Duplex scanning of vessels of the head and neck

Where to make an ultrasound of the head and what is needed for echoencephalography, let us consider these questions. The US of the head is a method of diagnosis, with the help of which it is possible to reveal pathologies of the brain. The study is based on harmless ultrasound radiation that penetrates through the tissues and bones of the skull into the brain substance.

Duplex scanning (gray-scale echography with color Doppler coding and spectral Doppler analysis, applied to the intracranial part of the cerebral vasculature - transcranial duplex scanning) currently serves as the main method for diagnosing various types of pathology of the cerebral vascular system. Duplex scanning combines the possibility of visualizing the lumen of the vessel and the tissues surrounding the vessel in B-mode (two-dimensional seroscale echography) and simultaneous analysis of the hemodynamic state by means of Doppler technology. According to the results of the study, data on the state of elasticity of the vascular wall (elasto-elastic characteristics), the functional state of the endothelium (its vasomotor activity), the presence, nature and prevalence of changes in the structure and thickness of the vascular wall, the violation of the integrity of the vascular wall (dissection), the presence of intraluminal formations, their localization, extent, echogenicity (indirect characteristics of density), the degree of disturbance of the permeability of the lumen of the sucker Yes, changes in the diameter of the vessel, vascular geometry (the presence of deformations, deviations of the vessel from the usual anatomical trajectory), abnormalities of the passage, course and branching of the vessels. Information on intraluminal flows (as a result of processing the reflected Doppler signal by the method of fast Fourier transform) can be presented in the form of color cartograms (color Doppler mode) and / or Doppler spectra (spectral Doppler mode) in conventional and transcranial duplex scanning. According to the research in the color Doppler mode, qualitative information on the blood flow is obtained [presence, nature (laminar, turbulent), cartogram filling defects, etc.]. The spectral Doppler regime allows us to characterize intraluminal flows quantitatively, i.e. To objectify the presence or absence of hemodynamic disturbances, and also to determine the degree of their severity. The resulting diagnostic information is based on the analysis of speed indicators and various calculated indices, which indirectly characterize the level of peripheral resistance and the tone of the vascular wall.

[1], [2], [3], [4], [5], [6]

Indications for the study of extracranial vessels

• clinical signs of acute or chronic cerebrovascular insufficiency, including headache syndrome;
• risk factors for the development of cerebrovascular diseases (smoking, hyperlipidemia, obesity, hypertension, diabetes mellitus);
• signs of damage to other arterial basins in the systemic nature of vascular processes;
• Planning of surgical interventions for various types of cardiac pathology, especially coronary heart disease (coronary artery bypass grafting, stenting of coronary arteries);
• pathology of surrounding organs and tissues with the potential for extravasal effects;
• clinical signs of pathology of the jugular veins (often thrombosis).

The high resolution of ultrasonic duplex scanning combined with non-invasiveness and the possibility of repeated repeated studies makes the method an indispensable tool not only in clinical neurology, but also in the implementation of comprehensive preventive screening in an asymptomatic population. Unlike ultrasonic dopplerography, small and medium stenoses of carotid arteries can be detected, and the possibilities of differential diagnostics can be significantly expanded. In this connection, it can be stated that duplex scanning is the main method of screening in persons without clinical symptoms of cerebral circulation disorders.

Indications for a transcranial duplex scan

• detection of duplex scans (or ultrasound dopplerography) of extracranial divisions of brachiocephalic arteries of stenotic / occlusive pathology - a potential source of cerebral blood flow disorders;
• the presence of indirect signs of intracranial arteries;
• signs of acute or chronic cerebral ischemia without certain established causes of its development;
• headache syndrome;
• Systemic vascular disease is a potential source of development of cerebral circulation disorders (arterial hypertension, diabetes mellitus, systemic vasculitis, etc.).
• the pathology of the substance of the brain (revealed using other imaging techniques - CT, MRI, scintigraphy, etc.), accompanied by a change in its structure and cerebral vascular circulation, clinical signs of intracranial hypertension;
• the need for dynamic monitoring of cerebral blood flow indicators to assess the effectiveness of ongoing therapy in the acute period of ischemic and hemorrhagic stroke and chronic cerebrovascular insufficiency, and to determine the state of the vessels at various stages of surgical revascularization, regardless of the type of the latter.

Objectives of ultrasound examination of arterial and venous systems of the brain at extra- and intracranial levels:

• diagnostics of stenotic / occlusive pathology in the arterial and venous systems of the brain, evaluation of its pathogenetic and hemodynamic significance;
• the detection of a complex of disorders associated with systemic vascular diseases;
• identification of vascular anomalies, arterial and venous aneurysms, arteriovenous malformations, anastomosis, cerebral vasospasm, venous circulation disorders;
• identification of early (preclinical) signs of systemic vascular pathology;
• monitoring the effectiveness of treatment;
• determination of the functions of local and central mechanisms of vascular tone regulation;
• assessment of the reserve capacity of the cerebral circulation system;
• the establishment of a possible etiological role of the revealed pathological process or symptom complex in the genesis of the clinical syndrome (syndromes) that exists in a particular patient.

The compulsory volume of the study for duplex scanning of the extracranial divisions of the brachiocephalic arteries includes the distal section of the shoulder of the head trunk, common carotid arteries throughout, internal carotid arteries before entering the cavity of the skull through canalis caroticus, external carotid arteries in the proximal regions, vertebral arteries in segments V1 and V2. If there are indirect signs of V3 segment damage, echolocation can also be performed in this section of the vertebral artery.

If there are signs of pathology potentially threatening the development of systemic (intracranial) hemodynamic disorders, Doppler blood flow characteristics in the supraclavicular (eye) artery are necessarily examined.

In the carotid arteries on an extracranial level, various stages of pathological processes with a complete structural analysis of intraluminal pathology can be identified. Vertebral arteries due to anatomical location peculiarities are visualized fragmentarily and are only available for monoplane scanning. This limits the ability of the method to diagnose various pathological processes. In particular, with high reliability in conditions of poor visualization quality, it is possible to detect only stenosing lesions with a narrowing of the lumen of the vessel more than 40-50% in diameter, located in zones accessible to the location. Echostructural analysis of intraluminal formations in the vertebral artery is usually not performed due to the extremely limited possibilities of visualization of the vessel walls. Load testing is used to determine the functional changes in vessel diameters. There are no specific objective ultrasound signs of extravasal compression of the vertebral artery in the canal of the transverse processes of the cervical vertebrae and in the area of the craniovertebral articulation. Doppler diagnostic criteria used for these purposes in everyday practice are of an indirect nature and require mandatory confirmation by methods that allow visualizing the area of extravasal effects (angiographic techniques in the background or with functional stress tests).

Investigation of jugular veins (internal and external), as well as veins of the vertebral venous plexus, is performed with suspicion of thrombosis of these vessels. The diagnostic value of Doppler blood flow parameters obtained in the spectral Doppler mode from the lumens of the above venous reservoirs and their significance in determining the pathological changes in cerebral venous hemodynamics in all other cases is questionable given the variability of venous outflow from the cranial cavity when the position of the body changes, as well as the impermanence of the structure veins, synchronization of blood flow in them with respiration and easy compression of the lumens.

The study of the cerebral vascular system by the method of transcranial duplex scanning has a number of peculiarities. Given the presence of obstacles in the form of skull bones on the way of ultrasonic rays, low frequency of radiation (on average 2-2.5 MHz) is used to increase the penetrating power. At such frequencies, the visualization of the vascular wall and the determination of the condition of the lumina of the intracranial arteries and veins is fundamentally impossible. The information obtained is of an indirect nature and is based on the results of the analysis of the color cartograms of the intracranial arteries and veins streams, as well as the corresponding Doppler spectra. Therefore, when transcranial duplex scanning, as well as with transcranial Doppler, evaluation of vascular changes and diagnostics of processes not accompanied by the formation of local (and systemic) hemodynamic disorders is impossible. Because of the unequal thickness of the bones of the skull, which determines their different permeability for ultrasonic radiation, echolocation is performed in certain areas, called ultrasound "windows", which do not differ from those in transcranial dopplerography. The amount and quality of information obtained by transcranial duplex scanning depends on the presence and severity of ultrasound "windows". The main limitations are due to a significant decrease in the quality of ultrasound imaging with a decrease in the acoustic "transparency" of the bones of the skull.

In carrying out transcranial duplex scanning, the mandatory protocol of the study includes the study of color flow cartograms, the Doppler spectrum and its characteristics in the middle cerebral arteries (segments M1 and M2), the anterior cerebral arteries (segment A1), the posterior cerebral arteries (segments P1 and P2), the inner siphon carotid artery and its intracerebral portion, vertebral arteries in segment V4, the main artery and a number of venous trunks (veins of Rosenthal, the Venus Galen, a straight sinus). To determine the functional consistency of the connective arteries of the Willis circle (in cases of hemodynamic equilibrium), compression tests are performed (short-term, within 3-5 s compression of the lumen of the common carotid artery above the mouth). Such manipulation leads to characteristic changes in blood flow in segment A1 of the anterior cerebral artery (with the functional consistency of the anterior connective artery) and segment P1 of the posterior cerebral artery (with functional consistency of the posterior connective artery). The functional consistency of other macroanastomoses (pericallic, extracranial) in the absence of signs of collateralization of the blood flow at rest is not determined. Currently, actively developing issues related to the use of visualizing ultrasound methods in the clinic of urgent angioneurology. Proceeding from the possibilities of duplex scanning, the research tasks for acute disorders of cerebral circulation of the ischemic type are as follows.

• Determination of possible causes of ischemic stroke.
• Research and evaluation of background blood flow in the extra- and intracranial arteries and veins and the state of reactivity of the cerebral circulatory bed.
• Establishing sources of collateral redistribution of flows, their consistency and sufficiency.
• Monitoring of blood flow in one or more vessels to confirm the effectiveness of pathogenetic and symptomatic therapy.

Duplex scanning can presumably identify possible causes of ischemic stroke.

In the study of extracranial divisions of brachiocephalic arteries, differential signs characteristic of stenosing atherosclerosis, thrombosis, macroemboli, angiopathy, vasculitis can be identified. In transcranial duplex scanning, verification of steno-occlusive / occlusive lesions is possible with the determination of the degree of their severity without concretizing morphological equivalents, as well as the identification of specific phenomena that are characteristic for disrupting autoregulation of cerebral blood flow, cerebral angiospasm, and so on. When revealing a stenosing atherosclerotic lesion of carotid arteries, an analysis is made of the echostructure of the atherosclerotic plaque and the degree of impaired passage of the lumen of each affected vessel. In accordance with the current classification of atherosclerotic plaques, homogeneous (low, moderate, increased echogenicity) and heterogeneous (with predominance of hypoechoic and hyperechoic components, with the presence of acoustic shade) of the plaque are distinguished by echostructure and echogenicity. Complicated include atherosclerotic plaques with ulceration, hemorrhage and atherothrombosis. The last lesions are classified as so-called unstable, they are most dangerous in terms of the development of cerebral embolism and thrombosis. When suspicion of the embolic nature of ischemic stroke, it is first of all necessary to pay attention to atherosclerotic plaques of the above types. The degree of narrowing of the vessel may not play a significant role in this, since plaques are often complicated, accompanied only by local changes in hemodynamics due to an insignificant (up to 40-50%) reduction in the lumen of the artery. In the absence of obvious causes of arterio-arterial embolism, and in some cases and in their presence, it is necessary to conduct an echocardiographic study to exclude the cardiac arterial genesis of cerebral circulation.

The second possible cause for the development of acute ischemia is the occlusion (or non-occlusive thrombosis) of the cerebral arteries at the extra- and / or intracranial level. In thrombosis of extracranial parts of carotid and / or vertebral arteries, a typical ultrasound picture is determined, including intraluminal formations that vary in echogenicity and extent, leading to a reorganization of local and systemic hemodynamics, determined in the spectral Doppler regime. In some cases, when analyzing the echogenicity, geometry, mobility, prevalence of intraluminal formation, it is possible to differentiate the primary (associated with the lesion of the vascular wall) wall clot from the embolus. Additional arguments in favor of the latter are the detection of an obstacle atypical location (for example, bifurcation of the common carotid artery with free lumens of the internal and external carotid arteries), an unchanged or unchanged vascular wall in the area of the formation, accompanying spasm of the artery. With the localization of stenosis and occlusion in the intracranial arteries, pronounced changes in the blood flow are determined in the form of a narrowing (disappearance) of the color flow chart in the zone of stenosis (occlusion) of the artery, a decrease in the rate of blood flow in combination with changes in the spectral characteristics of the blood flow proximal and possibly in the lesion. In parallel with this, as a rule, it is possible to register signs of collateralization of blood flow through the system of natural anastomoses (under condition of their availability and solvency).

Otherwise, the echographic picture appears with neo-occlusive thrombosis of the intracranial arteries. The main difference in this case will be the absence of a local hemodynamic drop in the obstacle area, probably due to the complex configuration of the stenotic canal. This circumstance often becomes a source of diagnostic errors in transcranial duplex scanning and a discrepancy with data obtained during angiography.

In the acute period of ischemic stroke, it is of fundamental importance to study the indices of cerebral blood flow at rest, both in vessels that supply blood to the zones of the developing focal lesion of the brain substance, and in other pools accessible to the study. The development of ischemic stroke can be a consequence of the failure of autoregulatory mechanisms of cerebral blood flow, in other cases - accompanied by such a breakdown. In this regard, most patients manage to register pathological changes in cerebral blood flow in one or several vascular pools. If autoregulation is disrupted at its lower border (with a critical drop in intraluminal pressure), a marked decrease in the rate of blood flow is noted, and hyperperfusion develops at the upper boundary, accompanied by an increase in the rates of intraluminal flows. Causes of brain hypoperfusion are more often stenotic / occlusive lesions or situations with an acute drop in systemic arterial pressure. At the heart of hyperperfusion of the brain is usually a pathological increase in systemic blood pressure. At the same time, with a local disruption of autoregulation in persons with hypertensive disease (usually in areas of adjacent blood supply) with the formation of lacunar infarcts, background blood flow in the leading arterial arteries may not significantly differ from the mean normative ones. In this case, carrying out stress testing aimed at activating the mechanisms of autoregulation allows the detection of local and / or generalized disturbances of cerebrovascular reactivity. No less important is the study of the presence, consistency and degree of functional activity of the system of natural anastomoses. Objectivization of adequate compensatory redistribution of blood flow in them with stenotic / occlusive lesions of brachiocephalic vessels is a favorable prognostic sign. In cases where no blood flow is observed at rest, it is necessary to use compression tests to determine its potential sources. Carrying out the latter requires caution in the prevalent atherosclerotic lesion of the carotid arteries.

With atherothrombotic and cardioembolic ischemic stroke, pathogenetic treatment can be carried out - thrombolytic therapy. Duplex scanning allows monitoring of blood flow and determining vascular responses in the affected area in both systemic and selective thrombolysis. Normalization of the flow in the affected vessel or an increase in the blood flow velocity in its lumen, a decrease in intensity or the disappearance of collateralization are objective indicators of the effectiveness of therapy. The lack of positive dynamics of the echographic picture can be regarded as a criterion for its inefficiency. There are often inconsistencies between the success of revascularization and the clinical effect.

The main task of visualizing ultrasound methods (as well as UZDG and TKDG) with hemorrhagic stroke is monitoring of arterial and venous blood flow in the intracranial arteries and veins to determine the presence and severity of cerebral vasospasm and intracranial hypertension. Ultrasound diagnosis of cerebral angiospasm is based on recording the pathological increase in linear velocity indices of blood flow in spasmodic arteries (peak systolic velocity, time-average maximum blood flow velocity) and the results of the Lindegard index (the ratio of peak systolic velocity in the middle cerebral artery to that in the internal carotid artery) . As an additional sign of angiospasm, a change in the response to metabolic functional exercise tests can be used. When monitoring Doppler indices of cerebral blood flow, timely adequate medication correction of vasospastic reactions is possible.

Various types of disorders of cerebral circulation, as well as other pathological conditions can cause critical violations of cerebral perfusion with the subsequent development of brain death. Duplex scanning is one of the basic methods that provide valuable information in this state. The basis for the conclusion on the presence of signs of cessation of cerebral circulation is the results of evaluating the linear and volumetric blood flow in extracranial sections of brachiocephalic arteries, as well as linear indices of blood flow in intracranial vessels. In the extracranial parts of the internal carotid arteries and vertebral arteries, signs of reverberation of blood flow can be revealed. The hemispheric cerebral blood flow is below the critical values of 15-20 ml / 100 g / min. When transcranial duplex scanning, there are no signs of arterial blood flow in the intracranial arteries.

With chronic disorders of cerebral circulation of various genesis (atherosclerotic, due to hypertonic, diabetic angiopathy, age involution, vasculitis, severe heart diseases accompanied by circulatory insufficiency, etc.), duplex scanning of extracranial divisions of brachiocephalic arteries can reveal signs of various pathological processes that not always directly related to the development of cerebral blood flow disorders. In contrast to acute cerebral accident, with chronic abnormalities of cerebral circulation against the background of atherosclerotic lesions of the branches of the aortic arch, the degree of stenosis of brachiocephalic arteries and the prevalence of the process are more important, given the role of these factors in the genesis of chronic cerebral ischemia and the limitation of opportunities for adequate collateral compensation.

Duplex scanning, like any other ultrasound technique, is operator-dependent and to a certain extent subjective. The success of using a set of visualizing ultrasound methods in clinical neurology, in addition to the experience and skills of the operator, largely depends on the technical characteristics of the equipment used. In this regard, in all disputable diagnostic cases, as well as in the planning of surgical treatment on the vessels of the brain, the X-ray contrast angiography and its varieties, recognized as the "gold standard" in angiology, serve as the reference method for ultrasound.

Ultrasound is an excellent alternative to costly MRI or CT examination. Diagnosis does not require special training and is allowed for patients of all ages, both pregnant and newborn. The duration of the procedure is 20-25 minutes, it is painless and safe for the body.

Kiev:

• Medical "Androtsentr" - Holosiivskyi Avenue (40th Anniversary of October), 59B, Hospital No. 10, administrative building, 2nd floor, tel. [phone].
• Medical-diagnostic center "Meddiagnostika" - lane of Builders, 4, ph. [phone].
• Medical Center "Euroclinic" - st. Melnikova, 16, tel. [phone].
• The network of medical clinics "Viva" - ul. Lavrukhina, 6, tel. [phone].
• Diagnostic and Consultative and Curative Center "CardioMed" - st. The militia, 7, tel. [phone].

Diagnosis of the head in Moscow:

• Network of polyclinics for children and adults "Family doctor" - st. Barrikadnaya, 19, tel. [phone].
• Medical Center "City Clinic" - st. Academician Kapitsa, 34/121, 7 tel. [phone].
• National Medical and Diagnostic Center - ul. Runaway, 31.
• Medical Center "Medisan" - st. Maroseika, 10/1.
• Medical Center "Affordable Health" - st. Zelenodolskaya, 41/1.

St. Petersburg:

• Multifield clinic "Profi Medica" - Bogatyrsky Avenue, 64, tel. [phone].
• AndroMed Clinic - ul. Zvenigorodskaya, 12, ph. [phone].
• Ultrasound "21 century" - st. Olkhovaya, 6/289, tel. [phone].
• Medical Center "Longevity" - lane Krestyansky, 4, tel. [phone].
• DTMT professor V.A. Fokina - st. Ivan Chernykh, 29.