> MRI 1.5 or 3 Tesla - what's the difference?

MRI 1.5 or 3 Tesla - what's the difference?

MRI (magnetic resonance imaging) is one of the most popular diagnostic methods in modern medicine. MRI is a non-invasive (not requiring intervention in the body) technique that is completely safe for human health and at the same time gives unsurpassed results in terms of accuracy.

The basis of the MRI method is the phenomenon of nuclear magnetic resonance, that is, a change in the "behavior" of the nuclei of hydrogen atoms under the influence of electromagnetic waves in the field of the tomograph. Unlike computed tomography, which uses ionizing radiation, the magnetic field is completely harmless to the body.

Types of tomographs and unit of measurement of field strength

All tomographs are conditionally divided into three groups - low-field, medium-field and high-field. This division is due to the indicator of the magnetic field strength generated by the tomograph. Low-field devices have a strength of up to 0.5 T, medium-field - 0.5-1 T, high-field - up to 3 T. Sometimes ultra-high-field devices with a power of more than 3 T are also classified as a separate group.

The designation "Tl" stands for "Tesla" - the unit of measurement of the magnetic field got its name in honor of the brilliant Serbian scientist Nikola Tesla.

Most modern clinics today have tomographs with a capacity of 1-2 Tl. It makes no sense to use devices with smaller field values, since they provide not very accurate and reliable data. The well-known formula is “the higher the field strength, the more accurate the result”. The "gold standard" of MRI is diagnostics on devices with a field power of 1.5-3 T.

The field strength depends on which magnet is installed in the apparatus. Inexpensive permanent magnets provide low tension, while more expensive superconducting magnets provide high.

Use of tomographs with different field strengths.

In some cases, not only medium- and high-field, but also low-field tomographs are used. Diagnostics with the use of such a device is much cheaper. So, MRI on a tomograph with a field of less than 1 T can be prescribed as a preliminary diagnosis. Often, MRI on such devices is prescribed in order to establish the presence of a tumor, but not to determine its boundaries.

Repeated diagnostics in case of insufficient data for making a diagnosis is always performed on medium- or high-field tomographs (with a field power of up to 3 T). Recently, however, most patients prefer to immediately pay for diagnostics on a good device, so as not to fork out twice. In cases where it is required to assess the condition of blood vessels, small structures, to identify the spread of metastases, only an examination on a tomograph with a field of at least 1.5 T is chosen. Only in this case it is possible to obtain reliable results.

On devices with a field above 4-5 T, MRI is not performed. Such tomographs are installed exclusively in research laboratories.

In addition to the quality of images, the field strength of the tomograph also affects such an indicator as the speed of diagnostics. The greater the field strength, the faster the survey will be completed. For example, examination of the same organ on a tomograph with a field of 1 T takes 15-20 minutes, and on an apparatus of 1.5 T - 10-15 minutes. A tomograph with a field power of 3 T allows you to reduce the procedure time to 5-10 minutes. In some cases, this is of great importance - for example, during the diagnosis of a child or a patient who is in serious condition.

High-field tomographs also allow you to see those structures that low-field devices simply do not distinguish. The minimum slice thickness (about 0.8 mm) makes it possible to take high-resolution images, which makes it possible to detect pathologies already at the initial stage. This is especially true in the diagnosis of oncological diseases, when the prognosis directly depends on the speed of diagnosis and initiation of treatment. Therefore, only high-field devices are used in oncology.

Magnetic resonance imaging (MRI) is one of the most modern diagnostic methods that allows you to study almost any system of the body. The most important characteristic of an MRI machine is the magnetic field strength, which is measured in Tesla (T). The quality of visualization directly depends on the field strength - the higher it is, the better the image quality, and, accordingly, the higher the diagnostic value of the MRI study.

Depending on the power of the device, there are:

At the moment, all major manufacturers produce MR scanners with a field of 3 T, which differ little in size and weight from standard systems with a field of 1.5 T.

Safety studies in MR imaging have not shown any negative biological effects of magnetic fields up to 4 T used in clinical practice. However, it should be remembered that the movement of electrically conductive blood creates an electrical potential, and in a magnetic field it will create a small voltage through the vessel and cause an elongation of the T wave on the electrocardiogram, therefore, in studies in fields above 2 T, ECG monitoring of patients is desirable. Physical studies have shown that fields above 8 T cause genetic changes, charge separation in liquids, and changes in the permeability of cell membranes.

Unlike the main magnetic field, gradient fields (magnetic fields perpendicular to the main, main, magnetic field) are switched on at certain time intervals in accordance with the chosen technique. The rapid switching of gradients can induce electrical currents in the body and lead to stimulation of peripheral nerves, causing involuntary movements or tingling in the limbs, but the effect is not dangerous. Studies have shown that the threshold for stimulation of vital organs (for example, the heart) is much higher than for peripheral nerves, and is about 200 T/s. When the threshold [rate of change of gradients] dB/dt = 20 T/s is reached, a warning message appears on the operator console; however, since the individual threshold may differ from the theoretical value, constant monitoring of the patient's condition is necessary in strong gradient fields.

Metals, even non-magnetic ones (titanium, aluminium), are good conductors of electricity and will heat up when exposed to radio frequency [RF] energy. RF fields induce eddy currents in closed loops and conductors, and can also create significant stress in extended open conductors (eg, rod, wire). The length of electromagnetic waves in the body is only 1/9 of the wavelength in air, and resonance phenomena can occur in relatively short implants, causing their ends to heat up.

Metallic objects and external devices are generally erroneously considered safe if they are non-magnetic and labeled "MP compatible". However, it is important to make sure that objects that are scanned inside the working area of the magnet are immune to induction. Patients with implants are only eligible for MR examination if the implants are both non-magnetic and small enough to heat up during scanning. If the object is longer than half the length of the RF wave, a high heat resonance may occur in the patient's body. The limiting dimensions of metal (including non-magnetic) implants are 79 cm for a field of 0.5 T and only 13 cm for 3 T.

Switching gradient fields creates a strong acoustic noise during an MR examination, the value of which is proportional to the power of the amplifier and the field strength and, according to regulatory documents, should not exceed 99 dB (for most clinical systems it is about 30 dB).

based on the article "Possibilities and limitations of high-field magnetic resonance imaging (1.5 and 3 Tesla)" A.O. Kaznacheeva, National Research University of Information Technologies, Mechanics and Optics, St. Petersburg, Russia (journal "Radiology and Therapy" No. 4 (1) 2010)

read also the article "Safety of magnetic resonance imaging - the current state of the issue" by V.E. Sinitsyn, Federal State Institution "Treatment and Rehabilitation Center of Roszdrav" Moscow (Journal "Diagnostic and Interventional Radiology" No. 3, 2010) [read]

MRI DURING PREGNANCY - IS IT SAFE?

Currently, MRI is a widely used method of radiation diagnostics, which is not associated with the use of ionizing radiation, as in X-ray examination (including CT), fluorography, etc. MRI is based on the use of radio frequency pulses (RF pulses) in a high magnetic field. The human body consists mainly of water, consisting of hydrogen and oxygen atoms. At the center of each hydrogen atom is a small particle called a proton. Protons are very sensitive to a magnetic field. Magnetic resonance imaging scanners use a constant strong magnetic field. After the object under study is placed in the magnetic field of the tomograph, all its protons line up in a certain position along the external magnetic field, like a compass needle. An MRI scanner sends a radio frequency pulse to the part of the body being examined, causing some of the protons to move out of their original state. After turning off the radio frequency pulse, the protons return to their previous position, emitting the accumulated energy in the form of a radio frequency signal that reflects its position in the body and carries information about the microenvironment - the nature of the surrounding tissue. Just as a million pixels form an image on a monitor, the radio signals from millions of protons, after complex mathematical processing, form a detailed image on a computer screen.

However, certain precautions must be strictly observed when performing an MRI. Potential hazards for patients and MRI staff may be related to factors such as:

Due to the "youth" of the technique, a small (worldwide) amount of accumulated safety data, the FDA (Food and Drug Administration, USA), together with the World Health Organization, impose a number of restrictions on the use of MRI, due to the possible negative impact strong magnetic field. The use of a magnetic field up to 1.5 T is considered acceptable and absolutely safe, except for cases when there are contraindications for MRI (MR tomographs up to 0.5 T - low-field, from 0.5 to 1.0 T - medium-field, from 1.0 - 1.5 T and more - high-field).

Speaking about long-term exposure to constant and alternating magnetic fields, as well as radio frequency radiation, it should be noted that there is no evidence of the existence of any long-term or irreversible effects of MRI on human health. So, female doctors and radiologists are allowed to work during pregnancy. Monitoring of their health showed that no abnormalities were noted in their health or in their offspring.

In magnetic resonance imaging of women of childbearing age, it is necessary to obtain information about whether they are pregnant or not. There is no evidence of the harmful effects of magnetic resonance imaging on the health of pregnant women or the fetus, but it is strongly recommended to perform MRI for women in position only with obvious (absolute) clinical indications, when the benefits of such an examination clearly outweigh the risks (even if very low).

If there are only relative indications for MRI, then doctors recommend abandoning this study in the first three months (up to 13 weeks of gestation, I trimester) of pregnancy, since this period is considered fundamental for the formation of the internal organs and systems of the fetus. During this period, both the pregnant woman and the child itself are very sensitive to the effects of teratogenic factors that can cause disruption of the embryogenesis process. In addition, according to most doctors, the first three months, the pictures of the fetus are not clear enough due to their small size.

Moreover, during the diagnosis, the tomograph itself creates a background noise and emits a certain percentage of heat, which can also potentially affect the fetus in early pregnancy. As mentioned above, MRI uses RF radiation. It can interact both with body tissues and with foreign bodies in it (for example, metal implants). The main result of this interaction is heating. The higher the frequency of RF radiation, the more heat will be released, the more ions are contained in the tissue, the more energy will be converted into heat.

To evaluate the thermal effects of RF radiation, specific absorption rate - SAR (specific absorbtion rate), displayed on the display screen of the device, helps. It increases with increasing field strength, RF pulse power, decreasing slice thickness, and also depends on the type of surface coil and patient weight. MRI systems are protected to prevent the SAR from rising above a threshold, which could result in tissue heating of more than 1°C.

During pregnancy, MRI can be used to diagnose pathology either in a woman or in a fetus. At the same time, MRI is prescribed according to ultrasound diagnostics when certain pathologies are detected in the development of the unborn child. The high sensitivity of MRI diagnostics makes it possible to clarify the nature of the deviations and helps to make an informed decision on whether to continue or terminate the pregnancy. MRI becomes especially important if it is necessary to study the development of the fetal brain, diagnose malformations of cortical development associated with a violation of the organization and formation of the brain convolutions, the presence of areas of heterotopia, etc. Thus, the reasons for MRI can be:

■ various developmental pathologies of the unborn child;
■ deviations in the activity of internal organs, both the woman herself and the unborn child;
■ the need to confirm indications for artificial termination of pregnancy;
■ as evidence or, conversely, refutation of a previously diagnosed diagnosis based on tests;
■ the lack of the possibility of ultrasound due to the obesity of the pregnant woman or the inconvenient location of the fetus in the last stage of pregnancy.

Thus, in the first trimester of pregnancy (up to 13 weeks of gestation), an MRI is possible for health reasons on the part of the mother, since organo- and histogenesis has not yet been completed, and in the second and third trimesters of pregnancy (after 13 weeks) - the study is safe for the fetus.

On the territory of Russia, there are no restrictions on MRI in the first trimester, however, the Commission on Ionizing Radiation Sources at WHO does not recommend any exposure to the fetus, which may in any way affect its development (despite the fact that studies have been carried out during which children under 9 years of age were observed, subjected to MRI in the first trimester of intrauterine development, and no deviations in their development were found). It is important to remember that the lack of information about the negative impact of MRI on the fetus does not mean the complete elimination of the harm of this type of study for the unborn child.

note: pregnant [ !!! ] it is forbidden to conduct an MRI with intravenous administration of MR contrast agents (they penetrate the placental barrier). In addition, these drugs are excreted in small amounts with breast milk, so the instructions for gadolinium drugs indicate that when they are administered, breastfeeding should be stopped within a day after the administration of the drug, and the milk secreted during this period should be expressed and poured out. .

Literature: 1. article "Safety of magnetic resonance imaging - the current state of the issue" V.E. Sinitsyn, Federal State Institution "Therapeutic and Rehabilitation Center of Roszdrav" Moscow; journal "Diagnostic and interventional radiology" Volume 4 No. 3 2010 pp. 61 - 66. 2. article "MRI diagnostics in obstetrics" Platitsin I.V. 3. materials of the site www.az-mri.com. 4. materials from the site mrt-piter.ru (MRI for pregnant women). 5. materials from the site www.omega-kiev.ua (Is MRI safe during pregnancy?).

From the article: "Obstetric aspects of acute cerebrovascular disorders during pregnancy, childbirth and the postpartum period (literature review)" R.R. Harutamyan, E.M. Shifman, E.S. Lyashko, E.E. Tyulkina, O.V. Konysheva, N.O. Tarbaya, S.E. Flock; Department of Reproductive Medicine and Surgery, FPDO, Moscow State University of Medicine and Dentistry. A.I. Evdokimova; City Clinical Hospital №15 named after O.M. Filatov; Department of Anesthesiology and Resuscitation, FPC MR, Peoples' Friendship University of Russia, Moscow (magazine "Problems of reproduction" No. 2, 2013):

“MRI does not use ionizing radiation, and no harmful effects on the developing fetus have been noted, although long-term effects have not yet been studied. A recently published guideline from the American Radiological Society states that MRI should be performed on pregnant women if the benefit of the study is clear and the necessary information cannot be obtained by safe methods (for example, using ultrasound) and cannot be waited until the end of the patient's pregnancy. MRI contrast agents easily cross the uteroplacental barrier. No studies have been conducted on the removal of contrast from amniotic fluid, just as their potential toxic effects on the fetus are not yet known. It is assumed that the use of contrast agents for MRI in pregnant women is justified only if the study is clearly useful for making a correct diagnosis in the mother [read source].”

From the article"Diagnostics of acute disorders of cerebral circulation in pregnant women, puerperas and women in childbirth" Yu.D. Vasiliev, L.V. Sidelnikova, R.R. Arustamyan; City Clinical Hospital №15 named after O.M. Filatov, Moscow; 2 SBEE HPE "Moscow State University of Medicine and Dentistry named after A.I. A.I. Evdokimov" of the Ministry of Health of Russia, Moscow (magazine "Problems of reproduction" No. 4, 2016):

“Magnetic resonance imaging (MRI) is a modern diagnostic method that allows you to identify a number of pathologies that are very difficult to diagnose using other research methods.

In the first trimester of pregnancy, MRI is performed according to vital indications on the part of the mother, since organo- and histogenesis has not yet been completed. There is no evidence that MRI has a negative effect on the fetus or embryo. Therefore, MRI is used for research not only in pregnant women, but also for fetography, in particular, for examining the fetal brain. MRI is the method of choice in pregnancy if other non-ionizing medical imaging methods are insufficient, or if the same information is needed as x-rays or computed tomography (CT) but without the use of ionizing radiation.

There are no restrictions on MRI during pregnancy in Russia, however, the Commission on Non-Ionizing Radiation Sources at WHO does not recommend any exposure to the fetus from the 1st to the 13th week of gestation, when any factor can in any way affect its development.

In the II and III trimesters of pregnancy, the study is safe for the fetus. Indications for MRI of the brain in pregnant women are: [ 1 ] stroke of various etiologies; [ 2 ] vascular diseases of the brain (anomalies in the development of blood vessels of the head and neck); [ 3 ] trauma, bruises of the brain; [ 4 ] Tumors of the brain and spinal cord; [ 5 ] paroxysmal conditions, epilepsy; [ 6 ] infectious diseases of the central nervous system; [ 7 ] headache; [ 8 ] violations of cognitive functions; [ 9 ] pathological changes in the sellar region; [ 10 ] neurodegenerative diseases; [ 11 ] demyelinating diseases; [ 12 ] sinusitis.

For MR angiography in pregnant women, the introduction of a contrast agent in most cases is not necessary, in contrast to CT angiography, where it is required. Indications for MR angiography and MR venography in pregnant women are: [ 1 ] cerebrovascular pathology (arterial aneurysms, arteriovenous malformations, cavernomas, hemangiomas, etc.); [ 2 ] thrombosis of large arteries of the head and neck; [ 3 ] thrombosis of venous sinuses; [ 4 ] identification of anomalies and variants of development of the vessels of the head and neck.

There are few contraindications for the use of MRI in the general population, and in pregnant women in particular. [ 1 ] Absolute contraindications: artificial pacemaker (its function is disturbed in the electromagnetic field, which can lead to the death of the examined patient); other electronic implants; periorbital ferromagnetic foreign bodies; intracranial ferromagnetic hemostatic clips; conductive pacemaker wires and ECG cables; pronounced claustrophobia. [ 2 ] Relative contraindications: I trimester of pregnancy; serious condition of the patient (an MRI is possible when the patient is connected to life support systems).

In the presence of heart valves, stents, filters, the study is possible if the patient provides the accompanying documents of the manufacturer, which indicate the possibility of an MRI indicating the magnetic field strength, or an epicrisis of the department where the device was installed, which indicates the permission conducting this survey” [read source].

Magnetic resonance imaging (MRI) is a widely used non-invasive diagnostic method in medicine that uses magnetic resonance. The action of the magnetic field does not pose a danger to human health. The strength of the magnetic field is measured in Tesla - in honor of Nikola Tesla, who won world fame for his research of magnetism and electricity.

Power of tomographs

For diagnostic studies, MRI of various power can be used. On this basis, they are divided into the following groups:

low-field - with a magnetic field strength of up to 0.5 T;
mid-field - from 0.5 to 1 T;
high-field - 1.5-3 T.

Ultra-high-field devices over 3 T are used only in scientific and technical laboratories and diagnostics are not carried out on them.

The capabilities of the tomograph depend on the strength of the magnetic field. The lower the tension, the lower the quality of the images and the more time spent on diagnostics. When examining the same organ, the time indicators are as follows:

1 T - 15-20 minutes;
1.5 T - 10-15 minutes;
3 T - 5-10 minutes.

Examination on low-field tomographs is cheaper, but can only be used for preliminary diagnosis and to answer the question of whether there is a tumor or not. If there is a tumor, then an additional study on a more powerful device will be required to establish its size and boundaries.

Which is more effective: MRI 1.5 Tesla or 3 Tesla

For most MRI scans, the 1.5 T machine is the standard and is most commonly used to assess the condition of blood vessels, detect metastases, and examine small structures. In terms of visualization quality and throughput, the 1.5 T tomograph is almost as good as the 3 T tomograph.

3T MRI devices are almost 2 times more expensive than 1.5 T MRI devices and require more thorough preparation of the room and compliance with safety measures when working with strong electromagnets. Spare parts and service for more powerful scanners are also more expensive.

The use of a powerful 3Tl tomograph is justified in cases where it is required to study the work of the brain with the smallest details. A higher examination speed is justified with a large influx of patients or diagnosing children and seriously ill patients. In all other cases, the use of a 1.5 T tomograph for medical institutions is more accessible and justified.

In the last decade, in medical practice, and in the minds of people who are not related to medicine, this abbreviation has firmly established itself, under which a sometimes frightening combination of the words “nuclear magnetic resonance imaging” is hidden.

Many of those who read these lines will immediately remember films or television series in which, at the most dramatic moments associated with car accidents or the threat of death of the protagonist, the latter is in serious condition, and he is placed in a “pipe” to find out how much is left ...

Everyday reality is more prosaic. Now the study is being done not only for a preventive purpose during medical examination, but even as part of anti-cellulite programs, to assess the thickness of subcutaneous fat! The possibilities of the method are quite wide ...

What is the principle of operation of MRI?

The tomograph works using the phenomenon of nuclear magnetic resonance. The fact is that all the cells of our body are saturated with hydrogen molecules, by acting on them with the field of the apparatus, it is possible to extract and “photograph” energy. In normal tissues, one content of charged particles, in those altered by a disease process, is another. All cells have their own characteristics. This is based on computer data processing and image display.

What is better, MRI 1.5 Tesla or 3.0?

It is believed that the more powerful the machine that scans the body, the better. It really is. The field of the desired frequency is created by superconducting electromagnets operating on liquid helium. The intensity of exposure is measured in Tesla units. Modern tomographs available to the general public operate in the range from 0.35 to 3 units. The best option is a high-field device with a power of 1.5 Tesla. "Trekhteslovki", as a rule, are used for scientific purposes.

Why use contrast?

We talked about how each type of cell has "its own energy values." The skeletal muscles of the shoulder have some indicators, the femur has others. In addition, any changes in the structure of the tissue lead to an internal restructuring of its vascular network. This phenomenon is used for differential diagnosis in oncological or demyelinating processes.

The contrast acts as a dye, litmus test. Where "suspicious" cells function, it accumulates. To date, this is the most informative type of research.

How harmful is an MRI?

At the present stage of development of medical science, it is believed that the harm from the impact of MRI is insignificant, more precisely, it is no more than from the operation of a mobile phone. Some scientists claim that the method is harmless even for pregnant women. In any case, no evidence to the contrary has been accumulated over 10-15 years. In this regard, the study can be performed repeatedly, regardless of the age and condition of the patient.

What are the types of MRI machines?

Without going into technical details, all machines can be divided into open and closed (tunnel) tomographs.

The first were designed specifically for the needs of veterinarians, because not every animal can fit in a narrow space. In medicine, they are used to examine large patients and those suffering from claustrophobia. However, the power of such devices does not exceed 0.35 Tesla.

Devices of closed type, they are "donut" or "pipe", have an intensity of exposure from 1.0 to 3.0 Tesla and are of greater interest due to their diagnostic accuracy.

When is an MRI indicated?

brain diseases: oncology, stroke, aneurysms, meningitis and encephalitis, multiple sclerosis, vascular atherosclerosis;
diseases of the spinal cord and neuropathy: tumors, demyelinating processes, circulatory disorders, syringomyelia;
osteochondrosis of the spine, protrusions and hernias of the intervertebral discs, stenosis of the spinal canal, compression of the nerve roots, metastases;
violation of the anatomy and function of the joints: damage to the ligaments and intra-articular components, osteoarthritis and rheumatoid arthritis;
pathological processes in the abdominal cavity and retroperitoneal space: abscesses, hematomas, inflammatory conditions, various neoplasms.

When is an MRI contraindicated?

Due to the powerful electromagnetic field, there are a number of absolute contraindications for the procedure in people who have electronic and metal objects inside the body. In this case, the study will create a situation that threatens a person: bleeding and burns.

Absolute contraindications include:

electronic middle ear and eye implants;
artificial pacemakers and valves;
hemostatic clips;
Ilizarov apparatus and external fixation devices;
weight and volume limit: body weight up to 120 kg

Relative contraindications are:

claustrophobia (fear of closed spaces);
the first trimester of pregnancy (there is no data on harm, but once again it is better not to risk it);
inadequate state of a person (alcohol or drug intoxication, panic attack);
serious condition of the patient requiring constant monitoring;
the presence of tattoos containing dyes based on metal compounds.

In any case, if there are foreign objects in the body, a certificate is required for the material introduced during the operation.

How is the research going?

You don't need a special referral from a doctor. You can perform an MRI of any part of the body of your choice, but if you have previous results, it is advisable to bring them with you. In this case, the doctor will have the opportunity to compare the pictures and judge the dynamics of the condition.

No special preparation is required. Before the procedure, all items containing metal must be left in the storage room: jewelry, keys, mobile phone, credit cards, coins and pens.

At the time of operation of the device, the person does not feel discomfort, he lies on his back, partially or completely being in the scanning part of the device. In order to avoid fuzzy images (artifacts), it is better not to move and keep an even pace of breathing.

Depending on the type of study, it can last from 20 to 50 minutes. All this time, the patient is under the supervision of a doctor observing from a neighboring office, and has feedback with him via a remote control.

Who interprets the MRI results?

The image is recorded on film. The conclusion is issued by the doctor of radiation diagnostics within 15-20 minutes. If an assessment of the state of the brain or spine was carried out, a neurologist consults for free. The examination lasts 20-35 minutes, during which the doctor collects an anamnesis, examines the patient and gives recommendations for the treatment and prevention of existing diseases.

Pros and cons of MRI

Magnetic resonance imaging is highly informative. Along with this, there is a duration of the procedure and a restriction on the use of the method in persons with metal objects in the body.

Neurologist, manual therapist. I work in the center of manual therapy A.B. Sitel, I also conduct an appointment at the “Overcoming” clinic. I answer online questions from site visitors.

The principle of operation of tomographs is to fix the reaction of the nuclei of hydrogen atoms in the human body to electromagnetic radiation in a constantly operating magnetic field. The strength of electromagnetic waves directly depends on which organs need to be examined. Its value is measured in Tesla.

MRI is a high-precision innovative method of examining organs and tissues of the body in order to make an accurate diagnosis. The procedure is non-invasive, completely safe for both adults and children.

The apparatus on which the study is carried out - a tomograph - is shaped like a pipe with electromagnetic waves passing through it. The patient is placed inside this tube, and for a certain time (40 minutes on average) he must remain still in order to obtain the most accurate result. The diagnosis is made within 30-60 minutes after the procedure, which is extremely important in cases where the patient needs emergency care.

Power of MRI machines

with a low field - from 0.23 to 0.35 Tesla;
with an average field - from 0.5 to 1 Tesla;
with a high field - 1.5 - 3 Tesla.

The higher the voltage (power), the better the images of the sections of the examined organs in different projections are obtained, which, after processing by a computer program, are displayed on the monitor. Thus, the most accurate results can be obtained using high-field devices - 1.5-3 Tesla. Especially qualitatively, they detect and visualize small neoplasms that less powerful tomographs cannot distinguish.

In turn, low-field devices are widely used for primary diagnostics. If it happens that after an examination on a 0.23-0.35 and 1 Tesla device, doctors still have doubts about the diagnosis, they can prescribe a second procedure on a powerful MRI. All three types of devices are equally safe for health, and studies on them can be carried out as many times as necessary for the final diagnosis of the disease.

When is an examination on a powerful device necessary?

There are cases when a tomograph with a sufficiently high power of 1.5 Tesla cannot detect serious disorders (for example, the spread of metastases), and then a situation arises when only the highest-field device is needed. If low-field devices take pictures of slices every 6 mm, then high-field devices take pictures every 1.5 mm, which makes it possible not to miss a single change and make a more accurate diagnosis. There are also 5 Tesla tomographs, produced in single copies for scientific purposes, but it is almost impossible to find them in our clinics.

Only the attending physician determines in each individual case which apparatus should be used for the procedure, based on the patient's condition and the tasks set, and also taking into account the fact that there are many contraindications to the MRI procedure on the latest 3 Tesla tomographs.

Research cost

The difference in the cost of tomography on devices of different capacities does not differ significantly. For example, in Moscow, an MRI of the brain on a 0.35 Tesla tomograph will cost an average of 3,500 rubles for a patient, and the same study on a 1.5 Tesla machine is only 1,000 more expensive. The difference between examinations on devices of 0.23 and 3 Tesla (with the lowest and highest power) does not exceed 1.5 thousand rubles on average.

This material is presented for educational purposes only, cannot be used for self-diagnosis and does not replace the advice of a doctor.

MRI not less than 1 5 tesla

MRI 1.5 or 3 Tesla - what's the difference?

Types of tomographs and unit of measurement of field strength