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) What is MRI? 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. It can be used to examine your heart and blood vessels, and to identify areas of the brain affected by stroke.