Featured Videos

TAIPEI, TAIWAN (UroToday.com) - Introduction and Objectives: Ultrasound images of kidney stones display a bright stone with a distal shadow. We hypothesize the width of the shadow is a more accurate predictor of true stone size than width of the stone image.

wceMethods: Forty five calcium oxalate monohydrate kidney stones ranging from 1–10mm were imaged in a water bath. The width of the stone and the shadow was measured at depths of 6, 10, and 14 cm. A linear mixed-effect model was used to compare measurements of shadow width and depth versus true stone size. Subgroup analysis was performed to determine the percentage of stones that were over-classified as greater than 5mm when true stone size was less than 5 mm.

Results: Measurement of stone width compared to true stone size resulted in mean overestimation at 0.9 +/- 0.8mm, 1.5 +/- 1.0mm, 2.0 +/- 1.2mm at 6, 10, 14cm depths, respectively. Overestimation of stone width increased with depth (p < 0.001). Measurement of shadow width compared to true stone size resulted in an underestimation of -0.02 +/- 0.4mm, - 0.04 +/- 0.6mm, and - 0.19 +/- 0.8mm at 6, 10, 14cm depths, respectively. The acoustic shadow was a better predictor of true stone size at all depths (p < 0.001). Subgroup analysis demonstrated that over-classification occurred in 17/60 cases (28%) when the stone width was measured and 7/60 cases (12%) when the shadow width was measured.

Conclusions: Stone size was consistently overestimated when directly measuring stone width and worsened with increasing depth. Measuring shadow width significantly reduced overestimation of true stone size.

Source of Funding: This work was supported by NIH DK043881 andDK092197, andNSBRI throughNASANCC 9-58.

Listen to an interview with Ryan Hsi, one of the authors of this study.


Presented by Franklin Lee,1 Barbrina Dunmire,2 Jonathan Harper,1 Ziyue Liu,3 Ryan Hsi,1 Michael Bailey,1, 2 and Mathew Sorensen1 at the 32nd World Congress of Endourology & SWL - September 3 - 7, 2014 - Taipei, Taiwan

1University of Washington Department of Urology, USA
2Applied Physics Laboratory, USA
3Indiana University Department of Biostatistics, USA


Publications focusing on urological cancer treatments through original commentary & articles
Everyday Urology Volume 3 Issue 1

Everyday Urology™ - Oncology Insights

From the Editor

PCAN cover

Prostate Cancer and Prostatic Diseases

From the Editor


Newsletter subscription

Free Daily and Weekly newsletters offered by content of interest

The fields of GU Oncology and Urology are rapidly advancing. Sign up today for articles, videos, conference highlights and abstracts from peer-review publications by disease and condition delivered to your inbox and read on the go.