Difference Between MRI Scan and CT Scan

What is the difference between MRI Scan and CT Scan?

To assist in the diagnosis of a broad variety of medical disorders, doctors request MRI or CT scans. Despite having distinct means of producing pictures, both types of scans have comparable applications. An MRI scan employs radio waves and powerful magnetic fields, whereas a CT scan uses X-rays.

Although MRI scans give higher detailed pictures, CT scans are more widely used and less costly. In this article, we examine the distinctions between MRI and CT scans as well as their applications, techniques, and safety.

Radiation exposure and the presence of a magnetic field are the two main distinctions between an MRI and a CT scan. A CT Scan does not utilise a magnet, and an MRI does not use radiation. In other words, for certain patients, one is safer than the other. A CT scan is not a suitable choice for those who are radiation sensitive if they have metal in their body (such as a pacemaker, stent, implant, etc.).

Additionally, an MRI takes around 30-45 minutes and is ideal for looking at soft tissue, whereas a CT scan typically takes about 15 minutes and is better for looking at organs and bone fractures.

What is an MRI and a CT scan?

Doctors may view inside body components using MRI and CT scans. There are two main methods for producing precise pictures of inside body parts: CT scans and MRI scans. The pictures may then be examined by doctors to look for anomalies like joint damage, malignancies on organs, or bone fractures.

A CT scan is sometimes referred to as a CAT scan, which is short for computerised axial tomography. A person lies down within a huge X-ray equipment known as a CT scanner during a CT scan. A computer receives images from the scanner.

CT scans

  • Radiation from CT scans – Because CT scans are made up of many x-rays, there is some radiation exposure, but very little.
  • Uses – Excellent for seeing bones, but great for soft tissues, particularly when combined with intravenous contrast dye.
  • Cost: Typically less costly than an MRI
  • Very little time passes. Depending on the size of the region being scanned, the test only needs 5 minutes.
  • Patient comfort – Because of the machine’s open design, worries about being in a small room are rarely an issue.
  • Responses: Allergic reactions to intravenous contrast are uncommon. It can harm the kidneys, especially in those who already have renal issues, have diabetes, or are very dehydrated.
  • Patients who weigh more than 300 pounds might need to go to a facility with a table, among other restrictions.


  • Uses for MRI radiation – None – Excellent for seeing minute variations in soft tissues
  • Cost: Frequently more costly than CT scans.
  • Time – The duration might vary from 15 minutes to 2 hours depending on the bodily area being checked.
  • Patient comfort – Anxiety may be brought on by the small tube. Patients who are uncomfortable with the standard equipment can now be treated using open MRI machines.
  • Allergic responses to the IV contrast are quite rare.
  • Limitations – Although huge patients may be handled with an open MRI scanner, the size of the tube may limit the size of the patient. The magnetic field may interfere with several metal implants in the body, including pacemakers, some prosthetic joints and rods, and even some tattoos.

How does a CT (CAT) scan operate?

Multiple X-rays are taken at different angles during a CT scan, which uses the results to create a three-dimensional picture of the organ system being studied. A three-dimensional computer model of the internal organs is created when a computer analyses all the different X-rays that were obtained from diverse perspectives.

What is the procedure for an MRI (magnetic resonance imaging) scan?

Superconducting magnets and radiofrequency radiation are used in MRIs to examine the body. A few mismatched atoms are lined up in the magnetic field’s north or south positions by the magnetic field (keep spinning in a normal fashion). The mismatched atoms spin in the opposite direction when radiofrequency is applied, and when radiofrequency is removed, they revert to their original location where they are generating energy. The computer receives a signal from the energy released, and the computer applies mathematical equations to turn the signal into a picture.

Which is safer, a CT scan or an MRI?

Both CT scan and MRI scan are generally considered to be rather safe. There may, however, be issues. Aneurysm clips (clips of the vessels within the brain) can come loose and cause the patient to bleed to death, hence MRI scans shouldn’t be performed on individuals who have them unless they are confirmed to be MRI safe.

The presence of some cardiac pacemakers or defibrillators presents another issue with MRIs since the magnets can lead to faults in these battery-operated devices. Any metallic objects that may interact with a magnetic field, such as metal shavings in an organ, the eye, or an extremity, may be attracted to it.

Are MRIs and CT scans painful?

CT scans are rapid, painless, and give your doctor useful information about your health. Additionally painless, MRI scans offer more comprehensive soft tissue pictures than CT scans. Unless the person has certain contraindications for the scan, as previously noted, MRI scans have no negative effects on the body. However, MRI scans take a while, and some patients find the small entrance to be claustrophobic, which may be nerve-wracking, particularly when the loud magnets reset. The patient’s degree of comfort may suffer as a result. Additionally, the patient must remain still while the photos are being obtained.

Can an MRI or CT scan detect cancer?

In the majority of cases, a tissue sample is used to conclusively diagnose cancer. Although they can reveal “masses” that are probably tumours (clusters of cancer cells), CT and MRI scans are not a reliable method for diagnosing malignancies. The optimal location to do a biopsy in order to conclusively detect cancer may be determined using both CT and MRI images. Additionally, CT and MRI can provide your oncologist—a medical professional who specialises in cancer—a clearer sense of if or where cancer has spread (metastasized) in the body once it has been detected in the patient.

Why would an MRI be necessary following a CT scan?

If a CT scan is utilised to diagnose soft tissue issues, the level of information is constrained. What happens to a professional athlete who gets hurt is a fantastic illustration. To check for fractures, he or she can have an X-ray or CT done on their ankle or knee. If there is no fracture, the doctor will often request an MRI to obtain a much more precise image and determine whether or not the ligaments and other soft tissues of the damaged area have sustained any damage. The optimum treatment plan for that athlete may be chosen using the information from the MRI.

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