Live And In 3 D, Your Body At Work
Cliff Burks, 74, has mild coronary-artery disease but didn't want to have another angiogram. Twenty years ago, the retired construction-company owner from Galveston, Tex., had undergone the procedure, in which dye is injected into an artery to provide a clearer X-ray image of the heart's blood vessels. "It was uncomfortable, to say the least," says Burks of having a catheter threaded through an artery in his groin and then up to his heart. No wonder he jumped at the chance to try a noninvasive imaging technique that didn't even exist three years ago. Using a $250,000 ultrasound device, physicians were able to get a three-dimensional view of his beating heart. "It was amazing," he says. "There was my heart pumping on a screen in 3-D." Doctors could tell right away everything was fine, compared with the three hours or so it would have taken to reach a diagnosis with an angiogram. As a result, Burks was on his way home in a heartbeat.
The marriage of better imaging devices with computers in the past five years has allowed "views inside the body never before seen," says Masood Ahmad, Burks's doctor and director of echocardiography at the University of Texas Medical Branch in Galveston. Moreover, these images are obtained with little or no discomfort to patients. Physicians--using the latest developments in sound waves, radio waves, X-rays, and magnetic fields--not only can cost-effectively examine the body's organs and other structures in exquisite detail, they can watch them at work, whether they're beating hearts or bending knees.
Doctors, primarily at major research institutions and teaching hospitals that can afford the equipment, are still sorting out how best to use the technologies. However they are utilized, these imaging procedures may eventually cost less than traditional or invasive types of examinations, because none requires sedation or hospitalization. The scans are likely to run from $500 to $5,000, depending on the part of the body to be studied and the degree of detail needed. Magnetic resonance imaging (MRI) generally costs the most, ultrasound the least.
Medicare and private insurers have yet to provide coverage for these tests, since many of the technologies' applications are still considered experimental. But that may change in a year or two, says David J. Vining, associate professor for diagnostic radiology at Wake Forest University School of Medicine in Winston-Salem, N.C. "The science is there, so the funding will follow."
One new device is called a multidetector computed tomography (CT) scan. The scanner has multiple rings of X-ray detectors that circle around the patient, picking up more details in a quarter of the time it takes older models, which have only one ring. "It takes you longer to drop your drawers and get on the table than it takes to complete the scan," says Vining, whose hospital has one of the $1 million machines. Made by General Electric, Siemens, and Marconi, the devices came on the market less than two years ago. Doctors and technicians take the scanner's finely rendered images and feed them into the same types of computers used to create virtual-reality video games. "The perspective we gain is incredible," says Geoffrey Rubin, co-director of Stanford University Medical School's 3D Imaging Laboratory, which uses a multidetector CT scan. "We have taken recent gains in imaging and leveraged them with technology developed for the entertainment industry."
Three-dimensional views of tumors can be rotated for a better vantage point and finer analysis. Aortic aneurysms can be measured to determine precisely the size of the stents and grafts to be surgically implanted. Doctors have also used these technologies to perform so-called virtual colonoscopies, with an accuracy of up to 90%, in a mere 20 seconds.
MRI has taken a leap forward, too, a result not only of subtle improvements in equipment design but of "a better understanding of which pulse sequences" of radio waves through a body in a magnetic field "will yield the best pictures," says Philip Alderson, chairman of the department of radiology at Columbia University Medical School in New York. The images have become so refined that for the past two years, doctors, aided by computers, have been able to perform what is known as functional MRI, in which they track the movement of oxygen to monitor blood flow and phosphorus to assess metabolic activity.
This is ideal for discovering vascular problems and diagnosing cancerous growths--and it can also help in the exploration of how the mind works. By watching the flow of oxygen and consumption of phosphorus, "we can actually watch how the brain responds to different stimuli and discover key cognitive pathways," Alderson says. Already, researchers at the University of Pennsylvania School of Medicine in Philadelphia and the University of Alabama School of Medicine in Birmingham are using functional MRI to learn more about such brain disorders as Alzheimer's disease and schizophrenia. The technology also holds great promise for testing the efficacy of drug regimens, such as chemotherapies aimed at blocking the formation of the blood vessels that stoke tumors.
A newfangled version of the oldest imaging technology, ultrasound, also has made it to market. Until three years ago, it was impossible to use ultrasound to examine a three-dimensional image of the heart in real time--as Dr. Ahmad did--because the organ's movement distorted the picture. But Volumetrics in Durham, N.C., developed tiny transducers that, when placed between the patient's ribs, rapidly fire sound waves in a pyramidal fashion. The technology can therefore capture the entire heart in one shot--rather than the several shots needed by older models that emit only a two-dimensional beam.
Ultrasound has become sensitive enough to show blood flow, an improvement that might make some biopsies unnecessary. Researchers at Thomas Jefferson University Medical College in Philadelphia are using ultrasound devices made by companies such as Medison and Siemens to determine if growths in the uterus and breast are cancerous simply by looking at their vascular activity--without lifting a scalpel. Thanks to these advances, the kindest cut is no cut at all.
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