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I felt my scope gliding along the bone. I was seeing structures I’d previously known only vaguely from news stories about football players’ knee injuries. The white pad of cartilage was the meniscus. The twist of meaty-looking fibrous tissue was the anterior cruciate ligament, or ACL. My scope slid off the bone and I was floating free in the fluid at the joint. I aimed the scope through the white architecture of bones to explore the ACL. Suddenly, without feeling any resistance, I had plunged through the ligament, doubtless crippling my patient for life.
“You can go through the ACL on this,” Spitzer said. “We still need to work that out.”
We had moved around a corner after the video display. What I’d just performed, badly, was a primitive kind of virtual surgery. The patient wasn’t real; it was the digital ghost of Jernigan again, this time adapted for a machine that operates on the same idea as a flight simulator. The resistance I felt as I pressed against tissue, the palpable hardness of the bones, were supplied by a robot arm pushing against me as the computer directed. I watched my progress on a monitor, just as a surgeon does when he uses a scope. I could look down and see the knee where my hand felt it--an illusion accomplished by projecting the monitor’s image to a screen beneath me.
Soon Spitzer took me to the basement. We passed through two sets of double metal doors to see the equipment. First, a dolly that had held the frozen corpses when they were sawed into four pieces. The tool with which Spitzer and his colleagues accomplished this task looked like nothing but an oversized hacksaw.
Then, into the cooler, which is an improvement: during Jernigan’s sectioning, the work went on in an old facility without air-conditioning, and the temperature often reached 100. In this new set-up, the corpse and the cameras and the circular grinding head suspended from the ceiling are all in a refrigerated chamber. A technician sits in a booth outside, controlling the cameras and watching through the windows. We went into the chamber. It had the oily smell of a woodworking shop, minus the sawdust. The digital camera set-up looked curiously primitive, with black cloth draped in the manner of 19th century photography. There was a remote-controlled nozzle for spritzing the flesh with alcohol between shots and a remote-controlled airhose for brushing away the shavings. That, too, is an improvement; when Jernigan was sectioned, photographers had to be in the room hosing the flesh off by hand.
As all this continuing work implies, the University of Colorado group is far from finished with the digitizing of cadavers. Having satisfied the contract with the NLM, Spitzer’s team went on to work with corporate sponsors. One result was the knee-surgery simulator. Another appears at first glance to be a human torso wedged into a box. It’s actually a simulator that trains physicians to make injections into the celiac plexus, a tangle of nerves near the aorta. Such injections are used to relieve severe pain in, for example, terminally ill people. The trouble is that reaching the celiac plexus with a needle is a tricky procedure with considerable risks for the patient and few training opportunities for interns. The simulator lets the trainee feel a subtle aortic throb when she gets the needle to the right place.
Another simulator I encountered elsewhere allowed me to run a scope down the GI tract of a mannequin. It made realistic retching noises as I blundered about. The screen showed me a bleeding ulcer. I rammed the scope around, trying to get in position to cauterize the spurting wound. The patient moaned, retched, and lay silent. I had killed him.
Spitzer isn’t content to simply develop applications for the two cadavers already made virtual. He spoke of taking 15,000 slices on the next cadaver, improving the detail of the Visible Human Female by a factor of three. He described the need for cadavers of every ethnicity and every body type, for women before and after menopause, for people of every age.
Shoving a gigantic floppy disk into a computer set-up, he revealed another accomplishment: a virtual fetus. Like Jernigan, the fetus moved toward the viewer, revealing itself in progressively deeper cuts.
You must have three additional drawings to show the anatomy of women, for the womb and fetus make much mysterious.
Leonardo da Vinci
The National Library of Medicine isn’t finished with the idea either. Michael Ackerman, the biomedical engineer who put the project together, said work is continuing on sorting out the “artifacts” in the Visible Human data--for example, the slight distortions freezing produces in soft tissue. There are also problems with resolution; the tiny bones of the inner ear are too small to be seen in detail on the existing Visible Humans. Despite such problems, the virtual cadavers have already been used to design prosthetic limbs and as crash-dummies in simulations. Lawyers have used them to illustrate injuries in court cases. They've replaced real cadavers in some anatomy classes. The army is working toward using the data to simulate battle wounds, a need currently met by shooting up livestock.
Another idea in development is to combine MRI or CT images from a specific patient with the virtual bodies. The result would allow doctors to look at, and even practice on, simulations of their particular patients. (“Your doctor could practice on a virtual you,” Spitzer told me, pointing emphatically to the vicinity of my sternum.) Since such images are transmissible, doctors could get long-distance help from specialists. Surgeons could operate on battlefield soldiers by remote.
Artists have incorporated Visible Human images in exhibited work. Ackerman told me about seeing the images displayed as holograms at the Maryland Science Center. He watched people watching the display. “I now know why a composer goes to a concert to hear his own music,” he said.