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 RF frequency, the more large quantity 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 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.

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 negative impact 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 Intensive Care FPC MR Russian University Friendship of Peoples, 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 undeniably 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) - modern method diagnostics, which allows 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 techniques 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 head 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].

> 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 device. 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 pictures in high resolution which makes it possible to detect pathologies at an early 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.

The Tesla Model S five-door premium-class electric car made its official premiere in the fall of 2009 at a car show in Frankfurt, however, only as a prototype, but was first shown to the public back in March at a press conference in Los Angeles. Serial production of the machine started in the first half of 2012, and already in June, shipments to the first customers began.

In 2014, the Americans upgraded the Escu, adding several all-wheel drive versions, increasing engine power and introducing a new interface for the multimedia complex.

The Tesla Model S looks beautiful and expressive, and it is unmistakably guessed in the stream, although from some angles it resembles other cars. A deliberately aggressive front end with an evil look of xenon optics, a long and swift silhouette with an actively sloping roofline, “muscular” wheel arches and retractable door handles, a powerful rear with beautiful LED lights and a massive bumper – externally, the electric car fully corresponds to its premium status. And at the same time, it is in no way inferior to eminent competitors with conventional engines.

The electric liftback experienced another update in April 2016, and this time the main changes were in the exterior design - the appearance of the five-door was retouched in the spirit of the Model X crossover and the Model 3 three-volume.
The front end of the car has changed most noticeably - the large black plug imitating the radiator grill has disappeared from it, giving way to a thin bar with the brand logo, and instead of bi-xenon optics, LED has appeared. From other angles, the “American” has completely retained its outlines.

According to its overall dimensions, the “eska” belongs to the European class “E”: its length fits into 4976 mm, width - 1963 mm, height - 1435 mm, and the wheelbase - 2959 mm. The ground clearance of the electric vehicle is 152 mm, however, when installing the optional air suspension, its value varies from 119 to 192 mm.

The interior of the Tesla Model S is a real delight, because it is built around a 17-inch interactive console, located in the center of the front panel, which manages all the main functions of the car. This decision made it possible to abandon the scattering of buttons, leaving only a couple of classic toggle switches on the dashboard - opening the glove box and turning on the emergency gang. The tidy is represented by another color screen, only smaller, and the classic multifunctional “steering wheel” looks the most mundane, sporty truncated at the bottom. The interior of the electric car is tailored with premium materials that combine leather, aluminum and wood.

At the front, in the California “esque”, comfortable and supple chairs with well-developed lateral support and a sufficient set of electrical adjustments are installed. The rear seats in the car are less hospitable - the sofa has a flat pillow and shapeless backs, and the sloping roof presses on the heads of tall passengers.

As a result of restyling in 2016, the interior of the car remained the same in terms of design, but acquired new materials and finishes.

With practicality, the Tesla Model S is in full order: with a five-seat layout, the volume of the cargo compartment is 745 liters, and with the second row seatbacks folded down, 1645 liters.

There is also an additional trunk in the front of the electric car, but its capacity is much more modest - 150 liters.

Specifications. The “filling” is the main “highlight” of the “eski”, because the machine is driven by an asynchronous (induction type) three-phase electric motor (there are several of them on all-wheel drive versions) of alternating current, the output of which depends on the modification, combined with a single-stage gearbox and a set of lithium-ion batteries in quantities from 5040 to 7104 pieces.

• 60 a 306-horsepower electric motor is installed, delivering 430 Nm of torque throughout the entire range, which provides the car with acceleration to the first “hundred” after 5.5 seconds and 210 km / h of maximum speed. Batteries with a capacity of 60 kW / h allow it to travel up to 375 km on a single charge.
• For modification with index " 75 "A power plant with a capacity of 320 "horses" is provided, the output of which is 440 Nm of peak thrust, powered by 75 kW / h batteries. It takes 5.5 seconds for such an electric car to start accelerating to 100 km / h, its “maximum” is limited to 230 km / h, and its “range” exceeds a little over 400 km.
• Under the Tesla Model S 60D there are already two electric motors with a total power of 328 horsepower (525 Nm of torque), making the liftback all-wheel drive. This version exchanges the first “hundred” in 5.2 seconds, peaking up to 210 km / h, and on “one tank” it is able to cover at least 351 km thanks to 60 kW / h batteries.
• "Eska" marked " 75D"has in its arsenal a pair of electric motors, jointly generating 333" mares "and 525 Nm of torque. Such characteristics make the “green” car a real sports car: it “shoots” to the first “hundred” after 5.2 seconds, and it stops speeding up only when it reaches 230 km / h. Fully charged batteries with a capacity of 75 kW / h provide the five-door with a decent range - 417 km.
• The next variant of the Tesla Model S in the hierarchy 90D equipped with two electric units, the total potential of which is 422 “horses” and 660 Nm of available torque. The electric car rushes to conquer the second “hundred” in 4.4 seconds and gains a maximum of 249 km / h. Thanks to batteries of 90 kW / h, the car overcomes 473 km of track on a “full tank”.
• The version called " 100D"Driven by front and rear electric motors, which together give out 512" horses "and 967 Nm of torque potential. The first "hundred" of such a five-door submits in 3.3 seconds, and the "maximum speed" does not exceed 250 km / h. Batteries for 100 kW / h provide her with a "range" of 430 km.
• "Top" solution Tesla Model S P100D it is equipped with two power plants: the rear electric motor develops 503 horsepower, and the front one develops 259 “mares” (total output is 762 “horses” and 967 Nm of peak thrust). Such characteristics "catapult" the car from standstill to 100 km / h after 2.5 seconds and allow it to accelerate to 250 km / h. On fully charged batteries with a capacity of 100 kW / h, the electric car covers about 613 km.

It takes more than 15 hours to fully charge Tesla Model S lithium-ion batteries from a regular 220V household network, depending on the modification. When using a NEMA 14-50 standard connector, this cycle is reduced to 6-8 hours, and at special Supercharger stations (you won’t find such in Russia) - up to 75 minutes.

The California electric car is built around a flat "winged metal" battery storage unit, to which aluminum subframes and bodywork are attached. In running order, the "eska" weighs from 1961 to 2239 kg, and its mass is distributed along the axles in a ratio of 48:52 (for the all-wheel drive P85D - 50:50).

"In a circle" on the machine, an independent chassis is installed: in front - double wishbones, in the back - a multi-link layout. An air suspension is available as an option.
All Model S wheels use disc brakes (355mm front and 365mm rear) with four-piston Brembo calipers and ABS, and its steering system is an electric power rack and pinion.

Options and prices. In Russia, the Tesla Model S is not officially sold, but on the "secondary market" you can buy such an electric car at a price of 4.5 million rubles. In Germany, the car can be purchased at a price of 57,930 euros (~3.68 million rubles at the current exchange rate), but including taxes, its cost rises to 69,020 euros (~4.39 million rubles).
As standard, the “American” is equipped with eight airbags, xenon headlights, a 17-inch touchscreen multimedia system, a digital instrument panel, power accessories, ABS, ESP, a dual-zone climate control system, a factory audio system, LED taillights and many other equipment.