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Cardiovascular disease has been the leading cause of death worldwide for centuries. An average of 17 million people die each year from CVD. The scientific community claims that the situation will worsen, and the number of victims will skyrocket. In order to protect your own body as much as possible and stop ailments in time, you should regularly visit a doctor and undergo diagnostics. modern, MRI is considered informative and accurate-study. How often should a study be carried out, does a magnetic field affect the human body, and what do you need to know about cardiac tomography?
Specificity of the scanned area
MRI involves scanning the entire cardiovascular system, and not just a separate organ. The heart is a fibromuscular organ that is responsible for the flow of blood through the blood vessels. This is possible through constant rhythmic contractions followed by relaxation (the combination of actions creates a cardiac cycle).
The heart of vertebrate living organisms consists of endothelium, cardiac and connective tissue. In this case, the heart muscle is distinguished into a special type of striated muscle tissue, since it is found only in the heart.
The average person’s heart beats 72 times per minute. In 66 years, the organ will complete approximately 2,5 billion cardiac contraction and relaxation cycles.
The magnetic resonance imaging scanner faces a difficult task. The equipment must fix several types of tissues and differentiate them.
Moreover, the body is in constant motion, which also affects the effectiveness of the scan. How exactly is the diagnosis carried out and how informative are the images obtained?
The principle of operation of a magnetic resonance tomograph
The principle of operation of MRI is based on the study of the magnetic properties of human tissues that are saturated with hydrogen. It is known that a person mostly consists of water, and it contains elementary particles – protons.
If you place a proton in a powerful magnetic field, the particles will change their spatial orientation and begin to emit radio waves with different intensity and frequency. The MRI machine is this powerful magnetic field. Moreover, it captures radio waves, calculates the location of the protons to which they are attached, and therefore finds the hydrogen atom itself.
Modern tomographs are equipped with sources of a strong magnetic field, which improves the information content of diagnostics. In medical practice, both permanent neodymium and electromagnets operating in liquid helium are used.
They differ in the strength of the magnetic field. In constants, it reaches up to 0,7 T, in electromagnets – from 1 to 3 T. As a rule, the accuracy of MRI images is identical when using different sources.
Only the “response” of tissues to the study differs. The picture quality largely depends on the settings and the size of the equipment. For tomography of the heart, only electromagnets from 3 T are ideal.
Virtual Endoscopy
The development of computer technology has led to the emergence of a new diagnostic method – virtual endoscopy. What is it and how does it work? Virtual endoscopy is performed using a computer or magnetic resonance imaging scanner. This is a non-invasive technique that allows you to view internal cavities without inserting an endoscope. Special computer programs broadcast the image of the scanned area in real time. The specialist can observe the diagnosed area through the monitor screen at any angle, as in a standard endoscopic examination.
Virtual endoscopy is indicated for severe pathologies of the cardiovascular or respiratory system, when manipulations with the endoscope are impossible. The method is used in oncology, urology, angiology and other branches of medicine. The diagnostic results are given to the patient in DICOM format for further examination by other specialists.
Contrast tomography
Contrast tomography is used to improve differentiation fabrics and organs. So the picture becomes clearer and more informative, and it is much easier for the doctor to navigate in received images. The vast majority of MRI contrast agents contain gadolinium. It enters the body intravenously, spreads through the bloodstream, staining all organs in its path.
With MRI of the heart, an intravenous method of administration is used. Gadolinium interacts with hydrogen protons, which increases the contrast of the three-dimensional image. The substance is considered completely safe for the human body and is excreted naturally through the kidneys.
The decision to conduct a contrast tomography is made by the doctor. In most cases, a standard diagnosis without the use of auxiliary manipulations is sufficient.
Moreover, it is with contrast agents that a high risk of side effects is associated.
Indications and contraindications for the procedure
MRI is considered a safe procedure with a minimal list of contraindications. There are absolute and relative contraindications. The first category includes the presence of a pacemaker, a ferromagnetic or electronic middle ear implant, a ferromagnetic Ilizarov apparatus, large metal implants, or ferromagnetic fragments. What is it connected with? All these devices can affect the magnetic field, distorting the final result. As a result, the diagnosis will be uninformative, and the person will spend personal time and material resources.
Indications for cardiac MRI:
- congenital or acquired organ defects;
- violations of the functionality of the cardiovascular system;
- thrombosis, cysts, cancerous neoplasms, regardless of the nature and stage;
- assessment of the functionality of the heart after a heart attack;
- general diagnostics of the organ before/after surgery, evaluation of the effectiveness of the therapeutic course, control over the recovery process.
Do not undergo magnetic resonance imaging without first consulting a doctor.
Even preventive examinations should be carried out as directed. Self-medication can only harm both psychological and physical health. Trust your doctor and strictly follow his instructions.
Relative contraindications include:
- insulin pumps, non-ferromagnetic implants, heart valve prostheses, hemostatic clips (not a contraindication if the device does not contain metal elements);
- decompensated heart failure;
- the first trimester of pregnancy (the scientific community still does not have enough evidence about the harm, benefit or neutral effect of the magnetic field on the fetus. But MRI is still preferable to X-ray or CT for a pregnant woman);
- claustrophobia, panic attacks, unstable psycho-emotional state, inappropriate behavior (the patient simply will not be able to follow the instructions of the medical officer, will receive tremendous stress and will not allow the study to be carried out);
- the need for physiological monitoring, the serious condition of the patient (be sure to inform the medical staff of even the slightest deterioration in the condition. The decision to postpone or refuse to scan or replace the method is made only by the attending physician);
- installed braces or dentures (may distort the MRI result and affect the functionality of the magnetic field);
- tattoos (provided that the tattoo ink contains metallic compounds. In modern tattoo parlors, such inks are rare. Metallic inks were common about 20 years ago).
In a separate category, contraindications to contrast diagnostics are distinguished. The first thing to pay attention to is the individual reaction of the patient.
Before scanning, a person is required to pass allergy tests for intolerance to a contrast agent, on the basis of which a decision is made on further diagnosis.
Contrast tomography is contraindicated in severe kidney pathologies, as this will complicate the removal of the drug from the body. Also, diagnosis is contraindicated in severe renal, hepatic and heart failure.
How is the scan of the heart and blood vessels
MRI of the heart and blood vessels is no different from scanning any other organ or system and does not require specific preparation. Etcand the use of contrast enhancement, it is desirable that the gadolinium-based preparation be administered on an empty stomach, in order to avoid side effects such as nausea, vomiting, dizziness and others.
Immediately before the tomography, the patient is asked to remove all metal-containing objects (jewelry, watches, belts, glasses) in order to prevent distortion of the results.
Also, the patient must provide the laboratory assistant with medical documentation. It includes a referral from a doctor for an MRI, a preliminary diagnosis, specific instructions roentgenlaboratory assistant (scan area with or without contrast, individual characteristics of the patient). Diagnostics lasts 25-30 minutes. With contrast amplification the time frame increases to 40-50 minutes.
Contrast tomography is performed under the strict supervision of a specialist.
After all the preparatory manipulations, the patient is placed on the retractable table of the tomograph. During the procedure, the body must be motionless. If you are afraid to make a careless move, ask the laboratory assistant to secure you with soft straps.
Method of conducting
The patient changes into a special medical suit (or his own laconic clothes without decorative elements) and lies down on the retractable table of the tomograph. The laboratory assistant retires to the next room from which he monitors the progress of the scan and is ready to help the patient in a critical situation. If the patient feels pain, discomfort, an attack of nausea, vomiting, or wants to interrupt the diagnostics for any other reason, the laboratory assistant is obliged to do this, eliminate unpleasant symptoms and decide on the further course of the MRI.
To report a problem to a laboratory assistant, click on a special signal bulb, which is in the patient’s hand during the diagnosis.
The patient on a special retractable table rolls into the magnet tube at a certain distance in order to the scanner is positioned over the patient’s chest, the X-ray technician goes to the next room, where he starts the tomograph on the computer. From that moment on, the device creates a magnetic field, searches for protons through a radio wave, and, through mathematical calculations, forms a complete picture of the cardiovascular system. Diagnosis is absolutely painless, the only caveat is the loud noise emitted by the tomograph. Most healthcare facilities provide patients with earplugs or earmuffs to relieve discomfort. During the scan, you may experience a feeling of warmth that spreads throughout the body or is localized in the chest. This is a normal reaction of the body, which will pass on its own.
Diagnosis does not affect the patient’s pace of life in any way. Immediately after the scan, you can go to work or walk. Formation and evaluation of diagnostic results is 30-60 minutesperformed by a radiologist. The results obtained are provided to the attending physician who sent for diagnosis.. He will match diagnostic data with anamnesis, the results of previous examinations, will make an accurate diagnosis and make a course of treatment.
Magnetic resonance imaging is a modern method for diagnosing the human body. The method is based on a magnetic field, which is not dangerous even for the most vulnerable categories of patients – children, the elderly and pregnant, lactating women. Possible risks and side effects associated with contrast gain during scanning, sincethe patient may develop an allergic reaction.
To avoid the development of dangerous symptoms – follow the recommendations of doctors and refuse self-medication. Enjoy the benefits of modern medicine and be healthy!