[MOL] Magnetic Surgery Info. [00046] Medicine On Line

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[MOL] Magnetic Surgery Info.

ST. LOUIS (AP) -- Surgeons may some day treat brain tumors and heart ailments with the click of a computer mouse through what is known as the Magnetic Surgery System.

Washington University neurosurgeon Ralph Dacey recently used the pioneering magnetic surgery technique to direct a biopsy needle to the brain tumor of a 31-year-old man. The December 17 biopsy at Barnes-Jewish Hospital indicated the man needed chemotherapy.

The Magnetic Surgery System will be tested on four other brain tumor patients over the next several months, Dacey said Tuesday. Several years of trials will likely be necessary before the procedure is commonly used.

Dacey and officials with Stereotaxis Inc., which helped develop the system, believe it will help in getting surgical tools -- and perhaps medicine -- to hard-to-reach areas of the brain and the heart. They say it may eventually help treat aneurysms, coronary artery disease and other ailments.

Bypasses sensitive areas

For a traditional biopsy, a surgeon would manually push a rigid needle via a long, narrow catheter through the brain to the tumor.

Magnetic surgery allows the catheter to follow curved routes, bypassing sensitive areas of the brain, or travel along blood vessels to or near the heart, Dacey said.

Surgeons around the country said the procedure appears promising.

"I just think this is a better way," said Warren Selman, professor of neurosurgery at Case Western Reserve University in Cleveland.

"I think part of our problem is getting around structures that are in the way," Selman said. "The ability to steer around an object instead of merely go through it is an exciting development."

In magnetic surgery involving a brain tumor, a small hole is drilled in the patient's skull. The surgeon places a plastic bolt in the hole to provide entry for a guidewire with a magnet that travels through a catheter about the width of a strand of spaghetti.

The surgeon views magnetic resonance images (MRIs) of the patient's brain on a computer screen. The three-dimensional view allows him to plan the best route to the tumor.

Mouse guides magnet to tumor

The patient's head is placed in a machine between superconducting magnets and a catheter is inserted through the bolt. The surgeon, sitting at the computer console, uses a mouse or joystick to guide the magnet to the tumor in about five minutes. The guidewire positioning system pushes the small magnet through the brain, with the fields from the superconducting magnets controlling its direction.

When the head of the instrument reaches the desired area, the surgeon pulls out the guidewire, leaving the catheter in place to act as a tunnel. He then inserts a tiny surgical tool through the catheter that snips out a tissue sample for the biopsy.

Universities and laboratories around the United States have been developing magnetic surgery for more than a decade. Trials have been previously performed on animals.

Doug Kondziolka, professor of neurosurgery at the University of Pittsburgh, called the procedure very promising but said there are concerns.

"How reliable is this way to control something deep in the brain?" he asked. "For example, control of the magnetic field, the control and accuracy of the manipulation."

Dacey said the procedure is safe, even in the event of a computer failure. If that happens, he said, surgery would be performed manually.

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