Radiation, or imaging, research methods occupy an important place in the diagnosis and differential diagnosis of kidney disease. Their role has especially increased in recent years due to the technical improvement of methods, which significantly increased their resolution and safety. Due to the development of radiation diagnostics, ideas about the prevalence of certain diseases (for example, ischemic kidney disease) and their role in the development of terminal renal failure have changed. Modern visualizing research methods allow not only to get an idea about the structural features of the kidneys and urinary tract, pathological changes in them, but also to assess the renal blood flow, filtration function, tubular transport, urodynamics. Renal imaging is of great importance for diagnostic manipulations (kidney biopsy) and surgical interventions on the kidneys, urinary tract, and renal vessels.
In accordance with the physical principle of obtaining images, imaging research methods can be divided into:
- ultrasound (ultrasound of the kidneys and urinary tract, USDG of the vessels of the kidneys and urinary tract);
- X-ray (review radiography of the urinary system, excretory urography, CT);
- magnetic resonance (MRI);
- radioisotope (renography, dynamic renal scintigraphy).
The introduction of contrast media and digital image conversion was a revolutionary change, greatly expanding the possibilities of visualization of the kidneys. At the present time, the improvement of contrast preparations with the aim of increasing their safety continues. Contrast agents are now used not only in X-ray diagnostics, but also in magnetic resonance imaging (MRI), USDG of the kidneys.
Digital transformation of images with the subsequent creation of a three-dimensional image of the organ is used not only for CT and MRI, but also for ultrasound, radioisotope examination (single photon emission computed tomography). Digitizing images allows secondary analysis using special filters that increase contrast, allows you to archive a large amount of information for the purpose of re-analysis, assessment of the dynamics of changes, instantly transmit it over long distances for consultation. Increasingly, invasive modifications of ultrasound and ultrasonic ultrasound are used, which make it possible to obtain images with high resolution and minimal interference due to the approach of the radiation source and the sensor to the object of study.
In addition to improving the quality of the image, another way to improve radiation diagnosis is to expand the possibilities of studying the function of organs, including metabolic features in tissues. New MRI and radioisotope studies (positron emission tomography) have this capability.
Although diagnostics using imaging methods is performed primarily by representatives of a special medical specialty - radiology (radiology), the nephrologist must have basic skills that allow the kidney image obtained using different methods to be interpreted well to represent the strengths, weaknesses and limitations to the use of each because it is his task to determine the indications for the use of certain methods, to compare their results with the data of anamnesis, the doctor Examination, laboratory tests, final diagnosis. Joint conferences, analyzes of the most difficult diagnostic cases involving nephrologists and radiologists are very useful.
In nephrology, the field of application of radiation methods is very wide: it is not limited to the study of the kidneys. So, they can be used to diagnose tumors of various localization, pulmonary and bone tuberculosis in case of suspected paraneoplastic or paraspecific nature of kidney disease, to study joints and the heart in systemic diseases of the connective tissue with kidney damage, etc. In patients with chronic renal failure, radiation and other instrumental methods of research play an important role in the diagnosis of cardiovascular complications and problems of vascular access. This chapter is devoted to visualization of the kidneys and the possibilities of various radiological methods in the diagnosis of their diseases.
Changes in the kidneys, according to radiation diagnostic methods
The picture of kidney damage in various diseases has its own characteristics that must be known and taken into account in the diagnosis. However, the specificity of changes in the kidneys detected using radiation diagnostic methods is usually low, and the diagnosis can be made when taking into account complaints, anamnesis, physical research, laboratory and instrumental tests. As nephrosclerosis increases, the peculiarity of structural changes inherent in a particular nosology disappears, therefore, in examining a patient with severe chronic renal failure, in many cases it is difficult to determine its cause.
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Complications and safety
The safety and tolerability of radiological examinations of the kidneys are determined by the following factors:
- the harmful effects of radiation;
- toxicity of contrast and radiopharmacological drugs;
- the risk of complications associated with invasiveness of diagnostic procedures.
In addition, psychological aspects (radiophobia; claustrophobia during CT and MRI) must be taken into account.