In this essay, safety issues and hazards of MRI will be discussed and methods for safe imaging will be explored through review of suitable literature.
MRI is a "way of obtaining very detailed images of organs and tissues throughout the body without the need for x-rays or "ionizing" radiation. Instead, MRI uses a powerful magnetic field, radio waves, rapidly changing magnetic fields, and a computer to create images that show whether or not there is an injury, disease process, or abnormal condition present" (Patient-Safety MRI, 2010). MRI has turned out to be an excellent investigation tool because of it ability to provide good contrast between various tissues in a particular region. For example, in the brain, a good contrast is provided between white matter, gray matter and cerebrospinal fluid (Diwadkar and Keshavan, 2002). The technology of MRI mainly employs 3 components for imaging and they are pulsed radio-frequency fields or RF, high static magnetic field and time-varying gradient electromagnetic fields or EMF (Roboman et al, 2006). For the purpose of MR imaging, the patient is placed in a "large, tunnel or doughnut-shaped device that is open at both ends" (Patient-Safety MRI, 2010) (Refer Figure-1). The examination causes no pain or tissue injury, although loud noises are heard during the procedure. There is also a risk of mechanical injury due to ferromagnetic objects kept in the scanning room unintentionally. The main hazards concerned with magnetic fields are interactions with the equipment and interactions with human tissue. As far as human tissue interactions are concerned, the most worrisome interactions are with blood flow, ears and cardiac cycle (De Wilde et al, 2007).
The main safety issues which are of concern on exposure to high static magnetic field are are both mechanical and biological effects and their consequences. In clinical MRI scanning, the strength of magnets used range between