Magnetic resonance imaging is considered one of the safest methods of radiation examination of tissues. This method uses magnetic radiation, while all other examination devices include the use of X-rays, which can cause adverse effects. What will an MRI of the knee show? During this procedure, the doctor receives the most accurate information about structural changes or damage even at the initial stage of the disease.
How MRI works
The action of magnetic resonance imaging lies in the fact that certain tissues are exposed to radiofrequency pulses of various structures and durations. They differ in signal intensity, which affects the degree of contrast when obtaining a three-dimensional image.
Liquids usually have a strong signal, so they are brightly colored, but bone tissues have a weaker signal, which makes them dark in the image. MRI of the knee can show a picturein all planes. This feature makes it possible to examine areas, such as knee joints, that cannot be examined by other types of examination.
Indications for knee MRI
This research method is the only one that detects the following diseases: Glanzman's myodystrophy, adhesive disease that occurred at the initial stage of the tumor. In addition, MRI is widely used to detect anomalies in various anatomical structures of the knee - blood vessels, venous system, nerve trunks.
Thus, the indications for the procedure are the following pathological conditions:
- damage to connective tissues (meniscus, tendons);
- tumors;
- fluid in the joint;
- bleeding;
- sports injury;
- infectious diseases;
- implant failures and more.
What can a knee MRI show?
What could such a study show? Thanks to this examination, you can see quite a lot of anatomical structures. The resulting image clearly shows the state of the bone component, as well as nearby tissues. Comparing an MRI scan of a he althy knee with an MRI scan of an injured joint makes it easy to see the problem.
Thus, this type of tomography shows the following elements of the knee:
- Bone tissue. MRI of the knee joint provides an opportunity to studyinflammatory and degenerative changes in the bones, patella, head of the joint, fractures, cysts, etc.
- Cartilage. Thanks to this study, it reveals how worn out the cartilage tissue is, and also detects micro-tears and cartilage tears.
- Ligaments and tendons. The knee is formed by various elements - muscle tendons, internal, external, posterior and anterior cruciate ligaments, patella. MRI detects their stretching, tearing and loss of elasticity.
- Meniscus. The knee joint consists of two types of meniscus: medial and lateral. They often rupture when injured and can only be detected with an MRI.
Preparing for the procedure
MRI of the knee is a diagnostic method for which you do not need to prepare in advance. But still, it is worth considering the following recommendations:
- Scanning and making a large number of images, from which they subsequently form a three-dimensional image, takes quite a long time - about 40 minutes. The patient must lie still during this time. In this case, you can ask the doctor for a pillow.
- Induction coils contribute to the creation of not only a powerful magnetic field, but also a loud knock. Suspicious and easily excitable patients may experience discomfort, so it is advisable to use a sedative.
- MRI is performed in a completely enclosed space (tube), so claustrophobic patients are also advised to take sedatives.
- The contrast agent used in diagnostics causes allergies in many people, so if you are prone to allergic reactions, you should tell your doctor about it in advance.
- During the study, a powerful magnetic field is created that can disable the patient's pacemaker or damage tissues containing metal elements (pins, metal-ceramic dental crowns, staples). In this case, the procedure should be abandoned.
Before the examination itself, the patient must remove all metal objects, and his clothing must be loose and not restrict movement.
Contraindications
In addition to the fact that a powerful magnetic field disables pacemakers and damages tissues with iron present in them, there are several other reasons why knee MRI is contraindicated:
- Pregnant and lactating women are not allowed to undergo tomography with a contrast agent, as it is toxic and can be excreted in milk. Also, the magnetic field can adversely affect the fetus, therefore, during pregnancy, MRI is performed only in the most extreme cases, for example, if the mother has a tumor.
- Children under 6 years old are also given this procedure only under special circumstances.
- If the patient weighs more than 120 kg, then he is not allowed to be examined, as he simply will not enter the scanner.
- If a knee injury causes severe pain, then the person will not be able to lie still, which is the main condition for the examination. In this caseit is worth abandoning the procedure.
- Patients with kidney failure are prohibited from MRI.
How do they do it?
Many people are interested in how a knee MRI is done. Magnetic resonance imaging of the knee joint is performed in the same way as in the study of other organs, only in this case, the induction coils will be located at the level of the affected knee.
The patient lies on a special retractable couch, his position is fixed with pillows and rollers, after which the table is rolled into a closed tomograph tube. During the study, the patient must be absolutely motionless, since the high accuracy of diagnosis depends on this. The tomograph makes a cut every 0.3-0.6 cm, so even the slightest movement is reflected in the results of the examination.
During the session, none of the medical staff will be near the patient, but just in case, two-way communication with the operator is provided. If dizziness, nausea and panic occur, the patient can report this to the operator.
Many are interested in the question: "If an MRI of the knee is scheduled, how long does it take?" Typically, such a procedure lasts from 10 to 40 minutes, and the patient receives the result in his hands 1-2 hours after its completion. But the doctor performing the MRI can refer the result to the referral specialist.
Using contrast agent
There are situations that during the procedure, the patient needs to enter an intravenous contrast agent. Such a methodMRI is called contrast and is used to identify processes that are not visible during conventional diagnostics. Its essence lies in the fact that the injected drug begins to change the parameters of the surrounding tissues.
Almost all substances are made on the basis of iron oxide and gadolinium, but have different mechanisms of action. Before conducting such a study, be sure to find out if an allergy to a contrast agent can occur. When choosing an institution where an MRI of the knee will be performed, you should find out if there is resuscitation equipment there. But complications are very rare.
Which is better - MRI or ultrasound of the knee?
It is necessary to consider these two most popular methods of examination. Ultrasound of the knee joint is performed using ultrasonic waves, and MRI is a computer-based research method based on magnetic resonance of atomic compounds that make up certain tissues.
Ultrasound is usually recommended for examination of internal organs in order to diagnose their disorders. MRI is used to diagnose bone diseases in the human body.
Also, ultrasound is completely safe and has virtually no contraindications, no matter what area is examined. But when performing an MRI, a rather large magnetic field is created, which is why this method of examination has certain contraindications and in some cases it cannot be performed.
Don't forget about the availability of such methods. Due to the simplicity of this study,like ultrasound of the knee, its cost is very low, and therefore it is accessible to all segments of the population. But not many people can afford an MRI.
Thus, it is impossible to answer the question of which method of diagnosing the knee joint is better. Therefore, only a specialist can determine the feasibility of a particular method.
Cost of procedure
The cost of an MRI of the knee joint is several times higher than other diagnostic methods. The high cost of the procedure is due to the high information content of the images, on the basis of which an accurate diagnosis is made.
The cost of an MRI of the knee joint ranges from 3,500 rubles and depends on the proposed diagnosis.
Patient testimonials
Quite a few patients are ordered by doctors to have an MRI of the knee. Reviews indicate that almost everyone was satisfied with this procedure. But not in any clinic you can go through it, since rather expensive equipment is required. According to patients, the accuracy of the result, the painlessness and safety of the study is what makes the procedure more and more popular every day.
Conclusion
Thus, although an MRI of the knee joint is considered a safe procedure, it is necessary to weigh the pros and cons before going for it. You can also consult with a specialist in this field. It is also important to find a good clinic that performs an MRI of the knee. It is important to have resuscitation equipment in it if the procedure will be accompanied by the introduction of a contrast agent.
