MRI of the eye orbits

Magnetic resonance imaging - a method of diagnostic research of various human organs, combining the knowledge of nuclear physics and medicine. This method is slightly less than 60 years, but it was actively applied only at the turn of the past and this century directly for the study of internal organs and brain. A little later the method has gained great popularity and in ophthalmology for the diagnosis of eye diseases, the cause of which is not visible during visual inspection. MRI of orbits and optic nerves allows detecting the slightest changes in various tissues and structures of the eye that affect the ability of a person to see. So, this method helps to identify the disease in its initial stage and begin treatment when it will be most effective.

[1], [2], [3], [4]

Indications for the procedure

Magnetic resonance imaging is considered one of the safest and most effective ways to detect various pathologies of the eye, carefully examining the internal structures that are not visible to the naked eye and not visible during the examination by a microscope. In addition, a more modern method of MRI helps to see such miserable changes in the eye that are not available by old methods.

In connection with the high diagnostic value of MRI orbits, it can be prescribed in the diagnosis of various pathologies of the eye:

• inflammatory processes with localization in different layers of the organ of vision,
• damage to the retina of the eye, for example, its detachment,
• tumor processes in the area of the organ with the determination of their exact location and size (even small formations of small sizes of 1 mm are determined),
• hemorrhages in the eye with the determination of their cause, thrombosis of the vessels of the eye,
• injuries with the determination of the severity and volume of damaged tissues, with the detection of the remains of foreign bodies that caused trauma to the eye,
• changes in the corneal layer,
• disturbance of the functioning of the optic nerves (for example, with suspicion of glaucoma ), reduced visual acuity, the appearance of incomprehensible pain in the eye with the definition of their cause,
• the state of the organ of vision in diabetes mellitus, hypertension and other pathologies, in which the blood supply to the eye is impaired.

Through MRI, it is possible to determine the location of foreign bodies in the internal structures of the eye, to identify inflammatory foci and to assess their size, to find hidden tumors, and under the control of MRI to take the material for biopsy.

If there was a trauma to the eye, MRI allows you to assess its consequences and complications, the size and nature of damage to internal structures as a result of trauma, the possibility of treatment in each case.

When a person's vision deteriorates or the motor activity of the eyes is disturbed (a squint appears , the patient can not focus the vision on a particular object), it is simply impossible to determine the cause without examining the internal structures. MRI provides an opportunity to see and assess the degree of lesion (atrophy) of the muscles or nerves responsible for eye movement, and outline measures to correct the defect.

Quite often, the cause of visual and pain disorders is hidden from us, and it can be detected only by actually penetrating the eye, observing his work, assessing the changes taking place there. This is exactly what magnetic resonance imaging provides. Although the procedure is called MRI of orbits, in fact it also allows visualization of visual muscles, nerves and lacrimal glands, pathology of the eyeball, changes in fatty tissue, due to which its demand is growing.

[5], [6]

Preparation

MRI of orbits and optic nerves is considered to be simple and generally safe procedure, which does not require special measures to prepare for diagnosis. Usually it is prescribed by an ophthalmologist during the reception and examination of the patient, if the statement of the exact diagnosis causes him difficulties.

A person can go through the survey on the same day or later, when such an opportunity arises. The fact is that not all medical institutions are equipped with the necessary equipment. In addition, the MRI procedure will not be free for everyone.

The main condition for obtaining a high-quality image is considered to be immobility of the patient during the examination, about which a person is warned in advance. If the patient is very nervous, he has symptoms of claustrophobia or severe pain, which does not allow him to remain immobile, and shows the use of sedatives that reduce nervous excitability.

Patients with mental disorders or serious eye trauma, in which they experience unbearable pain, require additional fixation of the limbs. If the above measures do not help, the doctor may resort to anesthesia administered intravenously.

Since the investigation of organs is carried out by means of a magnetic field, any metal objects that can distort it must be removed. It is about jewelry and clothing with metal elements (locks, buckles, buttons, buttons, decorative pads, etc.). If the body has metal in the form of crowns, implants of organs, electronic devices that support the functions of the body, it should be told to the doctor at the time of admission. It may be necessary to clarify the material of dentures, if the patient is not sure of his information.

During the MRI, contrast substances can be used that facilitate the diagnosis of tumor and inflammatory processes, help to assess the condition of blood vessels. This question is also stipulated in advance, because on the eve of the procedure (5 hours before it), the patient will have to give up eating so that no components of the food can influence the result of the study. The optimal option is the introduction of contrast on an empty stomach.

To exclude intolerance of contrast medium and anaphylactic reactions before the introduction of the drug, a sample is applied, applying the drug to the exposed areas of the skin in the area of the wrist. The doctor necessarily specifies the weight of the patient, because the amount of contrast introduced depends on this.

The drug is administered intravenously in the form of injections or infusions (drip) in the area of the elbow fold. The patient may feel dizzy, feverish, hot flashes, nausea, but this is not terrible, because it is considered a normal reaction of the body to contrasts. The introduction of drugs for MRT orbits with contrasting is under the supervision of a doctor. For the next 30 minutes, the patient is observed by the medical staff.

Half an hour after the administration of drugs, the active substance of which accumulates in different tissues in different concentrations, it is possible to proceed with MRI diagnostics. During this time, the medicine will spread through the bloodstream and reach the area under investigation.

Technique MRI of the eye orbits

MRI orbits, like any other diagnostic procedure, is not carried out for the sake of interest. Therefore, it should be taken seriously. After examination of the patient by a specialist, he gives direction for a diagnostic study. With this direction and the results of previous studies of the organs of vision, the patient is directed to the diagnostic room.

The radiography that is familiar to us differs somewhat from the magnetic resonance tomogram, although both studies are identical and pursue the same goals. An uninitiated person can shock the device a little in the form of a long volumetric tube, located horizontally. It is in this tube (capsule) that a magnetic field is created that allows the image of the organ under investigation to be displayed in full detail on the screen.

In order to relieve tension and fear of the apparatus and procedure, the patient explains how the eyes make an MRI, that the procedure can show in each specific case what consequences this study has for the body.

The principle of operation of magnetic resonance systems of an open or closed type is based on the fixation of the motion of hydrogen atoms, saturating the tissues of the organism, under the influence of a magnetic field. The illumination of different parts of the image depends on the number of molecules of gas accumulated there.

The procedure of MRI is rather complicated in execution and requires the patient to be immobile. The easiest way to do this is in a horizontal position, when the person is as relaxed as possible. For these purposes, the tomograph has a retractable table, onto which the patient is laid, fixing his head in a special device. If necessary, belts can fix other parts of the body.

Since only the head region is examined, the table is shifted so that only it is inside the apparatus. The body is outside the scope of the tomograph.

Before starting the procedure, patients are offered to use earplugs, since the device is characterized by a not very pleasant monotonous sound, which can cause anxiety and cause unwanted movements.

The procedure itself is considered rather long compared with radiography. By time, it takes from 20 to 40 minutes, during which a person must lie still. If contrast agents are used during the study, the procedure can be delayed for another twenty minutes.

During the study, the doctor is usually outside the diagnostic cabinet, but the patient can contact him at any time by phone, if there is an attack of claustrophobia or any other problem, for example, chest pain, shortness of breath, a feeling of lack of air, which happens during the procedure with contrasting. In the same way, the doctor can give the necessary instructions to the patient.

To reduce nervous tension and calm the researcher is allowed to invite to the procedure of relatives. This is especially important if the diagnosis is carried out to the child. Still, the device for MRI is versatile, so it is large and can frighten a small patient.

Contraindications to the procedure

Magnetic resonance imaging (MRI) is considered one of the safest procedures, because unlike computed tomography (CT) and radiography for its conduct, there is no need to use harmful x-rays. The magnetic field in the tomograph does not harm the health of a person of any age and condition, therefore, health disorders are rather indications for the study than contraindications to it.

The only absolute contraindication to MRI is the presence in the human body of ferromagnetic alloys and electronic devices (pacemakers, electronic implants of the middle ear, etc.). The magnetic field can adversely affect the pacemaker, imitating the heart rate and causing malfunctioning of the electron microscopic equipment implanted in the body.

As for metal implants from ferromagnetic alloys and metal fragments stuck in the body (for example, after wounds), the danger of the influence of a strong magnetic field lies in the fact that under its influence ferromagnets can appreciably heat up, causing a burn of tissues, and shift from place. Thus, the magnetic field can negatively affect ferromagnetic and large metal implants, Elizarov apparatus, ferromagnetic middle ear simulators, inner ear prostheses, containing ferromagnetic elements, vascular clips from ferromagnets located in the brain region.

Some metal implants (insulin pumps, nerve stimulators, valve prostheses, blood clamps, dentures, braces, endoprostheses, etc.) can be manufactured of their materials with weak ferromagnetic properties. Such implants are in the category of relative contraindications, but they must be reported to the doctor with the materials from which the device is made. After all, even these devices can contain ferromagnetic elements, and the doctor must assess how dangerous the effect of the magnetic field will be on them.

As for dentures, most of them are made of titanium - a metal with weak ferromagnetic properties, i.e. The magnetic field during MRI is unlikely to cause a reaction from the metal. But titanium compounds (for example, titanium dioxide used in tattoo paints) on a strong magnetic field can react differently, causing burns on the body.

In addition to non-ferromagnetic implants, relative contraindications include:

• early pregnancy (there is insufficient information on the effect of magnetic field on fetal development during this period, but this method is considered preferable and safer than CT or X-ray),
• heart failure in the stage of decompensation, a serious condition of the patient, the need for constant monitoring of the body's work, bronchial asthma, severe dehydration
• fear of confined space or claustrophobia (because of the impossibility of conducting research in a person who, for fear, can not remain stationary for half an hour or more),
• inadequate condition of the patient (alcoholic or narcotic intoxication, mental disorders will not allow to make clear pictures due to constant motor reactions),
• tattoos on the body, made with the use of paints containing metal particles (there is a risk of tissue burn if it is a particle of ferromagnets).
• Prostheses of the inner ear that do not contain ferromagnetics.

In these cases, the doctor decides whether or not to conduct an MRI of the orbits taking into account possible negative effects. In some cases, it is more appropriate to postpone the procedure for the time necessary to normalize the patient's condition.

If it is a MRI with contrasting, the list of contraindications becomes larger, nevertheless, it requires the introduction of chemicals into the body, the reaction to which can be dangerous.

MRI with contrast is not performed:

• pregnant women regardless of the gestational age due to the ease of penetration of drugs through the placental barrier (the effect of contrasts on the fetus has not yet been studied),
• with chronic renal failure (the contrast is excreted from the body for 1.5-2 days, but with violations of kidney function may be delayed for a longer period, because the recommended use of large amounts of liquid is considered unacceptable),
• at hypersensitivity to contrast preparations because of danger of development of serious allergic and anaphylactic reactions.
• patients with hemolytic anemia.

Before carrying out the MRI procedure for his own good, the patient is obliged to tell about any metal objects in his body including fragments from wounds, tattoos and used cosmetics (and better not to use cosmetics), remove all kinds of jewelry, watches, clothes with metal elements.

Normal performance

MRI of orbits and optic nerves is a diagnostic study that is assigned for a specific purpose. The aim of the study is to identify pathological processes in the tissues of the eye or to evaluate the results of treatment if the MRI is re-assigned.

MRI allows to study in detail the shape and quality of the orbit, the location and shape of the eyeballs, the state of the fundus, the structure and the course of the optic nerve, to reveal dystrophic changes in it and other abnormalities.

By means of MRI of orbits, it is possible to assess the state of the eye veins and muscles responsible for the movement of the eyeball (their location, the presence of seals and tumors), fat glands in the eye sockets.

With the help of MRI, the retina is damaged, which is the inner shell of the eye. The fact is that damage to the retina does not necessarily have to be due to trauma to the eye or head. Some pathologies of the inner shell of the organ of vision are associated with various systemic diseases (diabetes, hypertension, kidney and adrenal pathology). Magnetic resonance examination helps to identify pathologies such as retinal detachment, diabetic or hypertonic retinopathy, damage to blood vessels that supply retinal nutrition, degeneration or degeneration of this part of the eyeball, tumor and inflammatory processes, retinal rupture.

MRI of orbits with contrast allows to assess the state of the vessels of the eye, their blood filling, the presence of thrombi and ruptures. With the help of contrast agents it is easier to recognize internal inflammations. But most often the technique is still used to detect tumors with suspicion of oncology. With the help of MRI it is possible not only to detect a tumor in a certain area of the eye, but also to evaluate its shape and size, the presence of metastases, the influence on nearby structures and the possibility of removal.

Any abnormalities in the shape, size, and density of tissues detected by MRI of the orbits give the physician valuable information necessary for establishing the final diagnosis. In addition, during diagnostic activities, you can find some brain damage, which is also seen on the tomogram.

An example of an MRI protocol of orbits may look like this:

Type of research:  primary (if the study is repeated, also indicate the date of the previous one, with which the results will be compared).

Glaznitsy have a proper development, a pyramidal shape with clear and even contours of the walls. Foci of destruction or seals are not observed.

Eyeballs are spherical and symmetrical in relation to the eye sockets. The vitreous tissues are uniform, there is no change in the MR signal (this indicates a normal condition of the organ, for example, in inflammatory processes, the MR signal will be hyperintensive, with tumors - iso-intensive or hyperintensive).

Thickening of the shells of the eye is not observed. They have smooth and clear outlines.

The optic nerves are characterized by a correct course and clear contours without dystrophic changes or local thickening.

Orbital structures : The muscles of the eyeball have the correct arrangement, there are no thickenings on them. Fatty tissue, eye vessels and lacrimal glands without features. The furrows of the convectional surface of the brain are unchanged.

Visible structures of the brain : There is no displacement of the median structures. Cisterns of the cerebral base are not deformed. The lateral ventricles of the brain are of normal size and symmetrical arrangement. Areas of pathological density in the region of brain structures are absent.

Other finds : no.

The protocol described above (decoding) of MRI indicates that no pathological changes in the organs of vision have been detected in humans.

After receiving a photo and protocol of the study (and wait for about 30 minutes), the patient is referred to an ophthalmologist, and sometimes to a neurologist for the final diagnosis and the necessary treatment.

[7], [8], [9], [10], [11], [12], [13]

Complications after the procedure

Magnetic resonance imaging is one of the safest studies that allows you to scan various organs without harm to your health, and even get a three-dimensional image for a more detailed examination of the object of diagnosis. Even though the eyes and the brain are considered to be the most sensitive parts of the body and are too susceptible to the influence of various negative factors, MRI is carried out without fear for the health of these organs, since it does not carry a radiation load on these important but very delicate structures. Used in modern tomographs, the magnetic field does not cause any consequences for the eyes and vital organs.

MRI of orbits is a non-invasive procedure, i.e. Consider the internal structure of the eye can be without opening the tissues. This is another plus of the modern diagnostic method.

Under the control of MRI, additional diagnostic tests can be performed, for example, a biopsy if there is a suspicion of a malignant tumor process inside the eye. Yes, and to detect the tumor can be easily at an early stage of its development at small sizes. This helps to make an ideal MRI with contrast.

The three-dimensional image allows to estimate in all details the state of the organ, the only thing that can not get a clear image of the orbital walls, but all other structures are determined with great accuracy and without the health hazard that exists during CT. The safety of the magnetic resonance method makes it possible to apply it in the diagnosis of ophthalmic and other diseases in children. The truth is prescribed to children over 7 years of age who are already able to stay without movement for a long time and fulfill the doctor's requirements.

Disadvantages of the method are high costs, a relatively long procedure with the need to maintain a static position throughout the survey period (which is not as simple as it seems), the likelihood of heart rhythm disturbances and a large number of contraindications associated with metal and electronic implants.

Nevertheless, safety for the body is more important than any money, and time is not an issue when it comes to accurate diagnosis and human health. Those categories of people who can not get an MRI examination can resort to the help of other diagnostic methods (X-ray, slit lamp, biomicroscopy of the eye, etc.), so without the help of doctors they will not remain.

Complications during the time of MRI of orbits can only be if the contraindications to the procedure are ignored. And then in most cases they are limited to minor tissue burns or distortion of the results of the study if the patient does not claim a tattoo or implant. Usually those people who install devices that monitor the operation of vital organs and systems do not forget about them and always report before prescribing diagnostic studies. But if the information was concealed intentionally, it is already the responsibility of the patient himself, who was informed about the requirements for a qualitative diagnostic before the procedure was started.

[14], [15], [16]