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CT Scan & MRI: An In-Depth Comparison

While CT scans and MRI’s can seem similar, they both serve a very specific purpose in diagnosing patients. A CT Scan, otherwise known as CAT Scan, is best suited for viewing broken bones, viewing lung and chest problems, and detecting cancer. An MRI, on the other hand, is used for examining soft tissue in ligaments and tendon injuries, spinal cord injuries, brain tumors and so on.

Typically, CT scans are used more in emergency rooms because the scan is fast and effective. An MRI is a timely and tedious process. One advantage of an MRI over the CT scan is that the exam does not use radiation, while CT scans do.

Other Comparisons:

DETAIL OF BONE IMAGES:

CT: Provides good details of bone structures.
MRI: Offers less detailed images of bones.

DETAIL OF SOFT IMAGES:

CT: CT scans can show complex images, including bone, soft tissue and blood vessels at the same time.
MRI: Gives extra fine detail to soft tissue imaging.

TYPE OF IMAGING USED:

CT: Utilizes X-ray imaging.
MRI: Uses a large, internal field, RF pulse and 3 different gradient fields.

OPERATING PRINCIPLE:

CT: X-rays are detected by a detector & specialized system, which is computed using mathematical formulas to create an image. 
MRI: Body tissue containing hydrogen atoms are made to emit a radio signal, which are detected by the scanner.

How Do the Scans Work?

MRI Scans

Using powerful magnets and pulsing radio waves, detection coils in the MRI scanner read the energy produced by water molecules in the body as they re-align themselves after each RF alignment pulse. The data collected is reconstructed into an illustration through any axis of the body. As bones are basically devoid of any water, they do not generate an image. Instead, bones show as dark spots on an image. This is why MRI scans are used for soft tissue.

CT Scan

CT (Computerized Axial Tomography) scans use X-rays to generate images of the body, including bones. In the CT scanner, a tube containing the x-ray rotates around a patient, which also receives data as it passes through the body. A reconstruction processer takes the data collected and uses it to create an image.  Multiple scans can be done at once to improve image quality.

MRI Advantages

  • No exposure to radiation
  • Higher detailed images of soft tissue
  • MRI images can have more image contrast
  • MRI can change the imaging plane without moving a patient
  • For detecting tumours or certain cancer, MRI is far superior

CT Scan Advantages

  • CT scans can image bone structures
  • Patients who have had any kind of surgical clips, metallic fragments, cardiac monitors or pacemakers cannot take an MRI
  • CT scans are much faster
  • MRI's can be stressful to people who are claustrophobic
  • CT scans are generally cheaper

At Canada Diagnostic Centre, we evaluate our patient’s needs individually to find the best treatment option for them. Whether you are looking for a CT or MRI scan, you can be sure our technicians have the industry experience and knowledge to ensure you’re taken care of. Visit our CT and MRI services pages for more info.