Combined Scans Speed Cancer Treatment

PET/CT gives a better picture faster than MRI, study says

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HealthDay Reporter

TUESDAY, Dec. 23, 2003 (HealthDayNews) -- A new combined body imaging technique looks promising as a tool for cancer diagnosis and prognosis, German researchers report.

A combination of positron emission tomography (PET) and computed tomography (CT) did better than the older magnetic resonance imaging (MRI) technique in determining the spread of cancer in a study of 98 patients, doctors at the University Hospital Essen say.

All the patients, who had a variety of cancers, had both imaging tests. "Compared with MRI, PET/CT had a direct impact on patient management in 12 patients," says a report in the Dec. 24/31 issue of the Journal of the American Medical Association. "Results from MRI changed the therapy regimen in two patients compared with PET/CT."

A PET scan is done by injecting a radioactive tracer into a patient. CT imaging generates a three-dimensional picture by computer manipulation of X-ray plates. MRI puts patients in an intense magnetic field to generate a three-dimensional image.

It's too early to tell whether the combined technique will improve the ultimate outcome for patients, says study author Dr. Gerald Antoch, a resident in diagnostic and interventional radiology at Essen.

"PET/CT has only been available for a limited time," Antoch says. "Thus, data on the effect of increased diagnostic accuracy on patient survival are not yet available. Studies addressing this issue will be required in the future."

What can be said is the combined technique gives doctors more information faster, he says. A basic requirement of cancer treatment is knowledge about the stage of the disease, he notes.

"In most centers, tumor staging is still performed by the use of more than one imaging procedure, thus increasing the time between tumor diagnosis and complete tumor staging as well as the overall cost," Antoch says.

Information about the value of the combined technique should be available soon, he says.

"Several centers, including our institution, are currently performing studies on larger patient cohorts and different malignant disease," Antoch says. "The first of these studies are expected to be published in the middle of next year."

The Essen report is greeted enthusiastically in an accompanying editorial by cancer specialists at the Karolinska Hospital in Stockholm, Sweden.

"The day in which futuristic movies show a patient lying on a table, entering a tunnel-like device with blinking lights, only to return a few moments later with a rapid diagnosis and a specific treatment plan, does not seem as far away as once thought," write Drs. Lennart Blomqvist and Michael R. Torkzad. "Based on the article by Antoch and colleagues in this issue of the journal, it appears that the wheels of progress have been set in motion to realize this futuristic diagnostic approach."

If the combined technique lives up to its early promise, changes will be needed at cancer centers, Antoch says. PET/CT units were first installed two and a half years ago, and only about 400 units are now available worldwide, he says, while MRI units are more common.

"To install and use PET/CT for tumor staging, a hospital will have to have its own nuclear medicine department and radiology department or otherwise cooperate with external physicians who will work the system for them," Antoch says.

More information

Learn about the imaging techniques used in cancer treatment at the National Cancer Institute. You can learn about PET scans from the Radiological Society of North America.

SOURCES: Gerald Antoch, M.D., resident, diagnostic and interventional radiation, University Hospital Essen, Germany; Dec. 24/31, 2003, Journal of the American Medical Association

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