of sensors to the surgeon's probe. The two sensors on the probe act as transmitters while those on the head restraint serve as receivers, allowing the equipment to map the probe's movement through the brain in three dimensions.

"This is very much like a GPS system, except it's indoors, and instead of satellites, we have ultrasonic receivers," Mahajan said.

Because the receivers that replace the cameras take up so much less space, sightline problems don't occur. And because they remain in place - - not on the patient's head but close by - - recalibration in a sterile environment is a snap.

The new system is every bit as accurate as the old - - within one to two millimeters - - "and every day, we are making progress in making it even more accurate," Mahajan said.

"We are hoping to go sub-millimeter, which would make this even more attractive to neurosurgeons."

Then there's the price. Hospitals can pay as much as $500,000-$750,000 for standard image-guided neurosurgery equipment; Mahajan estimates the cost of this system to be significantly less - - perhaps in the neighborhood of $50,000-$75,000 after adding in the costs of the patent, development, hardware, overhead and so forth.

The technology could move beyond the brain, Mahajan believes. "A urologist in Springfield thinks he can use this in taking out stones from the kidneys," he said. "It's the same kind of problem. You want to make a small, precise incision, and you need to keep track of your instruments. It could be used in spinal surgery as well."

While Mahajan received a provisional patent on the process last year, it will take some time before the system shows up in operating rooms.

"This project is still in its infancy - - we don't even have a prototype yet," he said.

"But there has been a considerable amount of interest, and as the word has gotten out, we are having companies call us about it. A big company would have the resources to develop and package it. We've shown it has a definite application; we'll let somebody else take it from there."

Leading in research, creative and scholarly activities is among the goals of Southern at 150: Building Excellence Through Commitment, the blueprint for the development of the University by the time it celebrates its 150th anniversary in 2019.

(CAPTION: Brainpower - - Ajay Mahajan, a mechanical engineer from Southern Illinois University Carbondale, demonstrates an ultrasonic-based locational system that could pave the way for the development of a better brain surgery tool. Like GPS systems, Mahjan's device triangulates data from transmitters and receivers to show movement in three dimensions. Manufacturers could incorporate this technology to produce equipment that would be smaller, cheaper and easier to work with than the camera-based neurosurgery instruments currently used.)

Photo by Jeff Garner