Magnetic Resonance Imaging Essay

Magnetic Resonance Imaging (MRI) is a medical imaging technology that uses strong magnetic fields and radio waves to create graphic images of the body’s anatomical and internal structures (1). MRI relies primarily on the protons in fat and water molecules of the body, as these protons respond to the static magnetic field created in ways that allows for a high quality image to be generated (2). These images contrasts specific tissue and different anatomical structures. For example, MRI can reveal the gray and white matter in the brain, diagnose brain tumors and inflammation in certain body parts, and can create images of the spine, joints, abdomen, lungs--numerous parts of the body (2). .
First, MRI relies heavily on electromagnetic energy,
specifically radiofrequency energy. A magnetic field is created in a patient due to an electric current that runs through the coiled wires of the machine (4). These radio waves originated from a transmitter and change the environment of the protons and their chemical nature. In closer detail, the magnetic field generated stimulates and excites protons, and the protons react in ways that changes their spin and and energy levels (5). These protons absorb energy that allows them to move to a higher state and are under stress from the pull of the magnetic field. The termination of the radiofrequency waves causes the protons to realign back with the magnetic field as well as move to a ground state of energy (6). The time it takes for the protons to realign, as well as the change and reflection of the energy once absorbed generates a signal that is used to create cross-sectional images (6). In general, the duration of an MRI scan can last as long as 20-90 minutes (4), based upon the tissue that is being examined.
Continuing forth, it is the signals that are produced that allow physicians to differentiate and identify macromolecules, brain tumors, etc....
This difference is because each of these tissues have different magnetic properties. For example, tissues that are not healthy react differently to the radio frequencies compared to tissues that are healthy. Due to the vast amount of protons present in the body in water and fat, a clearer image is produced.The image that is created can have different contrasts and this is due to the contrasts agents that are used. Most contrasts agents contain the element Gadolinium and is given to a patient intravenously (6). These agents help to advance the rate at which protons realign with the magnetic field and in turn, produce a brighter image
(6).
It is important to note the technicalities associated with MRI. MRI is not safe to use with implants such as pacemakers and defibrillators (7). With that, the noise generated by the machine requires that patients are given protective ear devices because the noise can reach an intensity of 120 decibels (7). This noise can be damaging to the ear. Although rare, some patients are sensitive to gadolinium-based contrast agents that may result in systemic fibrosis (7).
Despite these risks, MRI differs from CT, X-rays, and Nuclear Imaging scans because it does not use ionizing radiation.
Ionizing radiation is radiation that can damage DNA and increase the risk of cancer tremendously. This form of radiation involves high-energy photons being absorbed by the body and penetrating the DNA (8). MRI differs from this because it uses non-ionizing radiation in the form of magnetic fields and radio waves and this type of radiation has not been linked to cancer yet. However, it is notable that most non-ionizing radiation is heat and patients run the risk of burns if they have metals or implants in their bodies.
In the final analysis, the MRI scanner is a powerful machinery generating an incredibly strong electromagnetic field. In fact, the MRI’s magnetic field is, “1000-4000 times stronger than the earth’s magnetic field” (10). The magnetic field serves the purpose of aligning the hydrogen protons in tissue, and calculating the energy changes and the realignment time. It is more effective because there is no risk of cancer associated with it and it can analyze a wide range of
macromolecules. Lastly, Gallium is important to consider because it is a type of nuclear medicine study that allows for the identification of tissue, tumors, and diseases. Gallium is absorbed by tumors and can be distributed throughout the body. A derivative of Gallium involves Ga-67, a radioactive isotope. The radiation that Ga-67 emits is not as bad as the radiation emitted from X-rays. Thus, in several ways, Gallium can be safer to use than other techniques. In fact, gallium can be used to identify and distinguish hidden tumors, as it is absorbed by cancerous tumors. It’s continuous uptake is indicative of infection, inflammation, or even cancer. All in all, there are many techniques that use radiation to generate images and reveal abnormalities.