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According to WHO statistics, cardiovascular disease is the number one cause of death worldwide. Experts believe that this particular group of diseases will remain in the deadly category for a long time, but the risk of developing pathology can be minimized if you lead a healthy lifestyle, give up bad habits and visit a doctor regularly. One way to diagnose the heart is computed tomography. What you need to know about tomography, in what cases is it prescribed and how x-rays affect the human body?
General characteristics of tomography
Computed tomography is a method of non-invasive layer-by-layer examination of the internal organs and systems of the human body. It is based on X-rays and complex computer algorithms that process the effects of the rays on the body. During radiodiagnosis, the anatomical features of the heart, the norms and pathologies of its functionality are evaluated. Additionally, the CT device covers the state of arteries, veins and the entire system of cardiovascular blood supply down to the smallest capillaries (the entire chest is scanned).
How is information collected? Pictures are taken using modern CT equipment, which is a table and X-ray emitters that scan the body in layers with an interval of 1 to 5 mm. The emitters penetrate through tissues of different density, and special sensors record this data and transfer it to a computer, where they are systematized by the program and assembled into one image. Each image obtained in this way can be viewed separately, or form integral three-dimensional models that are displayed on the screen.
Today, two types of CT are widely used: conventional (spiral) and multispiral. The first is more affordable cost, prevalence. You can do this in any city and in most private clinics. Multispiral, although it is more expensive, is distinguished by a reduced dosage of irradiation, a higher speed of conduction and increased accuracy. If there is a choice between these two methods, then it is better to choose MSCT – less risk, more informative. But conventional CT is still relevant, as it allows you to see various diseases, neoplasms, injuries and pathologies. For such an examination, there are no closed areas, and the tissues of the organs do not overlap each other.
A heart scan is different from a CT scan of other organs. This is due to the fact that the heart is mobile. Therefore, a camera is used that is synchronized with the contraction of the heart, getting in time with it. As a result, the pictures are static. On the screen, the picture is still and quite clear, which allows you to see all the structural features of the organ. The situation is complicated if the patient has an arrhythmia. In order for a person’s heart to work stably with a contraction rate of 65 beats per minute, he is given beta-blockers.
In some cases, vasodilators are also required, which are administered immediately before the scan.
The next step in the development of CT was the invention of devices with two radiation sources. They were first introduced in 2005. Since at high heart rate it is difficult to synchronize the camera with heart contractions, the use of 2 X-ray tubes solved this problem, allowing absolutely any images of the organ to be processed, regardless of the heart rate: the device penetrates the patient’s body with rays in layers of 1-2 mm. There are 64 in total in different planes. Thus, you can see the structure of the organ not only from the outside, but also from the inside. This is a good way to detect serious diseases even at their inception.
Contrast tomography
Contrast preparations help to enhance the overall picture, visually separate the organs from each other, highlight the necessary parts of the body for further study. Contrast is indispensable when checking the cardiovascular system. It helps to consider in detail the anatomical features of the organ and makes the scan results more accurate and reliable. In most cases today, iodine-based preparations are used – they easily penetrate into soft tissues without causing side effects, and just as easily come out of them. Although these drugs are safe, in rare cases they cause allergic reactions in patients with individual intolerance and serious kidney pathologies. In the first case, a person may develop an allergic reaction, in the second case, the body will not be able to quickly and effectively remove the substance. If their use is still necessary, the patient is given antihistamines. The contrast agent is administered intravenously or orally, depending on the area being examined. When diagnosing the heart, the first option is used.
The procedure with contrast lasts about 2-3 minutes, without it, even less – 1-2 minutes. Usually the patient does not feel discomfort, but because of the contrast, unpleasant sensations are possible: itching, nausea, urticaria. All this passes without a trace within a day. If the state of health has deteriorated, the patient must inform the doctor who is watching the procedure in the next room through the viewing window – the scan will be stopped. Communication is carried out by means of a special built-in loudspeaker.
Indications / contraindications for the study
| Показания | Противопоказания |
|---|---|
| Clinical manifestations of angina with ambiguous results of ultrasound, ECG, various tests and samples | Renal failure, individual intolerance to iodine-containing substances (with a contrast study) |
| Acute chest pain without identified etiology (to assess the degree of threat to life and start a therapeutic course) | Excess weight that exceeds the norm that the CT equipment can withstand |
| Confirmation/denial of such diagnoses as: myocardial infarction, dissecting aortic aneurysm, pulmonary embolism | Claustrophobia and mental disorders (the patient will not be able to follow the instructions of the laboratory assistant) |
| Non-invasive assessment of the state of the coronary vessels | Pregnancy (due to the detrimental effects of x-rays on fetal development) |
| Preoperative examination of the cardiovascular system | Thyroid pathology |
| Clarification of the results obtained during selective interventional coronary angiography (used if the artery cannot be catheterized or contrasted) | The general serious condition of the patient (inform the attending physician even about a slight indisposition. Perhaps he will decide to postpone the diagnosis and a new therapeutic course) |
| Diagnosis of congenital malformations of the coronary arteries and aneurysms | Diabetes |
Methodology and preparation for diagnosis
The study is within the competence of the X-ray laboratory technician. He conducts a preliminary briefing, studies the patient’s medical records, helps him to sit on a sliding table and monitors the scanning process.
Approximately 30 minutes before the start of manipulation, the patient takes an oral medication. It lowers the heart rate and is used only 1 time. Usually, drugs from the group of B-blockers are used. In a contrast study, a catheter is inserted intravenously into a peripheral vein (mainly the elbow bend). A contrast agent is injected through it, based on the scan cycles. After completion of the diagnosis, the catheter is removed.
As soon as the patient has taken the necessary position on the retractable table, the laboratory assistant adjusts the location of the equipment, gives specific recommendations (do not move, hold your breath, etc.) and leaves for the adjacent room. In it, the medical officer monitors the functionality of the machine and the condition of the patient. As soon as the CT machine is started, the gantry begins to rotate over the area under study. This is a special device with sensors that emit X-rays and transmit the information received to the main computer.
Important: when scanning the heart, you will have to hold your breath several times. The laboratory assistant warns the patient in advance about this and advises to carefully listen to the prompts through the loudspeaker.
During the scan, you need to lie still so as not to affect the effectiveness of the study. Even the smallest careless movement will not allow you to form a high-quality three-dimensional picture. Also, before the procedure, it is necessary to remove all metal elements from clothing and body. X-rays simply can’t get through the metal components, leaving blank white trails in the final image. Metal must be removed only from the diagnosed area. When scanning the heart, a metal belt buckle or decorative elements on trousers will not affect the overall result.
The duration of the procedure depends on a number of factors and is communicated to the patient before starting the diagnosis. Usually the time frame is 2-5 minutes. The results of computed tomography can be obtained on the same day, depending on the workload of the medical staff. The results are evaluated by a radiologist. The doctor must evaluate the images, compare them with the anamnesis and take them into account when making a diagnosis.
Alternative diagnostic methods
Refusal of CT may be justified by individual intolerance to iodine or fear of x-rays. Modern equipment has a minimal radiation exposure, but radiation can accumulate in the body, so it is necessary to maintain intervals between studies. Non-radiation techniques are suitable for multiple diagnostics. The next alternative is an MRI of the heart. A magnetic resonance tomograph obtains an accurate image of absolutely all structures of the heart, measures the speed of blood flow and visualizes the features of the structures of the organ. The method is based on the interaction of the protons of the human body and the magnetic field. Scientists consider MRI to be an absolutely safe procedure, and its only drawback is its high price.
One of the newest methods for studying the heart is PET CT (positron emission tomography), in which it is possible to assess the nutrition of the myocardium, areas with its deficiency, to determine the degree of cell viability, which is especially important before coronary artery bypass surgery. PET can help not only visualize the site of ischemia, but also reflect the rate of metabolic processes, which is beyond the power of other diagnostic studies. The negative aspects include its low availability for the population due to the cost of the procedure and the small number of clinics that are equipped with the appropriate equipment.
Important: one or another type of diagnosis is always determined by the doctor. Even preventive studies should be carried out under the supervision of a specialist.
Computed tomography helps to prevent, diagnose and develop a treatment plan for many pathologies of the cardiovascular system. Despite the minimal radiation exposure, the number of x-ray studies is limited. Get a CT scan only when ordered by a doctor, and for a general diagnosis, choose an ultrasound or MRI. Control your own body and be healthy.