Radiopaque is matter that does not allow a certain amount of electromagnetism to pass through. In modern medicine, radiopaque usually refers to substances that will not allow X-rays or similar radiation to pass. Radiologic imaging has been revolutionized by radiopaque dyes, or contrasts , which can be passed through the bloodstream, the intestinal tract, or into the cerebral spinal fluid and utilized to highlight computerized tomography (CT), magnetic resonance imaging (MRI), or X-ray images.
