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The coolest thing you can find in a hospital: MRI magnets

When the majority of people think of the term ‘medical diagnosis’, thoughts like protons spinning or magnetism may not immediately come to mind, yet they are arguably the most fundamental foundation of modern medical technology. Magnetic resonance imaging, or MRI for short, has long been considered the gold standard for medical imaging. From detecting tumours to examining damaged ligaments in a non-invasive way, the invention of MRI in the 1970s was truly revolutionary and bridged many areas of biology, chemistry and physics, accelerating the field of biophysics.


The production of detailed 3D images of the tissues inside our body through MRI is due to the magic of superconductors. Superconductors are, as the name suggests, a material that conducts current perfectly with nothing resisting it and without energy loss. This means that superconductors are able to maintain an incredibly strong magnetic field due to zero resistance, although they must be continuously bathed in liquid helium at around a temperature of 4 Kelvins/269 degrees celsius - almost as cool as outer space! When a body is present in the field of the MRI superconducting magnets, the protons in the hydrogen atoms of the water in the living tissue go from rotating randomly to now aligning with the direction of the strong magnetic field, parallel to the patient’s feet to the head. Depending on the type of tissue that the proton is found in, it rotates (precesses) at different frequencies. Next, radio waves from coils cause the protons to absorb energy, and when the source of radio waves is switched off, the protons ‘relax’ and re-emit the absorbed energy in specific wavelengths, which can be detected by the coils in the MRI machine. This is how an image of the body is produced.


In October 2023, researchers in Australia published a paper in the journal npj Digital Medicine about the use of AI in analysing MRI scans for multiple sclerosis (MS), an autoimmune disease that impacts the insulating covers of nerve cells in the brain and spinal cord. MS strips away the fat and layer of myelin protecting nerve cells and thus, the remaining area holds more water and this is reflected in an MRI scan. The researchers found that AI was more effective and successful in finding abnormal tissue, and was better at identifying loss of brain volume. Although it is unlikely that AI would entirely replace human diagnosis in the near future, it has been very helpful especially in the early stages of disease which may be hard to spot.


In the future, MRI is still expected to evolve and improve, for example, improving medical imaging for people with metal implants and reducing the time needed for scans.


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