"Doctor, I've been feeling dizzy a lot lately, please help me get a check-up, I want to do an MRI. ”
"You don't need an MRI in this case, so let's go for a CT scan first. ”
"How do I do a CT? My friend said that in this case, you have to do an MRI, is the MRI radiation too strong? That's why doctors rarely prescribe this test?"
"Old man, your situation is more suitable for CT examination, and MRI is not suitable for you. ”
Although the doctor repeatedly stressed that Uncle Wu did not need to have an MRI, he kept chattering, suspecting that the doctor did not give him an MRI because radiation can cause cancer.
1. Nuclear magnetic resonance radiation is high, and it is easy to cause cancer?
When it comes to the word "nuclear", I believe that many people's first reaction is to link it to radiation, believing that it will bring greater harm to health. MRI is also one of the examination items that everyone is more afraid of, and the door of the MRI examination room is very heavy, and the word "danger" is written on the outside of the door, which can't help but make people suspect that the radiation of MRI is very strong and can cause cancer.
Nuclear magnetic resonance, now known as magnetic resonance, uses a magnetic field and computer-generated radio waves to create detailed images of human organs and tissues.
About 70% of the water in the human body is imaging, and the principle of MRI is to use water quality sub-imaging. The hydrogen nuclei in the body in the magnetic field will vibrate, and the difference in the water vibration in different tissues will be processed by the computer, and finally the image will be displayed from any angle, which can distinguish the diseased tissue from the normal tissue. This test is mainly used to check for soft tissue lesions, to see liver and brain problems, and is often used to examine the brain and spinal cord.
Ju Shenghong, director of the Department of Radiology of Zhongda Hospital Affiliated to Southeast University, said that the word "nuclear" in nuclear magnetic resonance is not the nucleus of nuclear radiation, but the hydrogen proton nucleus, that is, the composition of water molecules in the human body.
Since MRI is not a hazard, why install a heavy door with a "hazardous" mark?
MRI examination relies on high-frequency magnetic fields, and it is necessary to eliminate the interference of electromagnetic signals as much as possible.
The "hazard" sign on the door is to warn patients and family members not to bring metal objects into the room, and there is also a loud noise generated during MRI, and the heavy door also has the effect of avoiding noise.
2. Why do doctors rarely recommend MRIs to patients?
MRI can be performed on most organs of the body, but in clinical practice, doctors are more likely to prescribe CT and X-ray examinations.
1. Inspection fee
The cost of X-ray examination ranges from tens of yuan to 100 yuan, and the price of CT examination will vary between different body parts, the price is in the range of about 200 to 700, but the cost of enhanced CT examination will be slightly higher, and the cost of MRI examination is also different for different body parts, such as heart scan is about 900, and MRI is a big burden for most people from the cost alone.
2. The duration of the inspection
X-ray imaging takes only a few seconds, while CT takes 3~5 minutes to complete. The MRI examination takes 20~40 minutes to do once, which is obviously not suitable for emergencies.
3. Some organs are not suitable
Organs with a lot of water molecules are more clearly examined by MRI, such as the brain, hepatobiliary pancreas, spine, spinal cord, muscles, bones and other lesions. However, there are few water molecules in the lungs, stomach, esophagus, and other areas, and it is difficult to achieve accurate results from MRI examinations. For example, most of the lungs are alveolar tissues that contain air, and there are no water molecules inside, so the results of MRI are even worse.
4. Special groups of people can't do it
It is not recommended to undergo MRI examination for patients with electronic implants such as pacemakers, insulin pumps, and nerve stimulators, as well as for people with metal prostheses, dentures, shrapnel, etc., as well as for people with cardiac stents, heart valves, orthopedic fixation materials, etc., otherwise it is easy to affect the normal function of the device and the results of the examination.
In addition, MRI is not recommended for people such as critically ill, agitated patients, children, pregnant women, and people with claustrophobia.
3. How to choose X-ray, CT examination and magnetic resonance examination?
Different examination items are suitable for different groups of people, so how to choose the right examination for yourself?
X-ray: X-ray examination is mainly used for screening, such as chest X-ray for basic physical examination, orthopedic trauma diagnosis of fracture, etc., and may also be used for screening for acute abdomen such as intestinal obstruction and intestinal perforation. This examination has the problem of many overlapping areas of images, and there is a high probability of misdiagnosis and missed diagnosis, and further CT examination is often required when the results are not clear.
CT examination: CT examination can be applied to any part of the body, and is generally used for the diagnosis of lung nodules, early lung cancer, lung infection, and can also be used for the diagnosis of brain trauma and cerebral hemorrhage. The disadvantage of this examination is that it has a certain amount of radiation, which is not suitable for children and pregnant women, and it has poor resolution of joint soft tissue and nerve tissue.
Magnetic resonance: Magnetic resonance examination has a significantly higher resolution of soft tissues than CT examination, and is suitable for the diagnosis of diseases of the central nervous system, joints and soft tissues. The disadvantage is that the detailed visualization of the lung and bone structure is poor, and the examination takes longer and is more expensive.
Before the examination, it is necessary to fully consult the doctor, according to the advice of a professional doctor, and do not blindly believe in a certain examination, which is unscientific.
Resources:
[1] "[Short Video to Refute Rumors] Nuclear Magnetic Resonance Has "Nuclear Radiation" Can Cause Carcino?
[2] "[Popular Science] Attention, these people can't do MRI", Baoding Second Hospital, 2023-03-16
[3] "How to choose the examination of radiology?", Hangzhou No. 1 Hospital, 2023-11-24
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