Magnetic resonance imaging (MRI) of the ankle joint

The ankle joint is the articulation of the bones of the lower leg with the foot. The joint consists of the fibula, talus and tibia of the human body. The joint itself is mobile, responsible for flexion / extension, abduction / adduction of the foot. The ankle is subject to many pathologies – from mechanical damage to osteoarthritis or oncological neoplasms. In addition to standard palpation or X-ray, MRI is used to diagnose the joint. In what cases is tomography required, what do you need to know about the study and how to properly prepare for the procedure?

How does an MRI work?

An MRI machine can be compared to a large magnet. If a source of protons is placed next to a magnet, then elementary particles will begin to emit radio waves. Each radio wave will differ from the previous one in intensity and frequency. Both of these characteristics depend on the location of the proton and the source of the alternating magnetic field. With magnetic resonance imaging, the source of protons is the person himself. The fact is that our body is almost entirely composed of water. The liquid consists of 2 protons, which have an interesting feature – spin. This is the intrinsic angular momentum of an elementary particle, which is equal to ½. As soon as a source of protons (a person) is placed in a magnet (tomograph), it begins to emit a lot of radio waves. The MRI machine captures the difference in the frequency and intensity of these waves, calculates the location of the protons that emit them, processes the information and turns it into an image of the internal environment of the body.

Contrast or sedation may be used during the scan. The first group of substances helps to improve the visualization of the image. The use of sedatives is aimed at relaxing the patient. Most often they are prescribed for hyperactive children and people with claustrophobia / various deviations of the psychological spectrum.

Advantages

Diagnostics helps to examine in detail each tissue section. The method is especially informative when it is impossible to conduct an endoscopic examination of certain organs or structures.

MRI is considered the safest and most informative method of modern diagnostics. It is believedthat the magnetic field does not exert negative influences on the human body, and the list of contraindications to this diagnostic method minimal. Magnetic resonance imaging can be used for multiple examinations, unlike x-rays or CT scans, which are based on x-rays.

Safety is not the only advantage of the method. MRI perfectly visualizes not only dense (like X-ray), but also soft tissues. The study allows you to increase the resolution of the image without loss of quality and clarity of visualization. The performance of MRI and CT is approximately at the same level, but some specialists prefer computed tomography due to more informative in relation to bone structures. The only drawback of the method MRI – high price. It is justified by the cost of MRI equipment and the need for constant care for it.

Possible risks when undergoing tomography

With the right technique, MRI does not pose any danger to the human body. But experts identify such possible risks:

1. Allergic reaction to the contrast agent. May range from mild itching to severe swelling Quincke or anaphylactic shock. In most cases, it is stopped by drugs.
2. Lack of information on the effect of the magnetic field on pregnant, so MRI only allowed after the first trimester of pregnancy.

Relationship between MRI and metal

The MRI machine is a huge magnet that, like all magnets, attracts metalthe elements. What does it threaten? Metal elements can be both inside (catheters / prostheses) and outside (piercing / decor elements on clothes). First, they can distort the performance of the study by affecting the magnetic field. The device will fix the wrong indicators, which will prevent the formation of an image and reduce the information content of the MRI to zero. Secondly, the patient may feel extremely uncomfortable when the metallized particles begin to be attracted to the magnet. The intensity of pain varies depending on the individual characteristics of the patient and the amount of metallic substance. One person may feel a slight tingling sensation, another an unbearable pain, after which they will not be able to continue scanning.

What is the connection between metal and tattoos? Even 20 years ago, tattoo inks contained metallic substances. In modern tattoo parlors, this practice has long been abandoned, but people who have tattooed up to this time cannot undergo an MRI. During the diagnosis, the magnet (magnetic resonance imaging) will begin to attract metal particles, which will cause extremely unpleasant symptoms in a person – from mild itching to severe pain. Be sure to tell your doctor if you have a tattoo. roentgenlaboratory assistant performing tomography. The specialist will assess the possible risks, check the concentration of the metallized substance in the tattoo and, if necessary, select an alternative diagnostic method.

Preparing for the procedure

In most cases, scanning annuitylaboratory assistant He needs to provide medical documentation – a referral from the attending physician, the alleged diagnosis, the results of previous studies. Based on the medical documentation, the laboratory assistant adjusts the device, evaluates the duration and specifics of the study. Before scanning, the patient must remove all metal objects, check for medicinal patches and tattoos.

Be sure to specify the duration of the study, the presence of a call button, ways to contact the laboratory assistant, whether contrast will be used and ask other questions of interest. There will be no opportunity for dialogue during the MRI because the machine makes a loud noise. If you feel pain or discomfort, press the call button to abort the scan.

In contrast MRI, gadolinium-based preparations are most often used. Make sure that you are not at risk, and the substance itself does not pose a danger to the body. Relevant information must be provided annuitylaboratory assistant along with the rest of the medical documentation.

Conducting diagnostics

MRI equipment looks like a cylindrical tube surrounded by a large round magnet. During the scan, the patient is placed on a sliding table, whichrides to the center of the magnet. There are also open tomographs. In them, the magnet does not completely surround the patient, but only from above and below (an open space remains to the right and left of the person). Open MRI is suitable for overweight and claustrophobic patients.

For the diagnosis of the ankle, a closed-type tomograph is used, since it gives a more informative and clear image.

When scanning the ankle joint, the laboratory assistant places the coil (a large moving magnet) closer to the area being examined. During the procedure itself, the patient must lie still for 20 to 40 minutes. The time frame depends on the specifics of the diagnosis, including the need use of contrast.

The patient may feel a pleasant warmth in the scanned area. This is a completely normal tissue reaction to exposure. elements built into the tomograph and in contact with the patient’s body. If you feel a more specific reaction – severe pain, itching, tingling, excessive heat, then be sure to report it. Medical staff will decide on further diagnostics, or eliminate unpleasant symptoms. After the procedure, the patient does not need adaptation, he can return to the usual rhythm of life.

Scanning of the ankle is also carried out on small devices. This allows you to work only on a specific joint, and not on the whole body. The power of the magnetic field in such devices is in no way inferior to standard MRI equipment, so the size of the tomograph does not affect the final image in any way.