Mathematical postprocessing analysis of contrast-enhanced computed tomography data of the kidneys in evaluation of split renal function in patients with kidney stone disease

Introduction. An original research work was performed to assess split kidney function by glomerular filtration rate (GFR) with mathematical analysis of the kidneys computed tomography (CT) data in patients with kidney stone disease (KSD). Objective was to evaluate the GFR and the parenchyma structure of each kidney and identify the possible patterns of contrast medium intrarenal transport with mathematical analysis of the kidneys CT data in patients with KSD.Materials and methods. Data of 27 patients of both genders with KSD were retrospectively analyzed. To evaluate GFR separately for each kidney we analyzed the data of contrast-enhanced CT (GFR reference values are 0.55 % of contrast medium per second). Inclusion criteria are as follows: 1) newly diagnosed SKD; 2) stone size ≤1,5-2,0 cm, no obstruction of the urine flow registered; 3) no kidney or upper urinary tract surgical history; 4) age - ≤45 years; 5) no severe chronic diseases. All of these allowed to minimize influence of any other disorders on split renal function except for SKD and conduct per se research.Results. The mathematic analysis of the contrast-enhanced CT data revealed GFR changes in 26 (96.3 %) out of 27 patients. Hyperfiltration was found in 12 (44.4 %) patients: right kidney GFR - 0.6-0.77 %, mean value - 0.65 %; left kidney GFR - 0.59-0.79 %, mean value - 0.67 %. Hypofiltration was found in 13 (48.1 %) patients: right kidney GFR - 0.2-0.54 %, mean value - 0.37 %; left kidney GFR - 0.2-0.53 %, mean value - 0.4 %. The GFR values significantly differed between the groups both for the right (p = 0.000014) and left (p = 0.000045) kidneys. We found no significant age-related difference between the groups (p = 0.895). As well as that no significant differences in Resistance Index both in magistral (right kidney: p = 0.221; left kidney: p = 0.850) and segmental (right kidney: p = 0.306; left kidney: p = 0.957) arteries between the groups with hyperfiltration and hypofiltration were observed. One patient demonstrated no changes in GFR, and the other one had hyperfiltration (0,62 %) in one kidney and hypofiltration (0,48 %) in another.Conclusion. Most of the patients (92.6 %) with SKD demonstrate GFR changes (either hyperfiltration or hypofiltration) that may indicate the disturbed intrarenal blood and urine flow through the kidney.