home Analyzes How does MRI differ from CT? In what cases is MRI better than CT? CT or MRI? Choosing the best diagnostic method MRI and PCT - what's the difference?

How does MRI differ from CT? In what cases is MRI better than CT? CT or MRI? Choosing the best diagnostic method MRI and PCT - what's the difference?

The effect of X-rays in diagnostic terms cannot be overestimated. Despite the fact that their properties were discovered many years ago, even more informative techniques - MRI and computed tomography - appeared much later. However, scientists managed to improve the above-mentioned devices, making a revolutionary breakthrough in the study of internal organs and systems of the human body, and identifying possible pathologies. Standard x-rays are not as accurate. Often, with this method of examination, inflammatory processes or neoplasms are still hidden from the watchful eyes of doctors. With the invention of new devices, diagnostic medicine has reached a new level of development.

CT and MRI are two different research methods

In this article you will learn:

There is a difference between MRI and CT, despite the fact that these devices may seem identical to ordinary people. It's all about different types of radiation, with the help of which doctors determine the presence of certain diseases in the patient's body. The basis of CT is x-rays, MRI is an electromagnetic field.

So, in the case of CT, you can study some organs and systems, and with MRI - others. The MRI machine responds to the “recall” of an organ when exposed to electromagnetic radiation. A comparison of CT and MRI also lies in the methods of preparation for examinations and possible consequences and side effects.

What is the essence of MRI?

The doctor receives the data already simulated. The device screen displays three-dimensional images of organs. In this case, the principle of obtaining information is similar to computed tomography, but the nature of the waves differs significantly. Due to this, using devices it is possible to study certain organs. Therefore, the question of which is more informative - CT or MRI - cannot take place. For some diseases, CT is indicated, for others - MRI.

The MRI machine operates on the basis of magnetic radiation

Under the influence of radiation from a magnetic resonance imaging device, each of the organs of the human body gives a unique “response”. Information is recorded and properly processed. All signals are converted. A three-dimensional image of the organ is obtained. At the same time, the doctor at the diagnostic center has an idea not only of the size of the organs, but also of the existing pathologies, since the system provides data in literally detail. The doctor easily rotates images, zooms in and out.

What is CT scan?

This abbreviation stands for computed tomography. The examination involves the use of x-rays. However, this is not an x-ray in our usual sense. The old method involves imprinting the organ on a specialized film. The picture is often incomprehensible even to radiologists themselves.

CT produces a three-dimensional image of the desired organ, since it is based on the activity of the volumetric system. The device “records” information while the patient is on the couch. At the same time, a lot of pictures are taken from different angles. Afterwards, the information received is processed and displayed in the form of a three-dimensional image on the device screen.

The information content of this technique directly depends on the specific settings of the device.

In what cases is MRI performed?

This diagnostic method is good when you need to look at the condition of blood vessels and body tissues. Patients come for an MRI with suspicions of the presence of tumors in any organs. Often, magnetic resonance imaging is used to assess the condition of the blood vessels in the brain and the functioning of the heart. At the same time, no one has canceled ultrasound, but it is important for doctors to have a complete and comprehensive picture of the patient’s condition.

MRI is often used to study the condition of the spinal cord

MRI is used to evaluate the activity of spinal cord structures and nerves. It is important to get tested for patients who have had strokes. Patients suffering from arthrosis and arthritis have the right to request a referral for an MRI from their treating doctor. Diagnosticians will look at the condition of muscle structures, as well as joints and cartilage.

What are the indications for CT scan?

This machine helps doctors understand whether a patient is bleeding internally. In injured patients, surgeons look at the type of damage and their extent. CT scan provides important information about the condition of teeth, bones, and joints. The presence of osteoporosis and other ailments of the skeletal system and spine is clearly visible.

Computed tomography is an excellent way to detect tuberculosis, pneumonia, abnormalities in the development and activity of the thyroid gland. CT diagnostics are indispensable when you need to find out about the condition of the gastrointestinal tract or urinary system.

CT scan helps diagnose various lung diseases

Is CT scan dangerous?

Computed tomography is contraindicated for pregnant women, since the examination is based on X-rays, which are dangerous to the fetus. Nursing mothers are also asked to refrain from this diagnosis, or not to feed the baby for some time, expressing harmful milk.

CT scanning is done for children when other methods are powerless, and the harm from the diagnosis itself on the equipment is less than what the disease can cause.

Computed tomography is contraindicated in patients with pathologies of the kidneys, thyroid gland, or unstable blood sugar levels. CT diagnostics are useless when the patient is overweight - over 200 kg. And the table itself, where the sick are placed, will not withstand such a load. One more nuance: CT scans should not be performed on epileptics, since a seizure can begin at any time. The examination on the device takes place in complete rest. Nervousness and tremors are not allowed.

As for harmful X-ray radiation, except for those categories of citizens for whom examination is completely contraindicated, others can undergo it even once every six months.

A CT scan is a type of x-ray, so it should not be done often.

What are the consequences of MRI?

If the subject's body contains metal implants, plates, prostheses with metal inserts, or braces, MRI diagnostics is contraindicated. Magnetic waves resonate during the research process. As a result, the consequences will be expressed not only in inaccurate diagnosis, but also in danger to the body.

It is important to remember that even tattoo ink containing metallic impurities can cause harm during MRI diagnostics. This is worth considering for those with beautiful patterns on their skin.

There is also a contraindication for “carriers” of pacemakers. This device may simply stop during magnetic resonance imaging, which leads to disastrous consequences.

In this video you will find information about the differences between CT and MRI, as well as the main parameters of both procedures:

During the examination, the patient must lie motionless for more than half an hour. This is undesirable for epileptics, patients with claustrophobia and pathologies of the nervous system (Parkinson's disease).

MRI can be done without consequences for pregnant and breastfeeding women. This device does not cause harm to other categories of subjects.

What are the differences in preparation?

You can take a sedative. Special preparation will be needed only when the procedure involves the introduction of contrast solutions into the blood for a more accurate diagnosis. Taking this into account, doctors warn against eating 6-8 hours before the procedure, regardless of whether a CT or MRI is performed.

Before a CT scan, the patient must remove all metal objects: dentures, hearing aids, earrings, rings, chains, bracelets. The procedure is carried out in clothes, so it is worth making sure that there are no metal objects lying around in your pockets.

When an MRI of the gastrointestinal tract or urinary system is prescribed, it is better for patients not to eat or drink 8 hours before the procedure, and in the earlier period to adhere to a special diet. You should not eat foods that cause increased formation of gases in the intestines. These are any vegetables, legumes, bread.

Before an MRI, you can drink activated charcoal, which extinguishes gases in the intestines. It is advisable to take antispasmodic medications as prescribed by your doctor. This will help obtain the most accurate examination result.

Nowadays, such types of research as CT and MRI are used in medicine. Both abbreviations CT and MRI contain the word “tomography,” which can be translated as “slice examination.” Patients ignorant of modern medicine may perceive CT and MRI examinations as very similar procedures, but this is erroneous. Their similarity lies only in the commonality of the procedure itself, as well as the application of the principle of layer-by-layer scanning with images displayed on a computer monitor. But the difference between CT and MRI is big. We will try to understand the difference between CT and MRI and how this affects diagnostic results.

How does CT differ from MRI?

Externally, they are the same: mobile tables and a tunnel in which the organs being examined or another area of the body are scanned.

But the main difference between CT and MRI is that these studies use completely different physical phenomena.

Computed tomography (CT) is based on the use of X-rays. The scanner rotates around the area of interest and displays images at different angles on the monitor. After computer processing, specialists receive a three-dimensional image of the desired area.
Magnetic resonance imaging (MRI) uses a magnetic field. The computer also processes the received information and produces three-dimensional images.

CT or MRI: which is better?

There is no point in discussing which method is better or worse: these are completely different methods that are used in different situations. Each research method has its own indications and. Each method is informative for certain organs and tissues in specific cases. In some cases and when diagnosis is difficult, it is even necessary or recommended to use both tomography methods.

MRI allows you to see soft tissues more clearly, but does not “see” calcium in the bones at all. And CT allows us to study bone tissue in more detail.

The MRI procedure is indicated for examination:

Strokes, multiple sclerosis, inflammation of brain tissue, brain tumors;
, trachea, aorta;
Ligaments, muscle tissue;
and intervertebral discs;
.
CT is prescribed for research and study:
Lesions of the bones of the base of the skull, temporal bones, paranasal sinuses, facial skeleton, jaws, teeth;
Defeats;
Organs;
Parathyroid and;
and joints;
Consequences of injuries.
When choosing a method for diagnosing diseases, the doctor also takes into account the patient’s health condition and factors that may interfere with tomography.

Despite obtaining the same results in both tomographs (these are volumetric images), CT is harmful to human health. MRI diagnostics, on the contrary, is completely safe (even for pregnant and lactating women), but, unfortunately, more expensive.

The advantages of magnetic resonance imaging are:

- High accuracy of received information
- Safety for the patient, including
- Possibility of repeated use of the procedure if necessary, due to its safety
- Acquiring 3D images
- The probability of receiving an error during scanning is almost zero
- No additional contrast required to study blood flow
- Great information value in the study of damage to the central nervous system, the study of vertebral hernias.

Advantages of computed tomography:

Reliable information
Possibility of obtaining three-dimensional images of the area under study
Clearer pictures of the skeletal system
Possibility of obtaining reliable information in case of internal bleeding, detection of tumors
Short duration of the examination
Possibility to undergo the procedure if there are metal or electronic devices in the body
Low cost.

Disadvantages of CT and MRI examinations

Of course, all types of research have both positive and negative sides.

The disadvantages of MRI include the following indicators:

It is impossible to fully study hollow organs (urinary and gall bladder, lungs)
It is impossible to carry out the procedure if there are metal objects in the patient’s body
To obtain high-quality images, you need to remain still and calm for a long time.

The disadvantages of CT include the following indicators:

Hazard to human health -
There is no way to obtain information about the functional state of organs and tissues, only about their structure.
Pregnant and nursing mothers and children should not undergo this tomography.
You cannot undergo the procedure often

In any case, when visiting the attending doctor, the patient will be prescribed an examination that will provide the necessary and accurate result. If you are prescribed both methods of examination, then in this case the differences in the methods do not play a fundamental role.

Contraindications for tomography (CT and MRI)

Each of the procedures has contraindications that may interfere if you decide to undergo examination.

do not prescribe:

Pregnant and breastfeeding women
For children at an early age
In case of frequent procedure
If there is plaster in the examination area
In case of renal failure.
Magnetic resonance imaging also has its contraindications:
Claustrophobia, schizophrenia
The presence of a pacemaker, metal implants, clips on blood vessels, or other metal objects in the patient’s body
Pregnancy in the 1st trimester
The patient is overweight (over 110 kg)
Renal failure (when using contrast agents).

It is imperative to consult a doctor before undergoing the test.

CT and MRI are used to diagnose and prescribe treatment for a huge number of diseases. You need to know that the purpose of a particular examination method depends on what part of the person’s body is being examined.

Innovative technologies in medicine make it possible to expand possibilities not only in the treatment of various pathologies, but also in their diagnosis. The use of CT and MRI today allows us to obtain more information than the usual and long-known methods - ultrasound, radiography and laboratory tests.

It is difficult to choose between these two studies, because they have relatively recently become available to patients in our country and many are not familiar with them at all. In order to understand which method will be best in a particular case, it is necessary to study in detail the features of the procedures.

What is the main difference between each study?

What is the difference between MRI and CT? Let's take a closer look at the features of these diagnostic methods.

Computed tomography (CT)

A diagnostic research method based on the use of x-rays. Unlike a conventional X-ray, the resulting image of the organ being studied will be three-dimensional and not two-dimensional. This effect is achieved through the use of a ring-shaped circuit that distributes the X-ray beams around the installed couch with the patient.

During the session, a series of images of internal organs are taken from different angles. This makes it possible to combine them later and obtain a computer-processed three-dimensional image. CT makes it possible to examine the organ layer by layer - “slices” on the most accurate devices reach 1 mm. — the technique involves continuous rotation of the device, which makes the picture more detailed.

Brain examination

Magnetic resonance imaging (or MRI)

A diagnostic technique that allows you to obtain a three-dimensional image of the organ being studied. The research method is based on the use of electromagnetic waves. affects hydrogen in the human body - makes it change position, this data is recorded by the device and compiled into a three-dimensional picture - a tomogram. The resulting three-dimensional image can be rotated to the desired projection, the organ can be examined through “slices,” and the problem area can be enlarged for a more detailed examination. The resulting images are informative and highly accurate.

So what is the difference between MRI and MSCT? The main difference: computed tomography is based on the use of X-rays, while magnetic resonance imaging is implemented using electromagnetic waves.

What is the difference between the types of tomography in practice?

What is the difference between CT and MRI, besides the effect of waves and rays, is the main question of the patient who doubts the choice of method. The difference between CT and MRI in practice:

MSCT is used to study the physical state of an object (anatomy), MRI is used to study the chemical state (anatomy and physiology);
MRI is more informative for scanning soft tissues, and CT (including spiral) is more informative for bone tissue;
magnetic waves have not been fully studied, but the method of their use has no limitation on the frequency of use, and X-ray irradiation cannot be carried out frequently;
MRI often involves placing a person's entire body in a tomograph, and CT often involves irradiating the area being studied.

Spine examination

The examination methods are modern and informative, but if you have access to both, you need to choose the one that is most suitable for your particular situation.

Indications for the use of CT and MRI

MSCT and MRI are used to diagnose diseases of all organs of the human body. But these methods are not equally well suited for studying the same organ - this must be taken into account when choosing.

Situations in which it is better to use computed tomography:

For craniocerebral changes: brain contusion, hemorrhage, traumatic brain injury, neoplasms (malignant or benign), pathological circulatory disorders in the brain.
Recent injuries with suspected internal bleeding.
Pathological lesions of the facial skeleton, thyroid and parathyroid glands, jaws, teeth.
Atherosclerosis of blood vessels, aneurysms and other pathological changes in the structure of blood vessels.
Spinal diseases: scoliosis, kyphosis, lordosis, osteoporosis, herniated discs.
Pathological: tuberculosis, pneumonia (pneumonia), cancer.
Diseases (tumors and stones are visible in detail on tomograms).

To obtain a clear picture and study the hollow organs, CT scans are performed using a contrast agent.

It is advisable to use magnetic resonance imaging in case of:

Brain lesions, namely: inflammation of the meninges, hemorrhage (stroke), tumors of various etiologies, multiple sclerosis.
Pathologies affecting joints, ligaments and muscle tissue.
Tumors in soft tissues.

MRI can replace CT in cases where the patient is diagnosed with individual intolerance to the contrast agent or has already been exposed to radiation, and repeated exposure to radiation in a short time is not desirable.

Advantages and disadvantages of diagnostic methods

Both methods are accurate, but there are situations when using a certain method will be more informative. In addition, there are some temporary and permanent individual contraindications and restrictions on the number of procedures.

Advantages of CT, MSCT:

clear three-dimensional image of the studied area;
the possibility of layer-by-layer study of the organ;
painlessness of the diagnostic method;
speed of research - exposure to rays lasts up to 10 seconds;
less radiation than when using x-rays;
effective for examining bone and muscle tissue, identifying bleeding and tumors;
requires lower financial costs.

Magnetic resonance imaging also has a number of advantages, some of which are consistent with the advantages of CT. Pros of using MRI:

high-precision information on a three-dimensional image;
the ability to rotate the image into a convenient projection;
layer-by-layer examination of the organ allows you to more accurately study the details;
the best method of research for neurological problems - there are no more accurate diagnostic analogues in this field of medicine;
safe for any age (used for children from birth);
guarantees - does not affect the mother and fetus; no influence of radiation.
there are no contraindications for frequent use, it is painless;
it is possible to save data in electronic form (convenient for studying pathology over time);

Despite the manufacturability of the processes, their effective use is limited by certain nuances. In order to choose the most suitable method for studying pathology, you need to take into account the disadvantages of each method.

Disadvantages of CT, MSCT:

radiation exposure (which is more harmful than the influence of electromagnetic waves);
It is forbidden to use by pregnant women and children;
it is impossible to obtain information about the functioning of organs; one can only consider anatomical changes in the structure.

The main limitation of use is radiation exposure - despite the insignificant amount of radiation, it is contraindicated for use in weakened patients, children and pregnant women.

Disadvantages of MRI:

not suitable for precise examination of hollow organs (gall and urinary bladders, blood vessels);
before the procedure, it is necessary to remove metal elements from clothing;
the examination takes a long time - 30-40 minutes;
not suitable for patients with claustrophobia;
weight restrictions are possible - the devices are designed for a weight of up to 110 kg (few models - up to 150 kg);
prohibited for use by people with fixed dentures and implanted elements - pins, clips, plates, pacemakers;
To ensure the clarity of the resulting images, you need to remain motionless for a long time (anesthesia is used when diagnosing children).

Preparing for the study

There are no particular difficulties in preparing for magnetic resonance imaging and MSCT. It is needed only in the case of using anesthesia for children (for MRI) and performing a CT scan with the introduction of a contrast agent. Before administering a sedative, it is recommended to refrain from eating and drinking for several hours. The same applies to the procedure for introducing a contrast agent. The contrast agent will be eliminated from the body faster if you drink plenty of fluids after the procedure.

The best choice of clothing for tomography is a special shirt (or any loose-fitting suit without metal parts). To undergo an MRI, you need to remove jewelry, dentures, glasses, hearing aids, and remove all metal objects from your pockets - keys, coins.

MSCT and MRI can be performed on children in the presence of parents, in which case the latter need protective aprons. If the procedure is performed under sedatives, the child should be under the supervision of doctors until the medication wears off.

CT or MRI: which is cheaper?

Both types of tomography are used less frequently than ultrasound or x-rays due to the insufficient distribution of equipment in the periphery of the country and the high cost of the study. CT is cheaper than magnetic resonance diagnostics, therefore, if there are identical indications, it is used more often. But do not forget that irradiation should not be carried out too often - despite the small dose, the procedure still does not have the best effect on the body.

What is better than MRI or CT? The influence of electromagnetic waves has not been fully studied, but there are significantly fewer contraindications to magnetic resonance imaging. Therefore, if there is financial opportunity, or if there is a need to assess the dynamics of pathological changes, this technique is more effective and safer.

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 examine the required area “in section”. However, the operating principles of computer and magnetic resonance imaging scanners 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 of both methods under consideration is that the necessary information is displayed on a computer, thanks to which the doctor has the opportunity to obtain a three-dimensional image of internal organs and tissues.

The main difference in the operating principle of MRI and CT is in the nature of the waves that the tomographs produce.

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

Video: Which is better - CT or MRI?

Due to the different types of radiation used, the capabilities of CT and MRI differ.

These differences are discussed in more detail in the table below:

CT scan
The best technique today for studying bone structures. Helps identify pathological neoplasms on the bone and inside it.	Doesn't do a good job of recognizing fractures. Ideal for identifying injuries associated with ligaments, joints, and menisci.
Effective when examining the lungs.	Ineffective when studying the lungs.
Detects calcifications of various parameters.	Small calcifications are not detected by electromagnetic fields.
Well suited for identifying “fresh” brain injuries.	Not always able to recognize hemorrhages in the brain. Ideally copes with the task of a general examination of the state of the brain.
Can be used to diagnose soft tissues.	It copes much better with identifying pathological conditions in soft tissues than any other diagnostic techniques.
Applicable for checking the peritoneal and pelvic organs, 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:

Impossibility of performing a CT scan due to the patient’s intolerance to the dye.
Inflammatory processes in brain tissue.
Diseases of muscle tissue, joints, ligaments.
Diagnosis of multiple sclerosis.
Pathological neoplasms of the spinal cord and brain.
Study of the structure of the pituitary gland and intracranial nerves.
Determination of the exact stage of cancer.

Despite the information content of both diagnostic methods under consideration, in some cases they cannot be prescribed. This is due to the specific nature of the waves on which the devices operate.

CT is not performed in the following situations:

The period of bearing a child.
Serious errors in the functioning of the kidneys and thyroid gland.
Diabetes.
Patients whose weight exceeds 200 kg. This is due to the fact that the table of the device is designed for a certain body weight.

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

There are many contraindications to MRI:

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 particles, this procedure is also not prescribed.
Electrical devices implanted into the body: hearing aid, pacemaker, insulin pump. Electromagnetic radiation can cause damage to these devices.
Attacks of claustrophobia.
Nervous disorders in which the patient cannot remain in a stationary position for a long time.

Women carrying a child can undergo the procedure in question. from the second trimester of pregnancy.

Video: What is the difference between CT and MRI, for what diseases?

Features of preparation and performance of CT and MRI – which type of diagnosis is safer?

Since both manipulations under consideration require the patient to remain motionless for a certain amount of time, sedatives can be used before the examination.
Before any of these procedures, it is necessary to remove all metal objects, incl. - removable dentures, hearing aids. Clothing must be without zippers.
Due to the use of a contrast agent, food and liquids are prohibited before a CT scan.
Upon completion of the diagnosis, you need to drink more so that the contrast leaves the body faster.
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 internal organs can be viewed, can cause an allergic reaction.

— With magnetic resonance imaging You only need to prepare in advance 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 cause 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 significantly less time than MRI: 10 and 40 minutes, respectively.

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

In terms of safety, it is considered a kind of “gold standard” 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 diagnostic can be performed as many times as needed.
Operation computed tomograph directly related to x-ray radiation, which leaves a certain negative imprint on health. Although the dose the patient receives is insignificant, this is the basis for limiting several CT diagnostic sessions in a row.

Each of the methods under consideration has a number of advantages:

Low probability of developing side effects upon completion of the examination.
No pain at the time of examination.
Obtaining accurate and reliable information regarding the condition of internal organs, tissues and bone structures.