Medicine: Clinical Imaging, Courtesy of Hollywood
Click the mouse to bring a three-dimensional human figure onto the screen. Click again, and the figure rotates. Another click, and the skin melts off to show the muscles and nerves. Click, and the muscles give way to the skeleton. An arm blocks your view of the ribs? Click, and the arm disappears. Click once more, and the bones are replaced by the vascular system. Veins in the figure’s legs show up white on the screen.
Click on them, and they open to reveal the calcification inside.
This is neither a video game nor a cartoon, though it shares technology with both. The figure on the screen in Hadassah’s 3-D imaging laboratory is a digital image of a patient who is experiencing severe pain in his lower limbs. The cause of his pain—blockage in his blood vessels—shows clearly on the monitor.
“Medical imaging has revolutionized diagnosis and, with it, therapy,” says Dr. Jacob Sosna, head of the computerized axial tomography unit in the Hadassah–Hebrew University Medical Center’s radiology department and director of its research and imaging laboratories. “In just over a century, we have moved from two-dimensional images of the skeleton to virtual patients.”
Imaging burst into medical diagnosis in November 1895 when German physicist Wilhelm Konrad Roentgen stumbled on a radiant energy that shines through the human body to reveal the structure of systems inside. He called it the X-ray, and within months, doctors in Europe and the United States were using X-rays to diagnose illness and injury.
It took over 70 years, however, for the technology that creates images of the body with external radiation to reach its second generation. From the 1970s, techniques such as CAT scanning, ultrasound and magnetic resonance imaging emerged, enabling visualization of soft tissue. “For the first time,” says Dr. Sosna, “a brain tumor could be directly diagnosed without opening the skull.”
As second-generation imagers grew more sophisticated, however, the volume of information they produced threatened to overwhelm radiology. “In CAT’s early days, it took an hour to scan…a small area,” says Dr. Sosna. “Now we scan the entire body in five seconds, down to the tiniest details and even moving parts, like the heart.”
Today’s high-end scanners create thousands of images, or slices, per examination—some 1,500 for a virtual colonoscopy, for example, and about 4,000 for a CAT angiogram of the heart. “On an average day,” he notes, “I’ll see 50,000 to 80,000 images.”
To cope with this data explosion, new technology was needed. That it arrived far more promptly than 70 years this time is thanks, in large part, to cross-fertilization of ideas from an improbable source: the entertainment industry.
This was not the first crucial collaboration between medicine and entertainment, notes Dr. Sosna. “The invention of CAT scanning was largely funded by the Beatles record sales,” he says. “They recorded with EMI, E-lectrical & Musical Industries, which was an industrial research company as well as a record label. The Beatles’s massive success paid for EMI research that produced the CAT scanner.”
This time, however, the collaboration is about technology, not money—about how to translate scanned images into digital models that make compelling 3-D renderings. It is a technology that underlies video-game design, has propelled cartoons into the world of computer animation and underpins movie blockbusters from 1991’s Terminator 2to 2009’s Avatar. Despite fundamental differences in their goals and culture, it seems that entertainment and medicine have much to offer one another.
Based on the digitizing of thousands of images, the technology they share is known as motion-capture technique. In radiology, the digitized images are the hundreds of thousands of CAT slices, which custom software transmutes into extraordinarily detailed 3-D images—virtual patients whose bones, tissues and organs are visualized onscreen.
The 3-D imaging laboratory at Hadassah–Ein Kerem is currently the only place in Israel that does this in a dedicated fashion, and one of only a few dozen worldwide. It was opened six years ago and is run by 3-D technologist Phillip Berman, who started out as a medical photographer and went on to run the 3-D lab at New York University LangoneMedical Center. Dr. Sosna enticed him to Israel and Hadassah in 2004.
“At most hospitals, CAT technicians and radiologists combine the images they obtain into a manageable number of frames at 3-D workstations in the department, as we do in our lab,” says Berman. “But a dedicated 3-D lab, separate from the commotion of a busy imaging department and staffed by 3-D technicians, allows far more comprehensive and in-depth image postprocessing. It is better placed to develop new applications and techniques and to devote…timely attention to the patient scans.”
Berman has, in fact, picked up critical findings more than once among the 200 patient scans processed monthly in the lab. On one occasion, it was an aneurysm in a 38-year-old patient; on another, a blood clot in the brain of a suspected stroke patient; and in a third, a pending rupture in the aorta of a 20-year-old road-accident victim. With each, he raced to alert their doctors, and all three patients survived.
Emergency calls, however, are the exception for the lab. A medium-sized room with four workstations, Hadassah’s 3-D imaging lab is a place where radiologists and technicians are pushing forward the outer edges of their discipline. “One of our lab’s major strengths is its very close links not only with the hospital, but with academe and industry,” says Dr. Sosna.
Hadassah has, from the start, he says, given its full encouragement and invested extra resources in the lab. The Hebrew University of Jerusalem’s computer science department collaborated in creating the lab and works with it in developing applications. The Dutch company Royal Philips Electronics is its major industrial supporter; Philips helped fund the lab’s establishment, lends the lab $100,000 computers for evaluation and explores ideas that the lab generates.
In its six years, the lab has carved itself a niche within Hadassah and has proved a valuable resource for Hadassah surgeons. “One way we help them is by visualizing the surgical site onscreen,” he says, “showing them, for example, the exact location and degree of calcification inside a patient’s vessels. Another is by converting images into physical models.”
These exact models are made by rapid prototyping, a process used by industry for the past 20 years to create items ranging from mobile phones to sneakers. It works by taking the thin, horizontal cross-sectional images from the computer and laying them down in successive layers of liquid, each layer dried and hardened by ultraviolet light before the next is added. The layers are then fused and the physical model is complete.
Dr. Sosna holds a model of a patient’s skull with the top third missing. “When there’s pressure in the brain following injury, the surgeon will sometimes remove part of the skull, to replace later when the pressure drops,” he explains. “By modeling this patient’s brain, we enabled the surgical team to plan the delicate replacement surgery before they even entered the operating room.”
While the computer design for such modeling is performed in the 3-D lab, model production is outsourced. Among the lab’s planned acquisitions is a rapid prototype printer to produce models on site. It is part of a future in which Dr. Sosna, Berman and their colleagues see the lab developing new tools and helping radiologists judge what to use when and keeping radiation levels to a minimum.
“Today’s physicians rely heavily on imaging,” says Dr. Sosna. “While it isn’t the first step in diagnosing every patient, 60 percent of hospital patients in the West are now scanned, and that number is rising. The tools are improving all the time, consigning time-consuming, subaccurate, painful and risky diagnostic procedures to the past. Hadassah’s 3-D lab is part of diagnostic imaging’s future.”