Wednesday, November 01, 2006

Finding Hidden Tumors

Continued from page 1

By Katherine Bourzac

If an NF patient's tumor becomes cancerous, Plotkin and Harris will look back at previous images to see if there were any warning signs--a metabolic reading slightly hotter than normal. The normal range of metabolic activity for NF-related tumors is simply not known, so it can be difficult to distinguish between a tumor with a high but normal metabolic rate and one that is likely to turn malignant. Plotkin says the hindsight offered by the Mass. General trial will provide clearer guidelines for physicians about which tumors may be precancerous and should be biopsied.

Whole-body MRI is less than a decade old, and the technology is currently not part of routine patient care in the United States. But Ara Kassarjian, a Mass. General radiologist working on the NF trial, says the major manufacturers of the strongest MRI scanners used in hospitals (including Siemens, General Electric, and Philips) are now making the machines with whole-body imaging capability. The primary technological advances over traditional MRI are a table that moves a patient through the machine smoothly enough not to blur the image and software that can seamlessly weave together five or six sets of images. Researchers are testing the technique in a variety of diseases besides NF. For example, physicians hope clinical trials in progress will show whether whole-body MRI can detect the spread of cancer.

The Mass. General researchers' trial will be run in full collaboration with a hospital in Hamburg, Germany, that also treats a large number of neurofibromatosis patients and performs whole-body MRI scans. To facilitate this long-distance collaboration, ­Harris has built a password-­protected online database where all MRI and PET images from patients at each hospital will be stored. Rather than seeing only a radiologist's report on images from the other hospital, the American and German researchers will be able to see original imaging scans from all patients. This will allow for more consistent analysis of both sets of images.

Plotkin hopes their study will take some of the guesswork out of diagnosing and managing neurofibromatosis. And in the future, he hopes to correlate the images with genetic tests, so he can better determine how gene abnormality affects the number and size of tumors in NF patients. "The ultimate goal is to understand why some patients are severely affected and others are not," he says. "This is the first step on that path."