1. Medical Resonance Imaging
MRI
The presentation is a short introduction to medical imaging and, in particular, Magnetic Resonance Imaging (MRI).

2. First medical images: X-rays
Discovered in 1895
Images of bones
What part of the body is this?
Wilhelm Roentgen, Professor of Physics in Worzburg, Bavaria, produced X-rays in It was quickly found that they could be used to show images of bones inside the body. First clinical X-ray department was set up in 1896 in Glasgow Royal Infirmary.
First X-rays included a kidney stone, an x-ray showing a penny in the throat of a child and an image of a frog's legs in motion.
X-rays good for visualising bone but not good at soft tissues (they pass straight through).
Image shows X-ray of a hand (including wedding ring) taken by Wilhelm Roentgen.
X-rays now used routinely but it is now also understood that frequent exposure to X-rays can be harmful. Patients generally get small exposure but radiographers take precautions to limit their exposure. For example, behind screened area or take X-ray remotely while they are in a protected area.

3. Magnetic Resonance Imaging (MRI)
See soft tissues such as muscles, blood vessels, ligaments and internal organs.
Images show the brain and other structures inside a human head.
MRI uses magnetism to be able to view inside the body. Unlike X-rays, it can image soft tissues. Images like these allow doctors to diagnose problems with great accuracy.

4. Magnetic Resonance Imaging
MRI scanners capture sections through the body.
Sections are used to make three-dimensional images.
MRI uses magnetism to be able to view inside the body. Unlike X-rays, it can image soft tissues. Images like these allow doctors to diagnose problems with great accuracy.
Images are built up in slices. The video clip shows a sequence of 25 slices that start at the top of the head and go downwards before returning to the top of the head. Main areas have been labelled.
The slices can be manipulated in the computer to give three-dimensional images of the internal features.
Click on video of scan to play and pause.

5. How does MRI work? It’s all about strong magnets.
Bar Magnet Strength = Tesla
It’s all about strong magnets.
How many bar magnets would you need for an MRI scanner?
Scanners contain incredibly strong magnets. In this instance the equivalent of about 600 bar magnets. These are in the circular part of the scanner. The person being examined lies flat in the scanner bed and this slides them into the scanner to examine the desired part of their body.
MRI scanner strength
= 3 Tesla

6. How Strong is the Magnet?
3 Tesla does not sound much but it’s very strong.
Loose metal objects are not allowed in the scanner room when the scanner is in operation. The magnet is so strong that even large objects are at risk of being pulled into the scanner.
However, the patient in the scanner feels nothing.

7. Seeing with magnetism
water molecule
hydrogen atom
electron
proton
The MRI scanner contains very powerful magnets that can be switched on and off independently. These magnets produce two strong magnetic fields at right angles to each other. The person in the scanner does not feel any effects of the magnetic fields but they do affect the hydrogen atoms inside their body.
When the person lies in the MRI scanner, one magnetic field causes the centres of the hydrogen atoms in the water molecules inside their body to become aligned with the magnetic field. The hydrogen atoms are now all aligned in the same direction and turning like spinning tops. The patient feels absolutely nothing.
The second magnetic field is turned on and off in a series of quick pulses. Each pulse causes the hydrogen atoms to change their alignment and then relax back to the original state when it is switched off. This is called resonance and is a little like twanging a stretched rubber band. These changes cannot be felt by the patient but they do cause tiny changes in the magnetic passing through your body.
The MRI scanner contains large, sensitive wire coils placed around the machine. They are able to detect the tiny changes in the hydrogen atoms caused by the pulsing of the magnetic field. It allows the scanner to build up a picture of where the water molecules are in the body and this shows the details of the internal soft tissues. The scanner takes many readings and uses the information to build up a computer-generated image of a slice through the part of the body that is being scanned. For example, sixty of the on-off pulses might be used to give twenty slices that give a complete image of the brain. This whole process would only take about three minutes and shows muscles, blood vessels and other tissues in remarkable detail.
The information can be used to create 2-dimensional, or 'flat' images of each slice or processed further to build a complete 3-dimensional view that can be explored and examined from all angles. Many of these 2-D and 3-D images have been used in the portraits that make up this exhibition.
An MRI scanner uses magnetism to ‘see’ the position of hydrogen atoms in water molecules inside the body.
This allows it to build up an image of the internal structures.

8. MRI images Human head. High resolution, with a 3 tesla magnetic field.
Image of a section that ‘looks down’ inside the head from the top.

9. Blood vessels in the brain
MRI images
blood vessels
The scanner can be set up to monitor blood flow through the brain.
Blood vessels in the brain

10. MRI showing nerve connections inside the brain.
Science or art?
MRI showing nerve connections inside the brain.
The Me, Myself, I project used MRI scans to merge the boundary between the application of science and art. The scans can be used to stimulate debate on what it means to be human.