MRI or computer diagnostics. MRI or CT of the spine: what is better, what is the difference

Both of these procedures have identical goals - they are designed for step-by-step scanning of the body, as a result of which the doctor has the opportunity to study the necessary area “in section”. However, the principles of operation of computed tomography and magnetic resonance imaging are completely different, which affects the capabilities of each of these devices.

Physical and functional features of CT and MRI: what is the difference?

The common point for both methods under consideration is that the necessary information is displayed on a computer, so that the doctor has the opportunity to obtain a three-dimensional image internal organs and fabrics.

The main difference in the principle of operation of MRI and CT is in the nature of the waves that are produced by tomographs.

• Computed tomography involves the use x-rays , which emanate from the domed outline. The couch with the patient is placed inside this very contour, which makes it possible to shoot the desired area from a variety of angles.
• The magnetic resonance device operates on the basis of electromagnetic waves . Radio frequency coils, which are located in the field of study, fix the transformations that occur with hydrogen atoms.

Video: Which is better - CT or MRI?

In connection with the application various types radiation, the capabilities of CT and MRI differ.

These differences are detailed in the table below:

CT scan
The best technique to date for the study of bone structures. Helps to identify pathological neoplasms on the bone, inside it.	Poorly copes with the recognition of fractures. Ideal for identifying injuries associated with ligaments, joints, menisci.
Effective in the study of the lungs.	Ineffective in the study of the lungs.
Detects calcifications of various parameters.	Small calcifications electromagnetic fields are not captured.
Good for detecting "fresh" brain injuries.	Not always able to recognize hemorrhages in the brain. Does the job perfectly general survey brain states.
Can be used for soft tissue diagnostics.	Much better at detecting pathological conditions in soft tissues than any other diagnostic technique.
It is applicable to check the organs of the peritoneum and small pelvis, as well as the chest.	Used to study the spinal column.

Indications for CT and MRI - are there any contraindications?

Magnetic resonance imaging will be more effective in the following situations:

1. Impossibility of CT scan due to intolerance of the staining substance by the patient.
2. Inflammatory processes in brain tissues.
3. Diseases muscle tissue, joints, ligaments.
4. Diagnosis of multiple sclerosis.
5. Pathological neoplasms of the spinal cord, brain.
6. The study of the structure of the pituitary gland, intracranial nerves.
7. Determination of the exact stage of cancer.

Despite the information content of both considered diagnostic methods, in some cases they cannot be assigned. This is due to the specifics of the waves on the basis of which the devices operate.

CT is not performed in the following situations:

• The period of bearing a child.
• Serious errors in the work of the kidneys, thyroid gland.
• Diabetes.
• Patients weighing more than 200 kg. This is due to the fact that the table of the apparatus is designed for a certain body weight.

In addition, CT scans are prescribed for children only if other diagnostic measures have failed.

There are many contraindications for MRI:

1. The presence of metal structures in the patient's body, as well as on the surface of the body: metal dental implants,. When using paint for a previously applied tattoo containing metal grains, this procedure is also not prescribed.
2. Electrical devices implanted in the body: hearing aid, pacemaker, insulin pump. Electromagnetic radiation can cause damage to these devices.
3. Bouts of claustrophobia.
4. Nervous disorders in which the patient cannot long time stay in a stationary position.

For women who are carrying a child, the procedure in question can be carried out from the second trimester of pregnancy.

Video: What is the difference between CT or MRI, for which diseases?

Features of the preparation and conduct of CT and MRI - which type of diagnosis is safer?

1. Since both of the manipulations under consideration involve the patient staying a certain amount of time in a stationary state, sedatives may be used before the start of the examination.
2. Before any of these procedures, it is necessary to remove all metal objects, incl. - removable dentures, Hearing Aids. Clothing should be without zippers.
3. Due to the use contrast agent, before computed tomography food and liquids are prohibited.
4. Upon completion of the diagnosis, it is necessary to drink more so that the contrast quickly leaves the body.
5. In case of hypersensitivity to certain drugs, the patient should notify the doctor in advance. The fact is that an iodine-containing contrast agent, through which you can view the internal organs, can cause an allergic reaction.

- With magnetic resonance imaging you need to prepare in advance only when examining the condition of the internal organs of the peritoneum and small pelvis.

In the first case, a couple of days before the manipulation, you should minimize the amount of products that can provoke gas formation.

On the day of the MRI, eating and drinking is prohibited. You should come to the diagnosis of the pelvic organs with a full bladder.

- CT scan takes much less time than MRI: 10 and 40 minutes, respectively.

In some cases, both procedures may be delayed: for example, when using sedatives before diagnosis.

• In terms of security, a kind of "gold standard" is considered Magnetic resonance imaging . The rays produced by the device do not cause any harm to health. This explains the possibility of its use in children and the elderly. In addition, this diagnosis can be carried out as many times as required.
• Functioning computed tomography is directly related to X-ray radiation, which leaves a certain negative imprint on health. Although the dose received by the patient is insignificant, but this is the basis for limiting the passage of several sessions of CT diagnostics in a row.

Each of the considered methods has a number of advantages:

1. Low chance of developing side effects upon completion of the survey.
2. Absence pain at the time of the research.
3. Obtaining accurate and reliable information regarding the state of internal organs, tissues and bone structures.

CT differs from MRI in terms of how it works. At the discretion of the doctor, one or another procedure may be prescribed. Depending on which area of ​​the body should be examined, the selected and diagnostic method. Also, in many respects, the diagnostic method depends on how many times short period time will need to be examined. Each of the methods has its own advantages and disadvantages. They are useful to know for a patient who must undergo diagnostic examination using a computer or magnetic resonance tomograph.

Both methods are highly informative and allow you to very accurately determine the presence or absence of pathological processes. There is a fundamental difference in the principle of operation of the devices, and because of this, the possibility of scanning the body with the help of these two devices is different. Today, X-ray, CT, MRI are used as the most accurate diagnostic methods.

Computed tomography - CT

Computed tomography is performed using x-rays and, like x-rays, is accompanied by irradiation of the body. Passing through the body, with such a study, the rays make it possible to obtain not a two-dimensional image (unlike an x-ray), but a three-dimensional one, which is much more convenient for diagnosis. Radiation when scanning the body comes from a special ring-shaped circuit located in the capsule of the device in which the patient is located.

In fact, during a computed tomography scan, a series of sequential x-rays(the impact of such rays is harmful) of the affected area. They are performed in different projections, due to which it is possible to obtain an accurate three-dimensional image of the area being examined. All images are combined and turned into a single picture. Of great importance is the fact that the doctor can look at all the images separately and, due to this, study the sections, which, depending on the settings of the device, can be as thin as 1 mm, and then also a three-dimensional image.

Thus, during a CT scan, the patient receives a certain dose of radiation, as with an x-ray, which is why the procedure cannot be called completely safe.

Magnetic resonance imaging - MRI

Magnetic resonance imaging also provides a three-dimensional image and a series of images that can be viewed separately. Unlike CT, the machine does not use X-rays and the patient does not receive any radiation dose. Electromagnetic waves are used to scan the body. Different tissues give different responses to their impact, and therefore an image is formed. A special receiver in the device captures the reflection of waves from tissues and forms an image. The doctor has the opportunity to enlarge, when necessary, the picture on the screen of the device and see the layer-by-layer sections of the organ of interest. The projection of the images is different, which is necessary for a full examination of the area under study.

Differences in the principle of operation of tomographs give the doctor the opportunity, when detecting pathologies in a particular area of ​​the body, to choose the method that in a particular situation can provide more complete information: CT or MRI.

Indications

Indications for conducting a survey using one method or another are different. Computed tomography reveals changes in the bones, as well as cysts, stones and tumor formations. MRI shows, in addition to these violations, also various pathologies soft tissues, vascular and nerve pathways, articular cartilage.

Indications for MRI	Indications for CT
Soft tissue tumors and suspicion of their presence	Bone damage, including jaw and teeth
State Definition nerve fibers in the internal organs, as well as the brain and spinal cord	Determination of the degree of damage to the joints in injuries and chronic diseases
Determining the state of shells spinal cord and brain	Identification of diseases of the spine, including intervertebral hernias, osteoporosis and scoliosis
The study of the state of the brain after a stroke and during multiple sclerosis	Determination of the degree of brain damage in neoplastic diseases and injuries
Determination of the condition of muscles and ligaments	Determination of the state of the chest organs
Determination of the state of the joints	Definition of neoplasms in the thyroid gland
Inflammatory and necrotic processes in organ tissues and bone tissues	Determination of changes in hollow organs
MRI of the lungs can be performed when establishing the presence of a tumor process even at the very beginning of its development.	Determination of the presence of stones in gallbladder and genitourinary system

In some cases, a computer or magnetic resonance tomograph can be used with an equal share of information content. Thus, depending on the equipment of the medical institution, the examination can be carried out using one or another type of equipment for scanning the state of the body.

Contraindications

Both scanning methods have some contraindications for use. In some cases, when the implementation of one method of research is not desirable or prohibited, the option of conducting a second one may be considered.

Contraindications for CT	Contraindications for MRI
Pregnancy	The presence of metallic elements in the body
Breastfeeding (if the procedure is performed, breastfeeding must be interrupted for 48 hours after the examination so that the child does not receive a dose of radiation)	The presence of implanted electronic correctors of the work of internal organs and systems
Children's age (the only exceptions are cases when there is no other way to determine the patient's condition, and the benefits of the diagnosis outweigh the risks of the procedure)	Presence of an insulin pump
Patient weight over 200 kg	First trimester of pregnancy
Nervous excitement in which the patient cannot remain still during the scan	Weight over 130 kg
Frequent use	Inability to stay still for as long as necessary for the procedure
Plaster cast at the site of examination	Claustrophobia

In the contrast-enhanced procedure, the contraindications for both procedures are the same. This is due to the fact that the contrast agent has limitations for use. It should not be administered in the presence of severe renal and liver failure and allergic to contrast.

If it is not known whether there is an intolerance to the agent, then a test for an allergy to a contrast agent is preliminarily performed. Several types of contrast can be used and, as a rule, it is possible to choose a tool that suits a particular patient.

How often can I scan

CT is performed using x-rays, and therefore frequent repetition of the procedure is not allowed. As a rule, it should not be carried out more than 1 time per year. If you have cancer, regular monitoring which is necessary, the minimum interval between examinations is 2.5 months. In this case, it is better to use MRI, in which there is no negative impact on the body of radiation, which is important to prevent complications. The procedure is not only safer, but completely harmless. MRI can be performed an unlimited number of times, and if necessary, even several scans in 1 day.

When using scanning with contrast, there are also no restrictions on the frequency of the procedure. The only thing to consider is the break between repeated injections facilities. It is desirable to withstand at least 2 days to reduce the burden on the kidneys. The contrast agent does not cause harm to health. If it is used for CT, then all the limitations are directly related to the X-ray exposure, and not to the effect of the contrast on the body.

Is it possible to have an MRI and a CT scan on the same day?

The principle of impact on the body during examination using computed tomography and magnetic tomography is different, and therefore, when they are combined, the body does not receive an overload. If necessary, both types of tomography can be performed on the same day without fear for health. It's completely safe.

The difference between methods in the study of the brain

Brain scanning is necessary for many disorders, including strokes, circulatory disorders and tumor processes. If you need to take pictures frequently to monitor the condition, then MRI should be preferred, since it does not pose a danger if it is often repeated. Which method will be chosen depends entirely on the equipment of the clinic and the patient's contraindications and restrictions to the procedure.

According to CT and MRI, when studying the brain, they receive equally accurate results, and therefore there will be no differences in diagnosis. Both types of research will show tumors, vascular disorders and foci of inflammation. Additionally, MRI can also determine the density of brain tissue.

An important feature of magnetic resonance imaging is the ability to detect the focus of an ischemic disorder 20 minutes before it develops. acute condition sick. Because of this, if a pathology is suspected, it is an MRI that is performed.

What is best for lung scanning

If there is a suspicion that the fragments of the ribs have affected the lungs during the injury, then a CT scan is indicated, since this procedure will most accurately demonstrate the presence of bone fragments. The same scan is used for injuries to rule out or detect bleeding. Since computed tomography is performed especially quickly, in emergency conditions it is the most optimal. Also, the procedure allows you to very accurately determine the presence of metastases; CT of the lungs also shows secondary cancerous tumors.

MRI of the lungs is more often prescribed for tumor and inflammatory processes. Examination shows such changes in soft tissues very clearly and allows you to track the dynamics of their development without the risk of excessive exposure of the body.

Differences in the effect of tomographs on the body allow you to get maximum information.

What is optimal in the study of the abdominal cavity

There are no strong differences in the information content of the methods. The exception is that CT better determines the density of organ tissues. abdominal cavity, and you can quickly establish the presence of solid formations and objects, bone fragments and bleeding. In case of traumatic injuries of the abdomen, CT is recommended, since the speed of the procedure makes it possible to identify dangerous violations in the shortest possible time.

MRI provides the most accurate information about the condition of soft tissues and the presence of inflammatory processes in the abdominal cavity. Because of this, the procedure is more often performed when examining the condition, pancreas, liver, spleen, intestines, etc.

What is more informative for diseases of the joints

In case of joint damage, including the hip joint, both CT and MRI are prescribed. Patients are naturally interested in which method is more informative and reliable. In case of disorders in the joints, magnetic resonance imaging is most often performed, which allows you to get maximum information about all tissues, including soft ones, inflammation of which is often accompanied by joint diseases.
In case of injury or chronic pathologies MRI allows you to determine the condition of even nerve fibers, tendons, ligaments and blood vessels.

CT of the joints is used for injuries when the presence of damage to the bones or their heads that form the joint is suspected. During this procedure, bleeding into the joint cavity and the presence of bone fragments are quickly detected. Also, this study is carried out for diseases and injuries of the joints, if there are contraindications for magnetic resonance imaging.

If it is necessary to regularly monitor changes in the joint, then only MRI is used, since X-ray overload of the body poses a great threat. For children with problems with the joints, only an MRI is performed.

Which scan is best

Each of the methods is highly informative. The choice of which examination will be carried out depends on the contraindications and which tissues should be examined first. If there is a suspicion of a problem with skeletal systems, the doctor chooses CT, and with soft ones - MRI. It cannot be said that one diagnostic procedure is better and the other is worse. Each method is more efficient for getting certain information. More dangerous to health is CT, but if the examination is carried out correctly, x-rays will not cause negative consequences.

Where is it done and how much does the procedure cost?

The cost of the examination depends on the scanning area and what generation of equipment is used (the difference in price depending on the type of device can be quite large). The clinic in which the procedure is performed also matters. In state medical institutions You can undergo a CT scan for 3-4 thousand rubles, and an MRI costs from 4 to 9 thousand rubles, depending on the organ being examined. The most expensive is a brain scan.

CT scan

Magnetic resonance imaging

The choice of diagnostic method remains with the attending physician. Both MRI and CT should only be done for medical purposes.

CT and MRI (computed and magnetic resonance imaging) in modern medicine are considered the most advanced methods for diagnosing the health of internal organs and human systems. There are very few problems that can escape the attention of radiologists studying the results of these two CT scans. Each of the methods has its own advantages and disadvantages, on the basis of which the patient and his attending physician can choose which diagnostic method is best.

But first, you should still understand what a study with CT and MRI machines is.

Technology

To determine the leader among the most modern diagnostic procedures, you first need to understand how they work. CT and MRI are united by the fact that during their conduct the patient lies on a special table-tray, which enters the main part of one or another apparatus. Examination on a computer or magnetic resonance tomograph allows you to obtain data in the form of a layered image (with a slice thickness of 0.5 mm), coming to the screen to specialists for visualizing the organ under study and deciphering the result. This is where the technical similarity between the two methods ends.

Computed tomography differs from magnetic resonance imaging in that it is performed using a low dose x-ray radiation, which passes through the body in a fan beam with simultaneous movement of the table with the patient inside the tomograph and the movement of the radiation source in the device itself. The rays are further converted into electrical signals, captured by special sensors and sent to a computer to process the data into images.

The MRI method is based on an artificial magnetic field in which the patient is placed. Lined up parallel to the surface of the field, hydrogen atoms, which are the most in the human body, under the influence of the tomograph signal, generate a special response that is captured by the apparatus. "Sound" from different types fabrics comes from different levels intensity, on the basis of which the device creates the finished image.

From a comparison of the methods of work of CT and MRI, we can conclude that a computer study, due to the use of radiation, is inferior to its rival, since the risk of an overdose of radiation excludes this procedure for pregnant women and young children.

About contraindications

The list of contraindications for CT and MRI has practically no common positions. So computed tomography is contraindicated:

• women during pregnancy and lactation;
• children under the age of 2 years;
• patients with body weight and volumes greater than the design of the apparatus allows.

When performing CT with the use of contrast, in addition to the listed groups of people, patients with:

• allergic intolerance to the contrast agent;
• renal (in acute form) insufficiency;
• diabetes mellitus;
• problems with the performance of the thyroid gland;
• general severe condition.

Diagnosis by MRI is prohibited for people with:

In addition to these factors, it may be difficult to perform an MR scan if patients have:

• claustrophobia;
• nervous disorders or an inadequate state due to intoxication (alcohol / drugs), panic, psychomotor agitation.
• a condition in which specialists need to exercise control over vital important indicators or carry out resuscitation.

Thus, the volume of contraindications for CT and MRI is approximately the same, therefore the best choice in favor of this or that method, the attending physician, who has the medical history and anamnesis of a particular patient, will help.

For different indications

Strictly speaking, CT is different in that it allows you to consider the physical state of the objects in question, and MRI serves to identify their chemical characteristics. Therefore, although both methods can be used in parallel to more accurately examine the same organ, CT is more often used to scan bone, and MRI is used to scan soft tissues.

Computed tomography is most often prescribed for:

MRI is the most effective method for:

• checking the condition of the spinal cord and brain;
• diagnostics of the state of the pelvic organs;
• monitoring the health of the esophagus, aorta, trachea;
• stroke detection late stage.

In addition to differentiation according to the most effectively detected diseases, CT and MRI methods differ from each other according to the principle better examination certain organs and systems of the body. So computer scanning is most often used to examine the skeleton, lungs, heart, liver, pancreas, urinary system. Such diagnostics allows to detect hemorrhages and tumors. different nature with the highest level efficiency.

In turn, MRI is a diagnostic method, with detailed visualization accuracy demonstrating all organs and systems hidden under dense bone structures, or having a high percentage of fullness with liquids. Such a scan allows you to get maximum information about the state of the skull, brain and spinal cord, the joint system, the structure of the intervertebral discs, and organs located in the small pelvis.

Preparation and procedure

If more data is needed to determine what better MRI or still CT, you can compare the process of preparing for a particular event and the actual procedure. In both cases, no special preparations are necessary, unless it is a scan with contrast injection.

To undergo a contrast CT scan, the patient will have to refuse food a few hours before the examination, especially if the procedure is carried out with the introduction sedatives(a common practice for dealing with claustrophobia and diagnosing children). If a person is allergic to a contrast agent or sedatives, doctors perform premedication, after which they place the patient on a table that enters the cavity of the tomograph. When performing a contrast scan, the procedure is performed twice - before and after the introduction of contrast, to compare the results. The process of tomography lasts 10-15 minutes, it will take longer to wait for the end of the sedatives.

The MRI procedure requires the patient to prepare in advance if a contrast agent is needed, and in this it does not differ from computed tomography. Also, preparation is needed for magnetic resonance scanning of the abdominal cavity and small pelvis - at least a couple of days before the examination, the patient should exclude foods that stimulate gas formation from the diet, immediately before scanning the abdominal cavity, he will have to give up food and water altogether, and to examine the organs of the small pelvis to take care of fullness Bladder. An MRI takes longer than a CT scan, up to 30-40 minutes on average, which people with claustrophobia or pain syndrome may seem like an eternity.

The most important comparison

Choosing best method diagnosis, the patient has to evaluate many factors: indications and contraindications, effectiveness and complexity in preparation and passage. For the most part, the attending physician can make the choice for him - if there is complete information about the state of health of the body of the person who applied for help, the specialist is able to make a choice in favor of CT or MRI (as well as prescribe both types of scanning). But the question of price is the most important factor which is evaluated by the patient.

Computed tomography is much cheaper than magnetic resonance imaging. The cost of CT in Moscow is on average from 4,300 to 5,000 rubles per department human body(with the introduction of contrast, the price rises to 6,000-7,000 rubles). The cheapest MRI scan starts at 5,000-5,500 rubles per area. Comprehensive CT examinations of the whole body will cost patients 70,000-80,000 rubles, the same MRI service - 85,000-90,000 rubles.

Of course, there are situations when, according to indications, a person can undergo only computer or only magnetic resonance diagnostics, however, in most cases, the patient has a choice, and very often this choice is decided in favor of a lower cost.

The borders are almost erased

All the advantages and disadvantages of the main diagnostic methods play important role in choise the best procedure, however, the more modern and powerful tomographs become, the more the differences between them are leveled. Innovative computer devices carry out scanning with a controlled and constantly decreasing dose of radiation. MRI machines are increasingly being created in the form of open machines, in which the patient can be subjected not only to direct scanning, but also to the necessary medical procedures. CT and MRI examinations are becoming available and convenient to use.

And the winner is

Equality. It is impossible to say with absolute certainty, "MRI is better" or "CT is the best method." Both methods have their drawbacks, both are capable of performing diagnostic miracles, looking for the smallest damage in the body. You can not even consider the problem of the high cost of MRI - there are situations when a cheaper CT scan is simply not able to help. Therefore, everyone decides for himself which examination is the best for him specifically (not forgetting to consult with his doctor).

Often, to detect dementia, there is a need for expensive diagnostic procedures. This is where the question arises: which study is preferable - magnetic resonance imaging (MRI) or computed tomography (CT).

It should be noted that these are completely different diagnostic procedures. the only common feature is an principle of layer-by-layer scanning of an object, body parts, organ. Let us find out what is the fundamental difference between these studies and when they are more often used.

There are no significant differences between these studies in terms of technique. The patient lies on a couch, which is placed in a "tube". A scanner moves along the object, which makes layered images.

The main difference between MRI and CT is the use of different physical phenomena to scan an object.

MRI vs CT: What's the difference?

CT examination is carried out using X-ray radiation, i.e. receive information about physical condition substances, magnetic resonance imaging is performed using a magnetic field and radio frequency electromagnetic radiation of the device, which gives an idea of chemical structure tissues, fixing the distribution of protons.

To obtain an image on a CT scanner, the same principle is used as in x-ray machines. Rotating around the patient's body, CT scanner takes a series of pictures from different angles. The resulting images are processed by a computer.

When conducting an MRI study, X-rays are not used. The patient is placed in a strong magnetic field, which causes all the hydrogen atoms contained in the patient's body to line up according to the direction of the magnetic field. Then the apparatus sends an electromagnetic pulse perpendicular to the direction of the main magnetic field. In this case, hydrogen atoms, which have the same vibration frequency as the signal, are "excited" and generate an electromagnetic signal, which is captured by the device. Various tissues (muscles, bones, blood vessels, and so on) contain different amount hydrogen atoms, and therefore generate response pulses of varying intensity. The tomograph recognizes and decodes these pulses and builds the image accordingly.

Fields of application of MRI and CT

With the help of MRI studies, soft tissues are well "visible": brain, muscles, nerves, ligaments, intervertebral discs etc. But, poorly "visible" hard tissues- bones of the skeleton containing calcium. It uses computed tomography or radiography.

Therefore, MRI is preferable for soft tissue lesions. It is widely used in neurosurgery and neurology (old brain injuries, cerebral infarctions at a late stage of development are clearly visible, and tumors of the brain and spinal cord are also detected). You can study the state of the vessels of the head and neck, using the natural circulation as a contrast.

Magnetic resonance imaging is not very informative in diseases of the lungs, gallbladder, bone fractures.

Computed tomography is ideal for diagnosing bone damage, kidney and lung injuries. CT examination is informative for diagnosing fresh bleeding, therefore it is used for fresh injuries of the head, chest, abdomen, cerebral infarctions at an early stage.

In addition, it is fundamentally different total time procedures. A CT examination of one area of ​​the body takes several minutes, while an MRI examination takes about 30 minutes.

As for the cost of the study, it directly depends on the cost of CT and MRI machines. For MRI studies, it is significantly higher, and the greater the magnetic induction of the device, the more expensive the study, but the higher the quality of the images.

Contraindications

Another important aspect is that pregnancy is a contraindication for CT (due to radiation), while MRI can be done after the 3rd month of pregnancy.

MRI is also contraindicated in those patients who have an implant, a pacemaker, or have periorbital metal fragments in the body, have artificial lens, metal prosthesis or clips, as well as rings, metal spirals. In case of aneurysm and arteriovenous malformation (AVM), only a CT scan is indicated.

In many cases, in order to set correct diagnosis doctors have to use both MRI and CT scans. The choice of one or another diagnostic method for a particular patient is determined by the doctor, taking into account fundamental differences these studies.

Video "The difference between MRI and CT examination"

A detailed analysis of the features of each technique will help to understand the difference between MRI and CT. Modern hardware diagnostics allows you to study the structure of organs and tissues in layers, provides a series of images of thin sections of the area under study. Both methods are shown with low efficiency. ultrasound and radiographs.

Computed and magnetic resonance imaging of the brain

Magnetic resonance and computed tomography have a number of significant differences that must be considered when choosing a diagnostic method. When comparing the two procedures, you should pay attention to the following factors:

• the method by which the scan is carried out;
• recommended scope of tomography;
• time spending;
• indications and contraindications for the diagnostic method;
• features of preparation for each study;
• types of contrast agent used in scanning;
• informative method.

MRI involves scanning tissues and organs using a magnetic field that penetrates the human body and causes a reaction that depends on the structures. Due to this feature, as a result of the study, it is possible to assess the state of the soft tissue structures of the studied area. CT is based on the use of X-rays, which also penetrate tissues and organs, but the intensity of their absorption is determined by the density of the structures of the area being examined.

The magnetic field allows you to visualize the state of soft tissues, so MRI is prescribed for diseases of the muscles and ligaments of the musculoskeletal system, pathological conditions nervous system, including the brain and spinal cord, pelvic organs and abdominal cavity.

MRI of the abdominal organs

To assess solid structures, CT is used, which is informative in differentiating diseases of bone and cartilage formations of the skull, spine, limbs, and chest cavity. Computed tomography shows the presence and size of neoplasms, hematomas, is effective in determining the pathologies of hollow organs, clearly visualizes the state of the lung parenchyma, heart and blood vessels.

Magnetic resonance and computer examinations have many differences, but preparation for either of them is practically not required. The techniques are simple and comfortable for the patient. Having determined the difference between CT and MRI, the patient can independently undergo the procedure in medical center in order to diagnose possible pathological conditions of the body.

How CT and MRI work

The principle of operation of tomography is to build images of tissue sections. The difference between CT and MRI lies in the method of obtaining tomograms of organs.

The principle of operation of CT

The method is based on the ability of X-ray radiation to penetrate the tissues of the human body, but, unlike the classical examination, CT provides a series of layered images taken at different depths. The thickness of the cut depends on the settings of the equipment.

When conducting CT, a modern device is used - a tomograph, which consists of a movable table and a ring. In the last - wide - part of the device are x-ray emitters. They commit circular motions, providing scanning of the studied area at the desired angle. The device, with the help of a complex computer program, converts the information into layered images and transmits the data to the monitor. The doctor can assess the state of the examined organ in the axial projection, if necessary, based on the obtained images, the sagittal and coronal planes are completed, and a 3D model of the scanned area is reconstructed.

To increase the information content of the method, a contrast solution is used, which is intravenously administered to the patient during the examination. The substance contains iodine, which is characterized by high radiopacity. Once in the blood, the solution visualizes vascular system of the examined organ, which allows assessing the nature of the blood supply and identifying diseases of the veins and arteries. CT with contrast is effective in the diagnosis of neoplasms, differentiation of diseases of hollow organs and soft tissues.

MSCT angiography of the vessels of the head and neck

How MRI works

The operation of MRI is based on the use of a magnetic field for scanning tissues and organs, the effect of which affects water dipole molecules. The tomograph reads the reaction of the cells and transmits the information to the computer monitor in the form of layered images.

Electromagnetic pulses cause an increased response from the soft tissues, which is the difference between MRI and CT. Solid structures do not give such a pronounced response to the action of the field, since the water content in them is much less.

The procedure takes place, like CT, in a closed room, where the patient is placed on a mobile table and placed in the tomograph tube. Magnetic resonance imaging takes longer than CT.

In order to increase the effectiveness of the examination, MRI uses contrast. This is special preparations gadolinium salts, actively reacting to magnetic waves. Contrast tomography is harmless to the body, increases the information content and quality of the images obtained.

MRI of the knee

CT and MRI: which is better?

When comparing which diagnostic method is better, it should be borne in mind that each study is assigned individually. The method of scanning depends on the area of ​​the lesion, the nature of the disease, and the health of the patient. Knowing what is the difference between computed tomography and MRI, you can choose a diagnostic method that will provide reliable and complete information.

The benefits of CT include:

• obtaining reliable information in the study of bone structures;
• clear image in the diagnosis of neoplasms, internal bleeding, hematomas;
• short duration of the study;
• the possibility of examination in the presence of metal implants and prostheses, as well as electromagnetic devices;
• low cost of the procedure.

When diagnosing the following conditions, it is preferable to choose the CT method, which in this case will give the best result:

• diseases and injuries of bones and joints;
• pathology of the organs of the chest cavity;
• thyroid examination;
• pathologies of the cardiovascular system;
• examination of the nasal sinuses;
• internal bleeding;
• diagnosis of traumatic brain changes and strokes.

Computed tomography will show the state of the organs, their shape, boundaries, visualizes structural changes, integrity violations, and reveals inflammatory processes.

Magnetic resonance imaging also provides reliable information and the possibility of obtaining a three-dimensional model of the organs under study. Other advantages of MRI are:

• patient safety;
• the possibility of repeated use for a short time;
• obtaining a clear image in the diagnosis of diseases of the central nervous system, determining herniated intervertebral discs.

MRI is preferable in the diagnosis of the following diseases:

• pathology of muscle tissue and ligaments of the musculoskeletal system;
• violations in the work of the abdominal cavity and small pelvis;
• pathological processes in the tissues of the spinal cord and brain;
• neoplasms and metastases in soft tissues, internal organs;
• pathological conditions of the joints;
• degenerative processes in the area of ​​intervertebral discs.

When prescribing an MRI or CT scan of the brain, you need to understand what the difference between these methods is. Both types of study provide a series of clear layered images and the possibility of 3D reconstruction. Magnetic resonance imaging is recommended to assess the condition meninges spinal cord and brain, with ischemic strokes and multiple sclerosis. CT is prescribed in case of traumatic lesions, hemorrhages and intracranial hematomas.

Arachnoid cyst of the brain on MRI

What are the disadvantages of MRI and tomography?

The main disadvantage of MRI is the need long stay in a confined space of a pipe. This method is not suitable for patients suffering from claustrophobia, as it causes them panic attacks. To obtain a clear image, doctors recommend to remain still during the entire examination, therefore, if necessary, parts of the body of the subject are fixed with special devices.

The magnetic field can damage pacemakers, the presence of metal prostheses negatively affects the operation of the tomograph. Patients with implants and implanted electromagnetic devices must inform the doctor about this.

Computed tomography takes less time, but this method is based on the use of x-rays. It can harm the health of the patient, so a re-examination is possible only after a month. Categories of patients with contraindications to radiological methods diagnostics are not allowed to computed tomography.

When diagnosing diseases of the blood vessels, neoplasms, inflammatory processes, it is necessary to administer a contrast agent, which is undesirable in patients with an allergy to iodine and in people suffering from renal insufficiency.

Contraindications for CT and MRI

Differences in the principle of operation of MRI and CT determine contraindications for each method.

Computed tomography based on the use of x-rays and the use of iodine-containing preparations for additional contrast is contraindicated in the following cases:

• pregnancy and childhood up to 5 years;
• a health condition that excludes the possibility of X-ray exposure;
• thyroid disease and its hyperfunction;
• diabetes mellitus with Metformin therapy;
• iodine intolerance, allergic reactions;
• kidney failure.

In these conditions, it is advisable to consider the option of MRI examination, which does not give radiation exposure to the body and does not require the introduction of iodine preparations. However, MRI also has a number of contraindications:

• presence in the patient's body metal structures and implants;
• the presence of implanted electrical devices;
• patient weight over 120 kg;
• claustrophobia.

Relative contraindications to MRI are pregnancy in the first trimester and childhood. The latter is due to the need for a long stay in a stationary state.

The choice of the method of hardware diagnostics remains with the doctor, who takes into account individual characteristics patient and the nature of his disease.

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