MRI of the knee: what does as do?
Pathological changes in the knee joint can be the result of trauma, inflammatory or degenerative process. Diseases caused by various reasons, can have similar symptoms, so diagnosis without additional methods of research can be difficult.
There are various methods of inspection, each of which has specific indications. The state of the meniscus is best shown by MRI, fractures and bone defects – a CT scan, and the conclusion about the presence of intra-articular cysts or effusions, it is better to make on the basis of ultrasound. Magnetic scanning is considered the most informative method of research, but at the same time has some limitations.
Which method is more suitable for examination of the knee joint?
To clarify the diagnosis using x-rays, CT scans, intra-articular endoscopy, ultrasound, and MRI. What method of examination can show a maximum of useful information, depends on what structure you want to visualize.
- Radiography is suitable for preliminary diagnosis of injuries, and to determine state changes of the bone surfaces in chronic degenerative processes of the joints in the dynamics.
- CT may detect traumatic damage to bone surfaces, AIDS in the diagnosis of arthritis and osteoarthritis, to identify fresh bleeding into the joint cavity. To examine the joints and cartilage structure, to evaluate the status of the meniscus with x-ray CT is impossible.
- Ultrasound gives information about changes to the size and shape of the meniscus, the structure of ligaments and synovial membranes. The validity of the results depends largely on the skill of the doctor who conducts the examination. On hands the patient receives only a description of the study and not the, as in the case of CT or MRI of the knee joint;
- Arthroscopy solely for diagnosis are infrequently. With this method, surveys can explore all the internal structure of the joint from the inside. Endoscopy can reveal to diagnose damage to the meniscus as accurately as possible. The drawback of the procedure is its invasiveness.
- MRI of the knee joint does not require special training, is noninvasive, safe and highly informative study. Magnetic scans perfectly visualized the cartilage, ligaments and surrounding soft tissue. Bone surface due to the peculiarities of their structure is also well visible.
For examination of internal structures of the knee joint used five different instrumental methods. Which one is the best to use for the diagnosis – the doctor will decide.
Indications for research
Usually magnetic scan administered after the baseline survey and establish a preliminary diagnosis. MRI of the knee joint may be recommended in the following cases:
- changes due to injuries with unsatisfactory results of x-ray methods.
- fresh traumatic injuries of intra-articular ligaments, meniscus or bone surfaces;
- preparing for surgery about a traumatic rupture of ligaments, damage of meniscus or chronic diseases;
- clinical signs of inflammatory or degenerative changes;
- malformations, functional abnormalities;
- indirect signs of the presence of intra-articular tumor of the cartilage or bone surface;
- the reason for the appearance of disease symptoms cannot be detected using ultrasound, CT or other methods.
Child MRI of the knee joint in the usual diagnostic center can be done if he was 7 years old. The younger children surveyed in institutions.
What diseases can you identify?
MRI of the knee provides detailed information on the status of the soft-tissue structures. On the basis of the obtained image can be judged:
- status of the joint ligaments and meniscus, the presence of discontinuities or thickening of the tendons;
- about the presence of the tumor intra-articular structures;
- strain on existing bone surfaces, changing the shape and width of the joint space arthritis or osteoarthritis;
- the presence of microtraumas bone surfaces, intraarticular hematomas and other accumulations of fluid in the synovial cavity.
Using the images obtained by MRI of the knee joint and the conclusion of the diagnostic centre and doctor can be better diagnostics, if needed to plan surgery. Magnetic scanning is often used for quality control of the conducted treatment.
How to prepare and what to bring?
MRI of the knee joint, most often, do without contrast enhancement, except for diagnosis of benign and malignant tumors. Any special preparations the study is not required, however, if you plan intravenous contrast-enhanced, 5-6 hours before the procedure must not eat or drink.
In addition to the direction of the attending physician, you need to take conclusions about the previous research findings (endoscopy, ultrasound, CT, MRI) – this will help the doctor when interpreting the results. In the presence of implantable electronic devices, prostheses or other metallic implants, you must have a passport to a device or a certificate from the operating surgeon with information about it. This may require the technologist to assess the presence of contraindications for the procedure.
How is an MRI?
MRI of the knee performed using CT scanners, closed or open type. Latest convenient for patients who are scared while in a confined space, as the research takes place outside the tunnel of the machine.
Before the examination the patient is instructed to change into special clothing. You can stay in his if there is no metal contamination, but pockets will have to pay. The presence of ferromagnetic materials can distort the results of the study, as well as to cause injury or damage to the unit.
The patient lies on a special couch, which can move inside the tunnel of the apparatus of the enclosed type or be positioned relative to the origin of magnetic fields in the MRI scanner with an open circuit. During the examination you may receive a sensation of warmth or tingling in the joint, after the end of the study it goes.
How long will the study depends on which deviation from the norm expected to see. The average magnetic scanning of the joint is doing in 30-60 minutes. The same time as the procedure itself, may take a transcript.
The presence of implanted electronic devices (pacemaker, cochlear implant, insulin pump) can be considered as a contraindication for the procedure, since the magnetic field can cause device damage, which will lead to complications.
The presence of metallic implants in the study joint makes MRI uninformative.
In the presence of metallic implants in other areas of the body scan is likely to be carried out. Often they are made from special alloys with paramagnetic properties. If the implant is installed to the left, the MRI of the right knee joint can be carried out. Metal inclusions located in the study area give interference, therefore, in such cases, magnetic scanning is impractical. Necessary information about existing damage can be obtained with combined CT and ultrasound.
Contrast-enhanced MRI cannot be conducted during pregnancy and in the presence of chronic kidney pathology. In this case, the existing damage can show ultrasound in conjunction with endoscopy of the joint.