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 one of the better choices if you need a diagnostic imaging procedure performed. Unlike CT scans or X-rays, an MRI does not use ionizing radiation that may cause DNA damage or cancer.