Diagnostic Imaging: MRI and CT Scans With so many non-invasive diagnostic imaging options, it is often difficult for patients to differentiate between the benefits and considerations of each technique. The decision about which is the right method for you will depend on several factors: speed, detail, accuracy, safety, and comfort. Computerized axial tomography (CT or CAT scan) is a diagnostic test that combines x-rays and a computer to produce detailed cross-sectional images of the body. With this method, a three-dimensional picture can be built and irregularities analyzed. CT scanning is particularly useful because it can be performed so rapidly. The first CT scanner came into operation in London, England during 1972. This is the method often used by archaeologists to investigate mummies! The latest innovation in CT technology is the helical, or spiral, CT scan which is able to generate an image in just 20 seconds as opposed to the traditional scan which takes a series of pictures every 5-10 seconds. The most significant consideration of this method is exposure to low level x-rays, similar to that of a chest x-ray. Magnetic resonance imaging, or MRI, was developed in the 1990’s and is widely considered to be the superior technique for soft tissue detail. In addition, MRI provides a way to look inside the body without exposure to x-rays. It uses large magnets, radio waves, and a computer to generate detailed, cross-sectioned images of the body. During an MRI scan, the patient is placed inside a long, narrow, tube-shaped device and must remain still for three to ten minutes at a time. Some patients find the small, enclosed space of traditional MRI’s claustrophobic. A new alternative, “Open” MRI, makes it possible for patients to be examined without the fear of being placed inside traditional MRI machines. This system is ideal for pediatric, elderly, claustrophobic, anxious, and obese patients, or anyone who would prefer not to go into a closed system. There is usually no difference in cost between open and closed MRI’s; however, there are other factors that should be considered. In the case of brain imaging, for example, the technique is equally confining in both traditional and open MRI’s. In addition, the new open units are not as powerful as closed units, resulting in an increased time the patient must remain still and some compromise in detail. There are no known risks or side-effects associated with either MRI method. It should not be performed, however, on some patients with metal implants within the body, pacemakers, or other electrical devices that are sensitive to magnetic fields.
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