Skip to content
Inicio | Blog | What is the difference between an MRI, a CT scan, and a PET-CT scan?

What is the difference between an MRI, a CT scan, and a PET-CT scan?

pexels-charlss-gonzhu-433318654-15277947 (1)
24 Jul 2026
3 Min
Diagnostic Tests

When it comes to making an accurate diagnosis, medical technology offers us various tools. It is very common to confuse tests such as MRIs, CT scans, and PET-CT scans, since they all allow us to see inside the human body. However, they use entirely different technologies and are prescribed for different purposes.

The main difference lies in the physical method they use and the type of information they provide: an MRI uses magnetic fields to study soft tissues; a CT scan uses X-rays to obtain quick and detailed anatomical images; and a PET-CT combines nuclear medicine with a CT scan to analyze the metabolic activity of cells.

Magnetic Resonance Imaging (MRI): Maximum definition without radiation

An MRI is a non-invasive test that does not use ionizing radiation. Instead, it employs a powerful magnetic field and radiofrequency waves to obtain detailed images of the body’s organs and tissues.

  • What is it used for? It is the test of choice for studying soft tissues, such as the brain, spinal cord, muscles, ligaments, joints, and abdominal organs.
  • What is the experience like? The patient lies on a table that slides into a tube-shaped magnet. At CreuBlanca, we have high-field MRIs (3 Tesla) that reduce testing time and offer exceptional image resolution, as well as open MRI machines for people with claustrophobia.

CT scan (Computed Tomography): Speed and anatomical precision

A CT scan (also known as a CAT scan) uses rotating X-ray technology connected to a computer to create detailed cross-sectional images or “slices” of the body.

  • What is it used for? It is ideal for visualizing bone structures, detecting internal bleeding, fractures, urgent traumas, and comprehensively studying the chest or abdomen.
  • What is the experience like? It is an extremely fast test. In just a few seconds, CreuBlanca’s state-of-the-art equipment acquires the images, keeping the radiation dose received by the patient to a minimum thanks to iterative reconstruction technology.

PET-CT scan: Early diagnosis at a cellular and metabolic level

The PET-CT scan is one of the most advanced diagnostic imaging technologies in modern medicine. It combines two tests in a single session: Positron Emission Tomography (PET) and a CT scan.

  • How does it work? Before the test, a small amount of a radioactive substance (radiopharmaceutical) is administered intravenously, which is absorbed by the cells with the highest metabolic activity.
  • What is it used for? It is essential in oncology, neurology, and cardiology. It allows for the detection of metabolic alterations in cells (such as tumors) long before a physical change becomes visible on a conventional MRI or CT scan.

Summary of key differences

To help you understand this at a quick glance from your mobile or device, here is a direct comparison:

Feature MRI (Magnetic Resonance) CT Scan (Scanner) PET-CT
Technology Magnetic fields (no radiation) X-rays Nuclear medicine + CT scan
Duration Between 20 and 45 minutes A few seconds/minutes Between 1 and 2 hours (includes rest)
Recommended for… Muscles, ligaments, brain, and joints Bones, chest, abdomen, and emergencies Oncology, neurology, and cellular metabolism
Preparation None required (unless with contrast) May require fasting or contrast Requires strict fasting and prior rest

 

High-precision diagnostic imaging at Clínica CreuBlanca Barcelona

Do you have a medical prescription and need to schedule your diagnostic test without waiting?

At CreuBlanca, we are a benchmark in diagnostic imaging in Barcelona. We have 4 medical centers equipped with the most advanced technology on the market, including 3 Tesla MRIs and low-radiation CT scans. Our team of specialized medical radiologists guarantees maximum reliability in the interpretation of results, delivering medical reports in very short timeframes.

We operate privately and are affiliated with more than 30 health insurance companies to offer you maximum comfort and agility in your healthcare process, from the initial medical visit to the completion of the test and its subsequent follow-up.

Request an appointment for your medical test or consultation here.

Tags:

cystitis
thrust
Privacy summary

This website uses cookies so that we can offer you the best possible user experience. Cookie information is stored in your browser and performs functions such as recognizing you when you return to our website or helping our team understand which sections of the website you find most interesting and useful.