A of the human body.”[1] The inventor
A life without illness has always been one of the maingoal for the human species. At the start of our existence it was discoveredthat natural remedies helped alleviate some of symptoms of various illnesses.Naturally, as humans evolved so did our ways of medical treatments. Whilemedicine is inherently mostly a biological science the machinery used toperform the tasks rely mostly on computer science and physics. Physics has made major discoveries in the lastcenturies that have made our lives unimaginably easier and safer. Modernphysics is the basis of MRI. “Magneticresonance imaging (MRI) is an imaging technique used primarily in medicalsettings to produce high quality images of the inside of the human body.
“1 Theinventor of the first MRI machine was Raymond Vahan Damadian. His studies aboutliving cells dove him to his first tries with NMR. Damadian found that tumorsand ordinary tissue can be discerned by the way their signals change with time.This led him to propose the initial full body magnetic resonance scanner and hewas the first one to play out a full body scan in 1977.2The first scan took about 5 hours to produce one image with was very elementarycompared to today’s scans.
3 MRIrelies upon the benchmarks of nuclear magnetic resonance (NMR), a spectroscopicsystem used by specialists to get physical information about particles. The procedure was called MRI ratherthan nuclear magnetic resonance in light of the negative implications relatedwith the word nuclear in those years.4The difference between MRI and the similar computer tomographic (CT) scans isthat MRI does not incorporate the usage of x-rays and thus is seen as the moresuperior option. However, MRI’s compared to CT scans are much longer andlouder, anything metal has to be removed before entering the machine and thismay cause problems to people with pacemakers.5Itis also a very closed off device and for the patients that have claustrophobiait is needed to use a different kind of “open” scanner.The way MRI works is that the scanner contains twointense magnets, these are the most critical parts of the gear. The human bodyis to a great extent made of water particles, which are contained hydrogen andoxygen molecules.
An atom is made out of electrons and a nucleus which consistof protons and neutrons. Protons have a positive charge and because of that aresensitive to magnetic fields. When performing the MRI scan a person is placedinside the scanner which then creates a magnetic field around the body.Normally the protons are scattered randomly across the body and do not followany kind of pattern but the when the magnet is turned on the protons strain tore-align themselves either north or south.
Then the magnet is shut down andgoes through the series again. The particles when going from an excited stateto their normal one emit radio waves. The scanner measure how the signalschange in time in the whole body and stores the information. Different types oftissues have different response signals and as Raymond Vahan Damadian noticedtumor tissue has a significantly different response signal than normal, healthytissue.The MRI scan image is then processed and developedwith high (bright) to low (dark) signal parts.
The image can be processed intwo different ways – T1-weighted or T2-weighted. The difference between them isin the areas that have high signals. In a T1-weighted scan only the fat partswould appear bright. That is what makes it very useful when scanning the brain.
In a T2-weighted scan the parts that would appear bright are fat and fluids.6That makes it more useful when identifying inflammation. When needed toc createa higher quality image contrasting liquids may be put in use. Usually they areinjected into the veins or straight into the joint in the event when making anMRI of a joint.
As written before, the main component of the magneticresonance imaging scanner is the magnet. They come in various shapes althoughthe most reliable and popular one would be the C shaped magnet. It is usually apermanent magnet made out of a ferromagnetic material, even though the mostcommon magnet used in today’s MRI machine would be the superconductingelectromagnet. It is the most expensive one but also the most reliable one withthe highest accuracy out of all of the possible choices. The main factor in themagnet that determines the quality of the image scan is the magnetic fieldstrength. It is measured in teslas (T). 1-3 T would be considered a highmagnetic field MRI scanner and different strength are used for different partsof the body.
7Another important part of the scanner would be the shims. The magnetic fieldcreated by a magnet is not useful by itself. It need to be completely stableand the same all throughout the procedure. “Ashim is a thin and often tapered or wedged piece of material, used to fillsmall gaps or spaces between objects8.”When the subject is placed in the magnetic field it loses its homogeneityand the shim coils restore it.
MRI technology is extremely useful is nowadaysmedicine. It has marginally helped us understand the working of the brain andhelped us diagnose brain traumas more easily. It is a completely non-invasiveway to diagnose a tumor, abnormalities in the spinal cord, cysts and othermajor illnesses.
It has also providedmore insight into how various mental illnesses affect the brain. Functionalmagnetic resonance imaging allows us to monitor the activity of neurons indifferent brain sections, which then allows us to compare various brain scansand see if there are any differences between patients with different diagnoses.Researches have been interested in the physical symptoms of various mentalillnesses that cannot be seen outside our bodies. A new study in 2017 by the RadiologicalSociety of North America discovered a relation between the abnormalities of thebrain when suffering from major depressive disorder and social anxiety disorderthat might explain why those two illnesses often come hand-in-hand. 9While as mentioned before, MRI scans are considered verysafe and reliable because of the fact that they do not expose people topossibly harmful ionising radiation like CT scans do there are still some risksthat need to be taken into account. The scanner is essentially a huge andextremely powerful magnet and it will attract anything metal to it, so a patientneeds to be screened thoroughly and the room should be checked thoroughlybefore beginning the procedure to limit the risk of any metal objects becomingprojectiles. The procedure itself is extremely loud and combined with a personbeing in a very small confined space can cause anxiety.
This makes it very hardto stay still during the procedure, which is vital for the image to developclearly. Some people with claustrophobia might have the option to use an openMRI scanner but it cannot perform all the tasks a closed one can. In the casewhere a patient is not able to stay still for the period of time needed or isan infant sedation might be needed. This, of course, bring in another set ofrisk that are not limited to MRI scanner but still might cause problems andcomplications.
Any patient with metal implants in their body or artificiallimbs will most likely not be able to go through the MRI procedure and willhave to look for an alternative method.10All in all, while this is a evolutionally device that has made modern medicineadvance in an even faster pace it does come with its own, in comparison small,disadvantages. 1 https://www.cis.rit.edu/htbooks/mri/inside.htm2 https://armenianweekly.com/2013/11/07/2003-nobel-prize-for-mri-denied-to-raymond-vahan-damadian/3 https://en.wikipedia.org/wiki/Raymond_Damadian4 https://www.cis.rit.edu/htbooks/mri/inside.htm5 https://en.wikipedia.org/wiki/CT_scan6https://www.ole.bris.ac.uk/bbcswebdav/institution/Faculty%20of%20Health%20Sciences/MB%20ChB%20Medicine/Radiology/MRI%20e-tutorial/page_04.htm7 http://www.teslasociety.com/mri.htm8 http://www.merriam-webster.com/dictionary/shim9 https://www.sciencedaily.com/releases/2017/11/171120085448.htm10 https://www.medicinenet.com/mri_scan/article.htm
