Magnetic Imagers Become Important Diagnostic Tool
A new and highly promising medical diagnostic tool, called magnetic resonance imaging, is rapidly becoming a fixture in many of the nation’s hospitals and outpatient radiology centers.
And emerging at a time when efforts to curb the growth of medical spending are finally yielding some results, these sophisticated million-dollar scanners also are testing the health care system’s new-found resolve to balance the introduction of new technology and cost control. For the first time in 20 years, health care’s share of the gross national product in 1985 showed a slight decrease, from 10.7% to 10.6%.
Even while the full capabilities--and limitations--of magnetic resonance imaging are still unclear, some health care experts are predicting that the scanners will render obsolete many uses of the X-ray and some functions of other widely used scanners, including ultrasound and the so-called CT scanner, powerful diagnostic tools introduced in the 1970s.
Procedures Simplified
Already, magnetic resonance imaging, a non-invasive technique, has simplified the diagnosis of multiple sclerosis, a degenerative nervous system disorder that afflicts 250,000 Americans. Previously, diagnosis usually required hospitalization and a test in which dye is injected into the canal around the spinal cord.
The new scanners also are proving valuable in the detection of other abnormalities in the spinal cord and at the base of the brain, such as herniated spinal disks, tumors and birth malformations.
The scanners, introduced in the United States five years ago, use magnetic fields up to 30,000 times stronger than the Earth’s, radio wave pulses and computers to generate images, which are photographed or displayed on a television monitor.
The current imaging technique, which involves no radiation, detects variations in the energy level of hydrogen atom nuclei in the body caused by radio wave pulses, when a patient is placed in a magnetic field.
“We are going to know a heck of a lot more about a lot of people’s insides,†said one health care analyst.
Source of Concern
But along with such enthusiasm is concern, at least in some quarters, that magnetic resonance imaging could end up increasing medical costs, through overuse, even as it actually cuts down on the need for some surgeries and diagnostic tests.
“If regulated and used properly for serious conditions, this could be an unbelievable cost saver,†said Dr. Meridith Weinstein, a professor of radiology at the Cleveland Clinic Foundation. But, Weinstein added, “If everyone with headaches insists on getting a scan because it is the latest technology, it could cost billions and billions.â€
The medical community’s enthusiasm for this very sensitive imaging technique was heightened in November when Medicare agreed to pay for the scans--a precedent that analysts say is already being followed by some private insurance companies, Blue Cross, health maintenance organizations and state Medicaid programs.
Magnetic resonance imaging is now the fastest growing area in radiology. The number of scanners in operation increased from 100 to more than 215 between 1984 and 1985, twice as many as in the rest of the world combined. The number is expected to top 300 next year. There are 15 scanners in the Los Angeles area and 39 in California.
Question on the Need
“The technique is diffusing maybe more rapidly than it should be,†said Dr. Gerald M. Pohost of the University of Alabama at Birmingham, chairman of the American Medical Assn.’s panel on the imagers. “At this point, the need could be met by fewer instruments than have been sold.â€
But spread of the imagers has been slow compared to rapid introduction of X-ray computed tomography (CT) scanners in the 1970s, said Dr. Earl P. Steinberg, an assistant professor of medicine and health policy at Johns Hopkins Hospital.
Five years after they were introduced, 921 CT scanners were in operation; more than 2,000 are now in use. This contrasts with the 215 magnetic resonance scanners in use five years after they came on the market.
One reason that magnetic resonance scanners have not caught on as quickly is that today’s cost-conscious hospitals are being much more selective in purchasing new technologies, Steinberg noted in a recent article in the New England Journal of Medicine. Radiologists also feel that other high-quality imagers remain better than magnetic resonance imaging for certain conditions, such as the rapid diagnosis of traumatic head injuries.
Other factors that have limited the sales of the scanners are technical uncertainties about which imager to purchase and installation delays related to shielding the powerful magnets. Too, some smaller hospitals are sharing scanners.
The Cost Is High
The scanners cost $1 million to $2 million, plus $150,000 to $1 million more to install. Charges for each study, including the radiologist’s fee, range from $500 to $900. They average about 25% more than the fees for CT scans.
Many scanners are currently operating at a substantial loss because they are not operating at anywhere near capacity. But there is a potential for a financial windfall as efficiency increases. “Some places are going to make so much money it is going to be obscene,†said one leading radiologist in the field.
Just one additional patient scanned each day could be worth in excess of $125,000 in yearly revenues, according to Dr. William Hanafee, professor of radiology at UCLA.
Medicare currently makes a single payment for each hospitalization. But in November a national advisory commission to Medicare proposed what would be a precedent-setting exception to that policy by recommending that additional Medicare payments be made for magnetic resonance scans on hospitalized patients.
The recommendation by the Prospective Payment Assessment Commission would probably speed the spread of the technique--and make it more difficult to control medical costs. Medicare is expected to reach a decision on the proposal in several months.
No Limit on Coverage
“We really don’t have an estimate of what covering these scans will cost,†said a Medicare policy analyst. “We are going to cover it and we didn’t put a limit on it.â€
About a third of the more than 200 imagers have been installed in outpatient facilities, where cost controls under Medicare’s prospective payment system to hospitals do not apply.
Some physicians contend that scanners should be located in outpatient clinics, where labor and overhead costs are lower. But other physicians such as Steinberg disagree, saying it may be a hardship for some hospitalized patients to get to these scanners.
The magnetic resonance phenomenon was demonstrated in 1946 by American scientists Felix Bloch and Edward Purcell, who shared the Nobel Prize for Physics in 1952 for this discovery.
The first image created with the technique--of two tubes of water--was published by Paul Lauterbur of the State University of New York at Stony Brook in 1973, which was also the year CT scanners were introduced in the United States.
Point of Confusion
The technique is generally known as “nuclear†magnetic resonance in the scientific community. But many physicians prefer to call it magnetic resonance imaging because they fear the reference to the “nucleus†of an atom may be confused with “nuclear†radiation.
The first scanner in Southern California was installed at the the Huntington Medical Research Institutes in Pasadena in May, 1983. Patients lie in a donut-shaped tunnel surrounded by the magnet for the 15 to upwards of 45 minutes it takes to complete a study. Some feel claustrophobic. Many fall asleep.
The imaging presents no known health hazards, but patients and staff must be careful to remove metal objects before entering the scanner room. The Huntington machine creates a fringe magnetic field which can erase the magnetic strip on the back of credit cards at 25 feet and stop non-digital watches.
One worker at a factory where a scanner was being made suffered a skull fracture when a screwdriver dropped by another worker accelerated down the tunnel. Another had his hands crushed when the oxygen tank he was carrying got close to the machine. Even the location of elevators or streets can influence where a scanner is to be located.
Huntington has been averaging 13 scans a day for the last 18 months, double the national average, Dr. William G. Bradley, the radiologist who directs the scanner, said. Up to 20 scans have been performed in a 12- to 14-hour day.
A Major Limitation
The imager’s extreme sensitivity in detecting multiple sclerosis and other conditions also highlights its major limitation--an inability to distinguish between different abnormalities. “This lack of specificity,†according to Johns Hopkins’ Steinberg, “is the biggest limitation of the technique.†One such example is a type of stroke seen in elderly patients which looks exactly like the abnormality caused by multiple sclerosis.
Another criticism is that the scanners have not been shown in general to lead to more cures for patients, according to Dr. John Braver, a radiologist at the Brigham and Womens Hospital in Boston. “The pictures are better and the doctors feel better when they make the diagnosis, but it is not clear what this means for patient outcome.â€
WHAT THE NEW SCANNER SEES Magnetic resonance imaging promises to make many uses of the X-ray obsolete. Scanners use strong magnetic fields, radiowave pulses and computers to generate pictures. At left, a cross-section of the brain shows light areas characteristic of multiple sclerosis, something that could not be seen using X-rays or a CT scanner. The scan eliminated the need for hospitalization and other diagnostic tests, including the injection of dye into the spinal canal, called a myelogram. At right, cross-section of the spinal column in the neck, showing pressure on the spinal cord by rupture of the disk that cushions the spine above and below. Surgery was performed to prevent further nerve damage, but other diagnostic tests, such as a myelogram or a computerized X-ray scan, were not needed.
