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| |  RSNA: Magnet-Guided Wires Allow Doctors To Perform Embolization On Deep Brain Aneurysms By Ed Susman Special to DG News CHICAGO, IL -- November 26, 2001 -- Researchers were able to demonstrate that a magnetic-guided wire can use a computerized road map to snake through tight turns in cranial blood vessels to deliver embolizing agents to dangerous aneurysms. Yesterday at the 87th scientific assembly and annual meeting of the Radiological Society of North America, doctors said the new system-still in its infancy-may help prevent aneurysm ruptures. "This new system allows us to get to the site of the aneurysm more safely and more quickly without having to perform open surgery," said Christopher Moran, MD, associate professor of radiology at the Mallinckrodt Institute of Radiology, Washington University School of Medicine, in St. Louis, Missouri. Moran demonstrated how he was able to steer the metal guidewire to reach and cross the aneurysm in three patients. Then, a catheter was advanced over the guidewire so that embolizing coil could be deposited in the aneurysm. "These results are proof of principle," said Michael Kraut, MD, professor of radiology at Johns Hopkins School of Medicine, in Baltimore, Maryland. "It’s remarkable. It’s something a lot of people here would like to be able to do." While doctors have known how to use catheters to deliver material to correct the aneurysm, many of these weakened blood vessels are located in remote areas of the brain. Using conventional, mechanically controlled devices for these endovascular procedures, even the most skilled operators have trouble directing the guidewire because torque, the ability to turn, is limited. Dr. Moran explained that while the guidewire is stiff as it enters the blood vessel-placing the patient at risk of a punctured blood vessel wall-the wire becomes flexible as it is advanced through the vessel. The new system provides magnetic control and simultaneous real-time x-ray visualization to guide a magnetized guidewire through the vascular system. Every second or two, a fluoroscope takes x-rays in two planes of the patient’s head. Metal markers show up on the images, which when superimposed, mark the guidewire’s position on magnetic resonance images in a computer console. The contours of the magnetic field are determined by the current flow to each of six magnets, and altering the contours changes the direction in which the small magnet moves. The doctor steers the guidewire by remote control from the computer console and can move it in any direction, in a complete circle or even backward. Dr. Moran, in a video of the procedure, also showed that the system even warns the doctor when the guidewire is too close to the vessel wall. "This magnetic guidance system will allow broader access to these types of procedures," he said. "It enables the interventional radiologist quicker, safer, easier access to bleeds and clots without the trial and error when time is critical." In the three-patient trial, Dr. Moran said the aneurysm was corrected in two patients, but the third was not corrected because the system indicated that the particular anatomy would not allow safe embolization. The study was supported by Sterotaxis, Inc., which supplied equipment and an honorarium to the investigators.
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