Kidney X-ray

It is difficult to imagine a modern urological clinic without radiation studies. In fact, it is thanks to them that urology has become one of the most precise medical disciplines. This is not surprising, since radiation methods allow the doctor to study in detail both the morphology and function of the excretory organs and detect pathological changes in them at early stages of development.

Indications for radiological examinations are very broad. They are prescribed to every patient who is suspected of having damage or disease of the kidneys, ureters, bladder, prostate gland. The appointment is made by the attending physician.

The head of the radiation department or a physician who specializes in radiation diagnostics selects the methods of examination and the sequence of their application. Qualified urologists, as a rule, are well trained in radiation diagnostics of damage and diseases of the kidneys and urinary tract and can, in contact with the radiologist, establish the order and volume of radiation examinations themselves.

Methods of radiological examination of the urinary system

General radiograph of the abdominal area. Many urological patients undergo a general radiograph of the kidneys and urinary tract at the first stage of the examination or after sonography. For this, the patient must be prepared - cleanse the intestines the night before and in the morning on the day of the examination. The patient must come to the X-ray room on an empty stomach. The exception is patients with acute renal colic: they must be examined without cleansing the intestines. The patient is placed on his back and the image is taken on a large film so that both kidneys, large lumbar muscles and the pelvis up to the level of the pubic symphysis are displayed on it.

The kidneys are not always visible on the general radiograph, approximately in 60-70% of those examined. Normally, they look like two bean-shaped shadows located at the level of ThXII-LII on the left and LI-LII on the right. Thus, the left kidney is located slightly higher than the right one. The upper poles of the kidneys are normally located closer to the midline of the body than the lower ones. The outlines of the kidneys are normally clear, their shadow is uniform. An individual variant is an arcuate bulge of the outer contour (the so-called humpbacked kidney). The ureters are not visible on the general radiograph of the abdominal cavity. The urinary bladder filled with urine can cause an oval or round shadow in the small pelvis. The normal prostate gland does not give a shadow on the images. The main purpose of general radiography is to detect stones, calcifications and gas.

Intravenous urography. This is one of the main X-ray examinations performed on patients with urinary system lesions. Intravenous urography is based on the physiological ability of the kidneys to capture iodinated organic compounds from the blood, concentrate them and excrete them with urine. During conventional urography, the patient on an empty stomach after preliminary bowel cleansing and emptying of the bladder is intravenously injected with 20-60 ml of one of the urotropic contrast agents - ionic or, more preferably, non-ionic.

Intravenous urography

Direct pyelography. Excretory urography in most cases provides for the study of the renal pelvis and calyces. However, in some patients, especially with weak excretion of the contrast agent, if it is necessary to examine the calyces and pelvis in detail, direct contrast of the upper urinary tract must be performed. It is performed retrogradely, through a catheter inserted in the ureter (retrograde pyelography), or antegradely, through a needle or nephrostomy tube (antegrade pyelography). The resulting radiographs clearly show all the details of the structure of the calyces and pelvis, and minor changes in their contours and shape can be detected. The limited use of direct pyelography is associated with the need for catheterization of the urinary tract and the risk of infection. This study is contraindicated in acute inflammatory processes in the kidneys and urinary tract, as well as in macrohematuria.

Renal angiography. A distinction is made between general and selective renal arteriography. In the first case, a catheter is inserted from the femoral artery into the abdominal aorta and its end is positioned above the origin of the renal arteries. If catheterization of the aorta through the femoral artery is impossible due to occlusive disease of the aortoiliac-femoral segment, translumbar puncture of the aorta with a lumbar puncture is used. Through a puncture needle or catheter, using a special injector, 40-60 ml of a water-soluble contrast agent is injected under pressure into the lumen of the aorta and a series of X-rays are taken.

A series of radiographs first shows an image of the aorta and its large branches, including the renal arteries (early arterial phase), then the shadow of small intraorgan arteries (late arterial phase), then a general increase in the intensity of the renal shadow (nephrographic phase), a weak shadow of the renal veins (venogram) and, finally, an image of the calyces and pelvis, since the contrast agent is excreted in the urine.

The renal arteries branch off from the aorta at almost a right angle at the level of L, or the disc between it and LV. The diameter of the trunk portion of the renal artery is 1/3 - 1/4 of the aorta cross-section at this level, the length of the right artery is 5-7 cm, and the left - 3-6 cm. The contours of the arteries are smooth, their shadow is uniform and intense. A more detailed study of the renal vessels is possible with their selective contrasting. A catheter is inserted directly into the renal artery and a contrast agent is injected through it under pressure. All the above-mentioned phases of renal contrasting are recorded on arteriograms. If necessary, targeted radiographs are performed. Renal arteriography is performed if renovascular hypertension (atherosclerosis, renal artery arteritis) is suspected and when planning operations for an abnormal kidney. Arteriography is also performed as the first stage in intravascular interventions, such as balloon dilation, embolization, and stent placement. As with other types of angiography, the technique of digital subtraction angiography (DSA) is preferred for contrast examination of the renal vessels. In order to perform selective venography, a catheter is inserted into the renal vein from the inferior vena cava.

Computer tomography. CT has significantly expanded the scope of morphological examination of the kidneys, bladder and prostate gland. Kidney examination is performed without special preparation in people of any age. On tomograms, a normal kidney has the shape of an irregular oval with smooth and sharp outlines. In the anteromedial part of this oval at the LI-LII level, the renal sinus is visible. At the same level, the renal arteries and veins are visible. To improve visualization of the renal parenchyma and differential diagnosis of volumetric lesions, a special CT is performed.

Currently, CT is the most informative method for identifying and differentially diagnosing volumetric processes in the kidney.

It is used to determine the stage of malignant kidney tumors. The method is highly accurate in diagnosing stones (including X-ray negative ones), parenchymal calcifications and pathological formations, in recognizing perirenal, periureteral and pelvic processes. CT is also effective in recognizing traumatic kidney injuries. Three-dimensional reconstruction on a spiral CT scanner provides the urologist and X-ray surgeon with a demonstrative picture of the renal vessels. Finally, CT is the main method of visualizing the adrenal glands and diagnosing their pathological conditions - tumors, hyperplasia.

Magnetic resonance imaging. Unlike CT, this method allows obtaining layered images of the kidneys in various projections: sagittal, frontal, axial. The image of the kidneys resembles that on CT, but the boundary between the cortex and medulla of the organ is better seen. The calyces and pelvises containing urine are distinguished as low-density formations. When a paramagnetic contrast agent is introduced, the intensity of the parenchyma image increases significantly, which facilitates the detection of tumor nodes. MRI clearly shows the urinary bladder, including its parts such as the bottom and upper wall, which are poorly distinguishable on CT. The capsule and parenchyma are determined in the prostate gland. The latter is normally distinguished by its homogeneity. Near the gland, in the retrovesical tissue, denser formations can be seen - the seminal vesicles.

Radionuclide examination of the kidneys. Radionuclide methods have become firmly established in the practice of urological and nephrological clinics. They allow detecting kidney dysfunctions at early stages, which is difficult to do using other methods. Clinicians are attracted by the physiological nature of the radioindication method, its relative simplicity and the possibility of conducting repeated studies during the patient's treatment. It is also important that radionuclide compounds can be used in patients with increased sensitivity to radiocontrast agents. Depending on the objectives of the study, one of the radionuclide indicators is selected from the group of nephrotropic RFPs.

Radionuclide study of the kidneys

Radiometric determination of residual urine volume. In a number of diseases, especially often when there is an obstruction to the outflow of urine from the bladder, some urine remains in the bladder after urination, which is called residual urine. A simple way to measure it is a radionuclide study. 1 1/2-2 hours after intravenous administration of the radiopharmaceutical, excreted by the kidneys, the radiation intensity above the bladder is measured. After the patient has emptied the bladder, the volume of urine excreted is determined and the radiation intensity above the bladder is measured again.