Coronary CT-angiography and computed tomography of the heart
Coronary CT-angiography allows to give a visual indication of the arteries feeding the muscle of the myocardium, to determine the presence or absence of narrowing of the lumen, the nature of the location and extent of pathology with the highest possible degree of reliability.
X-ray computed tomography (CT) is one of the most used radiological methods of diagnosis in modern medicine. However, for a long time, it is rarely applied to the study of the heart and blood vessels. This was associated with a low rate sectioning by conventional computed tomography (CT). In these devices the turnover time of the tube was comparable with the duration of the cardiac cycle. Practically the only kind of computer tomography (CT), suitable for imaging of electron-beam tomography (CRT), introduced in 1984 However, the number of these systems around the world was small (about 200).
Since 1998, after the advent of multislice CT (MSCT), this method has become widely used for studies of the heart and blood vessels. In recent years, the popularity of multislice computed tomography (MSCT) as a method of imaging the heart and blood vessels is constantly increasing.
One of the most important consequences of the rapid development of multislice computed tomography (MSCT) — implementation of this method for imaging the coronary arteries. Traditionally, for the purpose of obtaining images of coronary arteries used x-ray angiography, which until today remains the "gold standard" of diagnosis in this field. The need for coronary angiography is huge. However, it is clear that x-ray contrast coronary angiography cannot be performed in all patients who require it.
Thanks to the advent of spiral and multislice CT appeared the technique of CT angiography (CTA), which was used to assess the state of coronary arteries and the patency of venous and arterial coronary bypass grafts. This article describes the current status of the issue of the use of CT for noninvasive coronary CT-angiography.
Absolute contraindications for multislice computed tomography (MSCT) and electron-beam tomography (CRT) of the heart does not exist. Relative contraindications include:
- the overall condition of the patient (somatic, mental), making it impossible to maintain them motionless during the study and the breath-hold for 15-30 seconds
- excess body weight of the patient exceeding the maximum permissible load on the table for this model of CT scanner
Purpose of the use of coronary CT-angiography and computed tomography of the heart
We can distinguish the following applications of multislice computed tomography (MSCT) of the heart and coronary arteries (heart vessels):
- Detection of coronary atherosclerosis on the basis of identification and quantitative assessment of coronary calcification (see Cardiac Calcium Scoring)
- Non-invasive coronary angiography (see Cardiac Catheterization)
- Noninvasive bypass-graphy (arterial and venous shunts)
- Assessment of anatomy and function of cardiac chambers in congenital and acquired heart disease
- CT-angiography of the aorta, pulmonary artery, peripheral arteries and veins
To date, the multi-spiral computed tomography (MSCT) and electron-beam tomography (CRT) to detect calcification of coronary arteries is considered appropriate in the following situations:
- A survey of men aged 45-65 and women aged 55-75 years without established cardiovascular disease with the aim of early detection of early signs of coronary atherosclerosis
- Screening for coronary calcification can be used as the initial diagnostic test in ambulatory conditions in patients under the age of 65 years with atypical pain in the chest in the absence of established diagnosis of ischemic heart disease
- Screening for coronary calcification can be used as an additional diagnostic test in patients under the age of 65 years with questionable results of the load tests or the presence of traditional coronary risk factors in the absence of an established diagnosis of coronary artery disease
- This technique can be used for the differential diagnosis between chronic heart failure of ischemic and non-ischemic origin (cardiomyopathy, myocarditis)
However, in order to see the stenosis in the coronary arteries, to assess the patency of coronary bypass grafts or stents, or to study the anatomy of the heart requires the implementation of multispiral computed tomography (MSCT) with intravenous contrast media (coronary CT-angiography).
The actual problem is to assess the patency of coronary stents. The stents are clearly visible in computer tomography (CT), however, artifacts from metal hamper visualization of the inner lumen in coronary CT-angiography. New model CT scanners using thin slices and improved image reconstruction algorithms, can significantly improve the visualization of the inner lumen of the stent.
In addition to the diagnosis of stenotic lesions of the coronary arteries CT coronary angiography allows to detect various congenital anomalies of the coronary arteries, aneurysm of coronary vessels, in particular in Kawasaki disease.
CT angiography after stent placement in the abdominal aorta.
The importance of multislice computed tomography (MSCT) in the diagnosis of diseases of the heart and blood vessels in now is quite large. Given the development of medical technology, is expected to further increase in the use of this technique in clinical practice. Because of the tendency of the development of multislice computed tomography (MSCT) three-dimensional imaging has actually become the new standard for computed tomography (CT). Division computed tomography (CT) for the generation principle of motion of the system "tube—detector" looks outdated. Much more important options become power x-ray tube, the quality and quantity of detectors, systems of data collection and processing.
A lot of controversy is the mapping capabilities of computed tomography (CT) and magnetic resonance imaging (MRI) in studies of the heart. Both of these methods are now widely used in the clinic and the feasibility of their use will depend on the study objectives. Their diagnostic capabilities are also dependent on the type of diagnostic equipment available to the diagnostic unit, experience of personnel, availability of supplies, systems, processing and documenting data and other factors.