On what devices is it better to do mri? Types of tomographs: what power is the best MRI machine for diagnostics? What are the MRI machines

14.04.2020

Super high-field MR-system of expert class with tension magnetic field 3 T, with a full set of high-tech MR - coils for all localizations without exception (head, mammary gland, joints and "whole body"). In the MR-system MAGNETOM Verio managed to embody the incompatible:

on the one hand, the largest diameter of the aperture (70 cm) and the smallest length of the 3T system (173 cm), which reduces the discomfort associated with the study, makes it possible to provide care for overweight patients (table load capacity up to 200 kg) and patients with disabilities; the need and frequency of sedation in patients with signs of claustrophobia decreases;

on the other hand, the unprecedented informativeness of the method due to the high power of the magnetic field of 3 T. In clinical practice, the use of such a magnetic field allows the system to be used in functional neurology, orthopedics, breast research, angiology and cardiology at a fundamentally new level.

The innovative technologies underlying the MAGNETOM Verio MR system provide a tangible superiority over other MR tomographs, which can be formulated in a number of postulates:

the minimum currently study duration,
smaller slice thickness without loss of quality and resolution, which allows visualization of organs and tissues more thoroughly,
high signal-to-noise ratio, which in turn also guarantees a high-quality image, even if the patient's weight exceeds 100 kg,
the possibility of using 3D modeling, which provides additional diagnostic information due to the visualization of the pathological process in absolutely any plane,
the use of Tim ™ (Total imaging matrix) technology excludes additional repositioning of the patient and coils, which allows us, for example, to perform study of all central nervous system in less than 10 minutes!

MAGNETOM Verio's advanced field uniformity and a wide range of unique clinical applications set this system apart from the competition for high-end diagnostic MP studies at the highest level. Innovative technologies from Siemens expand the clinical capabilities of the method, form a variety of so-called clinical applications that allow the use of MR techniques based on a specific clinical task, taking into account the characteristics of this particular patient.

Siemens MAGNETOM Avanto 1,5 T, A Tim + Dot System

The most advanced and powerful MP \u200b\u200bsystem in the 1.5 T class of scanners with a unique "zero helium evaporation" technology. Leader in image quality, clinical capability and speed of MP examinations. MP system equipped with a unique Tim and Dot technology that allows you to work on a fundamentally more high level both in the quality of the obtained diagnostic images and in the range of clinical tasks to be solved. Matrix coil technology allows you to examine any area of \u200b\u200bthe body without the need to re-position the patient and without re-positioning the coils (up to a full body scan of 205 cm).

Tim-technology (Total imaging matrix) is a revolutionary development of RF path, RF coils and reconstruction algorithms using parallel imaging techniques. Tim - the first in the history of MRI to implement the concept of a surface coil of the entire patient's body and a multichannel radio frequency system to create a single imaging matrix. Tim Is, in a way, an analogue of multislice (multislice) CT technology. Tim makes MP exploration more flexible, more accurate and faster.

Siemens has developed technology performance optimization Dot (Day optimizing throughput) , the action of which extends to all stages of work. Basic principle of operation Dot - the maximum possible automation of the process of setting up and selecting the optimal parameters for MP-scanning (in each specific case, for each specific patient) with one goal - obtaining an expert-quality MP-image. The actions of medical personnel are focused on choosing from the options offered by the system of those items that characterize this particular patient. Dot allows you to select the optimal cardioscanning mode 50% faster, taking into account the anatomical and physiological characteristics of the patient, to speed up MP-studies in the field of neurology by 30%, and to simplify the preparation for expert studies. Dot expands and enriches technology Tim providing additional stability in image quality, reducing the risk of possible diagnostic errors.

MRI is a popular and reliable research technique internal organs... This diagnostic method is considered because it uses electromagnetic waves that do not harm the human body. For scanning, special devices called tomographs are used. The main components of the design of such devices are:

Software that receives and processes information;
Magnet;
Cooling system;
RF, gradient, shimming coils;
Protective screen.

There is a wide variety of equipment for MRI, which differ different characteristics... The question as to which device is better and what is the difference between them is quite popular, it requires an answer.

Being a complex technical equipment, tomographs are distinguished by a large number of features. The main ones include the following:

Device type;
Magnetic field voltage;
Duration of scanning of a specific area of \u200b\u200bthe body;

Discussion of these characteristics will help to select the appropriate type of device for magnetic resonance imaging.

Indoor or open

The main classification of MRI machines divides them into two types: open and closed tomographs.

A closed apparatus is a complex of a special moving table and a long pipe. The patient is placed in this tube, where the examination is performed.

This type of device has the following advantages:

Increased power (magnetic field intensity from 1.5 to 3 Tesla), the ability to conduct more detailed and high quality;
Higher screening speed compared to an open device;
Resistant to unforeseen patient movements.

The main disadvantages of closed devices are as follows:

Inability to study patients with large weight;
Difficulties in examining patients with;
A complete ban on working with subjects with electromagnetic or metal implants, prostheses, etc.

Open-view equipment includes tomographs with a working surface placed above the patient table. The only major difference is the top position of the magnet. There is free space on the sides of the patient, which reduces the feeling of anxiety and reduces noise.

Pros of open devices:

Ability to diagnose overweight people;
Comfortable conditions for exploring children and people suffering from a fear of confined spaces;
Less dependence on foreign metal objects in the human body. They will only interfere if they are directly in the area of \u200b\u200bthe diagnostic magnet;
Silence;
Lower cost.

Main negative side low power appears and, as a consequence, the difficulty of diagnosing small or weakly expressed formations or functional states.

The attending physician decides which device is best for MRI, who has assessed all the prerequisites and contraindications. The difference between open and closed tomography for a patient is solely in the field of psychology. It is easier for people with claustrophobia to undergo testing on the apparatus open type, patients without phobias will not notice significant differences. For a specialist conducting an examination, the main thing is the accuracy of the data obtained, and in this indicator, a tunnel tomograph has a significant advantage. For example, for MRI of the brain, high-field and ultra-high-field scanning modes are used, which are not available for an open device.

Classification by magnetic field strength

Another sign of the classification of diagnostic MRI equipment is the magnetic field strength, measured in Tesla.

This parameter directly affects the resolution of the tomograph, the quality and information content of the examination depends on it.

Experts identify the following classes of equipment:

Low floor installations. The field strength of the magnet does not exceed 0.5 Tesla. The information content of scanning on such devices is not great, the resolution makes it possible to see only objects not less than 5 - 7 mm, it allows to record only a gross, pronounced pathology. Qualitative examination of the brain or dynamic MR-angiography is not possible here;
Medium-field devices with 0.5 - 1 Tesla differ in information content, slightly exceeding the indicators of the first group, therefore, they are not popular;
High-field installations show a field strength of 1 - 1.5 Tesla and are the most common type of apparatus offering optimal quality for relatively little money. Such tomographs distinguish pathology up to 1 mm in size;
Ultra-high-field equipment with a tension level of 3 Tesla makes it possible to carry out high-quality cerebral circulation, spectroscopy and tractography, receive information not only about the anatomy of organs, but also about the functional parameters of the organism.

Equipment manufacturers

The main manufacturers of tomographs are Siemens and Philips corporations.

Siemens is a German concern, founded in 1841, operating in the industries of electronics, power equipment, transport, medical equipment and lighting. The corporation sells ten types of MRI machines that are highly economical, quality, safe and easy to maintain. The corporation's solutions are used in clinics almost all over the world.

The second leading manufacturer of tomographs is Philips. It is a Dutch corporation that has been active since 1891 and focuses on the healthcare, lighting and consumer products industries. The holding is a leader in the production of equipment for cardiology, home health care, emergency care and complex diagnostics.

Philips devices are no less popular with doctors all over the world due to their equipment with gradient characteristics and Sence technologies.

Summarizing

Magnetic resonance imaging devices are complex technological complexes with a number of characteristics that influence their choice as a diagnostic tool for patients. After analyzing the anamnesis and contraindications, the attending physician decides which tomograph is best for MRI in each case.

Closed devices make it possible to carry out deep and high-quality diagnostics of human organs. For example, for MRI of the brain, only high-field, and even better - ultra-high-field tunnel-type devices are used. However, they have high research costs and are not suitable for overweight people and patients with phobias. Open or low-field devices are suitable in cases of analysis of gross pathology, when images with moderate characteristics of organ imaging are enough for a doctor.

Magnetic resonance imaging is a diagnostic method based on the use of radio-magnetic radiation, the power of the MRI determines the voltage that the device generates. The examination is necessary for the diagnosis of many diseases in traumatology and orthopedics, surgery, oncology, cardiology and pulmonology. The MRI diagnostic method is harmless, unlike X-rays, it does not cause negative reactions and can be used.

The detail of the images obtained depends on the power of the MRI machine.

The unit for measuring the power of the tomograph is Tesla, it is the most important characteristic. There are 3 types of devices:

Low floor - power 0.3-0.5 T. They are distinguished by economical energy consumption and ease of use. The advantage is the low cost of the examination. Most clinics and diagnostic centers are equipped with such tomographs. Among the disadvantages of these MRI devices, one can single out the low information content of the examination, the resolution does not allow detecting objects less than 5-7 mm. It is impossible to carry out effective diagnostics of cardiovascular diseases, brain pathologies, MR-angiography on tomographs with low power. They are necessary only to identify large pathologies, among them intervertebral hernia... The examination time for one part of the body on a low-floor apparatus is 30-40 minutes.
High-field - with a capacity of 1-1.5 T. Today, these tomographs are the most preferred all over the world. They provide accurate diagnostics with minimal errors. They are used for a complete examination of all organs and systems. In most cases, powerful high-field tomographs detect vascular diseases without using contrast agent... The resolving power of magnetic resonance devices helps diagnose objects 1-2 mm in size. Some good high-field MRI machines allow you to diagnose the whole body in one scan, which is impossible with computed tomography... Regardless of the power, the examination time is 10-20 minutes.
Superfloor - the power of the devices is 3-7 T, they are mainly used in research institutes. The information content is very high, but the cost of examining them is beyond the reach of most people. Sometimes high power MRI machines are used to detect rare pathologies. They are used for MRI of the brain, they are able to perform tractography, spectrography, etc. The power of the MRI apparatus allows not only to diagnose brain diseases, but also to reveal microformations and features of the morphology of brain structures. With the help of ultra-field tomographs with increased power, scientists are examining the brain and hope to fully study the sensorimotor cortex.

Which is the best MRI scanner?

In practice, tomographs of 2 types are used: open and closed.

A closed-type tomograph is a hollow capsule in which a person is placed for diagnosis. The diameter of the device is 60 cm, and the depth is 2 m, the power is different. The advantages of a closed-type tomograph include the fact that it allows you to achieve a clear image due to the higher magnetic field strength. The capabilities of the field of tomographs allow examining any organs and systems of a person with the same accuracy. With a sufficient number of positive aspects, closed-type MRI has a number of disadvantages:

the device creates a significant level of noise, which can bring discomfort to the examinee; in most clinics, before the start of the diagnosis, the patient is given earplugs or headphones;
the inability to use in people with claustrophobia, a closed pipe can cause a panic attack even in a healthy person, therefore, before the examination, patients with a fear of a closed space are prescribed sedatives;
despite the high power, the closed equipment does not allow to maintain visual contact with the doctor, which can cause discomfort for the patient, it will be possible to communicate only using the microphone built into the tomograph;
the inability to conduct an examination in a patient weighing more than 120 kg;
mRI cannot be used for patients with injuries who have fixation of some parts of the body, a limb that is cast in a certain position will not allow diagnostics in a closed apparatus;
the impossibility of using for the diagnosis of small children, for an effective examination it is necessary to remain motionless for a long time, it is difficult for children to do this due to age;
inability to conduct MRI of the spine and other organs or systems in the presence of metal devices and electronic devices in the patient's body.

The open-type tomograph is very similar in power characteristics to classic apparatus, the difference is only in the location of the camera and a free side view. The advantage of the open device is the absence of a pull-out table, which allows prescribing examination for people with significant body weight. The procedure can also be performed by patients with a fear of a confined space. Open machine tomography is used in people with injuries and fractures, psychological illnesseswhich cannot be placed in a closed apparatus. Open MRI produces a low noise level, which makes the device more comfortable to use.

The power of an MRI unit is measured in Tesla (T)

Despite its power, an open MRI machine has a couple of significant disadvantages:

impossibility of creating a high magnetic field in open space, which affects the quality of the resulting images.
Open MRI does not allow diagnostics of small organs, vessels.

To carry out the procedure in an open tomograph, due to its power, it takes more time, the main indication for its use is confirmation of a previously made diagnosis. Open-type devices make it possible to undergo examination in more comfortable conditions, but give less clear images. Closed-type tomographs provide more accurate information, but they have a large number of contraindications.

To establish an accurate diagnosis and prescribe adequate treatment, sometimes you cannot do without professional diagnostics. High power MRI scanners can detect serious diseases and pathologies on early stage... When choosing a device, the patient should pay attention to the complexity of detecting the alleged pathology and possible contraindications... But the final decision should be entrusted to the doctor. Read on to find out in what equipment they make MRI with dental implants:

To date, the diagnosis of diseases with MRI devices is considered the most informative, although quite expensive procedure. The work of tomographs is based on the use of the phenomenon of nuclear magnetic resonance. MRI machines 3 Tesla and higher provide the creation of a super-powerful magnetic field, which allows you to get better images of the examined area. Does such a diagnosis harm the body?

The essence of the scanning technique

The examination does not require any intervention in the body (non-invasive method), and for its implementation, equipment that generates a certain magnetic field strength is used. The MRI study uses the effect of magnetic waves that change the behavior of the nuclei of hydrogen atoms that make up cells human body... The result of this action is photographs of the surveyed areas.

The essence of the technique is in the registration of emitted radio signals, which in whole and healthy cells differ significantly from the radiation of structures damaged by the disease. After processing the result by a computer, the doctor receives a series of images with well-visualized changes.

Modern MRI machines are capable of generating a field of varying power, which is measured in tesla (T). The unit for measuring magnetic intensity was named after the genius experimental scientist of the last century, who surprised the world with inventions in the field of electricity. Focusing on the strength of the generated magnetic field, the classification of tomographs is as follows:

for low-field devices - 0.25-0.35 Tesla;
for medium-field - 1.0 tesla;
for high-field - 1.5-3.0 tesla.

The magnitude of the field strength depends on the properties of the magnet installed in the device. However, it should be borne in mind that superconducting magnets are more expensive than low-strength magnets. Less expensive MRI devices with power below 1 Tesla do not make sense to use, their data will not be accurate and reliable.

What are the advantages of a 3 Tesla device compared to a low power tomograph:

less time will be required to conduct the study;
the resulting images will be of higher quality due to the high resolution;
small structures (vessels, joints, etc.) will be displayed with high accuracy.

It is important to know: in spite of the power of the equipment, a short time spent by a person in the range of a magnet does not harm health. Therefore, the diagnostics can be performed more than once. The appearance of unpleasant sensations is associated only with the use of contrast.

How tomographs of different power are used

1 T. The power of medium-field devices of this magnetic field strength is sufficient only for preliminary diagnostics. Tomographs help to establish the presence of a tumor or metastases, but with low image quality, without displaying thin structures and tissues.
1.5 T. Tomographs of this class can be used to assess the condition blood vessels, review of small problem areas, identification of the border of the metastatic zone. Only such tasks will guarantee reliable results.
2 T. The devices are not very popular because they are used to detect tumors and abnormal development organs have enough power of 1.5 Tesla. Despite good quality images and high accuracy, the details necessary for treatment are not visualized.
3 tesla. Thanks to high-field tomographs of this group, it is possible to better identify structures that are indistinguishable during examination with low-field devices. Scanning in this case is much faster, which is important for injuries, especially of the skull.
Diagnostics on tomographs 4 Tesla and more powerful are not performed, the devices are used for scientific research. MRI rooms are mainly equipped with 1.5 Tesla tomographs; for special types of scans, 3 Tesla tomographs are used.

Important. As a result of scanning the body with MR machines, layer-by-layer images of the selected area (slices) are obtained. The thinner the sections can be obtained, the more detailed the morphological picture of the tissues will be. The key to accurate diagnosis is a more powerful magnetic field, which shortens the procedure time.

Advantages of 3 Tesla tomographs

Despite the presence of a magnetic field in the area, the patient does not receive a dangerous radiation load, does not feel any special discomfort, except for the need to lie still. For the study of pathologies, tomographs of two types are used - open and closed. True, the power of open complexes, which provide tomography of a part of the body immersed in the camera, is somewhat lower than the power of closed devices, which is reflected in the quality of the obtained sections.

Examining the head area

For examination of brain structures, 1.5 T is often sufficient, therefore, MRI of the brain is performed with high-field devices of minimum power. But if it is necessary to clarify the picture and obtain high-precision results, the doctor can prescribe an MRI on a 3 Tesla machine. What information is provided to the doctor by a tomogram performed on this tomograph:

visualization of small structures of the brain with a higher contrast than on a 1.5 Tesla apparatus;
a detailed review of the membranes of the studied organ, the state of the vessels;
information about the smallest foci of neoplasms due to the thinnest (less than 1 m) tissue sections;
high-precision topography of the head structures after traumatic brain injury;
detailed information about the pathologies of the brain in the sections adjacent to the spinal zone.

Among the important advantages of the 3 Tesla complexes is the increased quality of the sections with high accuracy of the information obtained about the functioning of the brain. This can be achieved even without the use of contrast, and tomography is more informative than computer diagnostics, passes faster, does not expose the patient to X-ray irradiation.

How long will the MRI procedure take? When examining with a 1.5 T apparatus, the time of magnetic diagnostics will last 12-15 minutes. The duration of an MRI scan on a 3 Tesla tomograph will be reduced to 5 minutes.

Spine overview

For examining the spinal column, magnetic resonance imaging with a 3 Tesla tomograph is prescribed for back injuries, to detect structural anomalies, progressive pathologies. The use of high-field tomographs is important for examining small patients, people with severe injuries, when the speed of the procedure is important.

For what purposes it is necessary to undergo an MRI of the spine on a 3 Tesla apparatus:

detection of congenital malformations, injuries of intervertebral discs;
diagnosing places of narrowing of the spinal canal;
detection of tumors and their nature, metastases from other organs affected by oncology;
fixing areas with insufficient blood flow, damage to nerve structures.
identifying the consequences of osteochondrosis, the state of intervertebral hernias.

Disadvantages of 3 Tesla devices

Some patients suffer from intolerance to the confined space of high-field tomographs. If mild sedatives are not enough, the study will have to be abandoned.
MRI equipment with field strengths above 1.5 Tesla has limited dimensions of the tunnel where the table with the patient is located. Therefore, especially obese people will not be able to undergo diagnostics.
With high pain syndrome, which affects the back and neck, the patient will not be able to maintain immobility long time... This is especially true when using contrast media.

If the examined organ allows, a person can undergo MRI diagnostics on an open (low-field) tomograph or turn to alternative methods of examination. True, they do not guarantee high reliability and accuracy of the results.

Thanks to innovative technologies, high-power devices have been created today, giving higher image resolution. However, tomographs with a capacity of up to 7 Tesla are used quite rarely, only for detecting malignant tumors, since the equipment is extremely expensive. To obtain detailed sections on the state of the surveyed area, tomographs of a high magnetic field with a strength range of 1.5-3 Tesla are sufficient.