MRI of the knee joint - indications and contraindications

MRI is a highly accurate non-invasive study based on the phenomenon of magnetic resonance.

Its essence is that the nuclei of chemical elements in any tissue of the body can be imagined as magnets rapidly rotating around their axis. If these nuclei are placed in an external magnetic field, then their rotation axes shift, absorbing part of the radio wave energy (resonance effect). After the cessation of the external field, the atomic nuclei return to their original position (relax). The accumulated energy is released in the form of electromagnetic oscillations, which can be recorded with special equipment.

Medical tomographs record the resonance of hydrogen protons that make up the water molecule. Due to the fact that this method is very sensitive to even minor changes in hydrogen concentration, it makes it possible not only to visualize tissues, but also to distinguish their normal structure from pathology.

MRI of the knee joint - indications and contraindications

Due to the fact that joints are movable structures of the body, they are often susceptible to injury and various degenerative disorders.
Rapid diagnosis is often required, since delayed treatment can lead to subsequent complications and critical development of the pathology. One of the high-quality methods for recognizing abnormal processes in the internal structures of the body is MRI. Nuclear resonance screening is designed to recognize not only the location of disorders, but also to identify the cause of the disease in various parts of the body, including in the knee area. Due to the fact that the surveyed area has a small coverage area, the cost of the survey will not significantly affect the client’s financial condition. MRI of the knee is performed using high-power equipment, which allows you to reduce the duration of the examination and quickly obtain results.

Most often, the procedure is prescribed by a medical specialist, but diagnosis is available on the patient’s own initiative, as well as in emergency cases when screening must be carried out immediately.

The essence of MRI of the knee joint

The foundation of the technique is the possibility of using high-frequency natural magnetic fields for diagnostic purposes. MRI has been used in medical practice since the 70s of the last century. Over the past period of time, the development of the method has undergone significant changes towards the maximum development of the technical base. Tomographs are being improved almost daily, which makes it possible to obtain high-quality images of the area under study in the shortest possible time. Diagnostics using nuclear resonance is based on the generation of ultra-powerful magnetic fields, within the range of which biological fibers respond with a signature at the atomic level.

During the MRI process, a magnetic field is propagated by a hardware installation, and cellular particles, in response to such an influence, begin to resonate and emit response signals. The tomograph sensors capture these signals, process them and transmit them to the MRI machine monitor in the form of multiple photographic images.

Previously, the procedure took a long period of time, since the declared power of the equipment was not high and ranged from 0.3 to 0.5 Tesla. Today, there are tomographs capable of generating power up to 7 Tesla, but such devices are not used for medical purposes. Research is carried out on them in laboratory conditions.

To obtain correct, high-quality images, a power of 1.5 Tesla is sufficient, so these installations are most often used for procedures. The described diagnostic method rightfully occupies one of the leading places in clinical practice, as it allows for a quick and high-quality examination without injuring a person or causing harmful effects on the human condition.

Benefits of Magnetic Resonance Imaging

The method for diagnosing arthrosis is highly informative and safe, since it does not have a negative effect on the body.
Using MRI, you can examine even miniature objects, the size of which does not exceed 1 cm. This significantly expands diagnostic capabilities in the treatment of arthrosis or ostearthrosis of the knee.
You can see the joint and periarticular tissues from different angles - both transverse sections and longitudinal ones. There is no need to move the patient or the device for this.

What is the fundamental difference between CT and MRI? An experienced radiologist's take on this question:

What can be seen on an MRI of the knee joint?

In diagnostic practice, examination of the entire organism is very rarely prescribed. This is impractical, energy-consuming and financially unprofitable for both the clinic and the patient. This type of diagnosis is carried out only if there is a critical need and according to the testimony of specialists. Diagnostics is divided into areas of the human body; any area can be studied: the head, abdominal cavity, spine, neck, knee, etc. For each department, special equipment settings are used, which allow the source of the disease to be determined as clearly as possible.

MRI of the knee recognizes the following abnormal processes occurring in the joints of the lower extremities:

degeneration of bone and cartilage fibers, fractures of varying severity, noticeable and microscopic cracks in the structures of the knee;
the presence and chemical composition of liquid structures filling cavities and capsules, the presence of infections in them;
condition of the muscular and ligamentous apparatus, destruction and damage to fibers as a result of injury;
pathologies of blood channels, changes in the configuration of blood vessels, internal hemorrhages;
the presence of foci of inflammation and infection of various etiologies;
development of oncological formations and benign tumors.

The nuclear resonance screening method “sees” not only the contours and relief of the internal structures of an organ, but also its functional state and the chemical processes occurring in it. When using the method, it is possible not only to detect the location of the tumor, but also to determine the degree of its ingrowth into adjacent tissues, as well as the level of migration of cancerous processes into adjacent areas.

Features and advantages of MRI of the knee joint

One of the important features of nuclear resonance diagnostics is its non-invasiveness. This term means the absence of a penetrating effect on living tissues of the body. The patient often has internal disorders that are inaccessible to clinical diagnostic methods, visual external examination or palpation. That is why specialists decide to send the patient for an MRI. This study takes place without causing additional pain, without external influence on the organ.

Many people have the mistaken assumption that the procedure involves harmful radiation to the entire body. In fact, the operating principle of tomography is not based on the use of ionizing radiation. Magnetic fields do not affect human health at all, which has been proven by extensive experience in the use of MRI.

One of the advantages of hardware diagnostics is its maximum information content in making a diagnosis. As a result of the procedure, not only static photographic images are obtained, but also a high-quality multidimensional picture of the entire study area.

The safety of the technique allows you to significantly expand the range of potential patients, since the examination is available to people of any age, pregnant women and young children from the first days of life.

Examination in a modern clinic

When undergoing an MRI in our clinic, you can count on the high professionalism of our staff. The staff quickly resolves issues that arise during the study, reduces the duration of the procedure to a minimum without compromising quality.

As a result, MRI makes it possible to quickly identify injuries and acute illnesses and allows one to obtain valuable information in an urgent manner, for example, when transporting a patient by ambulance.
We employ experienced diagnosticians who take the most informative images. An official medical report is issued in digital and written form. Rate this article: (1 rated 5 out of 5)

When is an MRI of the knee prescribed?

The list of symptoms for which a patient is referred for diagnosis is quite wide. The most common reasons that prompt doctors to send a patient for screening are the following accompanying sensations in the knee area:

the presence of constant pain and stiffness during motor activity in the lower extremities;
inflammatory and degenerative processes leading to common joint diseases;
violation of the integrity of ligamentous tissues, compression of tendons and nerve canals;
microscopic or difficult-to-radiograph fractures, microcracks;
monitoring the condition of the meniscus after a knee injury;
development of a bacterial or viral infection;
chronic accumulation of liquid substance in the studied area;
oncological tissue lesions;
determining the patient’s operability in the preparatory stage for surgery;
as a method of monitoring the patient's condition in the postoperative period.

MRI of the knee is mandatory if neoplasms are suspected. This procedure is carried out with additional staining enhancement, which allows not only to see the oncology, but also to determine the nature of benignity or malignancy. During the procedure, the processes of the formation, the degree of their spread and the “power” of the supply of blood vessels are also visible.

Doctor ordering MRI

Most often, diagnosis of the lower knee joint using MRI is prescribed by a traumatologist, orthopedist or oncologist. The following situations may be grounds for conducting such an examination free of charge under the policy:

you have suffered a knee injury;
there is a suspicion of neoplasms;
there are symptoms of pathological changes in the joint;
Lost or reduced motor ability of the joint;
there is a need to clarify data from other diagnostic methods that turned out to be uninformative.

When is it prohibited to perform an MRI of the knee joint?

Any diagnostic procedure is accompanied by a list of prohibitions. MRI is no exception, despite the maximum safety of this type of diagnosis. Prohibitions on screening are divided into absolute and recommended, when the study is still possible if certain requirements are met and accompanied by additional measures.

Unconditional contraindications for MRI of the knee include:

The presence in the body of “sewn-in” metal elements, implants, fragmentation parts and electronic stimulators that cannot be removed. During the MRI process, a field of such power is generated that can lead to strong heating of the metal and its deformation inside living human tissue. These changes have a critical impact on the patient's condition and can lead to severe injury or death.
Initial period of pregnancy in women. Throughout the entire practice of using the method in medicine, no large-scale experiments have been conducted on the effect of high-frequency magnets on the intrauterine development of the fetus.
Chronic course of diseases of the urinary system, kidney diseases, accompanied by reduced functionality of excretion. The ban applies to the procedure in contrast mode, since the retention of dyes in the body leads to general intoxication.
The patient has an allergic reaction to medications during the planned administration of a contrast solution.

Conditional contraindications apply to such cases as:

severe obesity, which does not allow the patient to fit in the inside of the tomograph (120-200 kg);
increased degree of fear of tight spaces;
shock, extremely serious condition of a person;
CNS disorders accompanied by uncontrolled movements.

In the described cases, it is possible to undergo a knee examination in open-type hardware installations that do not have weight restrictions, as well as using analgesics or complete anesthesia. The specialist on duty makes a decision regarding the possibility of performing an MRI in an unusual situation.

What does the equipment look like?

There are two main types of MRI – standard closed and open. A classic magnetic resonance imaging scanner looks like a large cylindrical tube surrounded by a circular magnet. The patient lies on a movable table that moves into a tube with a magnet.

Some MRI scanners, called short-circuit systems, are designed so that the magnet does not completely surround the person. Some newer MRI machines have a larger opening, which is more comfortable for larger patients or those with claustrophobia. Other MRI machines are open only on the sides (open MRI). Open magnetic tomographs are especially useful for examining larger patients or those with claustrophobia. Newer open MRI machines provide very high-quality images for many types of diseases. Older open MRI devices may not provide the same image quality. However, some diseases cannot be diagnosed using open MRI. The computer workstation that processes the image information is located in a separate room from the scanner.

How to prepare for an MRI of the knee?

Screening based on nuclear resonance does not require lengthy preparatory manipulations, so in most cases it is enough to take care of comfortable clothing for the duration of the procedure, as well as prepare a package of documents, including a medical card with a medical history, a referral from a doctor and previous images and results of other MRIs, if they have been carried out previously.

If screening with contrast is planned, the patient should refuse to eat several hours before the procedure and come to the session on an empty stomach.

How preparation for research affects the result

It is important to remain still during the examination, otherwise the image quality may be somewhat distorted. Throughout the examination, the patient is under the supervision of a specialist. Inside, there is a button at hand to contact staff in case of an emergency. When examining children in the examination room, in exceptional cases (depending on age), an accompanying person may be present.

If you have a pacemaker, there are serious contraindications for MRI examination. You should consult your cardiologist as MRI may affect the implants and their function. When receiving a referral for diagnostics, you should have the implant passport with you.

Metal parts that are in the body (surgical screws, replaced joints, artificial heart valves, tattoos with metal particles) must be told to the doctor before the examination. Magnets can interfere with the normal functioning of pacemakers and can move pieces of metal that are present in the body.

A strong magnetic field can affect magnetic cards, electronic devices, and any magnetized metal body located inside or outside the body. Therefore, before entering the examination room, you must remove jewelry and watches. Personal belongings may be handed over to accompanying persons or placed in storage rooms located outside the examination room.

How is an MRI of the knee performed?

The diagnostic stages follow a standard plan:

Registration and questionnaires at the MRI center. At this stage, the radiologist on duty gets acquainted with the medical history and determines the area of the upcoming study.
Preparation. The patient is invited into a room with equipment, placed on the retractable part of the device, and either the whole body or only the knee area is fixed in a stationary state. Detailed instructions are provided.
MRI scan. Step-by-step screening is carried out under the full supervision of medical personnel, who can be contacted via a loudspeaker. The procedure lasts several minutes; in particularly difficult cases, the session may take a little longer. The patient should be patient and remain completely still throughout the entire MRI procedure.

Methodology for this procedure

Magnetic resonance imaging of the knee joint can be performed in closed-type equipment. The patient lies down on a couch located in the center of the tunnel, and a special knee coil with built-in blocks of special scanners is applied to the knee joint; The patient must remain motionless for 30 minutes while this procedure lasts. It is considered normal for the area of the knee joint to become slightly warm, but if this begins to bother the patient greatly, the x-ray technician who conducts the diagnosis should be informed.

If it is necessary to use contrast, a standard study is first performed, then the patient is rolled out of the magnet, a contrast agent is administered intravenously, and then the scan is performed again, subsequently comparing the images before and after the administration of contrast.

Contrast MRI of the knee joint

If there is a suspicion of the spread and active growth of aggressive cancer tissues, as well as to determine the nature of the tumor in the knee area, the scan is performed in a special enhancement mode - contrast.
The screening procedure involves intravenous injection of a staining solution, which makes the images clearer and also stains the vasculature feeding the tumor. Contrast is used not only for MRI, but also for other diagnostic purposes. Coloring preparations are safe and do not cause subsequent complications. However, if the patient is individually intolerant to medications, this diagnostic regimen should be abandoned.

1-2 days after MRI, the administered substance is completely absorbed in the liver and excreted through the urinary system. A staining test can only be prescribed by a doctor. The procedure takes longer than in the standard mode, as it takes time to inject and distribute the drug through the bloodstream.

Interpretation of MRI results of the knee joint

Careful study of the obtained photographic images and subsequent formulation of a conclusion requires additional time. New MRI images are compared with old results and images, deviations from the norm, the rate of development of pathology or the dynamics of the patient’s recovery are identified. A computer program also comes to the aid of diagnosticians, which allows them to compare the results obtained with the norm.

The diagnosis ends with the delivery of a preliminary conclusion and printed images to the client. MRI - documents can be presented in both printed and electronic versions (at the client’s request).

Decoding

The results of the tomography will be black and white images in three-dimensional format. They are deciphered by a radiologist. He carefully evaluates the anatomical features of the patient’s knee structure and notes all the anomalies found in his conclusion. The conclusion, together with MRI images printed on film or recorded on electronic media, is handed over to the person being examined. The decryption procedure takes on average 40-60 minutes. In complex and controversial cases, doctors are sometimes forced to resort to a second independent opinion. This is a situation where the patient’s images are additionally assessed by a radiologist of the highest category and expresses his independent opinion on the accuracy of the diagnosis. With the tomography data, the subject must make an appointment with his or her attending physician. It is he who, summing up all the data on the medical history, the results of analyzes and tests, makes the final diagnosis and proposes a treatment strategy.

An example of MRI decoding of the knee joint

On a series of MRIs of the right knee joint, the relationships in the joint are not disturbed.
In the area of the upper inversion and lateral pockets, an accumulation of effusion is determined in the joint cavity. The synovial membrane is hypertrophied. In the anterolateral sections, at the pre- and infrapatellar level, areas of edema of the subcutaneous fatty tissue are determined.

The patella is in the middle position. MR signal from the subchondral parts of the patella without pathological changes. The ligaments holding the patella are not changed. Hoff's fat body has a homogeneous structure. The patellar ligament has a homogeneous structure, the area of the tibial tuberosity is not changed.

The cartilaginous covering of the condyles of the femur and tibia is unevenly thinned, the articular cavity is moderately narrowed, and is more pronounced in the medial part of the joint. The bone contour of the condyles of the femur and tibia is not deformed. In the postero-central internal sections of the medial condyle of the tibia, a local area of cyst-like restructuring is identified subcortically, without pathological changes from adjacent trabecular sections. Small antero- and posterolateral marginal bone growths of the condyles of the femur and tibia are identified.

The anterior cruciate ligament is defined throughout its entire length, its structure is heterogeneous, the contour of the ligament is clear, and its overall integrity is preserved. Extrusion of the medial meniscus and an increase in the intensity of the MR signal from the posterior horn of the meniscus, with signs of damage, are determined. The intensity of the MR signal from the lateral meniscus, posterior cruciate and collateral ligaments is not changed, their integrity is not compromised.

In the posteromedial thigh, in the area of the intermuscular space of the medial head of the gastrocnemius and semimembranosus muscles, a cystic expansion of the mucous bursa is noted.

Conclusion:

MRI signs of grade 2 deforming arthrosis of the right knee joint; damage to the posterior horn of the medial meniscus; degenerative changes of the anterior cruciate ligament. Synovitis. Baker's cyst.

Alternatives to MRI of the knee

The main “competitors” of the nuclear resonance method are ultrasound, computer screening and radiography. It makes no sense to compare which of the listed methods is more effective, since each type of research has its own advantages and disadvantages, and is also prescribed in different situations and when setting different tasks.

Thus, ultrasound is prescribed as the initial method of diagnosis much more often. It allows you to assess the degree of damage to soft and tendon tissues. CT is a more modern variation of traditional radiography; they work on a similar principle, but differ significantly in the effectiveness of the procedure. Just like with MRI, internal structures are visualized, but computer scanning and x-rays are worse at determining the density of soft tissues.

Each method is effective in its own area. MRI can be compared with ultrasound in terms of safety, and with CT and X-ray in terms of information content.

Contrasting

MRI, like X-ray computed tomography, is often performed with the introduction of contrast. Contrasting takes additional time, in addition, you need to find out if there are any contraindications, for example, allergic reactions to contrast agents. Even when the documents prepared by the attending physician indicate the absence of allergic reactions, the procedural personnel are required to verbally interview the patient. Although time is lost, modern medical centers provide the maximum level of health safety.

The introduction of a magnetic contrast agent prolongs the study by about 15-20 minutes. In preparation for an MRI, medical personnel evaluate how a person tolerates a contrast agent, whether rashes characteristic of allergies appear, and doctors also ask about the sensations that the patient experiences.

In some cases, MRI is almost always associated with contrast (distal arms and legs), so the time spent on contrast preparation should be added to the time period of the examination itself. But when a patient is being prepared for an abdominal examination or a brain procedure, contrast is usually not needed, and the diagnostician gets the job done faster.

Where is it performed and how do I sign up for an MRI of the knee joint?

Finding a suitable medical institution specializing in MRI examination is not difficult, since MRI is available both in municipal clinics and in private tomography centers. A complete list of diagnostic institutions is presented on the page above, which allows you to quickly assess both the rating of each center and its price category. You can easily and quickly sign up for an MRI by calling the phone number listed on the portal. Our operators will provide comprehensive advice and offer free time to make an appointment.