A surgeon probes a patient's brain and sees her target: a swelling on the side of a blood vessel, like a blister on a tire where the rubber has worn off. It's an aneurysm. She uses tiny clips to cut it off from the blood vessel. But there's a problem: an unseen defect causes the aneurysm to burst, resulting in a massive stroke. But there's no problem — she can try again because it was all done in a simulator.
In the next few months, University Hospital Case Medical Center in Cleveland and UCLA will be testing a 3-D imaging system that, coupled with a tool that gives tactile feedback, will allow doctors to rehearse high-risk brain surgery. The system will be tested on virtual brain aneurysms, comparing the outcomes with real surgeries that were done without it.
Brain aneurysms are high-risk surgery because if they burst, they will send blood flowing through the brain, which causes a stroke. One method of treating it is to stop the blood supply to the area of the brain where the aneurysm is, and then use tiny clips on the "neck" of the swollen area to separate it from the blood vessel. After the aneurysm is "clipped" blood flow can be restored.
It isn't easy. Once the blood flow is stopped, a surgeon has only minutes to act, as depriving the brain cells of oxygen longer than that can cause damage. On top of that, she has to get the clips in the right place. The neck of the aneurysm may be in a spot the surgeon can't see well, and a slip could mean rupturing the blood vessel and causing a stroke.
That's where the 3-D imaging system comes in. Built by a company called Surgical Theater, the system employs CT and MRI scans and software to build up a three-dimensional image of the brain. A doctor can call up the image on a desktop and get a much better look at the shape and location of the aneurysm. The system can also link to the microscopes used during the surgery, sending the image to the doctor as the operation proceeds. It gives a look at the "back" of the blood vessel. "It's kind of like seeing the dark side of the moon," said Warren Selman, neurosurgeon-in-chief of University Hospitals who will be directing the trial there.
Selman said the idea for a surgical simulator came from overhearing a conversation between two former Israeli Air Force officers. They were talking about making flight simulators. "We would never dream of sending a pilot out on a sortie without rehearsing," Selman said. "But surgeons go out there unrehearsed."
The system, called the Surgical Rehearsal Platform, uses image data from real patients, rather than creating an idealized environment. It also comes with a haptic device called a Phantom, made by Geomagic, that gives tactile feedback, just like a surgical instrument adding to the realism. "If it doesn't make the surgeon sweat it isn't real enough," Selman said. "I want him to see that blood vessel burst all over the screen."
Such a system can also reduce costs, says Moty Avisar, president and co-founder of Surgical Theater — and one of the Israeli officers Selman overheard. He noted that the microsurgical clips used in aneurysm operations are expensive — about $500 each. When they aren't put in the right place they have to be thrown away.
Beyond aneurysms, the same system could be used for spinal surgeries, or certain kinds of brain tumors.
James Ausman, a neurosurgeon at the Ronald Reagan UCLA Medical Center, said via email he hasn't seen the system yet. "On the surface it is appealing," he wrote. Ausman noted that 3-D imaging in other fields such as heart surgery gives much more detail than conventional scans.
Selman also sees this as a valuable teaching tool. A simulator could let a resident practice a procedure many times before they step into the operating room with their teachers. Right now, a young doctor will go into the operating room and a senior surgeon will be there as well, directing a lot of the action. "Surgical training hasn't changed much in a century," Selman said. "With this you aren't always risking an actual patient."