Lameness (equine)
Magnetic Resonance Imaging (MRI) produces a 3-dimensional image that allows for exceptional evaluation of soft tissue structures, as well as the detection of boney change and the presence of excessive fluid accumulation associated with inflammation. Like CT, an MRI image may be viewed in various planes of orientation, improving visualization of anatomic structures and any associated pathologic change. MRI is considered the gold standard for diagnosing soft tissue injury within the foot. While it can provide a definitive diagnosis in cases where other imaging modalities have failed, it does have several limitations. Available magnet size restricts imaging to the level of the stifle or elbow, or below. MRI takes a significant amount of time acquire an image, which translates to long anesthesia times and therefore reduces the size of the area that may be imaged in a single session. The area thought to be associated with lameness must be placed in the MRI. MRI is therefore inappropriate for any lameness that can not be localized to a specific region of the limb. Additionally, MRI has limited availability and high cost compared to the other imaging modalities.
Safety of magnetic resonance imaging
There is no proven risk of biological harm from any aspect of a MRI scan, including very powerful static magnetic fields, gradient magnetic fields, or radio frequency waves. Some studies have suggested possible genotoxic (i.e., potentially carcinogenic) effects of MRI scanning through micronuclei induction and DNA double strand breaks in vivo and in vitro, however, in most, if not all cases, others have not been able to repeat or validate the results of these studies, and the majority of research shows no genotoxic, or otherwise harmful, effects caused by any part of MRI. A recent study confirmed that MRI at some of the most potentially-risky parameters tested to date (7-tesla static magnetic field, 70 mT/m gradient magnetic field, and maximum strength radio frequency waves), did not cause any DNA damage in vitro.