Most people have probably heard of (and probably had) an x-ray or ultrasound before. These, among others, are diagnostic imaging tests that help us "see" what's going on inside your body. Doctors and other healthcare practitioners throw these terms around all the time, but what's the difference between all these tests? Here's a quick lesson on some common diagnostic procedures and how they relate to the musculoskeletal system.
X-ray: X-rays create black and white images of the inside of the body. Various tissues inside the body absorb different amounts of radiation. Because bones absorb the most, they appear white. That's why x-rays are useful in identifying boney problems, such as fractures, osteoarthritis, and structural deformities. They are not helpful in diagnosing soft tissue disorders.
Ultrasound: Ultrasounds use sound waves to view structures inside the body. Because these waves cannot penetrate through bone, ultrasounds are useful in imaging soft tissues and fluid-filled spaces. Most people recognize the use of ultrasounds for viewing a fetus. However, ultrasounds are also helpful in identifying problems with ligaments, tendons, cartilage, cysts, swellings, etc.
CT scan: CT scans create cross sections or "slices" of structures in the body. They are more precise and reveal more information than a regular x-ray as they are able to identify both soft tissue and bone. CT scans are also able to image blood vessels and diagnose blood clots and bleeding as well. Because of such ability, they're helpful after accidents in determining internal injuries and bleeding.
MRI: MRIs are like the gold standard of imaging. The images produced by an MRI scan are clear, detailed, and accurate. MRI scans are able to diagnose a variety of conditions related to bones and joints, soft tissues, nerves, brain and spinal cord, internal organs, blood vessels, and many more. The downside of MRIs (in Canada) is that there are long waiting lists, and doctors will generally send patients for an x-ray or ultrasound first.
I hope this is a useful guide of the different types of imaging tests. I get questions from patients all the time whether an x-ray will show _____ or whether an ultrasound will show _____. It also helps when you know why your doctor is sending you for a specific test!
