Computed tomography (CT) of the heart and coronary vessels
The study of cardiac muscle and coronary arteries by CT has its own characteristics:
- Heart is constantly in motion: it is reduced passively shifted as a result of respiratory movements. To obtain an accurate volumetric image of the body require image synchronization on cardiac and respiratory rhythm requires a high temporal resolution of the apparatus;
- The investigated structures of the heart valves, the target branch of the coronary arteries are very small in size, so to obtain valuable diagnostic information requires high spatial resolution.
These problems were resolved with the advent of multislice technology the image. Modern spiral CT scanners are able to image from 16 to 256 slices per cycle of movement of apparatus and to set the scan step. Depending on the objectives of the study, it is possible to obtain either a full image of an organ in one cycle with a small spatial resolution, or a detailed synchronized passive movements picture of the heart and its arteries.
Determination of the calcium score (calcium score) is recommended in patients at risk of development of cardiovascular disease, but without clinical manifestations of the disease. Calcium-scalingpolicy in the following cases:
- overweight, obesity;
- increase in blood pressure;
- Smoking, regular alcohol consumption;
- adverse family history of cardiac diseases;
- insufficient level of physical activity;
- age over 40 years;
- increased levels of stress in their professional activities;
- metabolic disorders: thyrotoxicosis, diabetes mellitus;
- elevated levels of low density lipoprotein in the blood, high coefficient of atherogenicity.
In contrast angiography of the arteries of the heart with contrast, CT scan with determination of calcium index is a completely safe procedure, so you can get it without a doctor’s referral. This study only shows the amount of calcification, but does not allow to judge the degree of the stenosis of the examined arteries, therefore, when high index it is recommended to conduct CT angiography with contrast.
Non-invasive CT coronary angiography with contrast
To obtain images of the coronary vessels is used as a bolus of iodinated contrast material. Before the procedure, establish an intravenous catheter, connected to automationmanager. Contrast enters the bloodstream dosed during the entire time of the study.
The result of spiral coronary angiography is a three-dimensional spatial image of the blood vessels of the heart, which can be used to detect the stenosis. This study is a good alternative interventional coronary angiography, which requires special training and hospitalization. This study shows patients who have already identified any cardiovascular disease, surgery or calcium index on the results of screening imaging was increased.
The indications for MSCT angiography of the heart can be:
- chest pain of unclear origin;
- recurrent angina;
- suspected anomalies in the structure of valves or major blood vessels of the heart;
- evaluation of the blood supply to the heart muscle after coronary artery bypass grafting;
- postinfarction scars, suspected aneurysm of a major vessel or intracardiac thrombosis;
- the variances in the testimonies of the POS, Echocardiographic or biochemical analysis of blood, indicating the development of heart disease.
The preparation of the study and its conduct
A screening study does not require special preparation, computed tomography of the chest with contrast is performed on an empty stomach (do not eat or drink for at least 3 hours before the procedure). The day before the study it is recommended to avoid coffee, chocolate and soft drinks with caffeine, alcohol, and reduce the number of cigarettes smoked and eliminate emotional stress. These factors contribute to the increase in heart rate, and it has a bad effect on the accuracy of the study.
The increase in heart rate can make CT angiography uninformative, so in a day or two before the event it is recommended to eliminate caffeine, alcohol and nicotine.
Immediately prior to CT coronary angiography with contrast of the patient is examined by a cardiologist and if necessary, introduces tools, normalizing heart rhythm and reduces heart rate. The patient is then placed on the sliding bed system and the research begins.
Multislice scanners operate almost silently, tunnel machine wide, so fear of the closed space occurs. At the time of introduction of contrast can be felt the heat gradually spreads throughout the body. This feeling passes in a few minutes.
Including preliminary consultation with the doctor, the examination lasts no more than an hour. The time spent in the office – a few minutes. Analysis CT angiography of the chest with contrast requires time and attention, so the results are often issued on the following day.
Contraindications for computed tomography of the heart
General contraindications associated with exposure to ionizing radiation is:
- children’s age;
- malignant neoplasms whose treatment includes radiation therapy (total dose is calculated individually).
Most often, patients in this group do not require coronary angiography.
The second group of contraindications associated with the introduction of contrast, to the implementation of screening CT scan they have nothing to do. CT coronary angiography is not performed:
- when kidney disease associated with impaired filtration;
- the presence of Allergy to iodine-containing drugs;
- heavy forms of diabetes mellitus, thyrotoxicosis, bronchial asthma;
- if you plan or already carried out radiotherapy using radioisotopes of iodine.
And finally, there are special contraindications to spiral imaging of the heart. This high tachycardia or severe arrhythmias that are impossible to stop medication. This does not make the study of the threat, but deprives it of content. The apparatus records the image in the same phase of the cardiac cycle by synchronizing your work with the heart rate. If they occur too often, sensors will not have time to record information, and their irregularity makes it difficult to sync.