Marvellous MRIs

A look back through our archives has revealed some images taken in the early 1990s of Salisbury District Hospital’s MRI scanners. Depending on circumstances MRI scanners are generally replaced around every 10 years. A sequence of later images shows the delivery of a new MRI scanner being craned into the building. The design of the hospital includes this gap between the buildings to allow the crane to carefully lower the scanner. A removable wall allows the delivery and the heavy equipment can be moved directly into place. More recent images from December 2020, show an additional Stars Appeal funded MRI scanner being craned through the roof by Father Christmas and his elves. All this prompted us to take a closer look at how this technology works too.

patient wearing head guard about to enter scanner

Patient entering MRI scanner head first wearing a head guard

Patient waiting to enter scanner feet first

Nurse demonstrating magnet attracting the belt buckle which is pulled towards scanner

staff member shows metal part of belt being attracted to the MRI scanner magnet

View of MRI scanner from control room, with computer screens

View of the MRI scanner from behind the control panel

Radiographer stands by patient about to enter new MRI scanner

Article from Hospital Annual Review about new MRI scanner

MRI scanner on the end of crane hook about to be lowered down towards the building

MRI scanner is craned into hospital

MRI scanner being lowered down the side of the hospital building

MRI scanner is lowered down between buildings

MRI scanner on end of crane hook about to enter the side of hospital building

MRI scanner about to enter through removable wall section in side of building

bubble wrapped scanner being wheeled through wall of department

MRI scanner safely inside the hospital building

Man dressed as Father Christmas in cab of crane

Father Christmas delivers new Stars Appeal MRI scanner

large white scanner suspended on the end of crane hook

The scanner is craned in through the roof

man dressed as elf oversees delivery of MRI scanner wrapped with giant red bow

An elf oversees delivery of new MRI scanner, Dec 2020

How MRIs work

An MRI (magnetic resonance imaging) scanner is a large tube that contains powerful magnets. You lie inside the tube during the scan. At times the scanner will make loud tapping noises because the electric current in the coils is being turned on and off. It can take 15 to 90 minutes, depending on the size of the area being scanned and how many images are taken.

The human body is mostly water, which is made of hydrogen and oxygen atoms. At the centre of each hydrogen atom is an even smaller particle called a proton. Protons are like tiny magnets. In the scanner, the protons in your body line up in the same direction like needle of a compass.
Short bursts of radio waves knock the protons out of alignment and when the radio waves are turned off, the protons line up again.
This sends out signals showing the location of protons and also helps to see various types of tissue because the protons in different structures line up at different speeds.

Below is an MRI image of a human skull. The second image shows an apple that has been virtually sliced down from the top to the bottom in a series of thin layers. These images were made by MRI which shows details inside the apple without damaging it. Image credit: Alexandr Khrapichev, University of Oxford. (CC BY 4.0)