Researchers have developed a modified MRI technique that allows patients to be scanned for tumors without exposing them to radiation and the added possibility of developing radiation-associated cancers later in life.
This new method, published in an article in Lancet Oncology Feb. 18, uses MRI with a novel contrast agent to find the tumors.
According to the researchers from Stanford University School of Medicine and Lucile Packard Children's Hospital Stanford, while whole body PET-CT has been very effective in detecting cancers, a single exposure can equate to as much as 700 chest X-rays--an amount that could be particularly risky for younger patients.
MRI is a radiation-free alternative, but is incapable of distinguishing healthy from cancerous tissue in many body organs without the assistance of contrast agents, and existing contrast agents leave the body too quickly to be used in whole-body MRI exams, which take quite a bit of time.
But, the new modified technique uses a contrast agent consisting of nanoparticles of iron, which are retained in the body for days, and on MRI cause blood vessels to appear brighter, and healthy bone marrow, lymph nodes, liver and spleen to appear darker.
Researchers used this new technique on 22 patients ages 8 to 33 with lymphoma or sarcoma, comparing it to PET-CT. PET-CT detected 163 of 174 total tumors in these patients, while MRI found 158. None of the patients suffered any adverse reaction from the new contrast agent.
"We were able to find a new way to integrate anatomical and physiological MRI information and make it more efficient," Christopher Klenk, a postdoctoral scholar and the paper's lead author, said in an announcement.
Senior author Heike Daldrup-Link, an associate professor of radiology at Stanford, said that the researchers are sharing the technique with their colleagues around the county. Whole-body MRI is "slowly entering clinical practice, but clinicians are cautious and want to be convinced," she said. "The other barrier to wide adoption of MRI-based tests is lack of a billing code, a hurdle the researchers hope will soon be resolved. But there are no technologic obstacles to use of the new technique."