January 06, 2022
When you’re not feeling well, a health care provider can often make a diagnosis based on your symptoms, vital signs, and medical history. But when it comes to examining bones, internal organs, or soft tissues, diagnostic imaging tests may be required to get a clear picture of what’s going on inside your body.
X-rays, CT (computed tomography) scans, and MRIs (magnetic resonance imaging) are the three most commonly ordered imaging tests. Which one your doctor orders generally depends on what kind of an image is needed.
X-rays are the most commonly used medical imaging test and are widely available and accessible. X-rays are electromagnetic waves, which are a type of radiation. When an X-ray machine passes them through your body, different body areas absorb the radiation differently, creating an image of what’s inside. If you’ve ever broken a bone, you may have had an X-ray done, but this type of imaging test can also be used for checking other symptoms in the body, performing dental examinations, mammograms, and more.
This type of imaging test combines a series of X-rays taken from different angles around your body. A computer processes these images to create more detailed images than a single X-ray. They are used for internal injuries or to inform treatment for surgeries, cancers, or other disorders that require specific images.
MRIs use magnets and radio waves to create images of the inside of your body. These tests involve creating a magnetic field around your body and bouncing radio waves off different tissues and organs to create an image. Doctors recommend MRIs when a higher-quality image is needed than a CT scan produces.
MRIs have better imaging and no radiation, so it might seem counterintuitive that they’re used far less frequently than X-rays and CT scans. There are a few good reasons for that: MRIs are much more expensive than X-rays, and MRI machines are located in fewer facilities. It’s easier, faster, and less costly to get a CT scan — and for many ailments, the images are sufficient.
MRIs are also unpleasant. They can take up to an hour to complete and require the patient to lie completely still while the test is being done. The machine itself is loud, and while patients are often given headphones, they may still feel claustrophobic. Certain MRI tests require a dye called contrast, which can cause allergic reactions. Your doctor will generally only order an MRI when they think you need it.
Whether it’s a dental X-ray, a broken bone examination, or a cancer screening, diagnostic imaging tests are a vital tool used by health care professionals to help them make informed decisions about your health care.