Do MRI with joint endoprostheses. MRI after joint arthroplasty: the effect of magnetic fields on the composition of the implant

An MRI machine, by generating a strong magnetic field around a person, is able to investigate many disorders and pathologies of organs and tissues, but at the same time it can have a negative impact on the body of patients who have metallic foreign bodies. One of the contraindications for the MRI procedure is the presence of implants made of various metals and alloys. Implants are pins in bone tissue, joints, permanent constructions, pacemakers, dentures. Why, in the presence of metal implants, doctors recommend choosing a different method of examination, is their presence an absolute contraindication for the procedure? If there are metal objects in the body, in particular titanium, can I undergo an MRI or not?

MRI and metal plates

Depending on the attitude of any metal to the action of a magnetic field, they are divided into diamagnets (in the field they are subject to weak repulsion), paramagnets (weakly attracted by a magnetic field) and ferromagnets (strongly susceptible to the action of the field).

In exceptional situations, the doctor may prescribe an MRI if the patient has metal plates. In the presence of metal in the body, the examination can be carried out only if its immediate location is outside the magnetic field, or diagnostics will be performed on low-field equipment. However, in the vast majority of cases, metal prostheses are a contraindication to the procedure.

In the presence of titanium plates in the leg and other parts of the body, the diagnosis is carried out without restrictions, since titanium is paramagnetic and is not characterized by strong attraction in a magnetic field. MRI with a titanium prosthesis is as informative and harmless as without it.

MRI after stenting

After stenting, an MRI study is not only allowed, but also prescribed. Therefore, the answer to the question of whether it is possible to do an MRI after stenosis is positive. But the specialist conducting magnetic resonance imaging must definitely know exactly what material the stents are made of.

It is absolutely safe to conduct an examination with bioabsorbable stents, since they consist of a biopolymer - after a predetermined time they dissolve, but the lumen of the vessel is preserved.

In other cases, stents are made of inert metal alloys: stainless steel, cobalt alloys, etc. Note that the patient is required to strictly follow the instructions for the stent, i.e. if it states that MRI should not be done in the first few weeks after stenting, then this applies not only to the area where the stent is inserted, but to the entire body. Even if it is not directly located in the tunnel of the device, the magnetic field works equally strong in the room where the tomograph is installed.

Sometimes an immediate diagnosis is necessary when the presence of a stent is not known before the MRI, because the patient does not have time to report them. Practice confirms that the materials currently used for the manufacture of stents are not ferromagnets and do not respond to external action of the field, and, therefore, are MRI-compatible.

Is it possible to do an MRI with iron crowns

In the presence of old-style crowns made of iron, screening of the brain and heart cannot be done. The metal heats up significantly, which causes severe pain in the patient, deformation of the metal structure - the integrity of the implants can be broken or they fly off the teeth.

With crowns and dentures with metal ceramics, screening of the brain and heart area is allowed, but there is a high probability of an unreliable result due to a distortion of the response to magnetic field signals.

Regardless of the type of alloys of crowns and prostheses, it is allowed to conduct MRI of the lumbar spine, abdominal organs and retroperitoneal space, pelvic region and extremities in closed-type devices.

When installing pins, high-strength titanium implants are often used. Their presence does not affect the reliability of the examination results, moreover, the size of the pins is so small that the magnetic field does not have any significant effect on them.

Metal crowns made of polymer alloys also do not distort the signals of the magnetic field, however, you should check with the dentist about the possibility of conducting an MRI. Some designs heat up, so the procedure will cause significant discomfort to the patient.

If the patient has dental bridges, then they probably have separate parts - pins, plates, screws of various sizes. For their manufacture, diamagnets, ferromagnets and paramagnets are used - cobalt, iron alloy and nickel, which react differently to magnetic field signals. Therefore, you should check with your dentist what materials were used to make the prosthesis, and inform the tomography specialist - he will decide on the possibility of an MRI.

Can you do an MRI with braces?

Modern braces are made of expensive and durable alloys that do not deform under the influence of magnetic nuclear radiation and cannot move or injure the patient's oral mucosa.

Small structures do not distort the tomograph signals, do not heat up - their reaction to a magnetic field is very weak.

It is impossible to do MRI if a sufficiently voluminous structure - more than 20 cm - is fixed with ferromagnetic retainers. In this case, the bracket may become warm.

Do I need to do an MRI if a bracket is swallowed to accurately determine its position in the intestine? A large bracket cannot be swallowed, but a small one will come out naturally. To speed up this process, you need to eat more viscous porridge and drink liquids.

Braces do not affect the patient's condition during MRI, but because of them, you can get an insufficiently reliable result when scanning the brain, heart area, thoracic or cervical spine.

In cases where it is urgent to do a screening of the brain and cardiac system, and doctors do not see an alternative to MRI, you should contact orthodontists and remove dental implants. After tomography, they are again installed in the required volume.

Is it possible to do MRI with endoprostheses and other implants?

What to do if the patient has various kinds of implants right in the body? First of all, this must be reported to the specialist conducting the examination, since many metals are ferromagnetic and can move in the body under the influence of a magnetic field.

But for an MRI with a steel wire in the body, everything is not so simple. Iron causes the magnetic field to deviate from a given direction, which leads to distortion of the resulting images and the appearance of artifacts (defects) on them. In addition, the needle is able to heat up, creating discomfort for the patient.

Also, the answer to the question of whether it is possible to do an MRI with an endoprosthesis depends on what material it is made of. If titanium, then there are no restrictions. If from ferromagnetic materials, then this is a contraindication to the study. You can specify what metal the implant is made of in the design passport, which is issued to the patient after prosthetics.

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It happens that in people who have undergone surgical operations that entailed the installation of metal implants of significant size in the body, it becomes necessary to conduct such a medical study as magnetic resonance imaging (MRI), while such a study may be associated with a completely different organ where implant was placed. As you know, MRI is a highly sensitive examination method based on the impact of a constant magnetic field of high intensity on a person and the measurement of the electromagnetic response from different tissues. Naturally, the presence of a foreign metal in the body should theoretically make it difficult or even completely undesirable to conduct such a study. Sometimes radiologists motivate their refusal to perform an MRI by the fact that a metal implant, being in a high-voltage magnetic field, can heat up, collapse and damage the health of the subject. The behavior of the implant in such a study depends on the material from which it is made, its size and shape. In addition, experts pay attention to the low information content of the image due to the presence of an unnatural tissue pattern.

What is really happening.

Regarding the safety of MRI. Everywhere, including Russia, legislative acts have been adopted regulating the admission to the market of medical products intended for implantation in the human body. They state that all orthopedic endoprostheses and internal fixators (pins, bone plates, screws) must be made of non-magnetic metals and alloys, be inert in a magnetic field and pass the appropriate certification. Therefore, if your implant is certified, then the study should be safe both for the health of the patient and for the implant.

Regarding the low information content of the image, it can be said that in many countries, work was carried out aimed at increasing the informative value of MRI diagnostics. In particular, they resulted in the creation of the MARS (metal artifact reduction sequences) program, aimed at eliminating image distortions and soft tissue and bone artifacts in the area of ​​the hip joint endoprosthesis, arising from the presence of metal implants in the magnetic field.

Summarizing the above, we can conclude that MRI after endoprosthetics or osteosynthesis is acceptable, but we would consider it correct if the decision on the possibility of conducting such a study in each specific case was made by a qualified radiologist based on the documents submitted to him about the implant (certificate on the product, information about the material of manufacture and dimensions), the proximity of the examined organ to the place of implant installation and the possibility of obtaining the necessary informative value of the study.

If a person has undergone surgery, he is interested in whether he can fully live on. In cases where a foreign object is implanted into the body, fears are intensified. So, for example, patients who have implants inserted, a pacemaker installed, will not be able to undergo magnetic resonance imaging if necessary. And is it possible to do an MRI with a hip joint endoprosthesis - also not always.

Magnetic resonance imaging is an examination that allows you to examine in detail the entire human body, or an organ of interest. The procedure is carried out on a tomograph - a device specially designed for this.

Reading information becomes possible due to the influence of electromagnetic waves on the body, as a result of which hydrogen atoms react to magnetic resonance and allow scanning. The computer processes the data and produces a three-dimensional picture, where you can see all the processes that occur with tissues and blood vessels.

The main contraindication to MRI is the presence of metal and electronic objects in the body:

• implants;
• endoprostheses;
• plates;
• staples;
• screws;
• pins;
• clamps;
• fragments.

Endoprosthesis procedure

Sometimes it happens that a joint loses its function, for example, the hip joint. There may be various reasons for this:

• congenital pathologies;
• injury;
• infection;
• oncology.

Modern medicine has learned to replace the natural joints in the human body with artificial ones. The procedure is called endoprosthesis replacement. This is a successful method of returning anatomical functions to the body. The following joints can be replaced:

• hip;
• brachial;

What are endoprostheses made of?

Traumatology and orthopedics have been dealing with the issue of prosthetics of the hip joint for quite a long time. Every year, not only the operations themselves are improved, but also the composition of endoprostheses. Most often, structures are made of alloys:

• gland;
• nickel;
• cobalt;
• titanium.

The ratio in the alloy of different ingredients gives a different response to the impact of a magnet, and quite often critical for the patient, so the presence of such objects in the body as a hip replacement may be a ban on MRI.

How do metal objects behave under the influence of a magnetic field?

Each alloy has its own magnetic properties, so the behavior of a hip replacement during MRI is directly dependent on its composition. However, not only the material plays a role, the shape of the prosthesis itself is also important.

The endoprosthesis of the hip joint under the influence of a magnet can move from the established place, thereby causing unbearable pain. This applies to small items - clips, staples, clamps. The magnetic field can rip them off. As for the plates, pins, even a very strong field will not make them move, since the fixation of the element in the bone will be very strong.

Metal structures in the body, such as a hip replacement, can become hot. For example, a steel alloy under the influence of magnetic waves will heat up to a temperature of over 40 ° C, which will burn the joint cavity in which the prosthesis is installed.

If the prosthesis, plate, pin, screw are made of titanium alloys, then computer diagnostics are not contraindicated with such designs, since the magnetic field will not have any effect on them. However, the metal object will give a background and dark spots or blurring will appear on the MRI images.

Before going for magnetic resonance imaging, it is important to find out the composition of your prosthesis or device in the body, and it is best to take a certificate certifying the origin of the product, since the diagnostician will definitely ask her.

Can MRI be performed on patients with a hip replacement?

If it is necessary to do magnetic resonance imaging, and the patient has an endoprosthesis, then it is necessary that there are documents on hand that will indicate information about which implant he has installed, what is its composition and who is the manufacturer. Then, based on the data obtained, the radiologist examines the marking and concludes whether it will be possible to conduct an MRI procedure after arthroplasty.

However, even if the endoprosthesis of the hip joint installed in the patient assumes the presence of a metal exposed to a magnetic field, only those who are to have an MRI of the hip joint, spine, and pelvic organs should be worried. If a tomography of any other limb is prescribed, then the procedure can be safely carried out. Only it should be an open-type tomograph, where the magnetic scanner is located directly above the area under study. The endoprosthesis will not fall into the field of influence of the device and will not give any reaction.

Will a patient with an endoprosthesis be denied an MRI of the spine?

The permission for the MRI procedure also depends on the shape of the installed prosthesis or design. If in the hip joint the plate is shorter than 20 cm, made of titanium, then nothing interferes with the tomography.

However, if the prosthesis contains other metals, or it is a long pin, then in this case the doctor will most likely refuse such a diagnosis, prescribing computed tomography instead. Nothing will happen to the plate, but it will cause a lot of inconvenience to the patient, even during a standard MRI of the spine.

MRI for prosthetics of other joints

Endoprosthetics is a rather complicated operation, after which, for the first year, the patient is under constant control over the behavior of the implant or prosthesis in the body. Immediately after the completion of the surgical intervention, it is worth taking all the documentation with information about which implant was installed, whose production and from which alloy. This may come in handy in the future. As, for example, for magnetic resonance imaging, because no one is immune from this.

Is it possible to do MRI diagnostics with titanium plates - yes, it is quite possible, since they are not magnetic, which means they will not move, heat up, but they can distort the image of the organ, so the decision to conduct diagnostics or prohibit it is made by the doctor. Each specific case is burdened with its own characteristics and aspects, so any procedure and all appointments to it will be purely individual.

If the patient had a knee joint replacement, then problems with MRI can occur only on the lower extremities or on the spine. If the elbow joint was prosthetized, then tomography of the arm will be difficult, regardless of what metal composition the prosthesis had.

What are "artifacts" on MRI scans?

Artifacts (from Latin artefactum) are errors made by a person in the process of research. Artifacts significantly degrade image quality. There is an extensive group of physiological (in other words, related to human behavior) artifacts: motor, respiratory, artifacts from swallowing, blinking, random uncontrolled movements (tremor, hypertonicity). All artifacts associated with the human factor can be easily overcome if a person is completely relaxed during the study, breathes evenly and freely, without deep swallowing movements and frequent blinking. However, in medical practice, cases of using light anesthesia are not uncommon.

At what age can children have an MRI?

Magnetic resonance imaging has no age restrictions, so it can be performed on children from birth. But due to the fact that during the MRI procedure it is necessary to remain still, the examination of young children is carried out under conditions of anesthesia (surface anesthesia). In our center, examination under anesthesia is not carried out, therefore, we examine children only from the age of seven.

What are the contraindications for MRI?

All contraindications to MRI can be divided into absolute and relative.
Absolute contraindications for MRI are the following features of the patient: the presence of a pacemaker (heart pacemaker) and other implantable electronic devices, the presence of ferrimagnetic (iron-containing) and electric stapes prostheses (after reconstructive operations on the middle ear), hemostatic clips after operations on the vessels of the brain brain, abdominal cavity or lungs, metal fragments in the orbit, large fragments, shot or bullets near the neurovascular bundles and vital organs, as well as pregnancy up to three months.
Relative contraindications include: claustrophobia (fear of closed space), the presence of massive non-ferrimagnetic metal structures and prostheses in the patient's body, the presence of an IUD (intrauterine device). In addition, all patients with magnetically compatible (not ferrimagnetic) metal structures can be examined only after a month after the surgical intervention.

Do I need to have a doctor's referral to get an MRI?

A doctor's referral is not a prerequisite for visiting an MRI center. Your concern for your health, your consent to the examination, as well as the absence of contraindications for an MRI is important to us.

I get headaches often. Which area should have an MRI?

Any person is familiar with a headache, but if it recurs suspiciously often, of course, this cannot be ignored. We recommend that a patient with severe headaches undergo an MRI of the brain and its vessels. In some cases, this may not be enough, because the cause of headaches is not always associated with the pathology of the brain. Headaches can be the result of cervical osteochondrosis, so our specialists additionally advise to undergo MRI of the cervical spine and neck vessels.

How long does an MRI exam take?

The average duration of one examination in our center is from 10 to 20 minutes, however, it all depends on the changes detected: sometimes, to clarify the disease, the radiologist may extend the examination protocol and resort to the use of contrast enhancement. In such cases, the study time is increased.

There are fairly frequent cases when a person needs to install metal implants in the body, allowing artificial replacement of certain organs or parts of the body. One of the most popular types of prosthetics is the knee joint. When endoprosthesis replacement of the knee joint, there is a need for a diagnostic study, which is referred to as magnetic resonance imaging. Is it possible to do an MRI study with a hip arthroplasty if the procedure is performed to diagnose pathologies of other organs?

What is an MRI and conducting a study

MRI is a comprehensive or partial study of certain organs or parts of the body, carried out in order to identify pathologies, diseases and neoplasms. The need to undergo an MRI arises only when a person has painful syndromes, and it is not possible to determine the developing ailment with the help of examination and tests.

Magnetic resonance imaging is performed according to the relevant indications. This technique is one of the safest, harmless and painless procedures. The main advantage hidden in this type of diagnostic manipulation is to obtain the most detailed information about the organ or body part under study. During the study, images are created in the form of sections of the organ under study with a minimum step of several millimeters. Based on these sections, the specialist determines the presence of pathologies and abnormalities in the organ under study. If there are any, an appropriate conclusion is made. Based on the images received, the attending physician decides how to overcome certain pathological failures in the body.

It's important to know! One of the significant drawbacks of the MRI procedure is the duration of the diagnosis. On average, the study of one organ takes about 20-30 minutes, and when using contrast agents, the time increases to 40-50 minutes.

Often patients have a question, what is better computed or magnetic resonance imaging? It is impossible to give an unambiguous answer to the question, since both methods have their own purposes, although they are interconnected. It is worth highlighting the fact that when compared with CT, MRI does not emit X-rays, which are radioactive. During MRI, a constant magnetic field is created, which leads to the excitation of hydrogen atoms in human tissues and organs. Based on the oscillations of hydrogen atoms and ions, which are saturated in human tissues and organs, a visualization of the studied part of the body is created. The pictures that are obtained during this process are a high-resolution image that allows you to visually diagnose the disease.

MRI and endoprosthetics

The MRI procedure has a significant contraindication: the technique is contraindicated for persons who have metal inserts, prostheses, implants in the body. It is theoretically possible to make MRI diagnostics with metal prostheses, but it is important to take into account the fact that the metal will distort the results of the examination. This means that the expected high-precision image will be blurry and will not allow assessing the state of the organ under study.

Precisely because in the presence of metal elements in the body, it is not possible to obtain the highest quality image, the MRI procedure is contraindicated for such patients, but not in all cases. Now it is worth returning to the elements of arthroplasty. According to the legislative regulations approved in many countries, including Russia, it is allowed to use implants for installation in the human body that meet certain requirements. These requirements include:

• implants should be made mainly from metals that are not magnetic;
• they must have inertia;
• must also be certified.

From the above, we can conclude that MRI diagnostics with certified prostheses is allowed. An examination on a tomograph with such implants is completely safe and harmless, and it will not negatively affect the final results in any way.

To reduce the likelihood of distortions in the presence of metals, the specialist makes appropriate adjustments to the tomograph program. Often, a program such as MARS is used for these purposes. This program is intended directly for the elimination of distortions in the image of soft tissues and bones in the area of ​​the presence of a hip joint endoprosthesis. To reduce the likelihood of distortion, the specialist must be aware that the patient has an endoprosthesis.

Is MRI contraindicated in the presence of metal plates

If the results of the study are distorted, then not always the reason for this phenomenon lies in the metal plate. If the plate is installed in the knee joint, and it is planned to perform an MRI of the spine, then it will not affect the results of the study in any way. After all, the place where the plate is located is not exposed to a magnetic field, so the presence of image distortions is most likely due to the fact that during the session the patient did not lie still.

Is it possible to perform an MRI with metal prostheses, it all depends on where they are located and what parts of the body are planned to be examined. Many believe that the metal in the body can be magnetized to the walls of the apparatus. In reality, if the patient really has a metal plate that has the property of being magnetized, then when exposed to a magnetic field, it can simply heat up slightly and cause discomfort.

The popular question of whether it is possible to do an MRI with the presence of titanium plates has only a positive answer. The magnet does not affect titanium in any way, as well as ferromagnets, therefore MRI is allowed with such implants.

Summing up, it should be noted that it is possible to conduct MRI with a hip joint endoprosthesis if it is previously revealed that the material of the device is manufactured in accordance with certification. In each specific case, the decision to conduct a magnetic study is made by a specialist performing magnetic resonance imaging.