Associated ultrasound findings improve the accuracy of twinkling artifacts in kidney stone diagnosis

Abstract

Background: Twinkling artifact (TA) in color Doppler ultrasound is commonly used as a sign of kidney tract stone detection but the accuracy is limited as compared with unenhanced computed tomography (CT). Objective: Define the associated ultrasound findings that may improve the accuracy of TA compared with CT for diagnosing kidney stones. Materials and Methods: Prospective study was conducted on 128 TAs in patients sent for unenhanced CT KUB and performed color Doppler ultrasound on the same day. TA sizes and associated sonographic signs were recorded and analyzed with receiver operating characteristic curves (ROCs). The diagnostic reference was the CT scan. Results: There was a total of 128 TAs with the size of 3.95 mm (2.7-6 mm). Only 30 TAs showed as kidney stones in CT. The sizes of kidney stones in CT were 5.4 mm (3.4-6.4 mm) which represented a significant difference in TA size (P = 0.002). ROC curve analysis showed that 5 mm would be the optimal size of TA for kidney stone predictions. Other significant signs for improved diagnosis include echoic foci (P = 0.039), posterior shadows (P = 0.001), long TA tails (P = 0.001) and 2nd approach TA (P = 0.001). Then a predictive AT model was created to predict kidney stones, which moderately improved diagnosis accuracy for kidney stones with good agreement. Conclusion: The combination of TA and other sonographic signs are moderately associated with kidney stone diagnosis including TA size (> 5 mm), posterior acoustic shadow, long TA tail, junctional line location and focal Caliectasis.