Purpose: To compare the effectiveness of B-Mode and color-Doppler ultrasound imaging features, including "twinkling-artifact" with unenhanced CT for detecting millimetrical nephrolithiasis.
Methods: 397 patients were examined for suspected urolithiasis with US and CT were included. US findings such as echogenic focuses, posterior acoustic shadowing and twinkling artifact were examined for their ability to detect millimetricalcalculies (greatest diameter ≤5 mm) using CT findings as the gold-standard. The accuracy of US for measuring stone size was also investigated.
Results: 219 millimetriccalculies in 164 cases were detected by CT. The sensitivity and positive-predictive-values for the detection of microcalculies were 76.7 and 94.9 %, 85.8 and 88.3 %, 40.6 and 97.8 %, 68.9 and 94.4 %, and 38.4 and 97.7 % for the presence of B-Mode echogenity, twinkling-artifact, B-Mode echogenity with acoustic shadowing, B-Mode echogenity with twinkling-artifact, B-Mode echogenity with acoustic shadowing and twinkling-artifact, respectively. No significant difference between US and CT was observed in quantification of nephrolithiasis sizes (p = 913).
Conclusion: Twinkling-artifact based color-Doppler US is preferable for the sensitive detection of millimetrical nephrolithiasis; however, the high false-positive value of this technique, which can lead to an overestimation of the stone number, has to be considered.
Keywords: Nephrolithiasis; Twinkling artifact; Ultrasound; Unenhanced computed tomography.