Researchers develop radiation-free tumor scan

Researchers at the Stanford University School of Medicine and Lucile Packard Children's Hospital Stanford have developed a radiation-free scanning method for tumors in cancer patients.

The technique, which uses a modification of magnetic resonance imaging, could reduce patients' risk of developing secondary cancers later in life.

The research team found that the new MRI-based method is just as effective as normal cancer-detection scans that use ionizing radiation -- specifically, positron emission tomography-computed tomography.

"I'm excited about having an imaging test for cancer patients that requires zero radiation exposure," senior author Dr. Heike Daldrup-Link, associate professor of radiology at Stanford and a diagnostic radiologist at the hospital, said in a news release. "That is a big deal."

The research team compared the two techniques in patients ages 8 to 33 who had lymphoma or sarcoma, both diseases that can spread throughout tissues like bone marrow, lymph nodes, liver and spleen. The PET-CTs detected 163 of 174 total tumors in the 22 patients and the MRIs found 158 of 174 tumors. The two methods had similar levels of sensitivity, specificity and diagnostic accuracy, and the study showed that their capabilities are comparable.

Creating an alternative method is valuable because a whole-body PET-CT scan, although important for providing essential information for detecting cancer, exposes the patient to as much radiation as 700 chest X-rays. This exposure is especially risky for still-growing children and teenagers.

To create this new technique, researchers had to address some issues with a standard MRI. First of all, it takes up to two hours, whereas a PET-CT scan takes a few minutes. Also, it cannot distinguish healthy from cancerous tissue, and the chemicals injected into the body to make tumors visible leave the tissues too quickly to be used in a lengthy, whole-body MRI.

These hurdles were overcome to develop a useful whole-body MRI.

"We were able to find a new way to integrate anatomical and physiological MRI information and make it more efficient," said Dr. Christopher Klenk, a postdoctoral scholar and the paper's lead author.

Daldrup-Link added that their development has already been implemented in some children's hospitals, but that future research is still needed to evaluate its effectiveness in larger, more diverse groups of cancer patients, as well as its possible use for monitoring tumors over the course of cancer treatment.