They Help Doctors Discover What's Wrong, But Are They Always Worth It?

To explore the deepest reaches of the body without raising a scalpel has become the hallmark of computer-age medicine. Increasingly, doctors are turning to a new generation of million-dollar machines to help them diagnose and treat the most common, and some of the most serious, illnesses.

Emerging in the last decade or so, these technologies go far beyond conventional X-rays, which started the medical revolution in imaging nearly a century ago; the new devices use magnetic fields, electrical impulses and radiation to assess the damage caused by a heart attack, watch an epileptic storm in the brain or monitor the effectiveness of cancer treatment.

Magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET): Their names may sound like a bewildering alphabet soup, but the information they provide is anything but rudimentary. The detail and clarity of the images enable doctors to make a precise diagnosis and treat the problem without subjecting patients to exploratory surgery. In the past, for example, a person with symptoms of an abdominal tumor would undergo an operation. Today, an MRI could make the diagnosis. Imaging can provide answers quickly, accurately and painlessly. Moreover, the tests carry much less risk than surgery. "There's no doubt about efficacy," said Ronald G. Evens, director of the Mallinckrodt Institute of Radiology at Washington University in St. Louis. "But the real question is cost-benefit."

In an era of rapidly rising health costs, the dramatic increase in the use of high-priced technologies raises concern about the appropriateness of widespread testing. "Some imaging definitely avoids exploratory surgery, some buys peace of mind and some may be of so dubious merit that you could rule it practically unnecessary," said Princeton University health economist Uwe Reinhardt.

The pressure to use new imaging techniques stems from a "do more" philosophy shared by both doctors and patients, each seeking the best care available. Yet tests are sometimes ordered when they may be only marginally beneficial. For example, does every patient with a knee injury need a $1,000 MRI? Must all chronic headache sufferers undergo a $550 CT scan? Or should they wait for other neurological findings? "Those are the very tough questions," Evens said.

Furthermore, the growing number of malpractice suits, especially in certain specialties, has an impact. Doctors sometimes practice "defensive medicine" and perform multiple and possibly unnecessary tests as a barrier to potential litigation. If they were sued, they would have a series of test results to demonstrate that they had met the standard of care. Just how much defensive medicine is practiced is not known, but experts say that the concern about lawsuits helps fuel the use of expensive tests.

Health officials also point out that while imaging can reduce costs for some patients, it cannot always substitute for surgery -- and it often leads to more care, not less. When a CT scan confirms a tumor, surgery as well as radiation or chemotherapy is still required for treatment. The patient may have avoided exploratory surgery, but that is all. "It sometimes happens that people who have a scan done will then of course have to have the procedure {the surgery} done as well," said Gail Wilensky, administrator of the Health Care Financing Administration.

Imaging can also find problems no one suspected. A CT scan ordered because of a head injury may also detect a small tumor. In this way, better technology can lead to more testing, more treatment and additional costs.

Hospitals, too, have built-in incentives to buy state-of-the-art imaging machines. To attract patients in a fiercely competitive market, administrators know they must offer the most advanced treatment. This intensifies the drive to purchase big-ticket technologies. "A lot of places have CT's for convenience, for keeping up with the Joneses," Evens said. For patients, it's also the peace of mind that they have secured the most advanced medical treatment for themselves and their families. "And that," said Princeton's Reinhardt, "may be worth a fortune."

For patients, convenience is important. So is the peace of mind that they have secured the most advanced medical treatment for themselves and their families. "And that," explains Princeton's Reinhardt, "may be worth a fortune."

Three-Dimensional Computed Tomography (3-D CT) entury;rr

The ability to turn a standard CT scan into a three-dimensional picture is enabling doctors to gather more precise information about the structure of bone and tissue inside the body, ranging from broken limbs to tumors.

CT scans use rotating X-ray beams to measure the difference in tissue density. From this information, standard CT machines simulate a cross-sectional black and white picture on a television screen. A computer program then turns these pictures into 3-D images that can be rotated and examined in great detail.

For a 26-year-old New Jersey man with a crushed pelvis, this new technology spared him months in traction and repeated surgeries to repair his fractured bones, which would have otherwise healed incorrectly.

At Johns Hopkins Medical Institutions, surgeons studied a 3-D picture of his injuries on a computer screen about the size of a large TV set. With detailed information about the extent of damage, they felt confident about operating on him immediately. The man was back at work three months later.

The technology that turns a normal CT scan into a 3-D simulated picture has been around since 1978. But it has taken improved computer animation, such as the kind developed in the last five years by Lucasfilms, the California company that made the "Star Wars" movies, to make the technology available to doctors. Today, about 600 CT machines -- roughly 10 percent of the total number of CT scans in the U.S. -- offer 3-D technology at a cost of about $550 per scan.

The strength of 3-D CT is its high resolution -- the reason it can be used to study bone as well as soft tissue such as the liver, spleen, pancreas and adrenal glands. Doctors in the future hope to couple 3-D CT scan technology with angiography to investigate the heart and blood vessels in greater detail. Electroencephalography (EEG) Imaging

The development of high-speed computers enables this technology to monitor the electrical storms in the brain that signal an epileptic seizure.

EEGs use electrodes that painlessly attach to the head with a sticky conducting gel to measure electrical impulses in the brain. The electrodes lead to a machine where pens record the brain's impulses on a scroll of paper. Since EEGs generate reams of squiggly lines that must be analyzed by hand, researchers had tried since the 1950s to find a faster and more efficient way of reading the data. The solution came in 1979 with the advent of high-speed computers that compile EEG information and display it on a screen.

Measuring the brain's electrical energy was the idea of German researcher Hans Berger, who first attached electrodes to an individual's head in the 1920s in the hope of finding physical evidence for extra-sensory perception. What he stumbled upon instead was a valuable tool for investigating the brain.

Computerized EEG imaging is still largely a research tool used to collect information on epilepsy, manic depression, schizophrenia, tumors and learning disabilities. If researchers find that this technique can be used to diagnose some of these problems, it may well become an important tool for psychiatry. One advantage is its relatively low cost: about $10,000 to $20,000 for the technology; and anywhere from $200 to $900 per test. Magnetic Resonance Imaging (MRI)

One of the newest and fastest growing of the big-ticket imaging machines, MRI uses magnets to differentiate bone from tissue -- and detects a wide range of problems from torn knee ligaments to tumors.

Just a few years ago, for example, a patient with a herniated disk protruding from the spine would have been subjected to a painful test in which doctors injected a radioactive dye into the spinal fluid, then took X-rays.

But thanks to MRI, the diagnosis today can be quick and painless. The crisp image of the protruding disk enbables doctors to diagnose the problem and then schedule surgery to treat the disk.

Since its introduction just six years ago, more than 2,000 MRI machines have been sold in the United States at a cost of about $2 million each. MRI operates on the principle that molecules behave differently in magnetic fields and provides physicians with textbook pictures without using X-rays or radioactive dyes.

To undergo an MRI, patients lie on table that is moved through a coffin-like tube containing the magnetic field. Patients wear clothing during a scan, but all metal objects including watches, rings and belt buckles must be removed. The magnets involved in MRI are so strong that they can send metal objects flying through the air. For this reason, MRI machines are shielded in separate buildings.

Because MRI can detect differences in the way hydrogen atoms behave in normal and abnormal tissue, the device is especially good at finding tumors and is often used to monitor the effectiveness of cancer therapy. Positron Emission Tomography (PET)

What began as a research tool to explore the brain at a few key medical centers 15 years ago is now an established part of medical practice at some 50 U.S. hospitals. At many of those institutions, PET is increasingly used to make images of the heart.

The usefulness of PET is its ability to show how parts of the brain and body function, not just what they look like. Scans involve injection into the bloodstream of a chemical -- often the simple sugar glucose -- attached to a minute amount of radioactive tracer. PET measures where the tracer lodges and how long it takes to be metabolized. The results are displayed in a four-color picture on a TV monitor.

PET can show which areas of the brain gradually shut down in Alzheimer's disease. Researchers also use PET to map the places where heroin and morphine attach to brain cells and to isolate the receptor on the cell that is involved in cocaine addiction. In addition, PET pinpoints blockages in arteries near the heart. When a heart attack occurs, the question doctors ask is how much damage has been done? PET can point out which areas of the heart are still alive.

Its drawback is cost. Each PET machine requires installing either a $2 million cyclotron to produce the radioactive material, or paying $25,000 a month to a commercial company for radioactive tracers produced by a strontium generator. Each patient scan costs about $1,500. Single Photon Emission Computed Tomography (SPECT)

Easier, faster and cheaper than PET, SPECT is the machine doctors turn to when they need information about the brain, heart and other organs but can't afford a Rolls Royce to get it. Approximately 1,000 SPECT machines operate in the United States a little more than a decade after its introduction.

Like PET, SPECT measures function, not structure. Its resolution is not as accurate as PET -- one reason that about 20 to 30 percent of patients who have a SPECT scan may have to still undergo a PET scan in order for doctors to make a diagnosis.

But SPECT takes less time to perform and uses common radioactive isotopes that are easy to obtain and costs less to buy than those needed for PET.

The cost to the patient is about $500 to $600 for a brain scan; about $900 for a heart study.

SPECT can examine the spread of cancer throughout the liver. It's more sensitive than angiography -- a test used to locate blocked arteries -- in measuring blood flow to the heart and also can be used to study Alzheimer's disease in the brain, check kidney function and assess lung conditions.