MRI or CT scan difference. What to give preference: computed tomography or magnetic resonance imaging

Since the emergence of medicine as an independent branch, various instruments have been created for studying human organs. With the development of science in the 20th century, completely new devices for non-invasive diagnostics were created - X-ray and magnetic resonance imaging devices. You will learn about how the examination is carried out using these methods and what the difference between them is in this article.

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CT scan

What is tomography? This word is translated from Greek as “Section” and “Depict”.

That is, it is a process of obtaining an image of the body under study layer by layer, the roots of which go deep into history.

The development of tomography as a method began in the 19th century, when mathematicians analyzed integral equations, which a hundred years later would become the basis.

Later, in 1895, the famous scientist Roentgen discovered a previously unknown type of radiation, which was later named after him. X-rays allowed us to make a breakthrough both in diagnosing diseases and their treatment.

Important! X-rays are electromagnetic waves that lie beyond the visible spectrum and ultraviolet radiation. They have found their use in medicine due to their ability to easily pass through the object under study and illuminate the photographic plate. Thus, bones absorb this radiation more strongly than soft tissues, and as a result of uneven illumination of the plate, their outlines become visible

Although X-ray was a breakthrough at the time, it had a significant drawback. The photographs were recorded either on a special plate or on photographic film, and represented a two-dimensional image. The disadvantage was that the patient's body was translucent through, resulting in images of neighboring organs overlapped each other.

In the 50s of the 20th century there was a sharp leap in the development of cathode ray tubes - sources of X-ray radiation, as well as in the development of computer technology. This paved the way for further improvements in fluoroscopy technology, resulting in the invention computed tomography machine.

What it is? As in a conventional X-ray machine, the most important part is the source of radiation, which illuminates the object being examined.

Another, no less important element is the X-ray detector.

In its design, it is very similar to a modern digital camera, except that it is sensitive not to visible light, but to X-ray waves.

Between these two devices is the object being studied - the patient. The rays, passing through it, are absorbed with different strengths and are received by the detector. In order to get pictures from different angles, this pair is made in the form of a kind of “carousel” that rotates around the patient and illuminates him from all possible angles.

Finally, the last link is the computer. His tasks include collecting the received images together, and then processing them, ultimately obtaining 3D model of the object under study.

Magnetic resonance imaging

What is the difference between CT and MRI? Magnetic resonance imaging is a further development of non-invasive diagnostic technology. The first mention of work in this area dates back to the 70s of the last century, when it was suggested that it was possible to study objects using the phenomenon of magnetic resonance. Later, in 2003, pioneers in this field were awarded the Nobel Prize for their contributions to the development of medicine.

On what principle does it work? magnetic resonance imaging?

The cornerstone of this device is the phenomenon of nuclear magnetic resonance, which makes it possible to obtain information about the saturation of the object under study with a certain chemical element.

As the school chemistry course says, the nucleus of the hydrogen atom consists from one proton. This particle has its own magnetic moment, or, as physicists say, spin.

To make it easier for the reader to understand this, we will simply assume that the hydrogen nucleus is a miniature magnet that we deal with in everyday life. As we know from experience, two magnets tend to attract each other or push away, depending on their position. It is this property – the ability of a proton to change orientation in an external magnetic field – that is most important and allows us to answer the question: “What is MRI?”

Attention! The main design element of this type of tomograph is the magnetic field source. Electromagnets are most often used, although permanent magnets are also used.

By alternately changing the direction of the magnetic field, you can force the hydrogen nucleus to also change its orientation, while expending energy.

As a result, the atomic nucleus enters the so-called excited state, and then releases the accumulated energy back in the form of an electromagnetic wave.

Then the computer comes into play. Knowing the parameters of the magnetic field at the current moment, as well as analyzing the returned energy, the location of the particle is calculated.

Performing such calculations continuously, it appears ability to build a three-dimensional model the organ being studied. But, still, which tomograph is better?

Important! Initially, this method was called nuclear resonance magnetic tomography - NMR. However, the name was changed to MRI in 1986. This is connected with the Chernobyl disaster, as a result of which some segments of the population developed radiophobia - fear of radiation and everything “nuclear”, including the lack of desire to understand - “What is MRI?”

Safety of tomography for health

The topic of the safety of the tomography procedure is often raised by patients who have never undergone this type of diagnosis before. Let's try to figure out this issue and finally put an end to the topic: “Which tomograph is better?”

Safety of X-ray Tomography

X-rays are ionizing electromagnetic radiation. In large doses it can cause radiation sickness similar to the effects of gamma radiation. However, there is absolutely no cause for concern.

Modern tomographs are subject to the highest requirements regarding radio safety, so

So, for example, the annual radiation dose received from the natural background is approximately 150 mSv. While in one RCT diagnostic session the absorbed dose is about 10 mZV. But, you should remember that the procedure should be repeated no earlier than a six-month break.

Important! A complete contraindication to diagnosis is pregnancy. This is caused by the high teratogenicity of X-ray radiation - the ability to cause abnormalities in fetal development.

Special attention should be paid to the contrast agent. For certain types of examination, it is required to be administered intravenously to make the necessary organs clearer. In some cases possible allergies for this drug, which is also a contraindication.

MRI Safety

Carrying out this topographical study absolutely safe for the body due to the absence of X-ray radiation, which allows you to perform various types of MRI studies, and not ask the question “Which is safer.”

Magnetic fields have no effect on the human body, but at the moment there are no studies regarding harm and safety to the fetus. As a result, it is recommended to avoid the procedure in early pregnancy.

In addition, due to the presence of a strong magnetic field, there is a number of restrictions on diagnostics:

installed pacemakers;
metal dentures;
various metal-containing implants, including auditory ones;
Ilizarov apparatus, installed for complex fractures.

It is also worth talking about the signs of claustrophobia. This term means a panicky fear of closed spaces, which in some cases manifests itself even in those who have not previously suffered from it. In such cases it is recommended use of open type tomographs. Answering the question: what is more harmful than MRI or X-ray examination, it should be noted that MRI is an absolutely safe procedure.

Types of tomographic studies

What types of diagnostics are performed during tomography, which type of tomograph is best and which is safer? Let's answer this question.

Tomography allows you to conduct research absolutely any organ- there are no restrictions. Thus, the following departments are most often examined:

head and cervical regions;
rib cage;
abdominal and pelvic organs;
spine, bones and joints.

Often, when visiting a doctor, patients raise the question of which type of tomograph is better when examining a particular organ. There are also a number of nuances here.

How does CT differ from MRI? brain? Computed tomography is used to evaluate injuries to the skull and brain.

It also helps to visualize blood vessels well, which is required when diagnosing a stroke. MRI has proven itself to be excellent in detecting tumors, cysts, and Alzheimer's syndrome.

What to choose - MRI or CT scan of the spine? will help diagnose diseases of water-containing tissues, such as stenosis, intervertebral hernia or metastases of cancer.

CT is suitable for identifying abnormalities of bone tissue, its damage, as well as osteoporosis and other “purely bone” diseases.

Which is better: MRI or CT scan of the abdomen? Here, for the most part, preference should be given to MRI, due to the lack of bone tissue. In addition, modern MRI machines can monitor the flow of various fluids in real time. But still, the final decision must be made by the doctor.

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When diagnosing diseases of the spine and organs of the sacrolumbar region, magnetic resonance and X-ray computed tomography are very widely used. Both of these methods are additional research methods and serve to confirm or refute suspicions of certain diseases of the internal organs.

MRI and CT are used if there are certain indications and clinical symptoms indicating the presence or development of a particular disease. Very often, the symptoms of diseases are similar or even identical, and only studies using a tomograph can show the real picture of what is happening.

Of course, Magnetic resonance imaging can also be used in studies for preventive purposes, for example, to search for incipient tumors, determine the condition of blood vessels or changes in the tissues of internal organs caused by external influences in the form of toxins or harsh working conditions.

But MRI is still a rather expensive research method and is used only if there are certain reasons for its use. Computed tomography is a cheaper method, but the X-rays used in the tomograph become an obstacle to too frequent use.

MRI and CT in spine studies

Tomography in the diagnosis of the spinal column, especially its lower part, is used quite actively. Such studies are prescribed for:

lower back pain
injuries to the spine area
suspected cancer
osteochondrosis
protrusions and herniations of intervertebral discs
disorders of the blood supply to this area
inflammatory processes in bone or cartilage tissues
disorders of the lymphatic ducts
spinal cord canal stenosis

Which is better, MRI or CT of the spine cannot be answered unequivocally. In order to understand the difference between these methods, it is necessary to briefly familiarize yourself with the physical and chemical processes underlying them.

Principle of spinal MRI diagnostics

Magnetic resonance imaging uses as a basic phenomenon the effect of a high-intensity magnetic field on atomic hydrogen, which is found in large quantities in the tissues of the body. The nuclei of hydrogen atoms are arranged in a certain order along the magnetic field lines, without, however, leaving their places. They just turn in a certain way. In this state, they can vibrate in resonance with external exciting electromagnetic radiation of a certain frequency.

The vibration frequencies of atoms located in different tissues and organs differ, therefore the intensity of the signal, which is recorded by special sensitive detectors, is different. The resulting photographs are in black and white, in which the boundaries of organs, tissue structure and other smallest elements are clearly visible.

Principle of back CT scanning

X-ray tomography is a modified fluoroscopy. Only the intensity of the radiation is much lower and the emitters themselves are built in such a way that the beam of rays illuminates a narrow strip of the body. To obtain an image of the entire organ, the emitter must describe a circle around the patient’s body several dozen times.

CT differs from MRI of the spine in that magnetic tomography more clearly photographs cartilage and soft tissues, blood and lymphatic vessels and the hollow intestine. CT is indispensable for studying bone formations and bleeding. Images of inflammatory processes, salt deposits or disturbances in nerve tissues are also very well demonstrated.

The difference between MRI and CT of the spine is that the magnetic field is absolutely safe for humans and MRI can be performed an unlimited number of times. Computed tomography, although it uses very low-intensity X-rays, still exposes the body to radiation. Therefore, it is not recommended for pregnant women, children, or people who have recently had fluoroscopy.

An MRI image of the spine is as informative as a CT image. MRI or CT scan of the spine is best used with a contrast agent. In this case, neoplasms, various tumors, blood vessels of even the smallest size and metastases penetrating from other organs are very clearly visible. Stenoses, blockages, narrowings and inflammatory processes are reliably recorded. In the case of using data level contrast, both of these methods are almost identical.

Lack of timely treatment can lead to serious complications and even death, so if unpleasant symptoms appear, it is important to consult a doctor. In modern medicine, various diagnostic methods are used to determine the presence of a disease and the causes of its occurrence.

Common research methods are CT and MRI. There is a difference between them; they are not always safe for the body and are prescribed when indicated. Only a doctor will determine the advisability of prescribing the method. Let's figure out which procedure is safer and more effective when you need to do SCT or RCT.

Differences in the principle of operation of CT and MRI

The word “tomography” present in both names means that both CT and MRI are three-dimensional layer-by-layer studies of organs that guarantee high accuracy. Both methods were invented at the same time - in the early 70s of the last century; over the decades of the technology's existence, they were significantly improved. The main difference between them is the survey principle. They can also be distinguished by the extent of the harmful effects of the tomograph on the body.

Typically, magnetic resonance imaging, as well as CT, is prescribed to identify abnormalities in the functioning of internal organs. In both cases, there is no physical intervention in tissues and organs; MRI makes it possible to detect the smallest abnormalities.

The principle of magnetic resonance imaging is based on the action of a magnet and a scanner - the human body emits certain radio frequencies, which are recorded by the device. The received data enters the computer, and the tomogram displays information about the condition of the organs. A standard study takes from half an hour to two hours - the patient lies down on a couch, which slides into a capsule, a tomograph scans the organs, the information is sent to a computer monitor, and the images can be printed.

The computed tomography method is based on X-ray radiation. If a regular X-ray gives a flat picture, then a CT scan allows you to obtain an image of an organ in 3 planes. This diagnostic method has been one of the most common for many years, which is why any modern medical department is equipped with a tomography apparatus. Using a tomograph, you can get clear photos of the affected organs.

During the procedure, the patient also lies down on a special table, X-rays illuminate all tissues and organs, and the photo can be printed. The duration of the procedure is 10-20 minutes; immobility and absence of sudden movements are a prerequisite.

Indications and contraindications for procedures

There is a difference between CT and MRI depending on the indications and contraindications for the procedures.

Magnetic resonance imaging

Indications for magnetic resonance imaging:

Before going to the medical department, you need to know that this method has absolute and relative contraindications; in some cases, the accuracy of the examination results is reduced. If there are implanted metal elements (prostheses, joints, etc.), the patient must provide the doctor with instructions for the products, which indicate the possibility of performing an MRI.

Relative contraindications:

mental illness (epilepsy, fear of closed spaces);
1st trimester of pregnancy;
non-ferromagnetic implants, heart valves, nerve stimulators;
inability to remain still;
severe patient conditions requiring the use of medical devices (cardiac monitor, etc.);
tattoos on the examined area (if the paint contains metal).

Absolute contraindications to the study:

Contraindications for administration of gadolinium-based contrast:

renal failure;
hypersensitivity to substances containing gadolinium.

CT scan

Indications for computed tomography:

brain dysfunction;
diseases of the cardiovascular system;
head injuries, causeless headaches;
lung examination;
diagnosis of dysfunctions of the liver, reproductive, urinary, digestive systems, examination of the mammary gland;
damage to bone tissue, joints and spine;
oncological diseases.

During CT scanning, the body is exposed to strong radiation; frequent repeated procedures are prohibited. The method is contraindicated in the following cases:

Preparing for research

As a rule, preparation for going to the medical department for an MRI and computed tomography is not required - in the absence of special medical instructions, nothing needs to be done. Before a CT scan, you should get rid of all foreign objects and jewelry (glasses, hairpins, devices, etc.), however, the presence of metal joint implants is not a contraindication to the session. If the examination of the digestive organs involves the use of a contrast agent, the diagnosis is carried out on an empty stomach.

In the presence of psycho-emotional disorders and high excitability, the use of sedative medications is indicated. A few days before the procedure, it is necessary to avoid foods that cause flatulence (legumes, fresh products of plant origin), and it is recommended to take enterosorbents. Before diagnosing the pelvic organs, you should drink half a liter of water 30 minutes before the procedure.

Which method is more accurate and more informative?

It is difficult to say which method is better, more accurate and more informative. A comparison of methods allows us to answer this question - the data differ depending on which organ is being examined.

All information is displayed on black and white photographs, after studying which the doctor makes a diagnosis.

Computed tomography will be more accurate in examining:

musculoskeletal system (for bone injuries, bone tissue oncology), to determine tissue density;
lungs and mediastinum.

The information content of MRI is higher during examination:

Vessels - there is no need to administer contrast, such an examination allows you to establish areas of compression and narrowing, and determine the speed of blood flow. CT is recommended for atherosclerotic lesions.
Parenchymal organs - allows you to obtain more accurate images.
Brain - the images show areas of hemorrhage or ischemia, vascular pathology. The use of contrast makes it possible to detect minor tumors. CT is effective for intracranial hematomas, aneurysms, and atherosclerosis.
Hollow organs (esophagus, stomach, intestines) - in this case, both methods are equally effective, but MRI requires the use of contrast (both orally and intravenously).

What is safer - MRI or CT?

There are differences in the safety of the methods for patients. The difference is as follows: MRI is a safer diagnostic method, since CT uses x-rays, which can provoke the development of radiation sickness. When performing a CT scan, there are certain limitations that must be taken into account. For example, the SCT procedure is recommended to be carried out no more than once every six months; only one part of the body is examined in one session.

Cost comparison

Both procedures are expensive, so they are prescribed after an ultrasound and x-ray. MRI is a more modern and expensive method, since higher quality equipment is used for diagnosis.

The cost of CT and MRI examinations depends on the following factors:

equipment level;
personnel qualifications;
application of contrast;
region of residence;
clinic pricing policy;
availability of additional services.

The difference in the price of diagnosing one organ using different methods averages 1-2 thousand rubles. It is important to take into account the above factors - it is quite possible that MRI will cost less than CT in clinics with different pricing policies.

The cheapest medical procedures are in government institutions. The price of examining an individual organ using CT in Moscow is 2-4 thousand rubles, MRI - 3-5 thousand rubles, the most expensive is the examination of the spine and brain (up to 9 thousand).

The price of an abdominal CT scan in Moscow is 8-12 thousand, in St. Petersburg such an examination will cost 6-10 rubles, in the regions - 5-7 thousand. A study of the whole body costs an average of 70-100 thousand rubles. The type of contrast used also plays an important role - its cost varies between 2-5 thousand rubles.

When visiting the clinic for a CT or MRI scan, you must clarify in advance what is included in the price. Some hospitals pay separately for a report with a description and interpretation of images, recording diagnostics on removable media, and creating a personal computer profile of the patient on the hospital website. The list of services and their costs can be clarified in advance by phone or on the institution’s website.

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.