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    Matthew J. Krasin, MD

    Matthew J. Krasin, MD

    MR imaging tracks muscle damage from radiation

    Magnetic resonance (MR) imaging can spot the immediate injury caused by radiation therapy to the muscles of children undergoing radiation treatment for certain types of cancer, according to St. Jude investigators. This finding suggests that MR might one day be able to help clinicians predict the amount of long-term damage radiation may cause to muscles. A report on these findings appears in the October 25 online issue of Magnetic Resonance Imaging.

    The study’s findings are important because as radiation treatments become more advanced and complex, clinicians must have a way to predict the outcomes—including side effects—for specific patients, according to Matthew Krasin, MD, Radiological Sciences.

    The researchers used a technique called quantitative T2 to determine the extent of swelling in tissues before, during and after radiation therapy; and a technique called dynamic enhanced MR imaging (DEMRI) to study what happens to the blood supply at a microscopic level.

    Following infusion of a contrast agent, gadolinium, the team made 60 images of the same area, including a dynamic view of what was happening in the muscles during a 6-minute period.

    “The rate at which the contrast agent flows in and out of a region, or whether it leaks out of the blood vessel, helps us understand whether the blood supply is in poor or good condition,” Krasin said. “Changes in T2 measurements may indicate an increase in swelling following radiation therapy, which is evidence for inflammation that could be treated.”

    The clinicians believe that the early changes they see in muscle, such as swelling and leakage, might help them predict how much damage will occur in the muscles during the course of many months. By better understanding what causes these changes in muscle, clinicians will then be able to design better radiation treatments to avoid potential problems or treat the injury at an earlier stage.

    Other authors of the study include Xiaoping Xiong, PhD, Biostatistics; Sue Kaste, DO, Beth McCarville, MD, Thomas Merchant, DO, PhD, Robert Ogg, PhD, and Wilburn Reddick, PhD, all of Radiological Sciences; Larry Kun, MD, Radiological Sciences chair; Fariba Navid, MD, and Sheri Spunt, MD, both of Oncology; Andrew Davidoff, MD, Surgery; and former St. Jude employees Lijun Zhang and Fredric Hoffer.

    November 2006