An MRI scanner is similar to a camera. If you move during a photo shoot, your picture will be blurry. The same thing applies to an MRI. If you move during your MRI scan, your images will be blurry. Most scans will last about one hour, so it is important that you are comfortable. Cushions may be placed around your head; this helps hold your head still. A comfortable bolster may be placed under your knees to take the strain off your back from lying still in the scanner.