Magnetic Resonance Imaging (MRI). Guide. Magnetic resonance imaging (MRI) is a test that uses a magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the body.In many cases, MRI gives different information about structures in the body than can be seen with an X-ray, ultrasound, or computed tomography (CT) scan.n MRI scan can be done for the: 1  Head. 2  MRI can look at the brain for tumors, an aneurysm, bleeding in the brain, nerve injury, and other problems, such as damage caused by a stroke. 3  MRI can also find problems of the eyes and optic nerves, and the ears and auditory nerves.
:: a brief history of CT. The first clinical CT scan on a patient took place on 1st October 1971 at Atkinson Morley's Hospital, in London, England.
A multidetector CT is a very fast type of CT scanner that can produce high-quality pictures of the beating heart and can detect calcium or blockages in the coronary arteries. An electron beam CT scanner also can show calcium in coronary arteries. Your cardiac CT scan may be performed in a medical imaging facility or hospital. The scan usually takes about 15 minutes to complete, but can take more than an hour including preparation time and, if needed, the time to take medicines such as beta blockers to slow your heart rate.