Magnetic Resonance Imaging (MRI)

• What is MRI?
• How does MRI work?
• What is MRI used for?
• Are there risks?
• What are examples of NIBIB-funded projects in MRI?

What is MRI?

Magnetic Resonance Imaging (MRI) is a non-invasive imaging technology that produces three dimensional detailed anatomical images. It is often used for disease detection, diagnosis, and treatment monitoring. It is based on sophisticated technology that excites and detects the change in the direction of the rotational axis of protons found in the water that makes up living tissues.

How does MRI work?

MRI of a knee.

MRIs employ powerful magnets which produce a strong magnetic field that forces protons in the body to align with that field. When a radiofrequency current is then pulsed through the patient, the protons are stimulated, and spin out of equilibrium, straining against the pull of the magnetic field. When the radiofrequency field is turned off, the MRI sensors are able to detect the energy released as the protons realign with the magnetic field. The time it takes for the protons to realign with the magnetic field, as well as the amount of energy released, changes depending on the environment and the chemical nature of the molecules. Physicians are able to tell the difference between various types of tissues based on these magnetic properties.

To obtain an MRI image, a patient is placed inside a large magnet and must remain very still during the imaging process in order not to blur the image. Contrast agents (often containing the element Gadolinium) may be given to a patient intravenously before or during the MRI to increase the speed at which protons realign with the magnetic field. The faster the protons realign, the brighter the image.

What is MRI used for?

MRI scanners are particularly well suited to image the non-bony parts or soft tissues of the body. They differ from computed tomography (CT), in that they do not use the damaging ionizing radiation of x-rays. The brain, spinal cord and nerves, as well as muscles, ligaments, and tendons are seen much more clearly with MRI than with regular x-rays and CT; for this reason MRI is often used to image knee and shoulder injuries.

In the brain, MRI can differentiate between white matter and grey matter and can also be used to diagnose aneurysms and tumors. Because MRI does not use x-rays or other radiation, it is the imaging modality of choice when frequent imaging is required for diagnosis or therapy, especially in the brain. However, MRI is more expensive than x-ray imaging or CT scanning.

One kind of specialized MRI is functional Magnetic Resonance Imaging (fMRI.) This is used to observe brain structures and determine which areas of the brain “activate” (consume more oxygen) during various cognitive tasks. It is used to advance the understanding of brain organization and offers a potential new standard for assessing neurological status and neurosurgical risk.

Are there risks?

Although MRI does not emit the ionizing radiation that is found in x-ray and CT imaging, it does employ a strong magnetic field. The magnetic field extends beyond the machine and exerts very powerful forces on objects of iron, some steels, and other magnetizable objects; it is strong enough to fling a wheelchair across the room. Patients should notify their physicians of any form of medical or implant prior to an MR scan.

When having an MRI scan, the following should be taken into consideration:

• People with implants, particularly those containing iron, — pacemakers, vagus nerve stimulators, implantable cardioverter- defibrillators, loop recorders, insulin pumps, cochlear implants, deep brain stimulators, and capsules from capsule endoscopy should not enter an MRI machine.
• Noise—loud noise commonly referred to as clicking and beeping, as well as sound intensity up to 120 decibels in certain MR scanners, may require special ear protection.
• Nerve Stimulation—a twitching sensation sometimes results from the rapidly switched fields in the MRI.
• Contrast agents—patients with severe renal failure who require dialysis may risk a rare but serious illness called nephrogenic systemic fibrosis that may be linked to the use of certain gadolinium-containing agents, such as gadodiamide and others. Although a causal link has not been established, current guidelines in the United States recommend that dialysis patients should only receive gadolinium agents when essential, and that dialysis should be performed as soon as possible after the scan to remove the agent from the body promptly.
• Pregnancy—while no effects have been demonstrated on the fetus, it is recommended that MRI scans be avoided as a precaution especially in the first trimester of pregnancy when the fetus’ organs are being formed and contrast agents, if used, could enter the fetal bloodstream.

New open MRI machine

• Claustrophobia—people with even mild claustrophobia may find it difficult to tolerate long scan times inside the machine. Familiarization with the machine and process, as well as visualization techniques, sedation, and anesthesia provide patients with mechanisms to overcome their discomfort. Additional coping mechanisms include listening to music or watching a video or movie, closing or covering the eyes, and holding a panic button. The open MRI is a machine that is open on the sides rather than a tube closed at one end, so it does not fully surround the patient. It was developed to accommodate the needs of patients who are uncomfortable with the narrow tunnel and noises of the traditional MRI and for patients whose size or weight make the traditional MRI impractical. Newer open MRI technology provides high quality images for many but not all types of examinations.

What are examples of NIBIB-funded projects in MRI?

Replacing Biopsies with Sound
Chronic liver disease and cirrhosis affect more than 5. 5 million people in the United States. NIBIB-funded researchers have developed a method to turn sound waves into images of the liver, which provides a new non-invasive, pain-free approach to find tumors or tissue damaged by liver disease. The Magnetic Resonance Elastography (MRE) device is placed over the liver of the patient before he enters the MRI machine. It then pulses sound waves through the liver, which the MRI is able to detect and use to determine the density and health of the liver tissue. This technique is safer and more comfortable for the patient as well as being less expensive than a traditional biopsy. Since MRE is able to recognize very slight differences in tissue density, there is the potential that it could also be used to detect cancer.

New MRI just for Kids
MRI is potentially one of the best imaging modalities for children since unlike CT, it does not have any ionizing radiation that could potentially be harmful. However, one of the most difficult challenges that MRI technicians face is obtaining a clear image, especially when the patient is a child or has some kind of ailment that prevents them from staying still for extended periods of time. As a result, many young children require anesthesia, which increases the health risk for the patient. NIBIB is funding research that is attempting to develop a robust pediatric body MRI. By creating a pediatric coil made specifically for smaller bodies, the image can be rendered more clearly and quickly and will demand less MR operator skill. This will make MRIs cheaper, safer, and more available to children. The faster imaging and motion compensation could also potentially benefit adult patients as well.

Another NIBIB-funded researcher is trying to solve this problem from a different angle. He is developing a motion correction system that could greatly improve image quality for MR exams. Researchers are developing an optical tracking system that would be able to match and adapt the MRI pulses to changes in the patient’s pose in real time. This improvement could reduce cost (since less repeat MR exams will have to take place due to poor quality) as well as make MRI a viable option for many patients who are unable to remain still for the exam and reduce the amount of anesthesia used for MR exams.

Determining the aggressiveness of a tumor
Traditional MRI, unlike PET or SPECT, cannot measure metabolic rates. However, researchers funded by NIBIB have discovered a way to inject specialized compounds (hyperpolarized carbon 13) into prostate cancer patients to measure the metabolic rate of a tumor. This information can provide a fast and accurate picture of the tumor’s aggressiveness. Monitoring disease progression can improve risk prediction, which is critical for prostate cancer patients who often adopt a wait and watch approach.

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MRI Scans: Definition, uses, and procedure

A magnetic resonance imaging (MRI) scan uses a strong magnetic field and radio waves to create detailed images of the organs and tissues within the body. MRI can help with viewing injuries, tumors, certain heart problems, and more.

Since its invention, doctors and researchers continue to refine MRI techniques to assist in medical procedures and research. The development of MRI revolutionized medicine.

This article looks specifically at MRI scans, how they work, and how doctors use them.

Fast facts on MRI scanning

• MRI scanning is a non-invasive and painless procedure.
• Raymond Damadian created the first MRI full-body scanner, which he nicknamed the Indomitable.
• The cost of a basic MRI scanner starts at $150,000 but can exceed several million dollars.
• Japan has the most MRI scanners per capita, with 48 machines for every 100,000 citizens.

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An MRI scan uses a large magnet, radio waves, and a computer to create a detailed, cross-sectional image of internal organs and structures.

The scanner itself typically resembles a large tube with a table in the middle, allowing the patient to slide in.

An MRI scan differs from CT scans and X-rays, as it does not use potentially harmful ionizing radiation.

The development of the MRI scan represents a huge milestone for the medical world.

Doctors, scientists, and researchers are now able to examine the inside of the human body in high detail using a non-invasive tool.

The following are examples in which an MRI scanner would be used:

• anomalies of the brain and spinal cord
• tumors, cysts, and other anomalies in various parts of the body
• breast cancer screening for women who face a high risk of breast cancer
• injuries or abnormalities of the joints, such as the back and knee
• certain types of heart problems
• diseases of the liver and other abdominal organs
• the evaluation of pelvic pain in women, with causes including fibroids and endometriosis
• suspected uterine anomalies in women undergoing evaluation for infertility

This list is by no means exhaustive. The use of MRI technology is always expanding in scope and use.

Share on PinterestA person can listen to music in headphones to mask the loud and sometimes alarming sound of the MRI machine.

There is very little preparation required, if any, before an MRI scan.

On arrival at the hospital, doctors may ask the patient to change into a gown. As magnets are used, it is critical that no metal objects are present in the scanner. The doctor will ask the patient to remove any metal jewellery or accessories that might interfere with the machine.

A person will probably be unable to have an MRI if they have any metal inside their body, such as bullets, shrapnel, or other metallic foreign bodies. This can also include medical devices, such as cochlear implants, aneurysm clips, and pacemakers.

Individuals who are anxious or nervous about enclosed spaces should tell their doctor. Often they can be given medication prior to the MRI to help make the procedure more comfortable.

Patients will sometimes receive an injection of intravenous (IV) contrast liquid to improve the visibility of a particular tissue that is relevant to the scan.

The radiologist, a doctor who specializes in medical images, will then talk the individual through the MRI scanning process and answer any questions they may have about the procedure.

Once the patient has entered the scanning room, the doctor will help them onto the scanner table to lie down. Staff will ensure that they are as comfortable as possible by providing blankets or cushions.

Earplugs or headphones will be provided to block out the loud noises of the scanner. The latter is popular with children, as they can listen to music to calm any anxiety during the procedure.

Once in the scanner, the MRI technician will communicate with the patient via the intercom to make sure that they are comfortable. They will not start the scan until the patient is ready.

During the scan, it is vital to stay still. Any movement will disrupt the images, much like a camera trying to take a picture of a moving object. Loud clanging noises will come from the scanner. This is perfectly normal. Depending on the images, at times it may be necessary for the person to hold their breath.

If the patient feels uncomfortable during the procedure, they can speak to the MRI technician via the intercom and request that the scan be stopped.

After the scan, the radiologist will examine the images to check whether any more are required. If the radiologist is satisfied, the patient can go home.

The radiologist will prepare a report for the requesting doctor. Patients are usually asked to make an appointment with their doctor to discuss the results.

It is extremely rare that a patient will experience side effects from an MRI scan.

However, the contrast dye can cause nausea, headaches, and pain or burning at the point of injection in some people. Allergy to the contrast material is also seldom seen but possible, and can cause hives or itchy eyes. Notify the technician if any adverse reactions occur.

People who experience claustrophobia or feel uncomfortable in enclosed spaces sometimes express difficulties with undergoing an MRI scan.

Share on PinterestMRI scans work by rearranging water molecules in the body with magnets.

An MRI scanner contains two powerful magnets. These are the most important parts of the equipment.

The human body is largely made of water molecules, which are comprised of hydrogen and oxygen atoms. At the center of each atom lies an even smaller particle called a proton, which serves as a magnet and is sensitive to any magnetic field.

Normally, the water molecules in the body are randomly arranged, but on entering an MRI scanner, the first magnet causes the water molecules to align in one direction, either north or south.

The second magnetic field is then turned on and off in a series of quick pulses, causing each hydrogen atom to change its alignment when switched on and then quickly switch back to its original relaxed state when switched off.

Passing electricity through gradient coils, which also cause the coils to vibrate, creates the magnetic field, causing a knocking sound inside the scanner.

Although the patient cannot feel these changes, the scanner can detect them and, in conjunction with a computer, can create a detailed cross-sectional image for the radiologist.

Functional magnetic resonance imaging (fMRI)

Functional magnetic resonance imaging or functional MRI (fMRI) uses MRI technology to measure cognitive activity by monitoring blood flow to certain areas of the brain.

The blood flow increases in areas where neurons are active. This gives an insight into the activity of neurons in the brain.

This technique has revolutionized brain mapping, by allowing researchers to assess the brain and spinal cord without the need for invasive procedures or drug injections.

Functional MRI helps researchers learn about the function of a normal, diseased, or injured brain.

fMRI is also used in clinical practice. Standard MRI scans are useful for detecting anomalies in tissue structure. However, an fMRI scan can help detect anomalies in activity.

In short, fMRI tests what tissues do rather than how they look.

As such, doctors use fMRI to assess the risks of brain surgery by identifying the regions of the brain involved in critical functions, such as speaking, movement, sensing, or planning.

Functional MRI can also be used to determine the effects of tumors, stroke, head and brain injuries, or neurodegenerative diseases, such as Alzheimer’s.

How long will an MRI scan take?

MRI scans vary from 20 to 60 minutes, depending on what part of the body is being analyzed and how many images are required.

If, after the first MRI scan, the images are not clear enough for the radiologist, they may ask the patient to undergo a second scan straight away.

I have braces or filings, should I still undergo the scan?

Although braces and fillings are unaffected by the scan, they may distort certain images. The doctor and technician will discuss this beforehand. The MRI scan may take longer if additional images are required.

Can I move while I am in the MRI tunnel?

It is important to stay as still as possible while in the MRI scanner. Any movement will distort the scanner and, therefore, the images produced will be blurry. In particularly long MRI scans, the MRI technician may allow a short break halfway through the procedure.

I am claustrophobic, what can I do?

The doctor and radiologist will be able to talk the patient through the whole procedure and address any anxieties. Open MRI scanners are available in some locations for certain body parts to help patients who have claustrophobia.

A person can take medication prior to the test to ease anxiety.

Do I need an injection of contrast before my MRI scan?

A contrast dye can improve diagnostic accuracy by highlighting certain tissues.

Some patients may need to have a contrast agent injected before the scan.

Can I have an MRI scan if I am pregnant?

Unfortunately, there is no simple answer. Let a doctor know about the pregnancy before the scan. There have been relatively few studies on the effect of MRI scans on pregnancy. However, guidelines published in 2016 have shed more light on the issue.

Typically, doctors do not recommend contrast material for women who are pregnant.

MRI scans should be restricted during the first trimester unless the information is considered essential. MRI scans during the second and third trimester are safe at 3.0 tesla (T) or less. The tesla is a measurement of magnetic strength.

The guidelines also state that exposure to MRI during the first trimester is not linked to long-term consequences and should not raise clinical concerns.

Glossary of terms

Neurological terms

• Blepharospasm – spontaneous bilateral clonic-tonic contractions of the circular muscles of the eyes.
• Amyotrophic lateral sclerosis – a rapidly progressive disease of the nervous system caused by selective degeneration of motor neurons in the spinal cord, cortex and brainstem (motor neuron disease). The first symptoms of the disease are weakness of the muscles of the limbs, muscle twitches (fasciculations) and local muscle atrophy or bulbar (or pseudobulbar) disorders in the form of swallowing disorders (dysphagia) and speech by the type of dysarthria.
• Wilson-Konovalov’s disease (hepatocerebral dystrophy, hepatolenticular degeneration) is a severe progressive genetically determined disease with an autosomal recessive type of inheritance, which is based on a violation of copper metabolism with its excessive accumulation mainly in the liver and brain. The concentration of copper rises in the blood serum, its excretion in the urine (hypercupuria) increases, its increased deposition in organs and tissues, especially in the cornea (Kaiser-Fleischer rings). The main neurological signs: muscle rigidity, hyperkinesis, ataxia, pyramidal insufficiency, dementia.
• Parkinson’s disease – chronic progressive degenerative disease of the central nervous system, clinically manifested by impaired voluntary movements.
• Botulinum toxin (dysport) – toxin, which is produced by the bacterium Clostridium Botulinum, acts at the level of neuromuscular transmission, blocking the release of one of the chemical neurotransmitters – acetylcholine, thereby preventing the transfer of an electrical impulse from the nerve ending to the muscle, which leads to a weakening of hypertonicity -reduction of pathological muscle tension.
• Inflammatory polyneuropathy – multiple symmetrical lesions of the nerve trunks of an inflammatory nature.
• Generalized dystonia – dystonic movements and dystonic postures that involve both legs (or one leg and trunk) and at least one other part of the body.
• Hyperkinesias – involuntary, violent, automated movements, usually aggravated by excitement and diminished in severity by distraction, at rest.
• Tension headache – the most common type of headache. Pain can first appear at any age, almost always bilateral, localized in the occipital, temporal or frontal regions, has a pressing or squeezing character and is not accompanied by vomiting, but sometimes it can be combined with anorexia, nausea, light or sound phobia.
• Degenerative disease of the nervous system – a group of diseases of the nervous system, the manifestation of which are violations of higher brain functions. Higher brain functions can be divided into cognitive, affective and behavioral. Cognitive (cognitive) functions (memory, attention, thinking, orientation, speech, counting, etc.) provide a person’s ability to process information and use it to correct their actions. Affective and behavioral (emotional-personal) functions determine the formation and implementation of actual motivations, the regulation of behavior in the social sphere.
• Dementia (loss of mind, dementia) – acquired, caused by a chronic, progressive disease of the brain, usually gradually increasing disorder of various types of higher mental functions (memory, speech, thinking, ability to orientate, learning, etc.), emotional control, motivation , social behavior with preserved consciousness.
• Stroke – a severe form of acute cerebrovascular accident, more often developing in patients with atherosclerosis, arterial hypertension, as well as in case of rupture of intracerebral aneurysms, embolism of cerebral vessels and manifested by focal neurological symptoms that persist for more than 24 hours.
• Camptokarmia – a rare form of dystonia, predominantly involving the muscles of the trunk, often manifested by a sharp posterior hyperextension of the trunk, less often rotation occurs when the trunk is tilted to the side or the trunk is tilted forward.
• Cluster headache – a form of primary headache, characterized by paroxysms of strictly unilateral very intense, excruciating pain, grouped into peculiar bundles (clusters), separated by more or less long periods of remission.
• Facial hemispasm – disease manifested by paroxysms of unilateral clonic contraction of mimic muscles.
• Lumbodynia – lower back pain, often aching or bursting type, tend to increase when moving, when moving from one position to another and gradually subside in the supine position. Movement in the lumbar spine is possible, but limited due to pain.
• Lumboischalgia – pain and reflex disorders localized in the lower back, gluteal region and leg.
• Myasthenia gravis – a neuromuscular disease characterized by pathological, rapid fatigability striated muscles (intensification of manifestations after exercise and their decrease after rest).
• Migraine – paroxysmal headache, more often on one side (hemicrania), mainly in the frontotemporal region. The attack may be preceded by precursors in the form of changes in the emotional state, autonomic reactions and aura, manifested by short-term subjective sensations immediately preceding the headache.
• Myopathy – the general name of hereditary diseases in which metabolic disorders lead to primary muscle damage. Manifested by weakness, hypotension and hypotrophy of muscles, tendon and periosteal areflexia, limited range of active movements.
• Hereditary ataxia – a chronic progressive hereditary disease that manifests itself at the age of 30-45 years with slowly increasing cerebellar disorders in combination with signs of pyramidal insufficiency. The clinical picture is characterized by static and dynamic ataxia, intentional tremor, dysarthria, tendon hyperreflexia.
• Hereditary polyneuropathy – is a group of common hereditary diseases of the nervous system, the main clinical manifestations of which are caused by damage to the axial cylinders or the myelin sheath of peripheral nerves.
• Trigeminal neuralgia – short-term (up to 2 minutes) acute, burning, shooting pain in the zone of innervation of one or more branches of the trigeminal nerve. Attacks of pain are accompanied by vegetative disorders (hyperemia of the face, lacrimation, hypersalivation, etc.), and often by reflex contractions of facial and masticatory muscles.
• Neuropathy of the facial nerve – is manifested by acute or subacute signs of damage to the facial nerve (paralysis of mimic muscles). It can be provoked by hypothermia, intoxication.
• Neurogenic urination disorder – 1) bladder filling disorder, clinically manifested by frequent urination (more than 8 times a day), urge to urinate, periodic incontinence due to the fact that the patient is not able to voluntarily slow down urination (imperative incontinence). 2) a violation of the emptying of the bladder, manifested by a weakening of the urge, the need to strain at the beginning of urination, constant excretion of urine drop by drop and a significant increase in the volume of residual urine.
• Olivopontocerebellar atrophy – a group of chronic progressive hereditary diseases in which atrophic changes develop mainly in the cerebellum, inferior olive nuclei, in the pons proper nuclei and in related brain structures.
• Parkinsonism – syndrome, manifested by a combination of hypokinesia with rigidity, rest tremor and postural instability, associated with damage to the basal ganglia and their connections.
• Writer’s spasm – the most common occupational spasm in the form of a local paroxysmal tonic spasm. Occurs in the muscles of the hand, as a rule, during the act of writing. The cramp usually appears first in the fingers and then spreads in the proximal direction, may be accompanied by pain, sometimes tremors, myoclonus in the same hand.
• Plexitis – lesion of the nerve plexus, characterized by sensory, motor and trophic disorders.
• Radiculo-ischemia – ischemia of the nerve root, caused by compression of the vessels supplying it, is manifested by a sharp increase in pain, weakness in the foot, and impaired urination may develop.
• Radiculopathy – damage to the spinal roots of a non-inflammatory nature.
• Multiple sclerosis – chronic relapsing disease of the central nervous system, which is characterized by the formation of multiple scattered foci of demyelination in the brain and spinal cord.
• Vascular encephalopathy (dyscirculatory encephalopathy) – brain damage caused by chronic cerebrovascular insufficiency, causing diffuse changes in the brain tissue and scattered neurological microsymptoms, combined with emotional lability and intellectual-mnestic disorders, the severity of which is variable, but tends to to a gradual increase.
• Thoracalgia – chest pain.
• Cervicobrachialgia – pain associated with an inflammatory or degenerative lesion of the cervical spine extending to the arm.
• Cervicocranialgia – pain associated with an inflammatory or degenerative lesion of the cervical spine, usually localized in the occipitocervical region, but often extending to the frontotemporal region, shoulder and arm.

Neurosurgical terms

• Arterial aneurysm brain – limited expansion of the lumen of the artery or protrusion of its wall. Among arterial aneurysms, saccular aneurysms are the most common, less often – spherical, fusiform or S-shaped aneurysms. Arterial aneurysms are 10 times more common than arteriovenous ones. Arterial and arteriovenous aneurysms are of congenital origin, about 5% of arterial aneurysms are mycotic aneurysms that develop due to the entry of infected emboli into the cerebral arteries. A significant part of aneurysms are asymptomatic and can be determined by autopsy or angiography, magnetic resonance imaging-angiography as an incidental finding.
• Arteriovenous malformation – a vascular tangle of various sizes, formed by a disorderly interweaving of dilated arteries and veins of the brain.
• Atherosclerotic stenosis of the cerebral arteries – narrowing of the lumen of the artery caused by the formation of atherosclerotic deposits on the inner wall of the vessel.
• Hydrocephalus – a disease characterized by excessive accumulation of cerebrospinal fluid in the ventricular system of the brain as a result of difficulty in moving it from the place of secretion (cerebral ventricles) to the place of absorption into the circulatory system (subarachnoid space) – occlusive hydrocephalus, or as a result of impaired absorption – aresorptive hydrocephalus.
• Lumbar disc herniation is a displacement of the nucleus pulposus of the intervertebral disc with a rupture of the annulus fibrosus.
• Carotid-cavernous fistula-carotid-cavernous fistula post-traumatic – is a message between the internal carotid artery and the cavernous sinus. The etiology of KKS in the vast majority of cases of TBI is associated with a fracture of the base of the skull, and often the crack passes in the projection of the cavernous sinus. As a result of the injury, the complex system of “suspension” of the carotid artery in the sinus on the trabeculae is disrupted, the wall of the artery is torn and a fistula is formed, through which arterial blood is “discharged” into the venous bed.
• Brain tumors – a heterogeneous group of various intracranial neoplasms, benign or malignant, arising from the initiation of the process of abnormal uncontrolled cell division, which in the past were normal components of the brain tissue itself (neurons, glial cells, astrocytes, oligodendrocytes, ependymal cells), lymphatic tissue, blood vessels of the brain, cranial nerves, meninges, skull, glandular formations of the brain (pituitary and epiphysis), or arising from metastasis of a primary tumor located in another organ. The type of tumor is determined by the cells that form it. Depending on the localization and histological variant, the symptoms of the disease are formed. Brain tumors are relatively rare – about 1.5% of all types of tumors.
• Tumors of the spinal cord – account for 15% of all CNS tumors. There are extra- and intramedullary tumors. Extramedullary tumors can be located under the dura mater and above it. Extradural tumors are usually malignant (metastasized). Among subdural tumors, 70% are extramedullary and 30% are intramedullary. The most common subdural extramedullary tumors are neurinomas (30%) and meningiomas (25%). A typical picture of an extramedullary tumor consists of three stages: the stage of radicular pain, the stage of partial compression of the spinal cord (often in the form of Brown-Sequard syndrome) and the stage of complete transverse compression of the spinal cord. Following radicular pains at the level of the tumor (most often such pains are observed in neurinomas and metastatic tumors), para- or tetraparesis, loss of sensitivity and pelvic disorders gradually increase. Intramedullary tumors are most often gliomas; ependymomas are not uncommon in the region of the cone and cauda equina. In contrast to extramedullary tumors, in which sensory and motor disorders increase from the bottom up, intramedullary tumors are characterized by the development of spinal symptoms from top to bottom.
• Spinal stenosis is a chronic process characterized by pathological narrowing of the central spinal canal, lateral pocket, or intervertebral foramen by bone, cartilage, and soft tissue structures, with their intrusion into the spaces occupied by the nerve roots and spinal cord. Narrowing of the spinal canal caused by disc herniation, which leads to acute compression of the neurovascular structures, usually does not apply to stenosis.
• Stereotaxis – stereotactic surgery (or stereotaxis) is a minimally invasive method of surgical intervention when access is made to a target point inside the body or tissue thickness of an organ using a spatial scheme according to pre-calculated coordinates in a three-dimensional Cartesian coordinate system. In modern surgery, stereotaxis It is used mainly in brain neurosurgery, when exceptional accuracy is required in delivering a surgical instrument (biopsy, destruction or stimulation) to a predetermined area through the thickness of the brain without the risk of damage to structures critical to the health and life of the patient.
• Peripheral nerve injuries – open and closed. Open injuries are found in stab, cut, chopped and other wounds, as well as in gunshot wounds. The latter, along with mechanical damage to the nerve, cause concussion and bruising of the nerve and surrounding tissues, which greatly increases the severity of morphological changes in the nerve and surrounding tissues and affects the further course and prognosis of the recovery period. With closed injuries, the nerves are injured by the edge of a bone fracture, pressed down with blunt objects to adjacent bones, overstretched during dislocation of the joints, traction of the limbs, squeezed by plaster casts, a long-term tourniquet, and acute swelling of the limb.
• Traumatic brain injury – mechanical damage to the skull and intracranial structures – the brain, blood vessels, cranial nerves, meninges. The main reasons are traffic accidents, falls, industrial, sports and domestic injuries. Brain damage can be the result of: 1) focal damage, usually causing contusion (contusion) of the cortical regions of the brain or intracranial hematoma; 2) diffuse axonal damage involving the deep sections of the white matter. Allocate open craniocerebral injury (TBI), in which there is communication between the cranial cavity and the external environment, and closed.

• President of the Republic of Belarus
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• Ministry of Health
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• Partizansky District Administration
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• Catalog of medical centers
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• Republican Unitary Enterprise “Belpharmacia”
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• MedPortal.ORG – responsible medical portal
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• Republican Children’s Hospital of Medical Rehabilitation
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• Eurasian Society of Pediatric Neurosurgeons
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• Doctor Anna – operator of medical tourism in Belarus
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• A series of postcards BELTA “Fates folded into a triangle”.

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• National Legal Internet Portal of the Republic of Belarus
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How MRI works. MRI Center Siberian Regional Tomography Center in Novosibirsk

With the rapid development of global technology, many imaging techniques have been invented, such as computed tomography, radiography, and MRI imaging. Medical imaging is a technology that is used to obtain images of the human body for medical purposes such as diagnosing or investigating diseases. Imaging is also used for medical research, for example, using MRI technology, scientists have successfully obtained a three-dimensional image of the human brain, which has helped them in studying the functions and structure of this most important organ of the human body.

What is an MRI?

Magnetic resonance imaging (MRI) is one of the modern methods of radiation diagnostics, which allows non-invasively obtaining images of the internal structures of the human body.

The most important advantage of MRI in comparison with other methods of radiation diagnostics is the absence of ionizing radiation and, as a result, the effects of carcinogenesis and mutagenesis, which are associated with the risk of exposure to X-rays.

MRI is the only non-invasive diagnostic method with high sensitivity and specificity in detecting edema and bone tissue infiltration.

The development of MR spectroscopy and diffusion MRI, as well as the creation of new organotropic contrast agents is the basis for the development of “molecular imaging” and allows for histochemical studies in vivo.

MRI physics

MRI as a research method is based on measuring the electromagnetic response of atomic nuclei located in a strong constant magnetic field in response to their excitation by a certain combination of electromagnetic waves. In MRI, such nuclei are the nuclei of hydrogen atoms, which are present in large quantities in the human body as part of water and other substances.

The nuclei of hydrogen atoms – protons – have magnetic properties that can be used to create images.

Now more. The human body is 80% water. Water molecules are made up of one oxygen atom and two hydrogen atoms. All atoms are made up of nuclei around which there are a certain number of orbits of electrons. The nucleus of the hydrogen atom, the proton, emits pulses that are used to produce MR images.

Protons have a property called spin (from English – rotation). It can be thought of as a factor that causes the proton to rotate around its own axis and behave like a small two-pole magnet.

In a magnetic field, the axis of rotation can be oriented in the direction of the lines of force or against it, just as the poles of real magnets are attracted or repelled.

In practice, most protons are oriented in the direction of the magnetic field lines. The use of a beam of radio waves in MPT upsets this balance. When the radiation is turned off, the protons begin to return to their original state, which is different for different types of tissues. At the same time, they emit energy pulses, which are recorded by an MP tomograph. Based on these data, a tomogram is built.

The principle by which images can be built is that different organs or tissues inside the human body have a different number of water molecules, and therefore respond to electromagnetic waves at different speeds. Using a computer to calculate, it is possible to obtain images of organs and tissues just on the basis of this reaction rate.

About scanners

The tomograph is a big magnet. According to the strength of the magnet, scanners are divided into low-field (up to 0.5T), medium-field (from 0.5T to 1.0T), high-field (from 1.0 to 3.0T) and ultra-high-field (more than 3.0T). The most widespread in clinical practice are 1.5 T tomographs, which in most cases provide comprehensive information about the structure of tissues and organs.

The process of obtaining images with MR tomography is longer compared to other studies (ultrasound diagnostics, X-ray and CT), on average, scanning one area is about 20 minutes, during which the patient must lie still. High-field MR systems (1.5T) have a relatively fast image acquisition and processing capability compared to low-field magnets.

During a long scan, RF radiation can cause the patient to feel hot, to prevent excessive heating of tissues in modern tomographs, protection is installed that limits the strength of the radio frequency pulse, in accordance with international safety standards.

MRI scanners are divided into “open” and “closed” types. The first type is characterized by the absence of a closed aperture, which plays an important role for patients with claustrophobia, but such tomographs usually have a low magnetic field strength, and, consequently, resolution, in addition, studies are performed for a longer time. The vast majority of tomographs in clinical practice are of a closed type. In a closed tomograph, the patient is almost completely in a closed aperture, which makes it possible to achieve high resolution and scanning speed.

What MRI shows

Magnetic resonance imaging is successfully used to diagnose diseases:

• brain;
• spine;
• thyroid;
• liver;
• gallbladder and ducts;
• pancreas;
• kidneys;
• spleen;
• joints;
• spinal cord;
• vessels of the head, neck, abdominal region;
• pelvic organs;
• soft tissues;
• etc.

All of the above anatomical structures are perfectly visualized on MRI images. The results of diagnostics make it possible to identify deviations in the work of the organs under study with high accuracy.

When MRI is prescribed

The wide possibilities of magnetic resonance diagnostics make its use indispensable in the case of:

• the need for a primary diagnosis;
• conducting a comprehensive survey;
• preparation for surgery;
• tracking the effectiveness of the applied therapy and treatment methods.

In each individual case, the choice of diagnostic technique is carried out by the attending physician. Magnetic resonance imaging is more often than other methods used to detect diseases and injuries of soft tissues.

MRI is indispensable for diagnosis:

• Neoplasms.

Magnetic resonance imaging can clearly identify the boundaries and size of the tumor, as well as the degree of its germination in soft tissues. No other method of radiation diagnostics is able to give such a clear and detailed picture of diseases.

MRI also makes it possible to determine the nature of the tumor with a high degree of probability. Malignant neoplasms have fuzzy boundaries and grow into the surrounding tissues. Benign neoplasms, as a rule, are clearly differentiated from healthy tissues.

• Diseases of the brain.

The high accuracy of magnetic resonance imaging makes it possible to visualize such small anatomical structures as the pituitary gland and the sella turcica. Also, MRI with brain contrast is highly effective for diagnosing demyelinating diseases (multiple sclerosis, Parkinson’s disease, etc.), as it allows you to clearly see the structure of altered nerve tissues.

The image of the brain obtained using contrast-enhanced MRI of the brain is especially clear, since magnetic waves do not show hard anatomical structures well, and artefacts from the bones of the skull do not appear on brain images.