MRI

Question 1

What does MRI stand for?

Answer 1

Magnetic resonance imaging.

Question 2

How does an MRI work?

Answer 2

This uses a powerful magnet to generate a very strong magnetic field.

Water molecules contain hydrogen and oxygen atoms, and each hydrogen nucleus consists of a single proton. These protons act as magnets that line up in the magnetic field of the MRI scanner.

Short bursts of radio waves then knock the protons out of alignment.

When the radio waves are turned off, the protons become aligned again.

In the process, the protons send out radio signals that are picked up by the scanner, which show the exact location of the protons in the body, and computers use this data to create an image.

Question 3

Where are water molecules present?

Answer 3

In soft tissues of the body.

Question 4

What does an MRI scanner consist of?

Answer 4

A large tube containing magnets and a bed on which the patient lays.

The bed moves the person through the tube whilst the image is built. The computer creates a three-dimensional image of the body’s contents.

Question 5

How long does an MRI scan take?

Answer 5

15-90 minutes, depending on the size of the area being scanned and the level of detail needed.

Question 6

Can a patient eat before an MRI?

Answer 6

They can normally eat, drink and take medication on the day of the MRI.

Sometimes, they can’t eat in the 4 hours before the scan, or they may need to drink a lot of water before hand if the scan requires a full bladder.

Question 7

Why should medical history be taken for an MRI scan?

Answer 7

To see if there’s magnetic materials in the body, as these would be drawn to the powerful magnet used in the scanner.

Question 8

What are examples of metal implants or fragments that could interfere with the MRI scanner?

Answer 8

• pacemaker or implantable cardioverter-defibrillator (ICD): control irregular heartbeat.
• metal plates, wires or screws used for bone fractures.
• cochlear implant, drug pup implant and an eye implant.
• intrauterine device (IUD) or coil: contraceptive device (copper in uterus).
• artificial joints: replacements.
• metal objects like bullets.
• tattoos or permanent makeup: some ink contains metal traces, but most are safe in MRI scanners.