What is NMR, and how does it work?
Magnetic resonance imaging, or MRI, produces detailed images of organs and tissues throughout the body without the need to use x-rays or “ionizing” radiation. Instead, MRI uses a powerful magnetic field, radio waves, rapidly changing magnetic fields, and a computer to create images that show if any injury, disease, or abnormal condition is present.
The patient is placed inside the MRI scanner or system to perform an MRI exam, which is usually a sizeable donut-shaped device open at both ends. The powerful magnetic field aligns atomic particles called protons in body tissues containing water. The applied radio waves then interact with these protons to produce signals detected by a receiver inside the device. The rapidly changing magnetic field gives these signals specific characteristics. With the help of computer processing, cross-sectional images of the tissues are created in the form of skinny slices, which can be viewed in any orientation.
The MRI examination is painless, and, more importantly, the electromagnetic fields do not cause any known tissue damage. Sometimes the MRI system may make loud pounding, pounding, or other noises during the procedure. Earplugs are provided to prevent problems associated with noise generated by the scanner. You will be monitored at all times and will be able to communicate with the MRI technologist via intercom or other means.
What is NMR used for?
MRI is the procedure of choice for diagnosing any possible problems or conditions affecting different parts of the body. In general, MRI creates images that show differences between healthy and unhealthy tissue or abnormal tissue. Doctors use MRI to examine the brain, spine, joints (e.g., knee, shoulder, hip, wrist, and ankle), abdomen, pelvic region, breasts, blood vessels, heart, and other body parts. Body.
The strong magnetic field of the NMR system can attract objects made of certain metals (for example, metals known to be ferromagnetic, such as iron) and can move them suddenly and with great force. This poses a potential hazard to the patient or anyone in the path of the object. Therefore, great care is taken to ensure that foreign objects such as ferromagnetic screwdrivers and oxygen tanks are not brought into the NMR system area.
As a patient, it is vitally important that you remove all of your metal items before the exam; this includes external hearing aids, watches, jewelry, cell phones, and clothing with thread or metal hooks. In addition, makeup, nail polish, or other cosmetics that might contain metallic particles should be removed if applied to an area of the body that MRI will examine.
Various types of clothing such as sportswear (for example, yoga pants, t-shirts, etc.), socks, suspenders, and others may contain metallic threads or metal-based antibacterial compounds that may be dangerous. These items can heat up and burn the patient during MRI. Therefore, MRI centers generally require patients to remove all clothing that could be problematic before undergoing MRI.
The strong magnetic field of the MRI system will strip the patient of any ferromagnetic objects in or on the patient’s body, such as medical implants (e.g., specific aneurysm clips, drug pumps, etc.). Therefore, all MRI centers have extensive monitoring procedures and protocols to identify potential hazards. When followed carefully, these steps ensure that the technologist and radiologist are aware of the presence of any metallic objects so they can take the necessary precautions.
In some rare cases, the exam may have to be canceled due to the presence of an inappropriate implant or device for the exam. For example, MRI will not be performed when a ferromagnetic aneurysm clip is present because there is a risk that the pin will move and cause serious harm to the patient. In addition to possible movement or dislodgement, certain medical implants may heat up substantially during the MRI examination due to the radio waves (e.g., radiofrequency energy) used for the procedure. MRI-related heating may result in patient injury. Therefore, as a patient, you must inform the MRI technologist, before entering the MRI examination room,
The strong magnetic field of the MRI system can damage an external hearing aid or cause a cardiac pacemaker, electrical stimulator, or neurostimulator to malfunction or cause damage. If you have a bullet or other metal fragment in your body, there is a chance that it will shift position and possibly cause injury.
Preparation for the MRI exam
Generally, you will be given a gown to wear during the MRI exam. Before entering the MRI system room, you will be asked a series of questions (for example, using a particular question form), including questions about whether you have implants or devices. You will then be asked to remove all metal objects from your pockets and hair, as well as all-metal jewelry. In addition, any individual who will be present during your MRI will need to remove all metal objects and complete a control form. Please discuss them with the MRI technologist or radiologist before the MRI exam if you have questions or concerns.
As stated above, you will be asked to fill out the screening form about things that may be hazardous to your health or interfere with the MRI exam. Items that may be hazardous to your health or cause other problems during the MRI exam include:
- Certain cardiac pacemakers or implantable cardioverter defibrillators (IDCs)
- Ferromagnetic metal vascular clips were placed to prevent bleeding into an intracranial aneurysm or blood vessels.
- Some implanted or external drug pumps (such as those used to deliver insulin, pain-relieving drugs, or chemotherapy)
- Certain cochlear implants (for example, to be able to hear)
- Certain neurostimulator systems
- Catheters that have metallic components
- A bullet, shrapnel, or another metal fragment
- A foreign metallic object located in or near the eye (such things can usually be seen on an x-ray; metal industry workers are the ones with this problem)
Items that patients and their companions should remove before entering the MRI team room include:
- Wallet, wallet, purse, credit cards, cards with magnetic strips
- Electronic devices such as pagers, cell phones, smartphones, and tablets
- external hearing aids
- Metal jewelry and watches
- Pencils, paper clips, keys, coins
- Hair clips and barrettes, hair clips, and some ointments
- shoes, belt buckles, safety pins
- Any article or garment that has metallic fibers or threads, metal-based antibacterial compounds, metal zippers, buttons, snaps, hooks, or wires
Among the objects that could interfere with the quality of the image if they are close to the area examined are:
- metal spinal bar
- Metal plates, pins, screws, or mesh used to repair a bone or joint
- Joint prostheses
- Metallic jewelry such as that used in body piercing or body modification
- Some tattoos and permanent eyeliner (they affect the images, and there is a possibility of irritation or inflammation of the skin; black and blue pigments are the most problematic)
- Makeup (such as eye shadow and eyeliner), nail polish, or other cosmetics that contain metal
- Dental fillings or appliances (generally unaffected by the magnetic field but may distort images of the face or brain; same goes for orthodontic braces and retainers)
The problem of claustrophobia or anxiety
Some people undergoing an MRI exam may feel confined, locked in, and afraid. About one in twenty people may need a mild sedative to stay calm. Some centers allow a friend or relative to be present in the MRI room, which has a calming effect on the patient. If the patient is well prepared and knows what to expect, completing the exam is almost always possible.
Pregnancy and MRI
If you are pregnant or suspect that you are pregnant, you must notify the MRI technologist and radiologist during the verification procedure and before the MRI examination begins. In general, there are no known risks of MRI in pregnant women. However, MRI is reserved only for severe problems or suspected abnormalities in pregnant patients. In any case, MRI is likely to be less dangerous to the fetus than X-rays or computed tomography (CT). For more information, see the security page.
MRI and breastfeeding
- If you are breastfeeding, you must notify the MRI clinic when you book your appointment for the MRI exam. This is particularly important if you will be injected with an MRI contrast material. Under these circumstances, one option is to express milk before the MRI exam, which can feed the baby until the contrast medium has been removed from the body. It usually takes 24 hours for the contrast material to be eliminated from the body. The clinic or radiologist will provide you with additional information regarding this topic.