CRP and hydronephrosis: Examples involve ureteral density in non-contrast computed tomography (NCCT) [8], ureteral wall thickness (UWT), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) [2], grade of hydronephrosis [9], age, stone position [10], and the ratio of CT attenuation value of the ureter above to below stones [11].