What is the purpose of kidney renography, the basis of the technique and the field of its application

Renography of kidneys is a method of radiological examination of kidneys using radioactive components. Such diagnostics is organized after intravenous administration of a radioactive substance that accumulates in the kidneys and helps to detect pathology of the organ.

This diagnostic provides an opportunity to assess the functions of the kidneys and the rate of urinary retention. The method is used to monitor the condition of the kidney after a transplant operation, and also to assess the dynamics of the process. All patients with suspected renal damage are permitted to carry out renography. Due to the introduction of a small dose of radioactive material, this method has no contraindications, it also does not require special training and takes about thirty minutes. In connection with this, renography is also carried out for seriously ill patients.

This is important!

Often, radioisotope renography is used for the timely detection of complications, such as thrombosis of a reconstructed vessel in the postoperative period.

What is the basis for the procedure for

The method of renography is based on the properties of the epithelium in the renal tubules to selectively extract the hippuran from the blood and then remove it from the body along with the urine. The accumulation and subsequent removal of the hymn is recorded by scintillation sensors, which are installed above the kidneys, and takes the form of two curves - these are the left and right renograms of the left and right kidneys. The examination is not traumatic, does not require preparation and does not cause irradiation of the body.

Despite the fact that this method of diagnosis is highly sensitive, changes in functioning are recorded on the chart only provided that the artery of the kidneys is not stenosed for more than half. In this situation, false data may be revealed.

Areas of application of the

method Radioisotope renography is used for early diagnosis of kidney dysfunction, for assessing the dynamics of renal processes, and monitoring the state of the kidneys after surgery. The main advantage is the separate evaluation of the two kidneys and the subsequent comparison of the symmetry of the curves.

Segment changes provide an opportunity to establish the level of impaired renal function.

Most often, radioisotope renography is used for unilateral lesion of the artery of the kidney. Patients suffering from glomerulonephritis and amyloidosis usually have bilateral lesions in the form of parenchymal type curves. As nephropathy develops, the excretion of the hippuran changes more and the difference in the fluctuation of the curve decreases, it stretches out and becomes thicker. As a result, this diagnosis allows you to identify violations in the work of the body, diagnose complications and find the right treatment.

Implementation of the

method The study is conducted in a sitting position. Detectors are placed on the skin above the kidney, above the heart and large vessels. Then the patient is injected intravenously with hippuran. The radiograph is equipped with automatic devices that depict the curves of the dynamics of accumulation and excretion of the reagent for each kidney, the curve of cleansing the blood from the radioactive substance.

The images obtained after diagnosis are evaluated taking into account the shape of the obtained curve and its segments. This includes the secretory segment associated with the extraction from the blood of epithelial cells of the tubules of hippuran. Vascular segment - reflects the appearance of hippuran in renal vessels.

Excretory segment - displays the isotope together with the urine. When analyzing the image, it should be taken into account that the time to reach the highest level of the curve in the normal state is three to four minutes, the half-life, that is, when the curve is half-reduced, is 10 to 12 minutes. In addition, the difference between the curves for specific indicators between the two kidneys should not be more than 20%.

Time of maximum rise of the curve indicates the rate of secretion in the kidney - they can be normal or too slow. The half-life period of the hippuran from the body is correlated with the value of the length of time during which the amplitude of the height of the curve decreases exactly by half as compared to the maximum height. This indicator indicates the rate of secretion of hippuran in the kidneys, the state of the processes of urinary diversion.

The blood purification curve indicates the total state of the absorptive-excretory function of the kidneys.

Too slow purification of blood from the radioactive substance introduced to it is considered a sign of the patient's kidney failure. Simultaneously, the high sensitivity of the method makes it possible to establish not only a clinically manifested condition of insufficiency of the function of secretion in the kidneys, but also latent insufficiency, which at the time of the survey and earlier did not manifest itself in any way.

For the correct interpretation of the blood purification blood will need to calculate the percentage of the amplitude of the curve at the point on the sixteenth minute of the survey and the amplitude of the curve at the point on the fourth minute of the survey. With normal and unchanged total excretory function in the kidneys, this ratio is not more than 50%.In the opposite situation, blood purification is considered too slow, which is associated with the manifestation of kidney failure.

This is important!

With full thrombosis, occlusion of the artery of the kidney, the functional type of the curve manifests itself, which is characterized by a sharp decrease in the magnitude of the segment of the vessels with simultaneous complete absence of secretory rise in the curve and its decline into the excretory phase.

This diagnostic method is considered the most objective, safe and inexpensive, helping to establish the quality of the kidneys and upper urinary tract.

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