Magnetic resonance imaging ( MRI ) .Indications , contraindications MRI - Causes, Symptoms and Treatment .MF .

August 12, 2017 17:52 | Instrumental

Magnetic resonance imaging (MRI) in the diagnosis of diseases

Magnetic resonance imaging (MRI) - modern safe (non-ionizing radiation) a non-invasive diagnostic method that provides visualization of deep-seated biological tissue, are widely used in medical practicein particular in neurology and neurosurgery.

Magnetic resonance imaging (MRI), as the name implies, it is based on the phenomenon of nuclear magnetic resonance (NMR).The essence of this phenomenon in general is as follows: the core of the chemical elements in solid, liquid or gaseous substance can be presented as rapidly rotating around its own axis of the magnet.If these magnets core placed in an external magnetic field, the rotation axis will precess (t. E. Rotated around the direction of the line of force of the external magnetic field), and precession speed depends on the magnetic field strength.Now, if the sample is irradiated with radio waves, radio waves with equal frequency and precession frequency of the resonant absorption of e

nergy occurs radio "magnetized" cores.After stopping the irradiation of the nucleus of atoms of the sample will move to its original state (to relax), and the energy accumulated by irradiation, will be released in the form of electromagnetic waves, which can be registered with the help of special equipment.

in medical scanners used for a number of reasons for registration of proton NMR - the nuclei of the hydrogen atoms that make up water molecules.Due to the fact that the method used in MRI are extremely sensitive to even small changes in the concentration of hydrogen, with its help it is possible not only to reliably identify a variety of fabrics, but also to distinguish normal tissue from tumor.

Magnetic resonance imaging (MRI) provides an accurate image of all body tissues, especially the soft tissue, cartilage, intervertebral discs, and brain.Even the most minor inflammatory lesions can be detected by MRI.Structures with low water content (bone or lungs) imaging can not be due to poor image quality.

advantages of magnetic resonance imaging (MRI) over other methods

Magnetic resonance imaging (MRI) provides images of almost all tissues of the body, since it is possible to change the time of radio waves stream action.

Because MRI provides very detailed image, it is considered the best technique for the detection of various tumors, the study of central nervous system and diseases of the musculoskeletal system.As a result, magnetic resonance imaging (MRI) to receive a full, three-dimensional picture of the studied area of ​​the body.Thanks to magnetic resonance imaging (MRI) it is possible, without using contrast agents, carefully examine the many organs and systems.

modern scanners allow the scanning motodom obtain tomograms in arbitrarily oriented plane without changing the patient's position.In the MRI study uses similar principles CT spatial information and data.During one scan, for example, head and data collection is usually done with approximately 20 of the skull and brain levels with the slice thickness of 5.4 mm. The higher the intensity of the magnetic field imager, this value is expressed in Tesla, the thinner the slices can be made, the better the research, the more surely will result.The majority of clinical magnetic resonance imaging (MRI) have 0,5-1.5 Tesla magnets and only a few - 3T.A stronger magnetic field can provide a more detailed examination.Scan time depends on the goals and parameters of magnetic resonance imaging and an average of 2-7 minutes (for magnetic resonance imaging MRI of the head) to 60 minutes.Eventually appear on the display image of the tissue sections, for example brain tissue.

method of magnetic resonance imaging MRI makes it possible to visualize on the screen, and then on the x-ray film sections of the skull and the brain, spine and spinal cord.Information allows us to differentiate gray and white matter of the brain, to judge his state of the ventricular system, the subarachnoid space, detect many forms of disease, in particular bulk processes in the brain demyelination area of ​​inflammation lesions and edema, hydrocephalus, traumatic injuries, hematomas, abscesses and outbreakscerebrovascular ischemic and hemorrhagic type, by the way, ischemic lesions in the brain can be detected in the form of gipodensivnoy within 2-4 hours after a stroke.

An important advantage of magnetic resonance imaging MRI to CT is possible to obtain images in any projections: axial, frontal, sagittal.This allows visualization subtentorial space, spinal canal, acoustic neuroma reveal a cavity internal auditory meatus, pituitary tumor, subdural hematoma in the subacute stage, even in cases when it is not visualized by CT.

Magnetic resonance imaging (MRI) has become the primary method of identifying certain forms of anomalies: abnormalities of the corpus callosum anomalies Arnold Chiari, demyelination foci in the paraventricular and other parts of the white matter of the brain in multiple sclerosis.

On magnetic resonance imaging (MRI) before on computed tomography (CT) revealed foci of brain ischemia, while they can be detected in the brain stem, cerebellum, in the temporal lobe.On magnetic resonance imaging (MRI) are clearly visible contusion foci, abscesses of the brain and brain tissue edema zone.

Important role for magnetic resonance imaging (MRI) in ascertaining the causes of dementia.At the same time, changes in brain tissue non-specific and often times difficult to differentiate, for example, and ischemia foci of demyelination.

Valuable information is revealed on the MP-tomograms of the spine, especially in the sagittal sections.This rendered the structural manifestation of osteochondrosis, in particular the state of the vertebrae and ligaments, intervertebral disc prolapse and their impact on the dura mater, spinal cord, cauda equina, are visualized as intravertebral neoplasms manifestations gidromielii, hemorrhachis and many other pathological processes.

potential diagnostic magnetic resonance imaging (MRI) can be enhanced by prior administration of certain contrast media.As introduced into the bloodstream of contrast material is commonly used element from the group of rare earth metals - gadolinium, which has the properties of the paramagnetic substance is administered intravenously.

advantage of magnetic resonance imaging (MRI) to computed tomography (CT) scan is most evident in the study of those parts of the nervous system, the image of which can not be obtained by CT because of the overlap of the study of the brain tissue adjacent bone structures.In addition, magnetic resonance imaging (MRI) can distinguish inaccessible CT density changes of the brain tissue, white and gray matter, to identify brain tissue damage in multiple sclerosis and others.

When magnetic resonance imaging (MRI) of the patient is not exposed to ionizing radiation.However, for the use of magnetic resonance imaging (MRI) has some limitations.For example, magnetic resonance imaging (MRI) is contraindicated in the presence of metal in the cranial cavity of foreign bodies, there is a risk of their displacement by the magnetic field and, therefore, additional injury adjacent brain structures.Contraindicated magnetic resonance imaging (MRI) in patients in the presence of external pacemaker, pregnancy, severe claustrophobia (fear of staying in a small room).Complicating the use of MRI examination of its duration (30-60 minutes), during which the patient should be at rest.

Indications for magnetic resonance imaging (MRI)

Indications for magnetic resonance imaging (MRI) and preparation for the study, see the relevant sections:

MRI brain or pituitary
MRI brain vessels angioprogramma arterial
MRI vesselscerebral venous angioprogramma
MRI myelogram
MRI of the spinal cord and spinal : cervical spine MRI
neck vessels (extracranial arterial or venous program)
MRI of the spinal cord and spine: thoracic MRI
spinal cord and spine: lumbar-kresttsovogo department
MRI adrenal
MRI of the joint, an MRI of the elbow, MRI of the knee
MRI of the brain or spinal cord (including craniovertebral junction) with anesthesia
abdominal MRI MRI
pelvic

Contra magnetic- resonance imaging (MRI)

Absolute contraindications to magnetic resonance imaging (MRI):

metallic foreign body in the eye socket,
Intracranial aneurysms klipirovannye ferromagnetic material,
presence in the body of the electronic devices (pacemaker, for example),
Hematopoietic anemia(with contrasting)

relative contraindications to magnetic resonance imaging (MRI):

- External pacemaker,
- severe claustrophobia or inappropriate behavior,
- pregnancy (relative contraindication MRI is a pregnancy up to 12 weeks, as currently collectedinsufficient evidence of the lack of a teratogenic effect of the magnetic field),
- intracranial aneurysm, klipirovannye non-ferromagnetic material,
- metal prostheses, clips or fragments in non-scanned bodies,
- inability to maintain mobility as a consequence of severe pain,
- tattoos containing metal compounds,
- the need for continuous monitoring of vital signs *,
- alcohol or drug intoxication

* designed ventilators, adapted for indoor use MRI

Menstruation, the presence of an intrauterine device, as well as breast-feeding is not a contraindication forstudy.

final decision on the possible refusal of a patient by MRI takes just prior study standby MRI radiologist.

How is magnetic resonance imaging (MRI)

procedure magnetic resonance imaging (MRI) is painless and requires no special training to the study, except for examination of the pelvic organs.Before the study, MRI should continue medication (if you are assigned), we recommend a moderate meal.Offers a bathrobe, or can their stuff without metal zippers.Be sure to be asked to remove all accessories - watch, jewelery, jewelry, hairpins, barrettes.Also remove the wig, denture, hearing aid.It is very important to the MRI take off anything containing metal.Metal objects can disrupt the action of the magnetic field, which is used during the test, and the picture quality may be poor.In addition, the magnetic field may damage the electronics.

Be sure to inform your doctor if you are in the body of the metal joint prostheses, artificial heart valves, grafts electronic devices, electronic middle ear implants or implants in the dentition.The presence of metal in your body may be risky for you or act on the part of the MRI image.

The technique of magnetic resonance imaging (MRI studies) is in the patient's room in a horizontal position into a narrow tunnel scanner, the time depends on the type of study.The patient should remain fully immobility study anatomy.

Some MRI images produced by injecting a contrast solution through a vein in your arm.During the study, breathe calmly, do not move, you can talk to your doctor MRI through the microphone.

-speed magnetic resonance imaging (MRI machines) are shorter and wider, so much of your body is in the open position during the scanning process.Newer MRI machines are open on all sides, it can weaken the image quality, but such equipment is widely used for patients with claustrophobia and children.

To improve the diagnostic efficiency of magnetic resonance imaging (MRI) patients are advised to bring their own data from previous MRI studies, other methods of radiation, laboratory and functional diagnostics, as well as hospital records or referrals from physicians, indicating the area andobjectives of the study.

procedure magnetic resonance imaging (MRI), a painless.Needless to MRI equipment during operation does not reproduce a loud noise, which can cause unpleasant sensation.

Personal belongings, jewelry and valuables, clothing containing metal and electromagnetic devices are not allowed in the room MRI scan.

Magnetic resonance imaging, as any study has certain diagnostic limits, as well as the possibility of limiting the sensitivity and specificity in the diagnosis of pathological processes.In this regard, as well as when there is doubt in the feasibility of a study is recommended to consult a doctor or physician magnetic resonance imaging (MRI).

results of magnetic resonance imaging (MRI)

At the end of the survey you may be asked to wait until MRI images are examined and until it is confident that additional images you need.Then you go out and wait for the results of MRI studies.

Harmful if magnetic resonance imaging (MRI)?

Currently unaware of any dangers or side effects associated with magnetic resonance imaging (MRI).The MRI does not use ionizing radiation (x-rays), it can be done again.Theoretically, there is a small risk to the fetus during the first 12 weeks of pregnancy, so during this period, scans pregnant women is contraindicated.As at the time of magnetic resonance imaging, patients must lie inside a large cylinder, some of them may show symptoms of claustrophobia.Patients who experience a fear of closed space, must notify the physician, in this case, you can invite a procedure of magnetic resonance imaging (MRI) of a close relative.

Magnetic resonance imaging (MRI) continues to improve, expanding its scope:

Magnetic resonance angiography

Vascular MRI image is one of the innovations.MRI - is a safe way to assess the condition of arteries and veins all over your body.This procedure does not require the introduction of a catheter into arteries as required by conventional angiography.

Magnetic resonance imaging (MRI) allows researchers to assess the activity and vital activity of nerve cells in different parts of the brain functional magnetic resonance imaging (MRI) with functional tests

.Funktsionalnayamagnitno resonance imaging (MRI) of the brain evaluates the areas that control movement, speech, vision and memory.