Magnetic resonance imaging (MRI) of the eye orbits and optic nerves

MRI or magnetic resonance imaging is one of the most common methods for diagnosing the internal organs and tissues of living organisms. The study is based on measuring the electromagnetic response of hydrogen atoms. One of the diagnostic areas of tomography is the eye orbits and optic nerves. What you need to know about the study, how to properly prepare and what to expect from the procedure itself?

General characteristics of tomography

MRI allows you to study the human body based on the saturation of tissues with hydrogen and the characteristics of their magnetic properties. Let’s analyze the method of magnetic resonance imaging. The human body is almost entirely made up of water. Water, in turn, consists of 2 protons. The peculiarity of the proton lies in the back. This is the proper angular momentum (indicator of movement) of an elementary particle, which is equal to ½.

If you place this proton in a strong alternating magnetic field, then it will begin to emit a radio wave. Each of these radio waves will reside and transmit at a different frequency/intensity, depending on the location. The magnetic resonance tomograph captures these radio waves, thanks to which it finds the location of the proton itself. The equipment captures the signal from protons, processes them using special mechanisms and turns them into an image of the area under study. An MRI scanner can be called a big magnet, but the patient himself will be the “source” of protons.

Tomography is a separate category. with contrast. Patient intravenously a special contrast agent is injected, which spreads through the bloodstream and stains the organs / vessels. What does it give? Contrast improves the information content / clarity of the picture, helps the specialist to navigate the diagnostic results easier and faster. This type of MRI takes longer than the standard procedure.

Advantages of MRI over x-ray and computed tomography

The price and demand for MRI is much higher than for CT or X-rays. What is the rationale for this?

First, magnetic resonance imaging is considered an absolutely safe diagnostic method. Based on computed tomography and x-rays is x-rays that can harm the human body. The radiation exposure of x-rays is much higher, so it is permissible to do it only a few times a year. On modern computed tomographs, the radiation exposure is reduced, so the time frame between diagnostics is shorter.

Secondly, MRI gives a more informative result. X-ray is a flat image that only visualizes dense tissue. Magnetic resonance and computed tomography covers absolutely all tissues, produces a three-dimensional image, allows you to evaluate a specific section in detail.

Some experts prefer CT in terms of information content. Layer-by-layer shooting using complex algorithms really gives a complete understanding of what is happening inside a living organism. But the selection of diagnostics depends on a number of characteristics of the patient, the disease and the area being examined. In general, MRI is considered the safest and most informative methods. Its only drawback is the price. It is justified by the high cost of equipment and the need for its constant maintenance.

What do you need to know about the study area?

The human visual system is not limited to the visual apple. This is a whole multicomponent system that functions as a well-coordinated mechanism. The optic nerve and ocular orbits also belong to this mechanism.

The optic nerve is the second pair of cranial nerves. They transmit the signal from the retina to the brain and help us navigate the outside world. The nerve itself has an atypical structure and development. It is more like cerebral white matter, which is associated with the nuclei of the diencephalon and the cerebral cortex.

What clinical manifestations should be diagnosed? Even a slight decrease in vision can indicate problems with the optic nerve. Perhaps its conductivity is impaired, or a certain area of ​​uXNUMXbuXNUMXbthe fibers is affected, which limits the field of view. Visual hallucinations, regardless of etiology, should also be the reason for contacting a specialist.

The eye sockets or orbits are a paired cavity in the skull. It is in it that the eyeball with appendages is located. The volume of the orbit of an average adult person is 30 ml, of which 6,5 ml is reserved for the eyeball. MRI will help track the condition of the orbits, diagnose congenital or acquired disorders. Among them are various defects, the result of mechanical damage, oncological neoplasms, inflammatory processes, and so on.

Contrast MRI is contraindicated during pregnancy first trimester), chronic renal failure, hemolytic anemia and individual intolerance to contrast agents.

Why are tattoos, braces and metal devices considered contraindications?

MRI is a large magnet that can attract metal elements. The person within whom these elements are located can feel extremely unpleasant sensations – from minor discomfort to serious pain. It depends on the amount and characteristics of the metal inside. In addition to the implanted iron, before the diagnosis, it is necessary to remove all metal objects and design elements – earrings, belt, etc.

What’s wrong with tattoos? Even 20 years ago, ink tattoos contained small metal fragments. In modern tattoo parlors, this practice has become the exception, not the rule, which the client is always warned about. A patient who has a metallic tattoo applied to their body will experience tingling, pain, or itching during the diagnosis. Magnetic fields literally pull metal enzymes out of the ink, which leads to unpleasant symptoms. The reaction of patients can be specific – some do not feel pain, others interrupt the procedure due to an unbearable feeling.

Metallized substances can distort MRI results. In order not to waste time and material resources, be sure to inform your doctor about the presence of a tattoo. He will determine the presence / absence of metal particles and select an alternative diagnostic method.

Preparing and conducting an MRI

In most cases, scanning roentgenlaboratory assistant Before starting the diagnosis, he needs to transfer medical documentation. It includes a referral for magnetic resonance imaging, a preliminary opinion from a doctor and specific instructions. Based on medical records roentgenthe laboratory assistant adjusts the device and determines the further course of events.

The patient is checked for the presence of metal objects, tattoos and medicinal patches, then a general briefing is given and the procedure begins. The MRI machine makes an extremely loud and unpleasant noise, so each patient is given special protection – earplugs or headphones. The duration of the procedure may vary, but the average is 20-30 minutes.

Before starting the manipulation, be sure to clarify how long the scan will last, where the call button is located and how you can contact the staff during the scan. This should be clarified in case of force majeure, if you feel unwell or want to stop the diagnostics for other reasons.

The tomograph itself looks like a bigth pipe with sliding table. It is on this table that the patient is fixed with the help of fixing belts in a fixed position. It is important that the patient does not make unnecessary movements during the diagnosis, so as not to distort the information content of the image. As soon as the person is fixed on the retractable table, the X-ray technologist sets the tomograph ring at the desired point and goes to the next room to control the scan. From now on, he and the patient can communicate only through the speakerphone built into the equipment.

At the end of the examination, the radiologist helps the patient to get rid of the fixators and asks to wait at the office. MRI results are transmitted 30-60 minutes after the procedure in the format pictures, as well as on electronic media, if necessary. Time frames may vary, depending on the workload of the medical staff.

Evaluation of results

MRI evaluates the state of muscles, nerves, blood vessels and various structures that are exposed to a magnetic field. Tomography helps to identify cancerous tumors, infectious or inflammatory processes, structural tissue disorders, and so on. The interpretation of the obtained results is carried out by the doctorradiologist. He forms a conclusion and issues it, along with an MRI image, to the patient’s hands. In some clinics, information can be duplicated on electronic media at the request of the patient. Then the medical documentation is transferred to the attending physician, who issued the referral for an MRI. He compares the condition of the organs with complaints / other studies, makes an accurate diagnosis and develops a further therapeutic course.

Magnetic resonance imaging is one of the most informative and safe diagnostic methods. It can be used even by small children, and in some cases by pregnant women. Tomography can be performed not only as prescribed by a doctor, but also as a preventive measure for all body systems. The main thing is to strictly follow the instructions of the medical staff and be healthy.