Ultrasound: principles of diagnosis, types of research, features 3D and 4D ultrasound
Ultrasound examination( sonography) is one of the most modern, informative and accessible methods of instrumental diagnostics.Undoubted advantage of ultrasound is its non-invasiveness, i.e. in the process of research on the skin and other tissues there is no damaging mechanical effect.Diagnosis is not associated with painful or otherwise unpleasant sensations for the patient.Unlike widespread radiography, ultrasound does not use radiation that is harmful to the body.Table of contents: Principle of action and physical principles Investigation of individual organs of ultrasound of the heart ultrasound of the abdominal cavity ultrasound of the kidneys of the ultrasound of the thyroid gland ultrasound of the pelvic organs ultrasound of the mammary glands of ultrasound in pregnancy Is it dangerous?Ultrasound with 3D and 4D technology
Principle of operation and physical basis
Sonography makes it possible to detect the slightest changes in organs and to catch the disease at a stage when clinical symptoms have not yet developed.As a consequence, a patient who has undergone ultrasound has repeatedly increased chances of a full recovery.
Note : the first successful patient studies using ultrasound were conducted in the mid-fifties of the last century.Previously, this principle was used in military sonar systems to detect underwater objects.
Ultrahigh-frequency sound waves are used to study internal organs.Since the "picture" is displayed on the screen in real time, it makes it possible to track a number of dynamic processes occurring in the body, in particular, the movement of blood in the vessels.
In terms of physics, ultrasound is based on the piezoelectric effect.As piezoelements, which alternately operate as a transmitter and a signal receiver, single crystals of quartz or barium titanate are used.When high-frequency sound vibrations are applied to them, charges appear on the surface, and when applied to the crystals of current, mechanical vibrations are accompanied by ultrasound radiation.Oscillations are caused by a rapid change in the shape of single crystals.
Piezoelectric transducers are the basic component of diagnostic devices.They are the basis of the sensors, which, in addition to the crystals, have a special sound-absorbing wave filter and an acoustic lens to focus the instrument on the desired wave.
Important: The basic characteristic of the medium under study is its acoustic impedance, i.e., the degree of resistance to ultrasound.
As the boundary of the zones with different impedances reaches the wave beam, the wave beam changes greatly.Part of the waves continues to move in a certain direction, and a part - is reflected.The reflection coefficient depends on the difference in the resistance of two neighboring media.Absolute reflector is the area bordering the human body and air.99.9% of the waves go in the opposite direction from this interface.
In the study of blood flow, a more modern and profound technique based on the Doppler effect is used.The effect is based on the fact that when the receiver and the environment move relative to each other, the signal frequency changes.The combination of outgoing from the device and reflected signals creates beats, which are heard with the help of acoustic speakers.Doppler study makes it possible to determine the speed of movement of the boundaries of zones of different densities, ie, in this case - to determine the velocity of the fluid( blood).The technique is practically indispensable for an objective assessment of the patient's circulatory system.
All images are transferred from the sensors to the monitor.The resulting image in the mode can be recorded on a digital medium or printed on a printer for more detailed investigation.
Examination of individual organs
For the examination of the heart and blood vessels, a kind of ultrasound such as echocardiography is used.In combination with an assessment of the blood flow through dopplerography, the technique makes it possible to detect changes in the heart valves, to establish the dimensions of the ventricles and atria, as well as the pathological changes in the thickness and structure of the myocardium( cardiac muscle).During the diagnosis, you can also examine the sites of the coronary arteries.
The level of constriction of the lumen of the vessels makes it possible to detect a continuous wave of dopplerography.
The pump function is evaluated using a pulse Doppler study.
Regurgitation( movement of blood through the valves in the direction opposite to the physiological one) can be detected by color Doppler mapping.
Echocardiography helps to diagnose such serious pathologies as a latent form of rheumatism and coronary artery disease, as well as to identify neoplasms.There are no contraindications to this diagnostic procedure.In the presence of diagnosed chronic pathologies of the cardiovascular system, it is advisable to undergo echocardiography at least once a year.
Ultrasound of the abdominal cavity
Ultrasound of the abdominal cavity is used to assess the liver, gall bladder, spleen, major vessels( in particular - the abdominal aorta) and kidneys.
Note : for the ultrasound of the abdominal cavity and pelvis, the frequency is optimal between 2.5 and 3.5 MHz.
Kidney ultrasound can detect cystic neoplasms, enlargement of the renal pelvis and the presence of concrements( stones).This kidney examination is necessarily performed in hypertensive disease.
Thyroid ultrasound is indicated with an increase in this organ and the appearance of nodular neoplasms, as well as if there is discomfort or pain in the neck.Without fail this research is assigned to all residents of ecologically unfavorable regions and regions, as well as regions where the level of iodine is low in drinking water.
Pelvic ultrasound is necessary for assessing the condition of the organs of the female reproductive system( the uterus and ovaries).Diagnosis allows, among other things, to identify pregnancy in the early stages.In men, the method makes it possible to identify pathological changes in the prostate gland.
Breast ultrasound is used to determine the nature of neoplasms in the chest.
Please note: , to ensure the most intimate contact of the sensor with the surface of the body, a special gel is applied to the patient's skin before the study, which includes styrene compounds and glycerol in particular.
Ultrasound in pregnancy
Ultrasound scanning is now widely used in obstetrics and perinatal diagnostics, that is, for the study of the fetus at different stages of pregnancy.It allows to reveal the presence of pathologies of the future child's development.
Important: during pregnancy, routine examination with ultrasound is strongly recommended to undergo at least three times.The optimal time frame for which a maximum of useful information can be obtained is 10-12, 20-24 and 32-37 weeks.
On ultrasound, an obstetrician-gynecologist can detect the following developmental anomalies:
- non-solidification of the hard palate( "wolf mouth");
- hypotrophy( underdevelopment of the fetus);
- polyhydramnios and low saline( abnormal volume of amniotic fluid);
- placenta previa.
Important: in a number of cases, the study allows you to identify the threat of miscarriage.This makes it possible to place a woman in a timely manner in a hospital "for preservation", enabling her to safely endure the baby.
Without ultrasound, it is quite problematic to dispense with the diagnosis of multiple pregnancies and the position of the fetus.
Is it dangerous to have an ultrasound?
According to the report of the World Health Organization, which was prepared using data obtained in leading world clinics for many years, ultrasound is considered absolutely safe for the patient by research.
Note : indistinguishable for human hearing, ultrasonic waves are not something alien.They are present even in the noise of the sea and wind, and for some species, animals are the only means of communication.
Contrary to the fears of many future mothers, ultrasound waves do not harm even a child during fetal development, that is, ultrasound during pregnancy is not dangerous.However, for the application of this diagnostic procedure there must be some indication.
Ultrasound with 3D and 4D
The standard ultrasound is performed in 2D mode, that is, the monitor image is displayed only in two planes( relatively speaking, you can see the length and width).Modern technologies have made it possible to add depth, i.e.Third dimension.Due to this, a 3D image of the object under study is obtained.
Apparatus for three-dimensional ultrasound gives a color image, which is important in the diagnosis of certain pathologies.The power and intensity of ultrasound is the same as that of conventional 2D devices, so there is no risk of talking about a patient's health.In fact, the only drawback of 3D ultrasound is that the standard procedure does not take 10-15 minutes, but up to 50.
The most widely used 3D-ultrasound is now used to study the fetus in the womb.Many parents want to look at the face of the baby even before his birth, and on an ordinary two-dimensional black and white picture, only a specialist can see something.
But you can not consider the examination of the child's face a usual whim;The three-dimensional image allows to distinguish anomalies in the structure of the maxillofacial region of the fetus, which often indicate severe( including genetically determined) diseases.Data obtained with ultrasound, in some cases, can be one of the reasons for making a decision about abortion.
Important: must be taken into account that even a volumetric image does not provide useful information if the child turns his back on the sensor.
Unfortunately, so far only ordinary two-dimensional ultrasound can give the specialist the necessary information about the state of the internal organs of the embryo, so the 3D-study can be considered only as an additional diagnostic method.
The most "advanced" technology is the ultrasound in 4D.Time has now been added to the three spatial dimensions.Due to this, it is possible to obtain a volumetric image in dynamics, which allows, for example, to look at the change in the mimicry of an unborn child.
In the early stages of pregnancy( almost the entire first trimester), 3D and 4D images can represent extremely narrowly professional interest for the diagnostician.Identify the real violations of intrauterine development of the child becomes possible, starting from 20-24 weeks.
One of the advantages of 3D and 4D is that the validity of the data is not affected by the gassing process in the intestine, and the procedure itself can be performed at any degree of fullness of the bladder.
Konev Alexander, internist