If you suffer a blow to the head, your doctor may suspect that you may have a brain injury and order magnetic resonance imaging. MRI is the most commonly used imaging test to diagnose injuries of the central nervous system. The CNS includes the spinal cord and the brain.
The images that an MRI produces are high resolution and extremely detailed. Sometimes, an MRI can even produce 3D images. Usually, however, an MRI produces cross-sectional images. In other words, if you imagine your brain as being similar to a loaf of bread, each MRI image would be a single slice.
Advantages of MRI
An MRI is different from an X-ray. With a few exceptions, X-rays only take pictures of bones. An MRI can produce images of soft tissue. This makes it useful for diagnosing injuries of organs like the brain. Another advantage of an MRI is that it is noninvasive. In other words, your doctor does not need to open you up surgically to look inside you.
After a head injury, your doctor may perform both X-ray and MRI. Because of its ability to visualize bones, an X-ray can help identify a skull fracture, while an MRI can find damage to brain tissue.
Limitations of MRI
MRI cannot diagnose all brain injuries. Sometimes, the damage occurs at the microscopic level. If this is the case, an MRI may not be able to pick it up. This can occur with a type of trauma called a diffuse axonal injury. This causes widespread damage throughout the brain, but an MRI cannot detect it.
An MRI machine contains a giant magnet. If you have any metal anywhere on or in your body, it can affect the quality of the image. More importantly, it can pose a safety hazard. Before you have an MRI, you have to remove all jewelry. If you have metal implants, you may not be able to have an MRI at all. Tattoos can also affect your ability to have an MRI because some of the inks contain metal.
Despite these limitations, an MRI is usually effective at diagnosing brain injuries. That is why it is the test doctors tend to perform most often.