MRI: Indications for Conduct, Features and Rules of Preparation
Magnetic resonance imaging is a diagnostic method for studying the human body using nuclear magnetic resonance.
The principle of investigation is the effect on tissues and organs of electromagnetic waves, which are in a controlled permanent magnetic field of high tension.The excited excitation of the nuclei of hydrogen atoms gives a registered electromagnetic response, which is used as a result.
MRI refers to the most modern and accurate diagnostic examinations.It was developed in 1973 by P.Lautberg.In the USSR appeared in 1984 under the name of NMR( nuclear magnetic resonance).Since 1986, the name has been changed to modern.
The MRI uses a magnetic field strength of 1.5 Tesla.In the standard of this value, most of the equipment works.The thickness of the cuts from 1 to 5 mm allows you to see the fine details of the tissues and organs under investigation with a qualitative image.
The study provides an opportunity to conduct detailed diagnostics of all body tissues.It is especially convenient to use a three-dimensional image to obtain accurate information.
Note: one of the main advantages of MRI is its complete harmlessness, absence of radiation load.This allows for the study of patients who have contraindications to X-ray diagnostic methods.
Modern modifications of MRI include:
- virtual endoscopy, which allows to obtain a three-dimensional image;
- MRI diffusion, which registers the movement of intracellular fluid;
- diffuse-weighted tomography, which determines the movement of radio-labeled protons( used in oncology);
- MR-perfusion - diagnosis of blood flow( used for strokes, circulatory disorders, ischemic processes of organs);
- MR-spectroscopy is a combined method that allows detecting biochemical changes in liquids and tissues;
- MR-angiography, which makes it possible to obtain images of vascular sections.
All received information is recorded on the media.Table of contents: Indications for MRI Contraindications for MRI The safety of the study The rules for the preparation of the study What can be the sensation during the MRI
Indications for MRI
Magnetic resonance imaging is used to diagnose diseases of most organs and systems.The study can be carried out in a complex way, simultaneously capturing the whole organism.MRI has several advantages over CT( computed tomography), scintigraphy, arthrography, ultrasound, classical x-ray, angiography.More in detail about these advantages we will talk at the description of applied techniques MRI.
The most commonly used is an isolated variant of examination of individual parts of the body.Each of these methods has its own testimony.
Indications for MRI of the head region
The method allows to determine the pathology of the main cerebral vessels( constrictions, aneurysms, congenital anomalies), traumatic changes in the structures of the bones of the skull and brain, as well as complications( cystic formations, hematomas, fluid accumulation in the brain tissue).
As a result of the study, the neo-educational processes of the brain as a whole, and its separate structures( cerebellum, pituitary, trunk), inflammatory changes in the brain( meningitis, encephalitis, abscesses), brain atrophy in different diseases are determined.
The study provides an opportunity to find the pathology of anatomical formations of the middle and inner ear, diseases of the paranasal sinuses, orbits and eyeballs, and jaw joints.
Indications for MRI of the spinal cord
MRI with spinal cord diseases allows to detect anatomical defects in multiple sclerosis and encephalomyelitis, cystic and tumor processes;
MRI of the spine
The study successfully determines the number and location of intervertebral hernias, inflammatory changes in the spinal cord, vertebral joints( spondylitis and spondyloarthrosis), tumors, traumatic injuries, vascular changes, developmental abnormalities.The narrowing of the spinal canal, coccyx cysts are clearly revealed;
Indications for MRI of joints
Note: is the main advantage of MRI of joints in comparison with CT( computed tomography) is the ability to clearly define the structure of joints and soft tissues.The ligaments, menisci and synovial membranes are visualized.
Magnetic tomography has made it possible to develop diagnostics of early stages of necrotic changes in the femoral head, partially replacing the contrasting techniques of arthrography.She ousted and osteoscitigraphy in the issue of detecting metastases.
The study is used for inflammation of joints( arthritis), injuries of joint-muscular formations( ruptures of menisci, lesions of elbows, etc.), purulent-necrotic joint processes, osteomyelitis, fractures.
Painful processes in muscle pathologies, ligament and tendon problems are well visualized;
Indications for MRI of mammary glands
This type of examination is becoming more common, especially in determining pathologies of tumor nature.
Note : unlike mammography, it does not expose a woman to radiation.
Allows to differentiate the benign and malignant nature of neoplasms.Also visualizes mastitis, abscesses and other types of purulent inflammatory pathology of the mammary glands.The study is recommended to be conducted between 6 and 17 days of the female cycle;
MRI of the abdominal cavity
Note: study reveals fine anatomical details that are not available from ultrasound.
Indications for the conduct are:
- suspicion of liver and bile duct cancer, cirrhosis, cystic lesions;
- the need for dynamic observation of the treatment of tumor processes;
- diagnosis of liver size increase, consequences of injuries, cholelithiasis, pathological processes of the pancreas;
Note: MRI has the ability to conduct a study of the small and large intestine without standard radiographic techniques( irrigoscopy, colonoscopy) to the weakened patient, greatly simplifying patient preparation.
Before the procedure, a cleansing enema is made, then through a thin probe 150 ml of liquid is injected into the intestine to facilitate visualization.It is used for the diagnosis of inflammatory and tumoral processes of the intestine;
Indications for MRI of kidney and adrenal glands
MRI of the kidneys and adrenal glands is indicated for determining the size and volume of neoplasms, stones, in the diagnosis of abnormalities in the structure and location of the kidneys and urinary system in general.
Note: , especially renal MRI, has been shown to patients who can not perform urography using contrast agents ;
MRI of pelvic organs
It is used in women for the diagnosis of malformations and inflammations of the uterus and appendages, cystic formations of female genital organs, tumor processes and metastases, with suspected endometriosis.
Note: MRI allows you to visualize details that do not determine ultrasound.
Men diagnose anomalies of development of genital organs, hyperplastic processes of the prostate, cysts, inflammatory processes and tumors of the prostate and testes, bladder.
Contraindications to MRI
Contraindications to MRI are divided into absolute and relative:
- absolute - the presence of metal prostheses and vascular clips in the human body, a functioning pacemaker, auditory implant;
- relative - fear of enclosed space, severe psychiatric pathology in the stage of excitation, severe pain, not allowing to lie quietly, sometimes - the first trimester of pregnancy( in this case, you can postpone the study).
Note: presence of monthly, established intrauterine device, breast feeding contraindication for MRI is not.
Security issues for thestudy
During the examination, the tomograph creates a powerful magnetic field that can cause the movement of metal objects in the body( implants, locks, removable dentures, etc.), so if they are available, the MRI can not be used.Also, metal objects can affect image quality, which will lead to distortion of the result.On the availability of listed items you should inform the doctor.
Hearing aids and pacemakers may be damaged in the generated magnetic field.
Also, do not leave mobile phones or magnetic cards in the area of the device.Metal rings, chains and other decorations should be removed in advance in another room, usually for this is a locker room with a safe.
Rules for the preparation for the
To avoid errors in the analysis of the images obtained, the radiologist should have complete information about the patient being examined .He is provided with:
- a case history( statement), or an outpatient card;
- data from previous studies - computed tomography, and( or) MRI.
No special preparations are carried out on the eve.The food regime does not change.In the case of MRI of the intestine and abdominal organs, one should refrain from taking solid food for a few hours before the procedure.
Note: study lasts from 20 to 60 minutes, depending on the method used.Therefore, the bowel and bladder should be emptied beforehand.
During the MRI session, it is best to be dressed in natural fabrics, women are not recommended to use cosmetics, since the substances in it can affect image quality.
Small children before the onset of MRI are given sedatives or even mild anesthesia.
For the duration of the procedure, the patient wears special earbuds or earplugs to reduce the noise load of the procedure.Through them, communication with medical personnel will be carried out.
In addition, the patient will have a signal device in the hand in case of unforeseen sensations or reactions.Through it, you can give an emergency signal to the employees of the office.
What can be a sensation in the MRI
It is important to know that the patient does not experience any pain during the examination.You just need to lie still, breathe evenly and do not move.In some patients, the tomograph causes mental discomfort associated with the fear of an enclosed space.In the study of such patients, the presence of a loved one is permitted.
Alexander Lotin, medical reviewer