Piercing the body with precision pg. 4
Dawant, who with Fitzpatrick co-directs the Medical Image Processing Laboratory, has developed computational “atlases” of the brain and liver—marked by recognizable anatomical guideposts such as blood vessels—that can be “warped” to fit individual patient cases.
Similarly, Galloway and his colleagues have teamed up with surgeons to create intraoperative guidance systems that use optical tracking or articulated “arms” to track the surgical position in three dimensions.
The primary software platform, called ORION, for Operating Room Image-Oriented Navigation, can be modified to support neurosurgical and surgical applications, including ones such as liver surgery, where the target moves with patient breathing.
All this would not have been possible were it not for the astronomical increase in computing power, Miga adds.
“We solve about 80,000 coupled equations in a model, and we do that in about 15 to 18 seconds,” he says. “And when I say 80,000 equations, I’m talking about essentially a spatial understanding of how the organ we’re looking at is deforming or moving.”
A tracked surgical probe collects data from a brain tumor during surgery (left). The information is used to index pre-operative images to the correct slice of the tumor (right) and to display the surgical position on that slice on a monitor in the OR. The CT image (upper left), PET image (lower right) and two MR images (upper right and lower left) update in real time as the probe is moved.
Hitting the target
Thompson says the next logical step in cancer imaging is to develop a molecular imaging agent, “some unique marker in the tumor that you could target… that would allow the tumor to fluoresce” as the surgeon peers through the operating microscope.
With Vanderbilt chemistry professor Darryl J. Bornhop, Ph.D., Thompson is investigating another class of fluorescent molecules, the rare-earth lanthanide chelates, which potentially could be used to delineate tumors both in MRI scans and under the operating microscope.