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.
A magnetic resonance imaging (MRI) scan is a painless procedure that lasts 15 to 90 minutes, depending on the size of the area being scanned and the number of images being taken. Before the scan On the day of your MRI scan, you should be able to eat, drink and take any medication as usual, unless advised otherwise.