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.
What is an MRI? Magnetic resonance imaging (MRI) is an imaging test that uses a magnetic field and pulses of radio waves to take pictures of internal organs and structures. What are some common reasons why an MRI is performed? MRIs are often used to detect tumors, infections, internal bleeding, and internal injuries.