Technology: Magnetic resonance gets a feeling for sore muscles

日期:2019-02-28 09:12:04 作者:勾浙站 阅读:

DOCTORS in Dallas are using magnetic resonance imaging, MRI, for gauging the extent of damage to muscles. James Fleckenstein of the University of Texas Southwestern Medical Center also found that MRI can spot injured tissue weeks after the patient’s pain has gone. He says that it is better than existing methods such as enzyme measurements and biopsy, often pointing to damage that would otherwise remain hidden. MRI is a popular alternative to X-rays for looking at the brain, heart and other organs. Using a powerful magnetic field, MRI picks out elements by their resonant frequency; it is particularly good at detecting water, by the resonance of its protons. Fleckenstein used MRI to look at painful strains and at soreness in muscles, testing both trained marathon runners and weekend athletes. He found that injured muscles produce a white glow on the pictures. The glow indicates water in the tissue. Exercising changes the amount and distribution of water in muscles which is picked up in the MRI picture. The researchers were surprised to find that the painful areas, which glowed brightly and remained bright for weeks, were often not the primary muscles used in the exercise. The muscles adjacent to the main ones were often the source of pain. They were also surprised to find that injured muscles remained bright under MRI for as long as three weeks after the pain disappeared. ‘Abnormalities revealed by MRI are evidence that clinical evaluation alone, without MRI imaging to verify the location and extent of injury, may lead to an incomplete assessment of muscle damage and recovery,’ says Fleckenstein. ‘More research needs to be done to determine if the bright signal that remains means that the muscle needs more healing time before it is safe to reuse the muscle.’ He reported his results in the September issue of the journal Radiology. Besides taking a muscle biopsy or measuring the enzymes present, doctors use nuclear techniques to analyse sportsrelated injuries. Each has disadvantages. In a biopsy, a small amount of muscle is removed through a needle. The technique is invasive, destructive, and may not take a sample from the correct place within the muscle. Doctors also measure the amount of creatine kinase, an enzyme present when dead cells are being broken down. This indicates when tissue has been destroyed, but not always how much. With nuclear medicine, doctors inject radioactive tracers into the muscle and then make images. This is not hazardous,