Principles of magnetic resonance scanning

Magnetic Resonance Imaging (MRI) is an imaging technology that uses magnetic fields and resonance frequencies. Its principle is to use its strong magnetic field to temporarily rearrange the hydrogen atoms in the human body, and release unique signals through radio. After precision receiving instruments and computer calculations, unique multi-angle images and information are formed. Unlike X-rays or computer scans, MRI scans do not contain radiation.

Application

Compared with other imaging examination methods, magnetic resonance scanning is superior in examining the body’s soft tissues and nerve tissues. It is more commonly used to examine the brain, spinal nerves, joints, ligaments and muscles, heart, blood vessels, abdominal and pelvic organs, etc. Magnetic resonance scanning can also be used to diagnose some cancers. In addition to helping to detect the location of tumors, it also assists doctors in planning patients’ treatment plans and monitoring changes in tumors during treatment.Safety instructions

• The magnetic field of magnetic resonance scanning may cause metal objects to fly off, causing impact accidents, or displacing metal devices in the patient’s body, which may even lead to death. Therefore, patients must remove all metal objects or medical instruments from their bodies before entering the examination room.
• The magnetic field from an MRI scan can cause short-circuiting and failure of any internal device or electronic device, such as hearing aids or pacemakers. The patient must remove all electronic products or switch to a mode that can perform magnetic resonance examination. If there is any metal on the body that cannot be removed, it must be confirmed to be safe metal before the examination can be performed.
• The magnetic field of magnetic resonance scanning must be continuously rotated to produce images, and sound will be emitted during this process. The noise level generated is generally about 70 to 80 decibels, which may cause patients to feel anxious, uneasy, or even temporarily deaf. Medical staff will provide patients with earplugs to protect their hearing.
• Some MRI examinations require the injection of contrast agent, and a small number of patients will have mild drug sensitivity reactions such as skin itching and nausea; in rare cases, patients will have severe allergies that are life-threatening. In addition, injection of contrast agent into patients with severe renal failure may lead to systemic fibrosis, which may lead to death in severe cases, but these are rare cases.
• Although magnetic resonance scans do not contain ionizing radiation, there is no literature proving that magnetic fields will not affect the fetus. Therefore, women should avoid testing if they suspect or are certain to be pregnant.
• If the examination requires the injection of contrast agent, it is recommended that breast-feeding women wait 24 hours to allow the body to eliminate the contrast agent before breastfeeding as usual.
• Children or people with claustrophobia may feel pressured, frightened, or have difficulty breathing when entering the examination equipment tube, and may not be able to perform the examination. Radiologists will try different methods to help patients relax and shorten the examination time; however, in severe cases, sedation may be required before the examination can be performed.

Check process

Preparation before inspection

• Before the examination, the patient needs to inform the medical staff of any physical illness (such as kidney failure), whether he is taking any medications, any drug allergies or any other medical conditions.
• If the patient has metal implants in his body, he should inform the medical staff before the examination so that the medical staff can confirm that the MRI scan is safe for use before the examination can be carried out. These metal implants may include pacemakers or artificial heart valves, braces or previous dental implants, cochlear implants, neurostimulators or adjustable ventricular drainage valves, uterine devices, or any surgical implants containing metal. substance or instrument.
• Patients undergoing examinations of different parts may need to fast or stop taking medications before the examination, and should follow the instructions of medical staff.
• Patients must take off all metal objects they carry before the examination, and should avoid wearing jewelry, valuables or electronic equipment on the day of examination.
• Since cosmetic materials may contain iron powder, you should avoid wearing makeup on the day of the examination.
• If the patient suffers from claustrophobia, please inform the medical staff before the examination.

Preparation before inspection

• Depending on the examination site, the patient will be required to lie still on the examination bed and be equipped with different receivers. During this period, the patient must remain stationary. The radiologist may ask the patient to breathe as directed
• During the examination, the instrument will continue to make noise. Patients can wear the provided earplugs or earphones to reduce discomfort.
• Depending on the examination requirements, the patient may need intravenous injection of magnetic resonance contrast agent

Instructions after inspection

• After completing the examination and the medical staff confirm that the patient does not have any discomfort or allergic reaction, the patient can leave
• Medical staff will contact the patient to follow up on the examination report