Sunday, 9 September 2012

The Difference Between CT and MRI Scans

Left image - CT scan. Right image - MRI. Note the soft tissue detail in the MRI not visualised in the CT.

When I first began thinking about becoming a Radiographer, I was only vaguely aware of the differences between MRI and CT scans. Some people will have been examined using either of these techniques, but others may have only seen pictures, or seen 'examples' of scans on TV (e.g. on 'Holby City' and 'House'). Sure, on a first glance, they do look pretty similar in the detail and quality of their images, but that's where the similarity ends.

Let's start with CT scans, shall we?

Computed Tomography scans are a specialised type of X-ray. CT scans take 360-degree images of internal organs, the spine, and vertebrae. They combine x-rays and a computer to produce a cross-sectional view of the body part being scanned. Sometimes, a contrast agent (usually an iodine-based substance which is absorbed by abnormal tissues) is injected into the blood to make structures more visible.

CT is very good for imaging bone structures and the spine, and they are used more frequently when diagnosing conditions affecting the vertebrae and other bone structures.

MRI, or (for those who don't know) Magnetic Resonance Imaging, on the other hand, is completely different! Unlike CT scans, MRI uses a powerful magnet, radio waves and a computer to produce images.

The way it works, is that the computer sends radio waves through your body and collects the signal that is emitted from the hydrogen atoms (the magnetic properties in your body's organ and tissue cells). The images produced do look similar to CT scans, but the detail in the soft tissues is higher.

An advantage of MRI is that the contrast of the image can be changed. Different contrast settings highlight different tissue types. Contrast agents are also used in MRI scans, but they are not iodine-based.

I hope this has given you a good, brief(ish) explanation regarding the differences between CT and MRI. If not, well.....It was interesting for me to find out, anyway!

If you do want more information on MRI scans or CT scans, here are two links that go into more detail:


  1. Thanks! You have made some really good points here! There are differences in the costs for these studies based upon where they are completed as well as differences in the quality of radiology and staff support. It pays to compare these factors before completing either MRI scan or CT imaging.

  2. LifeVoxel.AI has developed a Interactive Streaming and AI Platform for medical imaging using GPU clusters cloud computing. It is a leap in cloud technology platform in medical imaging that encompasses use cases in visualization, AI, image management and workflow. It’s approach is unique that it has been granted 12 International patents. LifeVoxel.AI’s platform is certified for HIPAA compliancy. The platform was granted an FDA 510K approval for use in diagnostic interpretation of medical images.

    Interactive Streaming AI Platform RIS PACS

  3. LifeVoxel.AI platform helps imaging diagnostic centers and hospitals to save up to 50%+ over conventional RIS PACS with higher functionality. LifeVoxel.AI is the fastest RIS PACS available globally and have unimaginable capabilities of centralized PACS across all your network of Imaging Centers to single window HUB.

    RIS PACS software