Unexplained weight loss is defined as the unintentional loss of at least 10 pounds or 5 percent of body weight over a period of 6 to 12 months. This would be equivalent to a 200-pound man losing 10 pounds or a 130-pound woman losing six to seven pounds.
What It Is. Magnetic resonance imaging (MRI) of the brain is a safe and painless test that uses a magnetic field and radio waves to produce detailed images of the brain and the brain stem. An MRI differs from a CAT scan (also called a CT scan or a computed axial tomography scan) because it does not use radiation.
Magnetic resonance imaging (MRI) is a noninvasive test that uses a magnetic field and radiofrequency waves to create detailed pictures of organs and structures inside your body. The MRI machine will create a strong magnetic field around you, and radio waves will be directed at the area of your body to be imaged. 2  You wonât feel the magnetic field or radio waves. 3  During the MRI scan, the magnet produces loud tapping or thumping sounds and other noises.