Engineering News

Second sight for
surgeons

Real-time imaging in the OR will speed healing,

cut health-care costs

Newton, MA --Magnetic-resonance imaging transformed diagnostic
medicine over the last two decades. Now, it's about to change surgery too, as
machines capable of real-time, high-resolution displays of internal topography
make their way into the operating room.

"This has the potential to revolutionize the operating room as it is known today," claims Dr. Ferenc Jolesz, director of the image-guided therapy program at Boston's Brigham and Women's Hospital.

Instead of the tunnel-vision views from endoscopes, so-called image-guided therapies let surgeons see beneath the surface of organs and view their instruments in spatially correct context. Such therapeutic imaging will expand the range of minimally invasive surgical procedures and thus help lower the personal and financial costs of health care. Doctors and engineers involved say that they're only beginning to explore these machines' potential.

Dual-doughnut design. Two experimental designs illustrate that promise. General Electric's Signa MRT (magnetic resonance therapy) system features "dual-doughnut" magnets that allows a surgeon access to a patient positioned between them. Using non-ferrous instruments chosen to be compatible with the body's magnetic characteristics, the doctor can view the patient's internal organs on an LCD screen within the magnetic field.

Kirby Vosburgh, manager of the Imaging and Visualization Laboratory at the GE R&D Center, Schenectady, NY, explains that the machine represents several breakthroughs in MR design. Along with the split, cryo-cooled, superconducting magnets, teams from the R&D Center; GE Medical Systems, Milwaukee, WI; GE's manufacturing operations; and clinicians developed unique radio-frequency pulse generating hardware and advanced electronics and software to speed data collation.

How fast is the Signa MRT? "We can drive it like an ultrasound machine," says Vosburgh. Using a probe as a geometric position indicator, surgeons can image any area of interest within the field. Selection and execution of the proper RF and gradient pulse sequences for a given area takes 1/30th of a second. "With a conventional machine that could take days," jokes Vosburgh. "It's real-time and interactive."

A machine at Brigham and Women's is being used initially to guide needle biopsies as well as "thermal therapies" for treating tumors by freezing or heating with a laser. On the horizon: completely non-invasive thermal therapy using RF or ultrasound energy focused on tumors while the MRT monitors temperature changes, preventing damage to surrounding healthy tissue.

According to Vosburgh, the "real" inventions will take place over the next few years when doctors develop entirely new procedures made possible by the MRT--advances such as spinal surgery on a seated patient. The machine's success depends on such discoveries. "If they can come up with procedures that are obviously better than anything else available, people will see this as cost-effective."

Meanwhile, in Cleveland, doctors are working with an experimental technique that superimposes real-time ultrasound images of surgical instruments onto fixed, pre-operative 3-D MR images to guide surgeons during operations. Developed by Picker International along with doctors from the Cleveland Clinic Foundation, the system is currently limited to cranial surgeries, since unavoidable motion in other parts of the body quickly render pre-op

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