A Better Way To Track Cancer

PET/CT Dual Scan Effective In Determining If Cancer Has Spread

(AP)  A combination of two body-imaging techniques can more accurately tell doctors how far a patient's cancer has spread than full-body MRI scans, German researchers say

Their study compared full-body PET/CT scan technology with full-body magnetic resonance imaging in 98 cancer patients with tumors in such places as the lungs, head, neck, thyroid, gastrointestinal tract, liver and bones.

The dual technique is already in use in many hospitals across the country.

In the study, combined PET/CT scans correctly identified tumors, any cancerous lymph nodes and any further cancer spread in 75 of the 98 patients, or 77 percent. That compares with 53 out of 98, or 54 percent, with MRIs.

All patients were given both tests, which last almost half an hour each and involve gliding on a moveable platform through a cylinder.

The study, by Dr. Gerald Antoch and colleagues at University Hospital in Essen, Germany, appears in Wednesday's Journal of the American Medical Association.

Accurate imaging is crucial in establishing how far a patient's cancer has spread, determining the person's chances of survival, and choosing between surgery or some other treatment.

PET scans, or positron emission tomography, use a radioactive tracer to detect increased metabolic activity found in cancerous growths. CT scans — computed tomography — use computerized analysis of X-rays to detect tumors. The combined technique merges the two into a single exam, allowing doctors to see tumor anatomy and function simultaneously.

MRIs use magnetic fields and radiofrequency waves to produce three-dimensional images of normal and abnormal tissue.

Dr. Richard Wahl, director of nuclear medicine at Johns Hopkins Medical Institutions in Baltimore, said the first commercial U.S. use of PET/CT scan technology was at Johns Hopkins in 2001. He estimated at least 100 machines now are in use nationwide. He said Johns Hopkins doctors use the machine daily.

"It's a very good technique and their results are encouraging," Wahl said. But he noted that the study did not look at two of the most common forms of cancer — breast cancer and prostate cancer.

In an accompanying editorial, Drs. Lennart Blomqvist and Michael Torkzad of Karolinska Hospital in Stockholm, Sweden, called the study intriguing.

"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," they said. "It appears that the wheels of progress already have been set in motion."