How to find out what is happening inside the human body during illness? For centuries, the only realistic answer was to “cut and see” - not a very happy prospect for the patient! At the very end of the century, fluoroscopy was invented, and the capabilities of doctors fundamentally expanded. This method is excellent for obtaining images of dense tissues, primarily bones. But it was impossible to obtain a clear image of, for example, the brain with its help. That is why physicists and doctors continued to actively look for other methods of “candling” our body.
High tech
In the first years of its use, magnetic resonance imaging was called differently: NMR imaging, from the words “nuclear magnetic resonance.” It was renamed after 1986, when, in connection with the accident at the Chernobyl nuclear power plant, people began to fear anything containing the word “nuclear” in the name.
The principle, however, remains the same. It has nothing to do with radioactivity. The electromagnetic field that the tomograph generates affects the nuclei of hydrogen atoms present in any tissue of the human body. They generate a response signal, which is recorded by the device.
The nuclear magnetic resonance technique is used not only in medicine - it can be used to study the structure of almost any substance. But it was for its adaptation to the study of living organisms that American scientists Paul Lauterbur and Peter Mansfield received the Nobel Prize in 2003. The research itself that led to the creation of the tomograph was carried out in the late 1960s and early 1970s.
In science, it often happens that some idea is “in the air.” The use of nuclear magnetic resonance in medicine was explored at that time not only by Lauterbur and Mansfield. Back in 1960, the first prototype of a magnetic resonance imaging scanner was developed by Vladislav Aleksandrovich Ivanov, a graduate of the Leningrad Air Force Engineering Academy named after A.F. Mozhaisky. Unfortunately, the finalization of the device and the subsequent receipt of a patent took more than ten years, so Western scientists received an advantage in time - and therefore the laurels of discoverers.
Conducting a survey
An MRI of the heart is done in a special room, consisting of two rooms: one contains the tomograph itself, the second contains the doctor’s desk and a computer connected to the machine. A tomograph is a cylindrical device with a retractable table.
Scheme for cardiac MRI:
- familiarization with the rules of examination and behavior during the procedure;
- the patient changes clothes, takes off all unnecessary clothes, lies down on the extendable table;
- lying on the table in a motionless state, electrodes are attached to the patient’s body, and if contrast is available, a catheter is installed;
- automatic immersion into the cylinder and scanning begins.
The whole procedure takes no more than 40 minutes.
MRI of the heart is done using contrast in the following cases:
- diagnosis and analysis of vascular diseases;
- the need for clear images of the coronary vessels;
- detection of atherosclerosis in the initial stage;
- assessment of the risk of myocardial infarction;
- assessment after infarction consequences;
- preparation for cardiac surgery.
How it's done?
Magnetic resonance imaging is often compared to computed tomography (CT). Both methods provide layer-by-layer images of internal organs, but computed tomography uses X-rays, so the method allows you to look mainly at bones and dense tissue. MRI uses a strong magnetic field and is better suited for imaging soft tissue.
Carrying out an MRI requires quite a lot of time - 30-40 minutes, and it is highly advisable to remain motionless during the entire scanning period. Computed tomography is more convenient in this sense: it takes no more than 10 minutes. But magnetic resonance imaging is allowed to be done frequently, since it is not accompanied by the risk of radiation. Unlike CT, magnetic resonance imaging appears to be safe during pregnancy, according to studies. In Russia, it is not recommended to do it during the first trimester, but this is most likely a precaution.
When should you get an MRI?
— If we are not talking about traumatic brain injury or fractures, then MRI is several times more effective as a diagnostic method. We use additional programs that allow us to analyze biochemical and physiological processes in healthy and altered tissues and carry out accurate diagnosis of stroke even in the first hours, when other methods are useless, tumors, infectious (encephalitis, meningitis) and inflammatory (for example, multiple sclerosis) diseases, developmental anomalies. With the help of MRI, the doctor can see the blood vessels of the brain even without the use of contrast agents.
According to statistics, MRI of the spine is the most popular MRI examination in our country, and this is not without reason. In addition to the fact that there is nothing better for diagnosing the spinal cord and nerves, vertebrae, herniated discs, spinal cord and nerves, and cerebrospinal fluid have different colors on MR images. This makes the diagnosis clear.
MRI is the only method for studying the bone marrow and all its pathologies: benign and malignant vertebral tumors, inflammatory and degenerative changes.
There is a misconception that if there is a problem with the bones, then a CT scan should be done. Actually this is not true. Bone consists of periosteum and bone marrow. So, for bone fractures and bone tumors, you should definitely start with X-ray or CT, and for everything else, do an MRI.
In addition to bones, joints contain ligaments, tendons, menisci, cartilage... Something can be examined with good information using ultrasound or radiography, but to get maximum information about all structures of the joint, it is better to undergo an MRI.
In terms of diagnosing diseases of the abdominal organs, there is its own specificity. In this case, ultrasound is a cheaper and harmless method, CT with contrast is more expensive, but much more informative, and MRI with or without contrast is expensive, time-consuming, but harmless and very informative. The choice is largely determined by the specific task, and the decision which method to choose should be made by the attending physician. As a rule, they start with an ultrasound, and for a detailed assessment they resort to CT with contrast or MRI.
If we are talking about a tumor, it is better to immediately do an MRI. MRI is the gold standard in diagnosing tumors of the cervix and uterine body, vagina, prostate and rectum. Most studies are carried out precisely for this purpose. If you have a good apparatus and experienced doctors, the stage of the tumor process is determined in conclusion.
On the other hand, MRI is a frankly weak method in diagnosing the lungs, at least because it is technically very difficult to obtain good images in a short time. X-ray methods work better here. The second weak point of MRI is the periosteum. It has a black signal because there are simply few hydrogen protons, which means that to diagnose fractures, you again need to use radiography or CT.
Varieties
Magnetic resonance spectroscopy
Why: Allows you to determine the level of metabolism in a specific organ or tissue and reflects changes in metabolism, if any.
Bonus: The technique allows you to detect a violation of the blood supply to an organ or an inflammatory process even before pronounced symptoms appear, and stop the development of the disease at the very beginning.
Magnetic resonance angiography
Why: Used to study blood vessels, detects aneurysms, stenoses, atherosclerosis and even allows you to estimate the speed of blood flow.
Bonus: One of the options, 4D angiography, tracks the movement of blood throughout the body over time, and even “distinguishes” between arterial and venous blood flow.
Functional MRI
Why: Shows in real time how blood flow to certain parts of the organ changes. It is actively used for brain research: those nerve cells that are currently involved in work are most actively supplied with blood.
Bonus: A lot of psychological and neuroscience research is being done using fMRI. For example, in 2015, scientists from Oklahoma found that people who prefer to buy expensive organic products have increased activity in the insular cortex (responsible, among other things, for the feeling of disgust).
MRI in upright position
Why: Pathologies of the intervertebral discs, unless they have reached extreme stages, are hardly noticeable when the weight of our body does not press on the spine. Therefore, sometimes, to identify problems with the back, the patient, after a “regular” tomography, is turned 90 degrees in a supine position and placed vertically. A load appears on the spine - the same as that of a standing person. Protrusions and other problems manifest themselves, although they could be hidden in a horizontal position.
Bonus: During an upright MRI, the patient may be asked to flex or straighten their neck. Scanning in two positions further increases the information content of the study.
Diagnosis by neuromelanin
Why: Neuromelanin is a substance found in the cells of the substantia nigra of the brain. This area serves as the source of the neurotransmitter dopamine. Disruption of the substantia nigra is the main cause of parkinsonism.
Bonus: Neuromelanin has paramagnetic properties, which means that the places where it accumulates the most are visible on MRI. The amount of neuromelanin is an indicator of the activity of the cells of the substantia nigra, and if this activity is low, it is worth considering whether the patient is in the early stages of parkinsonism. Bonus: Most likely, schizophrenia can be diagnosed using the same method. Neuromelanin is also found in the locus coeruleus, the area of the brain that produces serotonin. It is assumed that problems in the system of neurons that produce and perceive serotonin are an important factor in the development of schizophrenia.
Virtopsy
Why: Used in forensics to assess the condition of the victim’s body, find injuries, and also find out what kind of weapon they could – or could not – have been caused. It is performed like a regular MRI. The results of a virtopsy (virtual autopsy) are easier to evaluate objectively than with a traditional autopsy, since it is not just a set of images, but also a lot of quantitative data.
Bonus: Virtopsy can be performed using a robot programmed to “illuminate” certain areas of the body.
MRI thermometer
Why: Sometimes they try to increase the effectiveness of radiation and drug therapy for malignant tumors by local heating of the affected tissue. To check whether the tumor tissue has warmed up to the desired temperature, and to avoid damage to healthy cells, a sensor can be installed in the tumor. However, in 2008, a much less painful method was tested on mice - MRI thermometry. It is based on obtaining resonance from hydrogen atoms from water and fat molecules contained in the tissues of the object under study. The frequency of radio waves emitted by hydrogen changes with the temperature of the tissues being examined, and the difference in these resonant frequencies allows one to accurately determine this temperature.
Bonus: By 2014, the technique had already been tested on living people, so it will soon be possible to see it in action in clinics.
WHAT HAPPENS DURING AN ATTACK
During an attack, a person becomes afraid that he will not be able to cope with the surging panic and will lose consciousness or will not be able to control himself. The heartbeat becomes very strong, shortness of breath, suffocation appears, and profuse sweating begins. A severe cough may begin. It seems to the person that his clothes are in the way; he tries to unbutton the top buttons, take off his coat or sweater. The strongest fear at this time is the fear of death.
CAUSES
- There is a congenital, genetic predisposition to this disease.
- Claustrophobia occurs against the background of disorders in the brain.
- Fears of enclosed spaces can be acquired and mainly come from childhood. Perhaps, during punishment, the child was locked in a dark, small room, or he fell into a hole from which he could not get out for a long time
People understand that they are not in danger, but they still cannot cope with this condition. No one can answer the exact question of why this happens to a person.
MRI and metal
The tomograph generates a powerful magnetic field that affects any electrical conductors present in the body: metal pins and endoprostheses, pacemakers, cochlear implants. The presence of complex electronic devices, as a rule, serves as an absolute contraindication to tomography, but this study can sometimes still be combined with prosthetic joints and similar mechanical devices.
Contrary to popular belief, the magnetic field of a tomograph is hardly capable of moving an endoprosthesis, much less pulling it out of the body. However, it may interfere with the localization of loosely attached objects, such as a clip on a blood vessel. The magnetic field can also heat the implants, sometimes noticeably to the patient. However, the main problem is different: foreign bodies create strong interference and sharply degrade image quality. An MRI with a metal prosthesis is not necessarily dangerous, but it is almost certainly useless - at least if you want to take a picture of the exact area in which the implant is installed.
The good news is that many modern implants are made from materials that cannot be magnetized and therefore do not interfere with MRI scanning. If you have any implant, be sure to find out what substance it is made of and ask your doctor to give you a certificate about whether a tomography is possible in your case.
Dentures and braces are most often made from alloys that cannot be magnetized, and therefore do not interfere with MRI, however, in this case, you need to be on the safe side: check with the dentist what materials he used, and convey this information to the doctor, who will perform MRI.
The list of contraindications for MRI also mentions the presence of tattoos made with metal-containing dyes; the reason is the same: the metal particles will heat up, shift and cause discomfort. However, it should be noted that modern dyes do not contain any metal particles. You should only worry if you got a tattoo forty years ago in the yard behind the garages, with a rusty needle, using a dye made by a folk craftsman from completely unknown ingredients.
Other contraindications to MRI
- Claustrophobia.
The tomograph is cramped, dark and noisy; you must be sure that this will not prevent you from remaining calm and still.
- First trimester of pregnancy
There is no proven harm to the child, but doctors prefer to play it safe.
- Weight more than 120 kilograms
In this case, the table may not support the patient, and he will be desperately cramped inside the pipe. However, a solution has already been created: an open tomograph. During the procedure, the patient is not in a cylinder, but in a semicircular groove, and the table of such a tomograph can withstand up to 200 kg. A similar option can be offered to those suffering from claustrophobia. True, open tomographs of sufficient power are just entering the market and are still quite rare.
TREATMENT AND INDEPENDENT OVERCOME FEARS
If you do not consult a doctor, a mild form of claustrophobia can develop into a severe form of the disease. An experienced doctor will help you cope with the problem using hypnosis and special exercises. Sometimes medications are prescribed.
It is recommended that during an attack, try to switch your thoughts to something else, start thinking about pleasant things. It is advisable to sit down and very much relax your body and muscles. You can pay attention to any object and carefully study it, silently listing the shortcomings or advantages you see. You can do breathing exercises and turn on calm music.
Claustrophobia: Symptoms. Causes. Treatment.
How much to hang in a Tesla?
The magnetic field induction of the tomograph is measured in Tesla. The unit is named after the inventor Nikola Tesla, who clarified much about the nature of electricity and magnetism. The more Tesla markings a tomograph shows, the more powerful it is and the more detailed images it can provide. Typically in medicine, tomographs with induction from 0.2 to 3 Tesla are used; high power is not required. Still would! The magnetic field induction of sunspots is only 3 times higher.
- 0.23-0.35 Tesla (low-floor) - preliminary diagnostics only. For example, such a tomograph will be able to determine whether there is a tumor or not, but will provide almost no information about its structure;
- 1 Tesla (mid-field) - such a tomograph will not allow you to examine the smallest details, but it is quite enough to get a general idea of the location and severity of the damage.
- 1.5-3 Tesla (high-field) – visualization of small areas of tissue. Such a tomograph will help to find metastases and determine whether there is a pathological change in the tissue around the joint capsule or inside the mammary glands after the installation of implants.
Author: Svetlana Yastrebova Published: October 19, 2021
Advantages of MRI at the NACFF clinic
- Expert-level research for the most complex diagnostic tasks. In addition to a modern tomograph, the “gold standard” in the class of 1.5 Tesla devices, the department is equipped with a full set of Tim 4G radio frequency coils, providing the highest quality images, flexibility in conducting research, and reducing diagnostic time. It is thanks to the receiver coils that an image is obtained when exposed to a magnetic field.
- Radiation diagnostic doctors with extensive practical experience. We understand that it is important for you not only to get an excellent image, but also its competent interpretation - a high-quality conclusion. That is why the staff of the MRI department of the NACFF clinic includes specialists with more than 15 years of experience, having experience working in large public and private institutions in Moscow, constantly improving the level of their qualifications and working closely with clinicians on any controversial issues.
- Comfort during research. Inside the tomograph tunnel there is a 6-level ventilation system, as well as lighting. During an MRI, the patient has the opportunity to communicate with doctors through an intercom. Special headphones muffle the sound of the device. Through the same headphones, if necessary, doctors’ requests (“inhale,” “exhale,” etc.) are received. The patient table can be lowered to a minimum height of 52 cm from the floor, which is especially important for the convenience of elderly patients, people with limited mobility, and children.
- Possibility of performing MRI on patients with increased body weight - the tomograph of the NACFF clinic allows performing MRI on patients weighing up to 150 kg.
- MRI in patients with claustrophobia. The combination of a 1.5 Tesla MAGNETOM Aera magnet with an open tunnel design - a diameter of 70 cm and a length of 145 cm of the entire tunnel - can significantly reduce claustrophobia in patients and increase the comfort of examinations. Additionally, MRI department specialists can place mirrors inside the tunnel so that the patient can see the staff during the examination and feel more relaxed.
