Scintigraphic signs of kidney injuries of I–IV degrees of severity and their compliance with the OIS/OI AAST classification: observational study

Abstract

INTRODUCTION: Mechanical effects on the kidney result in parenchymal disruption, haemorrhage formation, classified by OIS/OI AAST. Scintigraphy with 99 Tc-DMSA can determine the presence, prevalence of areas of ischaemia and implications for renal function. OBJECTIVE : By radiopharmaceutical accumulation, to assess the function of the injured kidney and to establish the consistency of the scintigraphic images with the radiological findings of the OIS/OI AAST classification. MATERIAL AND METHODS : Scintigraphy with 99 Tc-DMSA was performed in the immediate posttraumatic period in 196 patients who had Grade I–IV organ damage according to the OIS/OI AAST classification. The shape, size, and contours of the kidneys were visually evaluated. Based on the calculation of the uniformity and intensity of the indicator inclusion in the parenchyma the relative (total) kidney function was established. The degree and localisation of kidney damage were revealed on the basis of primary ultrasound and MSCT results. RESULTS : In the acute period of injury, Grade I–II were characterised by diffuse irregular distribution of 99 Tc-DMSA (from 75.0 to 100% of cases), but with increasing area and volume of injury, focal scintigraphic symptoms appeared (up to 25.0% of cases).In Grade III–IV, localised or extended focal deformation of the image contour and reduction of the overall kidney function prevailed. Comparative evaluation of CT findings with visual scintigraphy data demonstrated symmetry of visual information with sufficient accessibility, perceptibility, accuracy and correlated with OIS/OI AAST classification. DISCUSSION: Scintigram interpretation involves the interaction of two components: visual perception and subject-specific knowledge of human anatomical structures. This significantly differentiates it from clinicians’ conventional conception of the diagnostic process. Semiotics in the images included diffuse and focal changes, the basis of which is a disorder of haemocirculation with impaired uptake of radiopharmaceutical in the kidney parenchyma. For Grade I–II, hypoactive areas indicating the absence of significant damage are typical. Grade III–IV are characterised by localised areas due to reduced volume of functioning parenchyma. CONCLUSION: Scintigraphy in blunt kidney trauma demonstrates haemocirculatory abnormalities in the organ and a decrease in the amount of functioning parenchyma. Comparison of radionuclide images with computer imaging has a high degree of identity. The type of scintigrams allows grading them according to the OIS/OI AAST degree systematisation, which standardises the interpretation of radiological findings to improve the objectivity and quality of the study reports. Assessment of overall renal function makes it possible to predict the rehabilitative outlook of the injured kidney and the need for correction.