Unenhanced computed tomography findings of renal papillae in patients with a ureteral stone

In some patients with a ureteral stone without uretero-hydronephrosis, it is difficult to determine the location of the stone. The objective of the present study was to investigate the changes in renal papillae using unenhanced computerized tomography (uCT) and determine the side of calculi using the renal papillary findings in patients with a ureteral stone.

uCT data from 81 patients were retrospectively reviewed for this study. The inclusion criteria were unilateral ureteral calculi, no renal calculi and no hydronephrosis. For each patient, three measurements of CT attenuation of 0.05 cm2 area were made in the tip of the interested renal papillae, both stone side and non-stone side. Student's t test was used for statistical analysis.

Forty-one right-sided and 40 left- sided isolated unilateral ureteral calculi patients were evaluated by uCT exam. The average attenuations of the tip of the papillae in stone side and non-stone side were 34.1 Hounsfield units (HU) and 30.6 HU, respectively. There was a statistically significant difference between stone and non-stone sides (p< 0.05).

During routine practical uCT applications, it can be difficult to distinguish phleboliths, ureteral stone or the existence of non-opaque ureteral stone, so papillae density measurements can be a practical method to identify the existence of ureter stone and its location (side).