Oh my God, I need to do an "MRI" test! It's chilling, will I be scorched by the intense radiation? Will it be sucked into a machine like in a science fiction movie?
Or will you be deafened by the loud noise? In the face of MRI examinations, many people have all kinds of terrible images in their minds. But is that really the case?
1. What is MRI?
When it comes to "magnetic resonance", the first image that comes to many people's minds is a large cylinder like a space capsule.
Yes, the MRI does look like a time machine from a science fiction movie, but it doesn't have the magic of traveling through time.
However, it is able to penetrate the skin and bones, clearly showing the "landscape" inside the human body. The scientific name of this black technology is "magnetic resonance imaging", which is abbreviated as MRI in English.
The principle of magnetic resonance imaging is a bit "awkward": it uses a strong magnetic field and radio frequency pulses to resonate the magnetic moment of the hydrogen nucleus in the human body, and then collects electromagnetic signals through the receiving coil, and finally generates tomographic images of human tissues through Fourier transform processing.
This process is a bit like the star chaser "catching" the idol's exclusive signal through radio waves, and then restoring it into a clear photo.
However, an MRI is not as relaxing as chasing stars.
The person was asked to lie motionless in a small "capsule" for 30 to 60 minutes, accompanied by a deafening "thump".
It's not rock 'n' roll, it's the noise of the gradient coil opening and closing at high speed, like a bunch of dwarfs banging gongs and drums right next to your head.
In order to avoid accidents, the doctor will also tell the person to remove all metal objects.
This is not a "security check", but because the magnetic field of magnetic resonance is as high as 1.5 to 3 Tesla, which is equivalent to 50,000 times the magnetic field of the earth! If there are metal objects in or on the body, the magnetic field can create an attractive force with unimaginable consequences.
Although the process of MRI may seem "scary", it allows doctors to see through the inside of the human body like a "superman" and find some hidden lesions, especially soft tissue lesions.
Conventional X-rays can only show bone, while CT is able to show soft tissues, but it is inferior to MRI in terms of density resolution.
Magnetic resonance imaging is like a microscope that can see subtle changes in tissues such as the brain, heart, muscles, and ligaments.
For example, if an uncle has a herniated lumbar disc, the conventional X-ray may not be abnormal at all, but the MRI can clearly show whether the intervertebral disc is herniated and compressing the nerve.
For example, in patients with suspected brain tumors, CT may show only a blurred shadow, but MRI can tell whether it is benign or malignant, pilocytoma or astrocytoma.
Even for some mental illnesses such as depression and schizophrenia, MRI can help doctors determine whether there are abnormal changes in the brain.
2. Advantages and disadvantages of magnetic resonance examination
Magnetic resonance examination is like a "double-edged sword", and while exerting its power, there are also some "headache" shortcomings.
Let's talk about the advantages first, and the most applaudable thing is that it is non-invasive and radiation-free.
Unlike X-rays and CTs, which require transmitted rays, MRI relies only on a strong magnetic field and radio waves, causing "zero harm" to human tissues.
It's like a superb "stealth expert" who can sneak into his body and complete a "reconnaissance mission" without even noticing.
Especially for patients with chronic diseases who need multiple follow-ups, MRI can be used to avoid the long-term effects of radiation.
In addition, MRI has the best resolution of soft tissues, thanks to its ability to image from multiple dimensions and levels.
It's like a "camera" with no dead spots in all directions, not missing any detail.
While traditional non-contrast CT can only obtain cross-sectional images, MRI can provide cross-sectional, sagittal and coronal sections, which is very helpful for diagnosing certain diseases such as multiple sclerosis and spinal cord lesions.
Let's take a look at some of the "slots" of MRI. The high cost of examination is definitely one of the disadvantages of making people "flesh pain".
Since the cost of magnetic resonance equipment is often tens of millions of yuan, and each examination takes a long time, each person has to pay a high fee, which is undoubtedly a large expense for many families.
Surveys show that the average cost of an MRI in the United States is as high as $2,600, and some hospitals even ask for more than $3,500. Although medical insurance can reimburse some of them, the out-of-pocket expenses are still not low.
Another "crashing" disadvantage is the long inspection time. On average, a full MRI takes 30 to 60 minutes, and can take longer if the examination is extensive or requires enhanced scanning.
Lying motionless for an hour in a cramped "capsule" is an ordeal for anyone.
Especially for some claustrophobic or elderly patients, it is simply a "torture". There are also some children who can't control it and can't complete the examination at all.
The most "devastating" thing is the deafening noise. The loud noise of 100 to 110 decibels is like a rock concert scene, which is unbearable.
Although the doctor will provide earplugs or headphones, it is still not possible to completely block out the "attack" of noise. Many patients later said that they would rather get a few more injections than go to the MRI machine.
This noise not only affects the examination experience, but can also cause hearing damage in the long run.
In addition, MRI is not friendly to patients with certain special conditions. For example, patients with metal objects such as pacemakers and cochlear implants in their bodies may interfere with the normal operation of the equipment and even threaten their lives.
There are also critically ill patients who need to be examined urgently, and the inability to lie flat in the MRI cabin for long periods of time may delay the optimal time for treatment.
It can be seen that while the "double-edged sword" of magnetic resonance examination shows its edge, there are also some times when it is "stuck".
For doctors and patients, it is necessary to weigh the pros and cons on a case-by-case basis and choose the most appropriate examination method. So, when is an MRI not recommended?
3. Under what circumstances is it not recommended to do magnetic resonance?
While the advantages of MRI are numerous, for patients with certain special circumstances, MRI can be a huge "no-no" area, and stepping into it can have serious consequences.
For patients with a pacemaker implanted in their body, MRI examination is simply a "disaster". The strong magnetic field can interfere with the normal operation of the pacemaker, resulting in fast or slow pacing, and in severe cases, it can even be life-threatening.
It's like a "roller coaster" experience for a sophisticated watch, and the results can be imagined. For this reason, doctors usually do not have an MRI in a patient who wears a pacemaker unless absolutely necessary.
Cochlear implant recipients also want to say "no" to MRI. The electromagnetic field of magnetic resonance can affect the magnets in the cochlea, causing patients to experience symptoms such as dizziness, tinnitus, and in severe cases, permanent hearing damage.
It's like a person with a heavy "back of the ear" who is suddenly thrown into a rock concert, and the result can be imagined. However, with the advancement of technology, some newer cochlear implants have been able to adapt to MRI examinations of 1.5T and below, but caution is still required.
There is also a "dead hole" in MRI, which is a metal foreign body. If there are metal objects in or on the patient's body, such as surgical clips, dentures, tattoos, etc., a strong magnetic field will create an attraction, causing the metal foreign body to shift or even "splash", causing harm to the body.
It's like throwing a magnet into a box full of nails, and the consequences are unimaginable. Therefore, before an MRI scan, the doctor will ask about the patient's medical history and physical condition in detail, and if necessary, perform X-rays to rule out the possibility of metallic foreign bodies.
In addition, there are some "taboo" subjects for MRI examinations. For example, in pregnant women, although there is currently no evidence that MRI can cause harm to the fetus, MRI is generally not recommended for pregnant women to be safe, especially in the first trimester.
It's like taking an X-ray of a budding seed, and while it may not have an impact, no one wants to take the risk. Another example is a patient with claustrophobia, who may have a panic attack in the cramped MRI chamber, causing the examination to be interrupted. It's like putting a frightened bird in a cage, and the consequences can be imagined.
For some critically ill patients, such as acute cerebral infarction and trauma, MRI is not the first choice.
On the one hand, it is because MRI examination takes a long time, which may delay the optimal time for treatment. On the other hand, critically ill patients often find it difficult to cooperate with prolonged examinations and may even have unstable vital signs.
It's like having a seriously injured person participate in a long-distance race, which not only doesn't help, but can make it worse. In this case, rapid imaging methods such as CT may be more appropriate.
Although magnetic resonance examination is a very good medical imaging examination technique, it is not a "panacea", and it still needs to be carefully considered for some special situations.
The doctor will weigh the pros and cons according to the patient's specific situation and choose the most appropriate and safest examination method. For patients, being honest about their medical history and physical condition, and following their doctor's advice, is key to ensuring that the examination is safe and effective.
Only when doctors and patients work closely together can we give full play to the miraculous effects of MRI and make this black technology benefit human health.
epilogue
Magnetic resonance examination, the "black technology" in the medical imaging industry, is like a magical "magician", which can penetrate the skin and flesh and gain insight into the mysteries inside the human body; It is also like a sharp "double-edged sword", while exerting its power, there are also some times when it is "stuck".
With its advantages of non-invasive, radiation-free, and high resolution of soft tissues, it shines in medical diagnosis and has become the "nemesis" of many diseases.
However, for some special situations, such as metal implants in the body, claustrophobia, etc., MRI examination has become a "forbidden area", and stepping into it may lead to serious consequences.
In the face of the "magic box" of magnetic resonance examination, patients must not blindly "jump in", but should follow the doctor's advice according to their own situation, weigh the pros and cons, and choose the most appropriate examination method. Only with the close cooperation of doctors and patients can this black technology truly benefit human health.
The next time the doctor recommends that you have an "MRI", don't worry about it, I believe that under the careful guidance of the doctor, you will be safe.