The role of quantitative gray-scale ultrasound histogram in the differential diagnosis of infected and non-infected hydronephrosis

BACKGROUND: The early detection of infected hydronephrosis is critical before lithotripsy. A feasible and noninvasive diagnostic method is of considerable clinical attention. OBJECTIVES: This retrospective study was performed to find some quantitative evaluation parameters of B-mode Grayscale ultrasound histogram analysis that might assist the early diagnosis of infected hydronephrosis and test their diagnostic efficacy. MATERIALS AND METHODS: The ultrasound images and clinical data of 245 patients with hydronephrosis were retrospectively analyzed. Image J software was applied to obtain the gray-scale maps and the analysis results of the signal strength. The difference in the data between the infected and non-infected groups and the diagnostic value of the parameters were calculated. RESULTS: In this retrospective study, 70 patients with infected hydronephrosis and 175 patients with non-infected hydronephrosis were enrolled. The echogenicity of internal effusion and the echogenicity ratio of infected cases were significantly higher than those of non-infected cases (p < 0.05). The cutoff values were 23.82 (AUC= 0.859) of echogenicity of internal effusion, while 0.27 (AUC= 0.832) of echogenicity ratio. CONCLUSION: The quantitative evaluation of gray-scale ultrasound histogram is an objective and reliable method in differentiating infected from non-infected hydronephrosis.