Learn what separates Magnetic Resonance Imaging from Computerized Tomography and X-Ray. 

If you’ve ever heard your physician say that they need to see what’s happening inside your body, there’s a good chance you’re going to be prescribed one of several common medical imaging techniques. You may even have heard of these techniques before, but do you know what makes an MRI different from a CT scan or an x-ray?

While it’s easy to assume that they must all do the same thing (after all, they all offer a clear but non intrusive look beneath your skin) they actually have remarkably different uses, and the reason for that is entirely due to the technology that makes them possible. 

Here are the things that make each scan different and why your physician would order one instead of the others.

How does an MRI works?

How Do MRI Machines Work?

Unlike the other techniques on this list, MRI imaging doesn’t use radiation. MRI uses magnets and radio waves to see into your body. It is the newest technique of the three.

Up to 60% of the human body is made of water. MRI machines use large, powerful magnets to manipulate the water molecules in your body. The machine then detects those changes and uses them to create detailed cross sectional images of your body. Unlike CT and x-ray machines, there’s no radiation involved in this process, making it completely safe as long as there’s no metal in the room. Unfortunately, this can mean that people with implants such as pacemakers, inner ear implants, and other devices may not be able to be imaged in an MRI machine.

When Would I Need An MRI?

Magnetic Resonance Imaging is a powerful tool and can be used to detect and diagnose a wide range of disorders, injuries, and diseases. Its uses include:

  • Metabolic disorders
  • Tumors
  • Crohn’s disease and other inflammatory bowel diseases
  • Cirrhosis and other liver diseases
  • Calcium deposits, blood clots, or aneurysms
  • Vessel abnormalities of the brain
  • Stenosis (narrowing of the blood vessels)
  • Aortic narrowing

What Should I Expect?

When receiving an MRI scan, you’ll be placed in one of two styles of machine – traditional or open. For both, you’ll be asked to lie on a motorized bed and be positioned by a technologist. A traditional MRI machine uses a short tube that is open at both ends, while an open in an MRI you’ll be placed between two large plates above and below you with the sides completely open.  While both are perfectly safe, traditional MRIs can sometimes feel restrictive for larger patients or those suffering from claustrophobia. As the images are being taken, you’ll hear loud knocking sounds and will be asked to remain still or to hold your breath. As with our other techniques, your images will then be analyzed by a radiologist and detailed results will be sent to your physician.

X-ray – A Basic Look at What’s Beneath

As the oldest but also most commonly used of the imaging techniques on this list, it could come as no surprise that x-ray imaging is the one most people are most familiar with.

How Do X-rays Work?

X-ray imaging machines work by passing light or radio waves through an area of your body as radiation. As the waves pass through the different tissue densities of your bones, organs, and more, they’re absorbed or deflected. The ones that make it through are absorbed by a film positioned underneath the area being imaged. Those rays expose the film just like an old camera in order to create a clear 2D image of what they’ve passed through. Despite their age, x-rays are still widely used today because they are relatively affordable and do not require the more advanced equipment needed for other imaging styles. X-rays use a low dose of radiation and are perfectly safe so long as proper precautions are taken.

When Would I Need An X-ray?

Because of the speed at which they can be performed and the simplicity of the procedure, x-rays are widely used to diagnose and monitor a number of conditions. These include:

  • Broken or fractured bones
  • Dislocations
  • Tumors
  • Pneumonia
  • Osteoporosis and similar bone degeneration

What Should I Expect?

When undergoing an x-ray scan, a technologist will ask you to lie on a bed and position a film beneath the area being scanned. You’ll likely need to be repositioned at least once for images from multiple angles, and we may even take images of a healthy area as well for comparisons during diagnosis. Your images will then be analyzed by a radiologist and detailed results will be sent to your physician.

CT – An X-ray with More Depth

First invented in the 1970s, CT or Computerized Tomography imaging can be thought of as the next step in x-ray imaging technology.

How Do CT Scans Work?

Unlike x-ray imaging, which simply exposes a film beneath a selected area, CT scans use a 360º array of radiation and advanced computation to create a detailed 3D image of an entire section of your body, including organs and bones. While the image created is already more detailed than what you would expect from a traditional x-ray, technologists can further improve the detail with an injection of contrast dye, although this isn’t always necessary. Because of the advanced equipment and skill technologists needed to perform CT scans, they can be more expensive than x rays, but can also identify far more subtle and nuanced conditions.

When Would I Need A CT Scan?

Since they’re able to capture far more detail than a 2D x-ray, CT scans are used to identify and diagnose conditions that include:

  • Appendicitis
  • Cancer
  • Heart disease
  • Musculoskeletal disorders
  • Infectious diseases
  • Internal trauma
  • Kidney stones

What Should I Expect?

When performing a CT scan, a technologist will ask you to lie on a motorized bed, then position your body appropriately within a large ring. The ring will emit a short burst of x-rays, that create a detailed image of your body. The process will take up to 15 minutes, and you may be asked to hold very still or even to hold your breath. Your images will then be analyzed by a radiologist and detailed results will be sent to your physician.