Doctors use diagnostic medical imaging to find out the possible causes of illness, injury or pain, to help provide an accurate diagnosis. These images include X rays, CAT scans, MRIs, and ultrasound.
X-rays were the very first imaging technique and are still the most commonly used today. X-rays use radiation which produces rays that pass through the body. When striking something dense like bone the image appears white and when going through something hollow like the lungs the image appears black. Muscle and fat appear as shades of gray. Sometime a dye can be introduced into the body before the x-ray, to make certain organs stand out.
X-rays used to be developed on a type of photographic film which needed to be developed and stored. Now the x-ray images can be instantly viewed on a computer screen, eliminating the need for the old film technique. This is a landmark feature because not only are the digital images immediately available, but they can be sent instantly to another source, such as a consulting physician.
X-rays are still excellent for evaluating bones, teeth, the chest (including the lungs and heart), and swallowed opaque items such as coins and most pieces of glass. The digestive tract can be visualized using a dye, such as barium.
Computerized Axial tomography ( CAT/CT ) scans use x-rays with computers to produce 360 degree cross sectional views of the body. These views allow the physician to see details of bony structures, chest, heart and lung problems, cancers, and many other internal organs. A typical exam may take 10-30 minutes.
A CAT scanner is much larger and more complex than an x-ray machine. It is a very expensive piece of equipment and therefore more costly to the patient than an x- ray. In spite of the increased cost, CAT scans can provide the physician with much more information and diagnostic ability than can most x-rays.
CAT scans use substantially more radiation than conventional x-rays and therefore should be used only when absolutely necessary. Don’t hesitate to ask the ordering provider if the scan is absolutely necessary.
Magnetic Resonance Imaging ( MRI ) combines a very powerful magnet along with a computer and radio waves ( no radiation exposure ) to provide detailed, accurate images of bones, internal organs, soft tissue, and other internal body parts. Patients must be carefully screened to insure that they have nothing metallic in or on the body such as rings, necklaces, pace makers, metal implants and some tattoos, because of the use of the magnet.
MRIs often take at least 30 minutes or more and, as with the CAT scan, can take cross sectional images of the body area being studied. The patient needs to lie completely still inside of a large tube, which may be very difficult for a person with claustrophobia. While inside the tube, the MRI machine makes a very loud knocking sound, usually necessitating the need for wearing ear plugs. The MRI is the most expensive of all the imaging techniques.
Ultrasound uses high frequency sound waves to produce images of structures within our bodies. Like MRIs, it uses no radiation and is very safe. A small hand held device is pressed against lubricated skin and moves it around to capture the image. This exam can take from 30 minutes to an hour. Unlike the other imaging techniques, this exam can also be used in a doctor’s office or emergency room making it a very useful diagnostic tool in many circumstances.