You can now add a new kind of medical imaging to x-ray, sonogram and MRI: a laser microscope developed by Stanford researchers. It could help athletes train for the next Olympics by taking movies inside flexing muscles.
On one of the computer screens I looked at, it was the first movie ever taken of muscle cells contracting and extending inside a living human. It was taken in a Stanford lab by a team led by Michael Llewellyn and Scott Delp, in collaboration with Mark Schnitzer and Robert Barretto. In fact, it is Delp's own forearm muscles in the picture.
"CTs, X-rays, ultrasound, MRI's are really useful clinical imaging modalities," he says. "The big difference here is the resolution. We're able to see structures much smaller."
Here's how it works. A special glass fiber is inserted like a needle and aimed upward at an optical microscope. Invisible infrared laser light beams out of the microscope and through the needle. But the laser is not used like a flashlight. Instead, it excites the human cells so that they fluoresce, or glow in the dark.
The key discovery was that, when you illuminate muscle tissue with one color of laser light, a different color of light comes back, the so- called harmonic. And it's that light that makes it possible to image muscles in motion."
"When I first started this project," Llewellyn recalls, "I was never actually sure that it would ever work. I spent a lot of time when I got nothing. The most excited I think I ever was was the time we first imaged a human. Because the person is breathing, and talking, and really excited, so the muscle's twitching on its own. The first time we ever got an image with a person, I was pretty stoked."
Scott Delp agrees by adding, "The ability to image human muscle is really the breakthrough."
A breakthrough because it could eliminate a biopsy, with no need to remove flesh. It can enhance reconstructive surgery, too, according to Scott Delp.
"If a tendon, for example, is being transferred from a flexor to an extensor, and you want to adjust the length of the muscle so it has the maximum strength, we could image the muscle fibers, determine the optimal length, and set the muscle so that it has the maximum strength."
And a trainer could examine an athlete's muscles to monitor recovery time. The work is just one project to come out of the school's new Bio-X laboratory, on the cutting edge of bioengineering.