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X-rays, CT Scans, and MRIs–What is the Difference?

There are several different diagnostic imaging tests that may be used to help diagnose spinal conditions and other musculoskeletal problems–X-rays, CT scans, and MRIs are among them.

These tools allow your doctor to see the bones, muscles, tendons, organs, nerves and cartilage in your body to determine whether there are any abnormalities. Although they are all imaging tools, they serve different purposes and are used for different things. Patients often ask about the different imaging tests we use to help diagnose spinal conditions, so let’s break down what each type of test is used for.


How They Work: When you get an X-ray, your body is positioned between the X-ray machine and photographic film. The machine sends electromagnetic beams (radiation) through the body, which exposes the film. The bones absorb the radiation, but it passes through the skin and soft tissues because they are less dense. This is why the bones appear light on the film, while the surrounding areas are darker.

What They Are Used For: X-rays are the most common and widely-used of all of the diagnostic imaging tests. X-rays are often done first, even if other imaging tests are ordered. X-rays are best used to diagnose or rule out problems with the bones, such as a spinal fracture or abnormality. If a soft tissue disorder is suspected, further imaging tests may be needed.

CT Scans

How They Work: A computed tomography (CT) scan produces a cross-sectional image of your body. Although CT scans use X-rays, combined with computer technology, it produces a more detailed image than a regular X-ray. The CT scanner is shaped like a cylinder, and patients lie on a table in the center of the cylinder while an X-ray tube slowly rotates around the table, using multiple X-ray beams at different angles. A computer then combines these images to create three-dimensional cross-sectional images, with each image revealing a different level of tissue.

What They Are Used For: CT scans allow doctors to see the shape and position of the structures inside your body, including the bones, organs, and soft tissues. CT scans may be used to get a clearer image of problems with the vertebrae, such as fractures or deformities. It can also help to diagnose herniated disc, spinal tumors, and spinal stenosis. CT scans are often recommended if there is severe trauma to the spinal cord.


How They Work: Magnetic resonance imaging (MRI) produces cross-sectional images of the body like CT scans, but does not use radiation to produce the images. Instead, MRIs use electromagnetic waves and a computer to take high-resolution images of the bones and soft tissues in the body. The tissues in the body resonate with the waves, and the computer records and translates this data into detailed images. MRIs produce the most detailed images, but because the MRI magnets are very powerful, they cannot be used on patients with metal implants or objects in the body, including pacemakers.

What They Are Used For: Because they produce the most detailed images, MRIs are often used to inspect the discs and nerves in the spine. In many cases, MRIs are only ordered when conservative treatment fails to relieve the patient’s pain and the physician needs to inspect the source of the pain more closely. When an MRI is ordered, the physician usually has an idea of what may be causing the pain, and the MRI is used to confirm the diagnosis.

As you can see, different imaging tools serve different purposes in the process of diagnosing a spinal condition. Sometimes, a combination of these images may be needed to confirm a diagnosis. The ultimate goal of diagnostic imaging tools is to get the most accurate diagnosis possible so that we can give the patient the best treatment possible.