Assessment of differential renal function in unilateral hydronephrosis by unit area formula aganist classic method in Tc-99m DMSA scintigraphy before and after intervention

Relative kidney function of an affected kidney sometimes may be found exaggerated by Tc-99m DMSA scintigraphy in unilateral hydronephrosis. What is being aimed in this survey is to compare the effectiveness of both methods; rational kidney functions measured by classical method and rational kidney function measured by unit area in unilateral hydronephrosis with Tc99m DMSA scintigraphies before and approximately three to six months after surgical intervention.For his purpose 20 patients (12 male, 8 female; mean: 42,6 ± 18,5) who were treated due to unilateral hydronephrosis were included to the survey. Patients were evaluated by physical examination, laboratory tests and ultrasonography than Tc99m DMSA scintigraphy images were obtained before and after the surgical interventions. Relative kidney functions obtained by unit area method which is obtained by ratio of the counts in region of interest of the kidney and area of the kidney as pixel and by classical method in hydronephrotic kidney in preoperative and postoperative period. In hydronephrotic kidney pre-treatment unit area method with the classical method and after treatment the conventional technique with unit area method were compared with Pearson corelation and Bland-Altman analysis methods.As a result, in our study in determination of rational kidney function classical method and unit area method found to have significant positive correlation (94%) in preoperative period however the agreement between methods were low (mean: 2.3±1.96 SD:5.2). In postoperative period there was significant approximately 100% corelation between methods and additionally there were agreement (mean: 0.53±1.96 SD:2.3) between classical and unit area methods in determination of rational kidney function. In this study it was been shown there is a high error ratio that might influence the surgery decision in rational kidney function estimation by classical method in the kidney with hydronephrosis. Classical method is not a reliable method and estimation of rational kidney functions by unit area method must be preferred in hyronephrotic kidney.Keywords: Hydronephrosis, DMSA, scintigraphy, unit area.