Dopplerography (uzdg) of the vessels of the kidneys. Ultrasound of the vessels of the kidneys Ultrasound of the kidneys and renal arteries

With help ultrasound kidney vessels can be detected serious pathologies in real time. With the help of such a diagnostic measure, the position of these vessels is determined, their physiology is assessed. It is also important to consider their location relative to the kidney and determine the diameter, as well as identify possible obstacles to normal blood flow.

What methods are used to examine the renal arteries?

The following common methods are used:

UZDG - ultrasonic dopplerometry. This method works on the basis of the Doppler effect, in which ultrasound waves are able to be reflected from movable objects, which are blood cells.
duplex scanning. This method opens up the possibility of assessing not only the speed of blood flow, but also the chance to consider the anatomy of each vessel. This technique is advanced and will help to determine the entire spectrum of vascular pathologies, regardless of their level of development. This method makes it possible to find out the structure and caliber of the vessel, all the functional components.
Triplex scanning, it is also called color Doppler mapping or CFM. This method is similar to dopplerometry, but there is still an overlay of color blood flows on a two-dimensional image.

The most efficient for this moment It is considered a comprehensive study of blood vessels by all methods. This is the only way to get complete and reliable data with clear visualization. Pathologies can be detected on early stages development, which will simplify their treatment. At first, it is often asymptomatic. The harmlessness of such a procedure allows you to monitor the state of the arteries in dynamics and track all changes.

The essence of the CDC procedure

Color Doppler mapping is a method that makes it possible to assess blood flow in the vessels. The basis of the study is a combination of a two-dimensional image and an assessment of blood flow in accordance with Doppler indicators.

The diagnostician displays an image familiar to ultrasound, and in the place that is being studied, blood flows and, accordingly, their speeds are represented in color. The following colors will be visible on the monitor:

Red streams are blood that is moving towards the sensor.
Blue streams - blood that follows from the sensor.

The speed can be judged by the intensity of the color, the less pronounced it is, the slower the flow moves. The color flow method not only displays a visual picture, but also analyzes the direction, speed, and nature of the blood flow. The patency of the kidney vessels, their diameter, and resistance are also examined.

Using this method, you can install:

Is there a thickening of the vessel wall.
Are there blood clots?
The presence of atherosclerotic plaques.
crimp.
Excessive expansion of the lumen of the vessel - aneurysm.

When is a renal artery examination scheduled?

The main reason for the appointment of a Doppler study of the vessels of the kidneys is the suspicion of a violation of the inflow and outflow of blood to the organ. In the course of diagnosis, it is possible to subdue the causes of this, the form of the anomaly. The patient is sent to additional research kidneys, if a pathology is detected during a conventional ultrasound of the organ. Also cases of appointment are related to:

Impaired and/or painful urination.
The patient has swelling of the eyelids of the face in the morning.
Exist pain in the lumbar region, while they are not related to diseases of the spine.
With persistent hypertension.
If organ failure is suspected.
If tumors of the kidneys and adrenal glands are diagnosed.
If necessary, study circulatory system that keeps the tumor alive.
If necessary, track the dynamics of treatment.

As for contraindications, there are no absolute ones. The only thing if there is no urgent need surgical intervention, then the study is carried out after FGDS and colonoscopy. After all, during these procedures, the intestine starts a large number of air, which will become an obstacle for vascular diagnostics.

It is impossible to implement this method if there is an opening of a wound or burns at the location of the sensor for diagnostics.

Preparation measures and scheme of conduct

Long and large-scale preparation is not needed, but several steps should still be taken in order for the results to have high reliability and accuracy. Main stages:

3 days before the study, you need to go on a diet. At the same time, fatty foods, smoked meats, cabbage and legumes in any form, carbonated drinks should be excluded from the menu.
You can eat steamed porridge, vegetables, meat and fish during the preparatory period.
In the course of preparation, it is also worth taking sorbents, in accordance with the instructions.
If there are problems with flatulence, then it is also necessary to include enzyme preparations in the intake.
Before the study in the evening you need to have dinner no later than 18:00.
Also in the evening you need to make a cleansing enema and take Activated carbon at the rate of 1 tablet per 10 kg of weight.
The procedure is performed on an empty stomach, so you can not have breakfast in the morning.

If the patient has hunger pains or other severe pathological condition, then it is allowed to eat no later than 3 hours before the procedure.

Held by standard scheme. The patient frees the area under study from clothing, lie down on his side. A gel is applied to the skin, and a study is carried out.

Norms and pathologies

During the diagnosis, vascular pathologies can be detected. They are determined by comparing the norm with the data obtained. With the protocol of the study, you need to go to the attending physician, he will be able to decipher the data and prescribe treatment if necessary.

Conclusion. The combination of several methods in the study of renal vessels is considered the most effective and effective method, which allows you to identify pathologies at the very beginning of its development. Regular preventive examination mandatory for risk groups.

Ultrasound of the vessels of the kidneys is a method for examining the features of the location of arteries and veins, their diameter and blood flow velocity in them. Method doppler ultrasound(USDG of renal vessels) is based on the Doppler effect.

Why is this procedure needed?

Ultrasound of the kidney vessels is based on the fact that ultrasonic waves are reflected from red blood cells that are contained in the blood. The ultrasonic sensor picks up the reflected waves, after which they are converted into electrical impulses.

The result is a display on the monitor in a graphical form and with color photographs representing the flow of blood in blood vessels. Ultrasound of the renal arteries allows you to examine the arteries "from the inside" in real time, so you can notice a change in blood flow in them. This is due to spasm, narrowing or thrombosis.

Dopplerography of the kidney vessels helps to identify:

impaired blood supply to the body
the rate of blood flow in the arteries
early vascular disorders that caused atherosclerotic plaques
the presence of arterial stenosis.

The study of renal vessels is used not only to identify pathological processes but also to assess the effectiveness of the treatment.

Diseases for which the method is prescribed

pain in the lumbar region
renal colic
edema and cardiovascular disease
late toxicosis during pregnancy
endocrine disorders
sharp or chronic diseases kidney or genitourinary system(in this case, an ultrasound of the bladder may be recommended)
hypertension (high blood pressure)
clarification of the diagnosis, if there are any deviations from the norm in the analysis of urine
severe bruising in the lumbar region or injury
analysis of the state after transplantation of the studied organ
diagnosis of pathology of the vessels of an organ or tumor.

Ultrasound of the kidneys in children helps to identify vesicoureteral reflux, as well as to exclude congenital anomalies renal vessels.

Preparation for the procedure

The procedure must be carefully prepared, since the gases accumulated in the intestines make it difficult to visualize. If carried out qualitatively, it will favorably affect the accuracy of the survey results.

How is the examination

The study is carried out in a sitting position or lying on its side. On the skin in the lumbar region, the sonologist will apply a special gel that ensures close contact between skin and device sensor. Then the doctor will move the ultrasonic probe over the area under study, while simultaneously viewing constantly changing images (“slices”) on the monitor.

The procedure is painless and does not take more than 30 minutes. After the examination, you can immediately get down to business.

Deciphering the results and indicators of the norm

After the procedure, the sonologist must issue a conclusion, which contains a transcript of the study:

the organ must be bean-shaped
the outer contour has smooth and clear edges
hyperechoic capsule (thickness up to 1.5 mm)
the system of calyces and pelvis is not visualized, with full bladder she becomes anechoic
right kidney slightly lower than left
echo density of the pyramids is lower than that of the parenchyma
kidneys should be the same size or differ by no more than 2 cm
echo density matches renal sinus and perirenal tissue
the kidneys have the same echogenicity as the liver or it is slightly reduced
the concepts of "partial hypertrophy" of the renal cortex and "pillars of Bertin" are variants of the norm
indicators of the anterior-posterior dimensions of the organ - no more than 15 mm
kidney mobility during breathing - 2.5-3 cm
deciphering the indicators of the resistance index of the main artery - approximately 0.7 in the gate area, in the interlobar arteries - from 0.36 to 0.74.

The structure of the vessels of the kidney

The renal arteries arise from the abdominal aorta just below the superior mesenteric artery, at the level of the second lumbar vertebra. Anterior to the renal artery is the renal vein. At the hilum of the kidney, both vessels are anterior to the pelvis.

The PAP passes behind the inferior vena cava. LPV passes through the "tweezers" between the aorta and the upper mesenteric artery. Sometimes there is an annular PV, then one branch is located in front, and the other - behind the aorta.

Click on pictures to enlarge.

To study the vessels of the kidney, a convex probe of 2.5-7 MHz is used. The position of the patient is lying on his back, the sensor is placed in the epigastrium. Assess the aorta from the celiac trunk to the bifurcation in B-mode and color flow. Follow the course of the RAA and LAA from the aorta to the hilum of the kidney.

Drawing. In the CFM mode, on the longitudinal (1) and transverse (2) sections, the RSA and LSA depart from the aorta. Vessels are sent to the gates of the kidney. Anterior to the renal artery is the renal vein (3).

Drawing. The renal veins drain into the inferior vena cava (1, 2). Aortomesenteric "tweezers" can compress the LPV (3).

Drawing. At the hilum of the kidney, the main renal artery divides into five segmental ones: posterior, apical, superior, middle, and inferior. Segmental arteries are divided into interlobar arteries, which are located between the pyramids of the kidney. Interlobar arteries continue into arcuate → interlobular → glomerular afferent arterioles → capillary glomeruli. Blood flows from the glomerulus through the efferent arteriole into the interlobular veins. The interlobular veins continue into the arcuate → interlobar → segmental → main renal vein → inferior vena cava.

Drawing. Normally, with CDI, the vessels of the kidneys can be traced to the capsule (1, 2, 3). The main renal artery enters through the hilum of the kidney, accessory arteries from the aorta or iliac artery may fit at the poles (2).

Drawing. On ultrasound, a healthy kidney shows linear hyperechoic structures along the base of the pyramids (corticomedullary junction) with a hypoechoic path in the center. These are arcuate arteries, which are mistakenly regarded as nephrocalcinosis or stones.

Video. Arcuate arteries of the kidney on ultrasound

Doppler of kidney vessels is normal

The diameter of the renal artery in adults is normally 5 to 10 mm. If diameter<4,65 мм, вероятно наличие дополнительной почечной артерии. При диаметре главной почечной артерии <4,15 мм, дополнительная почечная артерия имеется почти всегда.

The renal artery should be assessed at seven points: at the exit from the aorta, in the proximal, middle and distal segments, as well as the apical, middle and inferior segmental arteries. We evaluate peak systolic (PSV) and end-diastolic (EDV) blood flow velocity, resistivity index (RI), acceleration time (AT), acceleration index (PSV/AT). See more.

The normal spectrum of the renal arteries has a pronounced systolic peak with antegrade diastolic flow throughout cardiac cycle. In adults, PSV is normal on the main renal artery 100±20 cm/sec, EDV is 25-50 cm/sec, in young children PSV is 40-90 cm/sec. In the segmental arteries, PSV drops to 30 cm/sec, in the interlobar arteries to 25 cm/sec, in the arcuate arteries to 15 cm/sec, and in the interlobular arteries to 10 cm/sec. RI at the hilum of the kidney<0,8, RI на внутрипочечных артериях 0,34-0,74. У новорожденного RI на внутрипочечных артериях достигает 0,8-0,85, к 1 месяцу опускается до 0,75-0,79, к 1 году до 0,7, у подростков 0,58-0,6. В норме PI 1,2-1,5; S/D 1,8-3.

Drawing. Normal spectrum of renal arteries - high systolic peak, antegrade diastolic flow, low peripheral resistance - RI normal<0,8.

Drawing. The spectrum of renal vessels in newborns: renal artery - a pronounced systolic peak and antegrade diastolic flow (1); high resistance on the intrarenal arteries is considered normal for newborns - RI 0.88 (2); renal vein - antegrade flow with a constant rate throughout the entire cardiac cycle, minimal respiratory fluctuations (3).

Doppler for renal artery stenosis

Renal artery stenosis can be found in atherosclerosis or fibromuscular dysplasia. With atherosclerosis, the proximal segment of the renal artery is more likely to suffer, and with fibromuscular dysplasia, the middle and distal segments are more likely to suffer.

Direct signs of renal artery stenosis

The aliasing indicates the location of the turbulent high-velocity flow where measurements should be taken. In the zone of stenosis PSV>180 cm/sec. In young people, the aorta and its branches may normally have high PSV (>180 cm/sec), and in patients with heart failure, PSV is low even in the area of stenosis. These features are offset by the renal-aortic RAR ratio (PSV in the area of stenosis/PSV in abdominal aorta). RAR in renal artery stenosis >3.5.

Indirect signs of renal artery stenosis

Direct criteria are preferred; diagnosis should not be based solely on circumstantial evidence. In the post-stenotic section, the flow fades - tardus-parvus effect. With renal artery stenosis on the intrarenal arteries, PSV is too late (tardus) and too small (parvus) - AT > 70 ms, PSV / AT<300 см/сек². Настораживает значительная разница между двумя почками — RI >0.05 and PI >0.12.

Table. Criteria for renal artery stenosis on ultrasound

Drawing. A 60-year-old patient with refractory arterial hypertension. PSV on the abdominal aorta 59 cm/sec. IN proximal PPA with CFM aliasing (1), PSV significantly increased 366 cm/sec (2), RAR 6.2. In the middle segment of the PPA with color flow aliasing, PSV 193 cm/sec (3), RAR 3.2. On segmental arteries without a significant increase in acceleration time: upper - 47 ms, middle - 93 ms, lower - 33 ms. Conclusion:

Drawing. A patient with acute kidney failure and refractory hypertension. Ultrasound of the abdominal aorta and renal arteries is difficult due to intestinal gas. On the segmental arteries on the left RI 0.68 (1), on the right RI 0.52 (2), the difference is 0.16. The spectrum of the right segmental artery has the shape of a tardus-parvus - the acceleration time is increased, PSV is low, the apex is rounded. Conclusion: Indirect signs stenosis of the right renal artery. CT angiography confirmed the diagnosis: at the mouth of the right renal artery, atherosclerotic plaques with calcification, moderate stenosis.

Drawing. Patient with arterial hypertension. PSV in the aorta 88.6 cm/sec (1). In the proximal RAP, aliasing, PSV 452 cm/sec, RAR 5.1 (2). PPA aliasing in the middle section, PSV 385 cm/sec, RAR 4.3 (3). In the distal part of the PPA, PSV is 83 cm/sec (4). On the intrarenal vessels of the tardus-parvus, the effect is not determined, on the right RI 0.62 (5), on the left RI 0.71 (6), the difference is 0.09. Conclusion: Stenosis in the proximal section of the right renal artery.

Doppler of the renal veins

The left renal vein runs between the aorta and the superior mesenteric artery. Aortomesenteric "tweezers" can compress the vein, leading to venous renal hypertension. In the standing position, the “tweezers” are compressed, and in the prone position, they open. With Nutcracker syndrome, outflow through the left testicular vein is difficult. This is a risk factor for the development of left-sided varicocele.

Due to compression, the LPW spectrum is similar to portal vein- spectrum above the baseline, constant low speed, contour smooth waves. If the ratio of the diameter of the LPV in front of and in the zone of narrowing is more than 5 or the flow rate is less than 10 cm/sec, we make a conclusion about an increase in venous pressure in the left kidney.

Task. On ultrasound, the left renal vein is dilated (13 mm), the area between the aorta and the superior mesenteric artery is narrowed (1 mm). Blood flow in the stenosis zone at high speed (320 cm/sec), reverse of blood flow in the proximal segment. Conclusion: Compression of the left renal vein with aortomesenteric "tweezers" (Nutcracker syndrome).

Compression of the renal vein is possible due to an abnormal location behind the aorta. The diameter ratio and flow rate are evaluated according to the above rules.

The nature of the blood flow in the right renal vein approaches the caval. The shape of the curve changes with holding the breath and can be flatter. The blood flow velocity is 15-30 cm/sec.

Take care of yourself, Your Diagnostician!

For better visualization of the renal arteries, it is recommended to perform ultrasound in the morning on an empty stomach, this avoids the "interference" that can be caused by the accumulation of intestinal gases that form during the day and after eating.

The last meal should be on the evening before the study. Longer fasting is not recommended due to possible development flatulence.

In preparation for the study, it is desirable to exclude smoking and the use of chewing gum. Oral intake allowed a small amount medications needed by the patient.

In the vast majority of patients, the study of PA (especially its distal parts) is possible without special preparation. Preparation is required when examining obese patients, as well as when duplex scanning is required on most VAs. In case of poor visualization of the PA (for example, in obese patients, with severe flatulence), you can try to scan the renal arteries with a breath hold at maximum inspiration. In a number of cases, this improves the quality of the study.

Duplex scanning of PA can be performed using mechanical sector, as well as vector and convex sensors with an electronic phased array with a frequency of 2.25 to 5.0 MHz. The optimal image is obtained using sensors with a frequency of 2.5 to 4.0 MHz.

To study VA from intercostal access, the sensor aperture should be small. To study the renal blood flow in newborns, high-frequency sensors with a frequency of 7.5 to 10.0 MHz are used. In pulsed wave Doppler mode, for spectral analysis it is necessary to use filters with the smallest possible frequency(from 50 to 100 Hz), which removes low-speed components that can affect the calculation of the resistivity index.

The size of the interrogated volume may vary depending on the caliber of the vessel being examined, but usually its size is from 2 to 8 mm. Due to the large depth of the location of the PA during the Doppler survey, a low pulse frequency (from 1000 to 1500 Hz) may be required, leading to an increase in the likelihood of an aliasing effect.

When performing ultrasound of the main trunk of the VA, the following accesses are used:

2.Posterior access. The patient is examined in the prone position. The sensor is placed 5–6 cm laterally spinal column(Fig. 16.6a).

The cross section of the kidney is visualized at the level of its gate (Fig. 16.6b).

lateral access. The patient is examined in the “lying on his side” position (decubital position). The sensor is installed along the axillary line (Fig. 16.7a), while the cross section of the kidney at the level of its gate is also visualized (see Fig. 16.7b).
Posterior access. The patient is examined in the supine position. The sensor is installed along the axillary line (Fig. 16.8).

The cross section of the kidney is visualized at the level of its gate (see Fig. 16.6b). In patients with a weakly expressed layer of subcutaneous fat when using ultrasound equipment latest generation it is possible to visualize the orifices of both VAs with longitudinal scanning of the abdominal aorta from the anterior approach (Fig. 16.7).

Peculiarities of plexus scanning in different groups of patients

In connection with the possibility of polyprojective ultrasound of the PA absolute contraindications to this diagnostic procedure practically non-existent. The exception is serious condition patient, the presence of a pronounced pain syndrome. In such cases, the issue is resolved individually. The duration of the study can be significantly reduced through the use of high-end ultrasound equipment by an experienced diagnostician.

In the presence of an aneurysm of the abdominal aorta and/or its branches duplex scanning PA from the anterior and posterior approaches is carried out very carefully and only if necessary, and if there is a suspicion of possible complication aneurysms and with large diameters of aneurysms, it is absolutely contraindicated. Caution is required in the use of these accesses and if available in abdominal cavity and retroperitoneal space of other additional three-dimensional structures, especially large ones - cysts, abscesses, tumors, etc. In the vast majority of cases, the posterolateral approach is the most acceptable.

Ultrasound of the renal artery is significantly difficult due to the large depth of the location and the small diameter of the vessel. The diameter of the VA in the region of the mouth is 5–6 mm and decreases towards the kidney to 3–4 mm.

When assessing blood flow in PA, a number of methodological difficulties arise:

a significant attenuation of the ultrasonic signal leads to the appearance of noise interference, which is reflected in the spectrum of the Doppler frequency shift (DFS);
the shape of the SDFS contour depends on the natural variability of the rhythm and stroke volume of the heart, as well as on the displacement of the studied VA in the field of the ultrasound beam, which is due to the natural mobility of the kidneys.

Obtaining reliable results with ultrasound of the PA depends on the characteristics of the patient's constitution, the severity of flatulence, the variant of vascular architectonics (the level at which the renal artery departs from the aorta, the angle between them, the degree of tortuosity of the vessel, the features of its division). To overcome the above methodological difficulties in the study of PA, it is recommended to use multiple projections of the location of the ultrasound sensor (including non-standard ones) in the same patient in the “on the back”, “on the stomach” and “on the side” positions. The results of the study also depend on the class of ultrasound system used and the experience of the researcher.

To conduct DS on the distal section of the main trunk of the VA, posterolateral, posterior, and lateral approaches are used. The kidney is visualized in cross section at the level of the hilum. The interrogated volume during DS of the renal artery is set at the hilum of the kidney outside its contour (Fig. 16.10). If you conduct a "survey" within the contour of the kidney, then you can erroneously register non-specific signals from the interlobar or arcuate arteries.

An anterior approach is used to assess blood flow in the orifice and proximal segment of the main VA trunk. In some cases (in thin people and with special training of the subject), when using a combination of all types of accesses, it is possible to visualize most of the main trunk of the VA.

To cover the entire area of the intended size of the PA, the size of the interrogated volume must be large enough (greater than the diameter of the main PA trunk). Small size of interrogated volume will increase the spatial resolution of the instrument, but will cause a decrease in the intensity of the backscattered signal. At the time of obtaining a high-quality recording of the SDFS spectrum, the patient should be asked to hold his breath, this allows you to get a recording of SDFS for several cardiac cycles (depending on the duration of the breath hold) and more accurately evaluate it.

When performing a duplex scan it is not always easy to determine the course and approximate size of the PA and, accordingly, correctly measure the Doppler angle and determine the desired size of the interrogated volume. The use of color domes makes it possible to successfully solve these problems. In modern ultrasound systems that use high-resolution sensors in high-speed and energy modes of color flow, it is possible to visualize not only the main trunk of the renal artery, but also all its branches, including small arcuate and cortical arteries (Fig. 16.11 and 16.12). In addition, the result of the study when using CFM in various energy modes will practically not depend on the angle of inclination of the ultrasound beam to the axis of the vessel.

Evaluation of scan results

SDFS obtained during duplex scanning of the renal arteries are evaluated both qualitatively and quantitatively.

When conducting qualitative analysis The shape, contour and width of the spectrum, the presence or absence of a “systolic window” under the SDHR curve, the ratio of the systolic and diastolic components of the spectrum are evaluated. The SDHR of the renal arteries is normally symmetrical on both sides and is characterized by a high exponentially falling systolic wave, as well as a constant and fairly high diastolic component and a narrow frequency spectrum zone. In a number of cases, the so-called "systolic window" can be observed on the SDCH, located below the systolic element (Fig. 16.13 a, b, c). During diastole, a fairly wide zone of low-frequency signals is determined.

Quantitative analysis of SDHR of the renal arteries includes the calculation of the speed and time characteristics of the spectrum (absolute indicators) and diagnostic indices (relative indicators). Absolute speed indicators include maximum (peak) systolic speed (Vmax), minimum (Vmin) and final (Vend) diastolic speed, as well as the average speed per cardiac cycle (TAMx) (Fig. 16.14 a, b). The time of systolic flow acceleration (T) is also measured.

When measuring velocities, their values must be corrected taking into account the Doppler angle. When calculating relative indicators, in addition to the indices of resistivity (RI = (Vmax - Vend) / Vmax), pulsation (PI = (Vmax - Vmin / TAMx) and systolic-diastolic ratio of velocities (Ratio = Vmax / Vmin), the renal-aortic ratio is often determined ( RAR) as the ratio of peak systolic velocity in the main trunk of the renal artery (Vmax RA) and peak systolic velocity in the abdominal aorta (Vmax AA).

For the renal artery, the average normal values(data from different authors are summarized) are: RI = 0.6–0.7; PI = 1.1–1.2; Ratio = 2.8; RAR = 3.5. The acceleration index is also calculated - the ratio of the acceleration times in the renal artery and the abdominal aorta.

There are several different forms normal SDHR of the renal arteries. The most significant qualitative and quantitative difference between normal SDFS of the main trunk of VA in young (20–30 years old) people and older (40–70 years old) people. In people older than 70 years, SDHS has its own characteristics, since the concept of a normal state of PA is very arbitrary in this age group.

In young people, SDFS is characterized by a concentration of velocities near the maximum frequency, a rapid increase in velocity in systole, its rather high absolute values, a pointed peak of the systolic phase of the spectrum, often the presence of an incisura and an additional wave before the onset of diastole with a possible irregular contour of the envelope maximum speeds into systole and high diastolic component (Fig. 16.15).

In the older age group, SDHR of the renal arteries is usually characterized by a slower increase in velocity in systole and its less steep decline, the absence of additional peaks and incisura, the always smooth contour of the envelope curve of maximum velocities, and lower absolute values of velocities throughout the entire cardiac cycle while maintaining their systolic-diastolic ratio (as in the previous age group) (Fig. 16.16).

When conducting a quantitative analysis, significant differences in these groups exist in the main trunk of PA between the values of the indices RI, PI, Ratio and T. There is a tendency to increase the values of all these parameters with age. This fact is easily explained by the regular changes that occur in the arterial wall as the body ages and lead to a decrease in its elasticity. The concept of a normal renal artery in people of the older age group is generally quite arbitrary and implies mainly the absence of hemodynamically significant pathology.

The absence of significant differences in the absolute values of the velocities by age groups is associated with the conditions for registering the SDFS (the main trunk of the PA in each case has its own characteristics). anatomical location and division options), as well as difficulties in visualizing the artery itself and, in some cases, correcting the Doppler angle.

Normally, the characteristics of blood flow in the arteries of various segments of the kidney are qualitatively similar to those in the main trunk of the VA. Moreover, there are no differences in the forms of pulsation waves and between different segments. When conducting a quantitative analysis in segmental VA, lower values of absolute velocities are revealed and the indices PI, RI, Ratio, and T do not differ significantly from the SDFS in the main VA trunk. windows "in the latter case due to the small caliber of the intrarenal arterial vessels (Fig. 16.17). To obtain more reliable information during duplex scanning of segmental arteries, it is necessary to use CFM in high-speed and energy modes (Fig. 16.18).