Figure 1
From: US detection of renal and ureteral calculi in patients with suspected renal colic
![Figure 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2F2036-7902-5-S1-S3/MediaObjects/13089_2013_Article_59_Fig1_HTML.jpg)
Gray-scale sonogram shows hyperechoic spot with posterior acoustic shadowing. Color Doppler sonogram shows a twinkling sign. A small renal stone. Unenhanced CT confirms the presence of renal stone.