Physics Of The MRI

MRI is an important form of medical imaging, It uses strong magnetic fields and Radio waves to help create images as opposed to X-rays and ionizing radiation.. First discovered simultaneously in 1947 by physicists Felix Block  and Edward mills Purcell who has the same name as me. The first clinical images were not created until 1977 physicist peter mansfield, Reymound demaidian and Paul materbur,

MRI machines have been used to detect a huge variety of illness and saved millions of lives. It is used in the diagnosis of soft tissue and joint injuries, spinal and head trauma and can even be used to detect tumors linked to a variety of illness including cancer.

MRI uses the magnetic properties of hydrogen. The hydrogen atom is composed of a single charged proton which has spin and produces a magnetic field moment. A very strong magnetic field is applied which is why I recommend you not to bring your keys into an MRI. This causes all the spins of the atoms to align mostly facing up but some also face down.  Since all these tiny magnetics are now lined up they create a bigger magnet which can be measured, this is the foundation of how an MRI works. When another pulse is applied the direction of this magnetic changes. The magnetic doesn’t like this and so it wants to go back to the direction of the original magnetic field created by the MRI machine. This is like how if you put a magnet near a compass it will not point north but the second the magnetic is removed it will turn back towards north. Different materials in our body have different amounts of hydrogen in them and so the time it takes for magnet to realign with the magnetic field (or the compass to point north again) is different for different materials and so we can determine the shape and type of material by measuring the time it takes.

References:

My JS presentation group (physics in medicine, by Luke Donegan, louis Killalea Edward curry and Malachy Halpin

MRI scan Better health:https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/mri-scan