Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, July 27, 1993 TAG: 9307270092
SECTION: EXTRA PAGE: 1 EDITION: METRO
SOURCE: By JOHN BARBOUR ASSOCIATED PRESS
DATELINE: LENGTH: Long
Thanks to the wizardry of the computer and some old scientific playthings, doctors can now prowl around inside the human body, take inventory of the organs, even the brain and the beating heart, see it all on television screens - without shedding a drop of blood.
Science has not quite made the body transparent, but it's getting there.
Fiber optics in the form of probes are investigating and in some cases treating the body's innards from stem to stern.
Magnetic Resonance Imaging and Computerized Tomography (Cat scans) are providing incredibly graphic pictures of virtually all the body's organs. And there are even newer devices that will tell experts what parts of the brain are working, how they can shift that burden to other parts, and what is amiss in the brains of schizophrenics and stroke victims.
Without shedding a drop of blood.
By marrying ultrasound and computers doctors can conjure up a three-dimensional picture of a living, beating heart from a variety of angles.
Without shedding a drop of blood.
It's approaching the sci-fi dexterity of "Star Trek" flight surgeons who get a whole body reading from a hand-held sensor.
In the right hands, today's diagnosis is much easier, less invasive than it used to be.
"Some of the things we used to do were not only torturous and risky but stupid," recalls Dr. Norman Chase, chairman of the department of radiology at New York University Medical Center.
Now doctors can see a large part of the large bowel by inserting a fiber-optic probe, and should they encounter a polyp, they excise it right then and there. Almost the entire upper gastrointestinal tract and the bronchi are visible with kindred devices.
The old-fashioned devices they replaced were large metal scopes that could not bend, were not maneuverable and caused the patient great discomfort.
Technological and scientific advances have a kind of geometric progression, Chase says.
"`Everything builds on what was before it," he says. "What we have in medicine is really the application many years later of technology that's already known. But you can't spend that kind of money on hardware in medicine that you do in the Defense Department."
An MRI machine can run from $1 million to $2 million. But on the other hand, Chase says, every hospital in New York City could be equipped with MRIs for the cost of one fighter plane.
So, while the technology was long at work in other fields, its emergence in medicine is only two decades old.
Quite often it is not only money, but the nation's priorities that retard or encourage new techniques.
It is the computer industry that drives some of the new diagnostic devices. Chase says they had high resolution monitors in the Defense Department "years and years ago," but they cost up to $200,000 apiece.
"You couldn't afford those in the medical industry," he says. "When they cost $2,000 to $3,000 each you could afford them. The same is true of the chips that allow screen resolutions of 2,000 to 4,000 lines. Those are enormously expensive and as they get cheaper and cheaper, when they cost a few hundred dollars, then they get into the medical business."
Many of the devices, notably the MRI and the Cat scan, were developed in the early 1970s.
Godfrey Hounsfield was working for the giant EMI, a British version of RCA. EMI was credited with early radar and commercial television. It also had a record company that featured the Beatles and a chain of movie theaters. Godfrey Hounsfield, who didn't even have a graduate degree, was a very small part of EMI.
"Godfrey had never come up with anything important prior to the scanner," Chase says.
But he had an idea, that you could send pencil-thin X-rays into the human body and record the absorption with scintillation detectors and photo-multiplier tubes, accumulate and do computations to reconstruct cross-sectional pictures of the brain and body.
Hounsfield's contraption essentially counted the photons that pass through a pencil-thin section of the brain, shifting the position and the angle until a semicircle around the brain was described. This enabled the computation of thousands of different points that could be translated into a picture in varying shades of gray.
It was called a Cat scan - for computerized axial tomography - and Hounsfield won a Nobel Prize in medicine.
Actually, Chase feels that Hounsfield's boss, an Austrian refugee trained in engineering in Britain, Rolf Schild, should share some of the credit, even though he is now largely forgotten. Schild, who started his own company making medical monitors and was subsequently bought out by EMI, inherited Hounsfield.
Schild was suddenly independently wealthy, had a large salary, a membership in a club and a company Jaguar. Where Schild deserves credit, Chase says, is he left Hounsfield alone to tinker, "let him play, without interfering."
So Hounsfield's basic contribution was the idea of a scanner.
The basic roadblock to further development was the limitation of available computers. The first images took 24 hours.
A computer equivalent in power to a modern PC cost millions of dollars and took up the floor space of two football fields in the late '60s.
"The PC was yet to come and the founders of Apple were still in high school."
The computer is also what enables the MRI to produce its image.
At about the same time Hounsfield was working on his CAT devices, researchers in the United States, Dr. Paul Lauterbur of the State University of New York at Stony Brook and Dr. Raymond Damadian of the university's Downstate Medical Center, were developing a new technique that would use the fact that atoms with an uneven number of protons in their nucleus act as tiny magnets.
Their work was later developed by British scientists.
The hydrogen atom, which has one proton, is the most frequently occuring atom in a living organism and is a major atomic constituent of water, fat and muscle, in fact of almost everything but bone. If one used the hydrogen atom as a signal source, the researchers reasoned, one could literally map the soft tissues of the body.
One does this by putting the body into a strong magnetic field which tends to realign the tiny hydrogen magnets which are in a sort of spin-wobble state like a worn-out top. If you send a radio signal into this sea of wobbling atomic nucleii, and knock them off by a few degrees, and then stop the signal, they will react by sending a weak radio signal back when they realign in the magnetic field.
By taking all of these signals, a computer can translate them into shades of gray and assemble a picture of whatever structure you are looking at.
"It's magnificent," Chase says. "The anatomy is just gorgeous."
"With MRI and Cat scans, you can see better. But you still can't differentiate between certain types of cells."
The various endoscopes, an outgrowth of Japanese optics, are quite valuable to gastroenterologists and chest physicians and ear-eye-nose-and-throat doctors. They start at about $5,000 to $6,000, which is affordable.
One of the most promising of new techniques, Chase says, is called magneto-encephalography. This device simply picks up very weak magnetic fields put out by the firing nerve cells in the brain. Researchers can tell with great accuracy what parts of the brain are working, what parts are responding to various stimuli and with great instancy.
"It has shown phenomenal results, showing that areas of the brain change even in the adult," Chase says. "It's really exciting work. Under your eyes you can see the areas of brain function change.
"That suggests maybe you can train the brain. If you have a stroke, train the brain to do the work that the damaged part once did."
The brain is the focus of another new technique called "functional imaging." It's based on the fact that there is a magnetic difference between oxygenated blood versus unoxygenated blood. By tracing those differences, experts can read what parts of the brain are active in response to motor activity like the wiggle of a finger or seeing or thinking.
In certain brain-tumor cases, the functional imaging techniques may differentiate certain functional portions of the brain so that tumors can be specifically located and removed without additional neurological loss. And Chase thinks it has potential in psychiatry where doctors may be able to read where the brains of some mental patients go awry.
It is probably more useful than Positron Emission Tomography, which came out at about the same time as the Cat scan and requires labeling certain compounds with positrons, positively charged particles about the same size as electrons. The positrons then split into two photons going in opposite directions. By capturing the photons, one can compute the activity of certain parts of the brain. Because of its complexity (it requires a cyclotron and highly skilled personnel) its primary value is more in research than in practical medicine.
The availability of MRIs in many more centers and the eventual ability to do functional imaging with those MRIs will make them more practical than PET scanning, which is done only at limited sites.
At Tufts University School of Medicine, researchers are using a German device that pairs up ultrasound and computers to form extremely clear 3-D pictures of the heart as it beats in very close to real time. Again without shedding a drop of blood.
The pictures, says Dr. Natesa Pandian, are more graphic in many ways than what a surgeon sees while he is operating on the inactive heart.
Today when surgeons use ultrasound, the pictures are grainy with poor resolution. And they are two-dimensional.
But using the echo-CT device, doctors either place a transducer or ultrasound probe on the patient's chest or pass it down the throat. In the latter instance, the transducer takes one millimeter-thick snapshots of the heart on its way back up.
These snapshots are then manipulated by the computer to give a live action picture that can be rotated, seen from a variety of angles, taken apart and put back together again.
For a surgeon, it's like taking off the blindfold.
When Dr. Joseph McCarthy, now 54, was learning his trade, the surgeon who was schooling him said that the greatest development in his professional life was antibiotics. In McCarthy's professional life it has been imaging, "the ability to see before you go in."
In his area, which is reconstructive surgery in the skull and facial area, Cat scans show him very precisely where the damage has been done and he can very nearly write a script for the surgery that will follow.
For surgeons in general, it means shorter procedures, less invasive probing, less loss of blood, less incapacitation for the patient and shorter hospital stays, says McCarthy of NYU's rehabilitation unit.
Sometimes it means not cutting at all when, for instance, a gallstone can be removed with endoscopic techniques.
If the bevy of modern devices has made surgery and medicine in general more efficient, it has not solved all of medicine's problems. People have to be trained to fully utilize the new technologies. Mammography, for instance, is a marvel in the early detection of breast cancer.
But in the United States it has been criticized for its unevenness. Britain is improving because they are spending more money on training and the right equipment, following the lead of Sweden and Holland where mammography is a very effective diagnostic tool.
Even the vascular system, the blood vessels of the body, are being exploited for therapy, as in angioplasty where arteries are widened by inflating a small balloon inside the artery.
by CNB