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Radiation diagnostic methods in nephrology
Last reviewed: 04.07.2025
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Radiation, or visualization, methods of examination occupy an important place in diagnostics and differential diagnostics of kidney diseases. Their role has increased especially in recent years due to technical improvement of methods, which has significantly increased their resolution and safety. Due to the development of radiation diagnostics, ideas about the prevalence of some diseases (for example, ischemic kidney disease) and their role in the development of terminal renal failure have changed. Modern visualization methods of examination allow not only to obtain an idea of the structural features of the kidneys and urinary tract, pathomorphological changes in them, but also to evaluate renal blood flow, filtration function, tubular transport, urodynamics. Visualization of the kidneys 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 image acquisition, visualization research methods can be divided into:
- ultrasound (ultrasound examination of the kidneys and urinary tract, ultrasound Doppler imaging of the vessels of the kidneys and urinary tract);
- X-ray (survey radiography of the urinary system, excretory urography, CT);
- magnetic resonance (MRI);
- radioisotope (renography, dynamic renal scintigraphy).
The introduction of contrast agents and digital image processing was a revolutionary change that significantly expanded the possibilities of kidney imaging. Currently, the improvement of contrast agents is continuing in order to increase their safety. Contrast agents are now used not only in X-ray diagnostics, but also in magnetic resonance imaging (MRI), ultrasound dopplerography of the kidneys.
Digital image conversion with subsequent creation of a three-dimensional image of an organ is used not only in CT and MRI, but also in ultrasound, radioisotope research (single-photon emission computed tomography). Image digitization allows secondary analysis using special filters that increase contrast, allows archiving a large amount of information for the purpose of repeated analysis, assessment of the dynamics of changes, and instantaneous transmission over long distances for consultation. Invasive modifications of ultrasound and ultrasound dopplerography are increasingly used, allowing, by bringing the radiation source and sensor closer to the object of study, to obtain images with high resolution and minimal interference.
In addition to improving image quality, another area of improvement in radiation diagnostics is the expansion of the possibilities for studying organ function, including the characteristics of tissue metabolism. New modifications of MRI and radioisotope research (positron emission tomography) have this capability.
Although diagnostics using imaging methods are primarily performed by representatives of a special medical specialty - radiology (radiology), a nephrologist must have basic skills that allow interpreting kidney images obtained using different methods, have a good understanding of the advantages, disadvantages and limitations of each of them, since it is his task to determine the indications for the use of certain methods, compare their results with the data of the anamnesis, medical examination, laboratory tests, and make a final diagnosis. Joint conferences and discussions of the most difficult diagnostic cases with the participation of nephrologists and radiologists are very useful.
In nephrology, the scope of application of radiation methods is very wide: it is not limited to the study of the kidneys. Thus, they can be used to diagnose tumors of various localizations, tuberculosis of the lungs and bones in case of suspected paraneoplastic or paraspecific nature of kidney disease, to examine joints and the heart in systemic diseases of connective tissue with kidney damage, etc. In patients with chronic renal failure, radiation and other instrumental methods of examination play an important role in the diagnosis of cardiovascular complications and vascular access problems. This chapter is devoted to visualization of the kidneys and the capabilities of various radiation methods in the diagnosis of their diseases.
Changes in the kidneys, according to radiological diagnostic methods
The picture of kidney damage in various diseases has its own characteristics that need to be known and taken into account in diagnostics. However, the specificity of changes in the kidneys detected using radiation diagnostic methods is usually low, and the diagnosis can be made taking into account complaints, anamnesis, physical examination, laboratory and instrumental tests. As nephrosclerosis increases, the peculiarity of structural changes inherent in a particular nosology disappears, therefore, when examining a patient with severe chronic renal failure, in many cases it is difficult to establish its cause.
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Complications and safety
The safety and tolerability of radiation methods for examining the kidneys are determined by the following factors:
- harmful effects of radiation;
- toxicity of contrast and radiopharmaceutical drugs;
- the risk of complications associated with the invasiveness of diagnostic procedures.
In addition, it is necessary to take into account psychological aspects (radiophobia; claustrophobia during CT and MRI).
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