March 17, 2025

Angelynn Tran

11th Grade

Fountain Valley High School

Magnetic Resonance Imaging (MRI) machines capture intricate details of soft tissues, bones, and organs in the human body without invasive procedures. Since its development in the 1970s, MRI technology has advanced significantly, transforming modern medicine and diagnostic imaging. MRI machines demonstrate how scientists utilize physics, magnetic fields, and technology to advance modern medicine, let's explore how it works!

The human body is made of 70% water. Because of the hydrogen atoms that make up water molecules, water is magnetic and very responsive to strong magnetic fields. Combining advanced technology and engineering, we are able to use the hydrogen atoms (protons) from the body and generate detailed scans of soft tissues, bones, and other structures in the body. 

In MRI machines, there is a large, hollowed-out cylindrical magnet that generates a strong magnetic field ranging from 1.5 - 7 Tesla - a unit of measurement to describe the strength of a magnetic field, named after Nikola Tesla. Once these machines are activated, gradient coils in the machines adjust the magnetic field to different magnetic strengths to target specific body parts. 

The MRI machine sends out radio frequencies that make protons in the body flip their alignment. Protons are always moving, but the presence of a strong magnetic field influences the protons' motion. Protons can either align parallel to the magnetic field- moving in the same direction as the magnetic field and in a low energy state, or antiparallel to the magnetic field- moving in opposite direction and in a high energy state. MRI machines target parallel protons and send out energy in the form of radio waves to those protons to make them antiparallel. Once parallel protons have absorbed the radio waves and flipped direction to antiparallel, the machine moves on to the next step: imaging. 

As the machine slows down and stops emitting radio waves, protons now in a high-energy antiparallel state return to their original position. This process releases energy from the radio wave absorption process. Radio frequency coils in the machine then detect this energy. A signal is sent to a powerful computer that translates this information and generates detailed images of the body. It's important to note that the patient must remain completely still during the scan so that signals from the body’s protons can accurately be spotted and translated by the imaging software.

Unlike many medical radio scans such as CT and X-ray, MRI uses lower energy radiation than ionizing radiation which could potentially cause chemical bonds to break in the body and alter DNA. This makes MRI scans a much safer option, especially for patients that require multiple scans. MRI scans also provide highly detailed images that can be used for neuro-based scanning, cancer detection, and muscular dystrophy. Modern advancements in technology have allowed us to create an MRI machine with a magnetic field of 7 Tesla. Diffusion Tensor Imaging, a specialized technique of MRI, uses water molecules from the white matter portion of the brain to provide detailed scans of neural fibers and pathways of the brain. Overall, using physics, technology, and engineering, MRI machines have made it possible for doctors to work with patients to diagnose and work with a wide range of medical conditions affecting the body.