Posted on 14th September 2017 in the categories: Magnetics

How Does MRI Scanner Work and The Role of Magnets

How does an MRI scanner work?

What is an MRI scan?

Magnetic Resonance Imaging (MRI) uses strong magnets to see your insides. An MRI is a screening test done to look at internal structures to identify and diagnose medical conditions. Over the years, MRI scanners have grown tremendously and are now being used more and more often. Doctors may require MRI scans to help diagnose conditions such as multiple sclerosis, brain tumours, torn ligaments, tendonitis, cancer and strokes, to name just a few. Basically, an MRI scan is the best way to see inside the human body without cutting it open.

Why is it important?

The MRI is very important because it helps locate and identify problems in the human body. Often these problems are ones that cannot be seen from the exterior of the body, helping both doctors and scientists identify a problem with a bodily organ before it’s too late.

Where are the magnets located?

The most important component of an MRI system is the magnet. The horizontal tube in which the patient enters, known as the bore, contains the strong magnet from front to back. The entire system proves incredibly strong with the ability of producing a large, stable magnetic field.

How MRI scanners work

In order to work, MRI machines simply use the power of magnetism. There are three main components that make an MRI machine function:

  • Primary Magnet
  • Gradient Magnets
  • A Coil

The main magnet is known as the primary magnet, and its role is to generate huge magnetic power. Our bodies contain several atoms, and every atom is polarised. This means that there is a north and a south pole on each atom. The electrons spin around the atom constantly, which causes the atom to become magnetised and act like a coil with a current running through it. The nonstop movement of electrons causes continuous motion of these mini magnets. However, when the large primary magnet is turned on, the electrons arrange themselves so that their magnetic field aligns with the primary magnet’s magnetic field.

The primary magnet is turned off and healthy atoms will resume their nonstop motion, causing their magnetic fields to magnetise. Unhealthy atoms have a harder time randomising, meaning they can be cancers or tumours. The process of turning the primary magnet on and off helps get an idea of where the slower moving masses are. Additionally, images are taken of the magnetic fields and are analysed for finding the slower atoms in the patient.

Moreover, the gradient magnets are of much lower magnetic strength compared to the main magnetic field. While the main magnet creates a powerful, constant magnetic field around the patient, the gradient magnets create a variable field. This allows different parts of the body to be scanned.

Below is a diagram show casing where the main components are located on an MRI scanner:

MRI Diagram

Safety Concerns

Although there are some concerns surrounding MRI’s, once you’re out of the magnetic field the human body and its chemistry return to normal. In addition, there are no known biological threats to humans from being exposed to magnetic fields of the strength used in medical imaging today.

Due to the incredibly high magnetic field, the MRI suite can be dangerous if safety precautions are not in place:

  • Credit cards or anything else with magnetic encoding will be erased.
  • Metal objects like keys, jewellery etc. can be pulled out of pockets or off the body without warning. Meaning they can become dangerous projectiles if they are taken into the scan room.
  • Big objects pose a risk too, vacuum cleaners, IV poles, patient stretchers, heart monitors and a number of other objects have all been pulled into the magnetic fields of the MRI scanner.

While these strong magnets are expensive, the magnetic field provided allows for the highest-quality imaging, and superconductivity keeps the system economical to operate. At Goudsmit UK we can assist you in selecting the most adequate magnetic material, grade, and the correct manufacturing process that is critical for optimum performance.

Goudsmit UK

From the design manufacture, and assembly right through to the logistics of these magnetic assemblies, Goudsmit UK can accompany you. Contact us today for more information at or speak to a member of our team on +44 (0) 2890 271 001.

For more information download our products and services brochure here.

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