Learn the truth about MRI scans and radiation, including common myths and facts to help you feel confident about this imaging option.Magnetic resonance imaging (MRI) scans are growing in popularity as a powerful diagnostic tool. They can be used to produce highly detailed images of internal organs and tissues, allowing the identification of anomalies and signs of disease early in disease progression, thus improving patient outcomes. The general public often assumes that MRIs are not safe due to radiation exposure - as is the case with other types of scans - however, MRIs are radiation-free, making public concern unfounded.
This article will detail how MRIs work and how they differ from other types of scans, and will debunk myths about MRI radiation and safety concerns.
MRI scans are used to produce detailed images of internal organs and tissues. The images are created by utilizing the magnetic properties of hydrogen atoms, whereby they can act like minuscule magnets. When put into a strong magnetic field inside the MRI scanner, the hydrogen atoms inside the body will align in the same direction along the magnetic field. Short pulses of radiofrequency waves are then used to knock the hydrogen atoms out of their magnetic field-induced alignment. After the radiofrequency waves are turned off, the hydrogen atoms will re-align to the magnetic field and, through doing this, will release a radio signal. This signal is detected by the MRI scanner and is subsequently used to create the image of the organ or tissue being scanned.
In computed tomography (CT) scans, a detailed cross-section of the area being scanned is produced by combining multiple pictures of the same area taken from different angles. This collection of pictures is taken using a narrow X-ray beam moving in a circle around the body. X-rays are produced using an X-ray beam from one angle projected onto a plate where the image will form based on how much radiation passes through bone, muscle, and other tissue. CT scans and X-rays, therefore, both use X-rays (a form of ionizing radiation) to form images of the body, whereas MRI scans are radiation-free.
The earliest medical imaging techniques all used radiation, and this historical connection has led many to assume that this is still the case today. A lack of awareness of developments in imaging technology has further convinced the general public that all imaging techniques use radiation.
Ionizing radiation possesses a high enough level of energy that it can damage the body. At the highest doses of radiation, such as from a nuclear accident, radiation can severely damage organs and tissues within the body. Low levels of radiation are used in medical imaging techniques as they have a much lower risk of harm. However, repeated low doses of radiation, such as those from specific types of medical imaging, over a long period can increase the risk of developing cancer. MRI scans use magnetic fields and bursts of radiofrequency waves to create images of your body, not radiation. MRI scans are therefore, a radiation-free way of imaging the body, and so are particularly beneficial for carrying out yearly routine screenings.
There are no known long-term health problems associated with temporary exposure to magnetic fields, such as those in an MRI scanner. As a result, MRI scans are safe for the majority of people. The main risks associated with MRI scans involve internal or external bodily metal being attracted by the magnetic field. There is a careful screening process to ensure that no metal enters the room containing the MRI scanner - this is to ensure that metal objects, such as keys, don’t become projectiles. It is essential that external metals, such as piercings or hearing aids, are removed from the body, as these will also be attracted to or damaged by the magnetic field. Healthcare professionals will carefully assess metal internal to the body, for example, joint replacements or pacemakers. Modern healthcare uses MRI-compatible metals, so these should not prevent a safe MRI from taking place.
There are minimal risks to pregnant women or children associated with MRI scans. As such, there are no FDA guidelines or restrictions on use in early pregnancy. MRI scans will sometimes use contrast agents injected intravenously to improve the detail and quality of images. Some of these contrast agents, such as gadolinium-based contrast agents, could harm pregnant women and fetuses. Although there is limited evidence for this, healthcare professionals will carefully weigh up the benefits and risks before exposing pregnant women to contrast agents.
The cumulative effects of ionizing radiation, such as from repeated CT scans or X-rays, have been demonstrated to increase the risk of developing cancer. No such cumulative effects have been seen from repeated MRI scans. A very small study (consisting of only 13 people) showed that repeated brain MRIs did result in a small increase in chromosomal breaks. However, the amount of damage per cell was so low that no chromosomal rearrangements were seen, and therefore, no increased risk of developing cancer was identified. This study concluded that MRI was a safe imaging technique. The effect of repeated MRI scans on pacemaker function has also been assessed; mild effects were seen, but none were clinically relevant or affected the safety or performance of the device.
MRI scans can distinguish between different types of soft tissue, making them particularly effective at diagnosing cancers found within soft tissue, such as brain or breast cancers. The high level of detail that can be obtained from an MRI image can identify cancer at its earliest stages when at its most treatable. In addition, MRIs are so detailed that, in some instances, they can be used to distinguish between aggressive and non-aggressive cancers.
Long-term monitoring of health conditions, such as multiple sclerosis or cancer, requires repeated medical scans. The increased risk of cancer with repeated exposure to ionizing radiation makes repeated imaging using radiation unfavorable. However, the lack of any long-term or cumulative effects of MRI scans makes them the preferred option for repeated medical scans to monitor disease development. This also makes them a good option for preventive healthcare, where yearly scans are used to check for signs of disease to catch them early or to prevent their development.
MRI medical imaging is commonly thought to involve harmful radiation. However, unlike other common imaging techniques such as CT scans or X-rays, MRIs do not use any radiation. Instead, they use magnetic fields to create images of the body. No harmful effects of magnetic fields have been identified, making MRI a safe, radiation-free, and non-invasive medical imaging technique safe for use by the majority of people, including pregnant women. The main safety concerns from MRI scans arise from the presence of metal within the body. Extensive screening is carried out by medical professionals before an MRI scan to ensure that any metal within the body, such as a pacemaker, is MRI-compatible and so will not cause any harm or be damaged by exposure to strong magnetic fields. MRI is, therefore, an effective tool for repeated use in long- and short-term health monitoring.
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