European Journal of Cardiovascular Medicine

Background: Sonography has been considered an excellent diagnostic imaging technique for the detection of both opaque and nonopaque renal calculi. The sonographic diagnosis of a calculus is usually based on the demonstration of a highly echogenic focus with an associated acoustic shadow. To compare the detection of urinary stones using standard gray scale ultrasound for diagnostic accuracy using the color Doppler “twinkling sign”. Material and methods: In our study 90 consecutive patients with various abdominal pathologies (not directly linked to renal lithiasis) were included in our study. All patients then underwent US at our department. Color Doppler US was performed using a red-and-blue color map and power Doppler US using a pink color map with a standardized Doppler protocol to detect the twinkling artifact. For color Doppler, gain was set to the point just below the threshold for color noise and the pulse repetition frequency (= velocity scale) was set to 64 cm/sec to eliminate color flow signals from renal blood flow. The color window size was adjusted to cover the whole renal sinus. Doppler imaging began with continuous sweeps of the renal sinus in the longitudinal and transverse planes. Result: On abdominal CT scans, 81 selected patients showed 90 renal lithiasis equal to or smaller than 5 mm. The diameter of renal lithiasis ranged from 2.6 to 5.0 mm (average diameter 4.1 mm). Out of 90 CT positive lithiasis, 50 (55.6%) were absolutely positive on gray-scale. Out of the 50 lithiasis, 14 were hyperechogenic foci with posterior shadow cone, but with a slight echogenicity difference, 50 showed both posterior shadow cone and a marked echogenicity difference, and 24 showed a marked echogenicity difference without posterior shadow cone. So, the posterior shadow cone appeared 40 out of 50 times, while marked echogenicity difference was detected 84 times. Conclusion: The stone size obtained by US was almost the same as that detected by NCCT; however, US is a limited imaging modality in detecting urinary tract stone, especially when used by an inexperienced radiologist, and in the case of smaller stone size, increased weight, and low grade of hydronephrosis.