Cardiac MRI: what shows?
Magnetic resonance imaging is a highly informative noninvasive study that allows the doctor to resolve many diagnostic questions in the most severe cases. MRI of the heart and coronary vessels allows one to obtain much more information than traditional ECG and Echocardiography (ultrasound of the heart).
The principle of operation of the method
The method of nuclear magnetic resonance allows to study the anatomical structure and functioning of the human body based on the content in various tissues of hydrogen atoms and their behavior in a magnetic field. In all tissues of the human body contains some amount of water in each molecule of which has two hydrogen atoms. In addition, all organic compounds contain many protons. Entering the magnetic field, they acquire the direction of rotation. When the external magnetic field ends, the protons themselves emit high-frequency radiation, which is registered by the sensors of the imager. Modern equipment generally uses electromagnets capacity of up to 3 Tesla.
Thus, in contrast to computed tomography (CT) scans do not use x-rays, so no radiation exposure. Bone structure do not interfere with the inspection of soft tissues. The resolution of the resulting images is so high that the method is called non-invasive endoscopy – that is, as if inside the body of a patient placed the video camera.
Indications for study
MRI is a high-tech method of examination of the patient. Scanner – expensive equipment, and therefore allow it to itself can only large hospitals. Dentists undergo special training to be allowed to work with the results of magnetic resonance imaging. That’s why cardiac MRI is not the most available procedure. It is assigned in the case that more basic research is insufficient for accurate diagnosis. Here is an approximate list of indications for MRI of the heart and coronary vessels:
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- tumors of the heart and mediastinum;
- complex congenital or acquired heart defects;
- myocardial infarction with ventricular wall rupture or a blood clot in one of the cavities of the heart;
- coronary heart disease;
- myocarditis and pericarditis;
- malformations of the aorta;
- aneurysm of the aorta.
Contraindications to the study
In connection with the specifics of the device scanner, some patients may not be admitted to the procedure:
- in the presence of metallic implants in the patient’s body (with the exception of titanium construction, as titanium is not ferromagnetic) metal under the action of magnetic radiation is heated and moves that may threaten the patient’s life;
- suffering from panic attacks, claustrophobia, mental disorders;
- women in the first trimester of pregnancy;
- patients in critical condition that requires constant monitoring of vital functions;
- people with a body mass exceeding the maximum value allowed for the model of scanner;
- studies with contrast – liver and kidney failure, pregnancy at any time.
Preparation and conduct of the study
An MRI without contrast does not require any training. If you plan a examination with contrast, you need to refrain from eating for 6 hours. Before you enter the room with the MRI scanner, you should:
- in detail to talk to the doctor about previous illnesses and operations, not forgetting to tell us about any allergic reactions;
- to remove all metal objects – jewelry, watches, clothing with metal buttons, buckles, buttons and locks.
When the patient is ready for examination, helping him to lie on the scanner couch. You must wear headphones, as the device makes a lot of noise when working. During the procedure, the doctor is in an adjacent room. For communication inside of the scanner there is a special button. Executes a series of images before and after intravenous administration of contrast material. The contrast allows the doctor to see blood vessels and to estimate their permeability.
What the study shows?
The result of magnetic resonance imaging is presented in the form of a series of images – layered «slices» in increments of a few millimeters. Due to its high resolution equipment visible the smallest details and anatomical features. A special computer program creates a 3D model. You can visualize the results in the video mode to rate of myocardial contraction.
By contrast one can clearly see the major coronary arteries and small vessels, a dense network entangling the heart muscle – identify areas of reduced or lack of blood flow, it is possible to determine the viability of tissues with poor circulation. The doctor will evaluate the following parameters:
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- anatomical structure of the heart and blood vessels;
- the volume of the chambers and blood flow in them;
- movement of the valves;
- the presence of foci of damage, inflammation, scarring or oxygen deficiency in the myocardium;
- when performing contrast – the incidence of coronary atherosclerosis.
Typically, when performing cardiac MRI have no difficulty. Introduction of contrast agent can cause allergic reactions, occur nausea and vomiting. To assist the patient diagnostic Cabinet is equipped with anti-shock styling.
Magnetic resonance imaging of heart and coronary vessels it is possible to resolve the diagnostic doubt of a doctor in difficult cases. The study is safe, requires no special training and anesthesia and gives a significantly larger amount of information compared to the ultrasound and electrocardiogram.