What’s the difference in X-rays, MRIs, and CTs?

Shedding some light on the 3 most common outpatient radiological exams.

It really boils down to what needs to be seen or what tissue is suspected to be causing a problem.

The quickest radiological exam of the three is an X-ray. Most of us have had an x-ray whether it was at our dentist or when we fell off the jungle gym in elementary school. X-rays illuminate bone with one single “snapshot” image at a time.  Under x-ray, a bone glows white and any break in that surface will be noticeable with a darkened area where there is a crack, break or imperfection on the bone’s surface. Therefore, X-rays are used frequently for traumatic bone injuries or to examine a bone deficit that would be easily detected under X-ray. An X-ray is generally not a sufficient radiological exam for tissue other than bone.

MRI stands for Magnetic Resonance Imaging. And it is just what it implies. It uses a magnetic field to produces images instead of using radiation. Similar to the CT, during an MRI the patient lays on a flat surface while the magnetic field generates pulses of images through the area being examined creating an orderly series for the doctor to view. MRI images will show soft tissue such as organs, tendons and ligaments, and it offers the best view of the spinal cord. Bone will not illuminate brightly with an MRI and this allows for better dense imaging of organs such as the brain which can see past the thick encapsulating skull bones that protect it. An MRI can be used to diagnose many things but it can be a neurologist or neurosurgeons best tool when it comes to looking into spinal cord injuries, infections or bleeding in the brain, and other central nervous system disorders.

A CT scan, or “CAT scan” is the big brother of the simple X-ray. A CT uses the same type of radiation as an x-ray but in a much more detailed way. While the patient lays on a flat surface, a CT scan will rotate independently around the patient and take multiple cross section images.  It is kind of like having a birds-eye view of your body that slowly moves from the top of the tissue being view and through to the bottom via a series of images. These series of images are placed on the CT’s integrated computer and the doctor is able to view each cross section image in the order in which it was taken and look for imperfections as the series progresses. A CT is ordered by a doctor in order to view bone, muscle, tumors, or blood vessels. It is usually better at viewing bone than an MRI so it is the preferred method for spine related problems.

Of these three radiology options, spine specialists like those at Orthopedic and Laser Spine Surgery, feel CT Scans are the most beneficial for their patients with spine concerns. A CT illuminates the vertebral bones brightly, gives clear views of the discs and other supportive structures, and offers important details with the cross section viewing.