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.
An MRI scan is not suitable for the patient if they have electrical appliances, such an a ear implant, implantable cardioverter defibrillator or pacemaker, or have any metal in their body such as surgical clips. But orthopaedic metal ware, such as artificial hips or bone screws, are not normally a problem.