What Does an Xray Show That an MRI Doesn’t?

When you injure yourself, your doctor will usually first want to make sure that you haven’t broken a bone, which is why she typically orders an x-ray before any other test. Sometimes, depending on several factors, she may also order an MRI scan.


Female with pain back pain and neck pain

The X-Ray

X-rays use a small amount of radiation (light energy) to capture an image. The radiation passes through your body very quickly, and when it hits something that’s dense (like a bone or other structure), it shows up in white so that a doctor of radiology can get a good look at the area and assess its condition. It’s a low-cost test that’s also quick and painless.  However, an x-ray can only show so much, and if it doesn’t show what’s causing a patient’s pain and swelling, a doctor may then order an MRI scan, which shows more detail because it captures an image in a different way.


The MRI Scan

MRI — short for magnetic resonance imaging — uses a powerful magnetic field with radio waves and a computer to generate detailed images of a specific area of the body. Perhaps the biggest difference between the MRI image and the x-ray image is that the MRI scan provides a 3-dimensional image. Unlike an x-ray, which takes just a minute or two, an MRI scan can take anywhere from 30 minutes to nearly an hour to complete.

And while x-rays are great at showing bone fractures, MRI scans are more suited to soft-tissue injuries, like torn ligaments or damaged tendons. That’s why, when an x-ray doesn’t show anything obvious, an MRI may be ordered to dig deeper for a less obvious injury. The MRI would never be ordered if a doctor suspects a broken bone. Not only don’t bony structures show up as well on an MRI scan, but the scan is considerably more expensive than an x-ray as well.


Risks Associated With Imaging Tests

X-rays use radiation, but usually a very small amount. However, small children can be sensitive to the effects of radiation, which is why doctors may choose to use another diagnostic test on a woman if she’s pregnant — an ultrasound or sonogram, for example. In general, the diagnostic benefits far outweigh the risks from x-rays.

There are also risks associated with MRI scans, although again, they’re generally low. Because MRIs use magnets, there can be issues if you have any metal (or electronic) devices within your body. (If you’ve ever had an MRI, you can probably recall the technician asking about that before administering the test.) If you have any of the following, you should let the MRI technician know …

  • a metallic joint
  • an artificial heart valve
  • a pacemaker
  • a bullet or a piece of shrapnel that was never removed
  • a cochlear implant
  • a metal clip or stent

Sometimes, an MRI scan will include an injection of a contrast agent, to aid in the imaging process. Some people may be allergic to these substances, and if you have a liver or kidney condition, be sure to let the technician know, since certain conditions affecting those organs may preclude the use of a contrast agent altogether.


You should also let the technician know if you are pregnant. This is more a precaution than anything else since the effects of magnetic fields on fetuses are still not completely understood by scientists.

Here’s another something to consider. If you have a — or multiple — tattoos, let the technician know since sometimes the darker-colored inks can contain metallic elements! (Not great news for anyone who’s into tattoos as body art!)

So while both are imaging tests, x-rays and MRIs use different methods of obtaining an image and serve very different diagnostic purposes.

If You’ve Been Injured

If you’ve been diagnosed with an injury, whether it’s a broken bone, a herniated disc, or another musculoskeletal condition, you’ll probably find that your treatment, like your diagnosis, will start with simple, but effective treatments like ice therapy, anti-inflammatory medications, and physical therapy. (Surgery is almost always a last resort.)

For the very best physical therapy programs and doctors in Luzerne Country and surrounding areas, trust the professionals at Cawley Physical Therapy and Rehab, with offices in Pittston, Kingston, Dunmore, and Nanticoke, PA. Give us a call today at 570-208-2787 or email us at cawleyptfrank@gmail.com.