ARRS 2022 Abstracts

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E1205. Reliability of Twinkle Artifact in Accurately Detecting Renal Calculi
Authors
  1. Kevin Neville; Lahey Hospital and Medical Center
  2. Sarah Ali; Lahey Hospital and Medical Center
  3. Zakariah Sekkal; Lahey Hospital and Medical Center
  4. Christoph Wald; Lahey Hospital and Medical Center
  5. Karen Reuter; Lahey Hospital and Medical Center
Objective:
Radiologists and clinicians alike commonly associate twinkling artifact on renal ultrasound with nephrolithiasis. Previous studies have compared the presence of twinkle artifact on ultrasound with findings of calculi on CT obtained following ultrasound. It has been suggested that there is a high false positive rate for twinkle artifact. Moreover, previous results suggest that the presence of twinkle artifact may rather be more indicative of the presence of calculi somewhere within the kidney, rather than at a specific focus of twinkle artifact.¹ The purpose of this study was to retrospectively correlate twinkle artifact with calculi seen on CT.

Materials and Methods:
Cases between April 2015 and November 2020 that had an ultrasound report mentioning twinkle artifact and had a CT within a 1 week after the ultrasound were included in the study. Each case was then retrospectively reviewed by three radiologists independently. The number and location of twinkle artifacts were documented as well as any calculi visualized on CT. Results were then analyzed to determine which foci of twinkle had a matching corresponding calculus in the same location on CT. Cases between the same 5 year period that had a CT within a 2 weeks after the ultrasound were then analyzed to determine whether the mention of twinkle artifact in an ultrasound report corresponded to having calculi anywhere in the kidney on CT.

Results:
Within a 5 year period, a total of 107 patients were found to have an ultrasound and CT within a 1-week period. Of the 151 foci of twinkle artifacts seen on ultrasound, there was a matching calculus on the CT correlate in 96 instances. The true positive rate of twinkle artifact on renal ultrasound was 64%, and the false positive rate was 36%. Of those who had an ultrasound and CT within a 2-week period, twinkle artifact was mentioned in 342 reports. Correlation with CT found 268 cases had calculi somewhere in the kidney, while 74 had no evidence of calculi. The positive predictive value for calculi anywhere in the kidney was found to be 78%.

Conclusion:
Twinkle artifact has historically been associated with nephrolithiasis, but recent studies suggest that there may only be a limited association. Our study found that the true positive rate of twinkle artifact on renal ultrasound was 64%, and the positive predictive value for calculi anywhere in the kidney was 78%. This suggests that the presence of twinkle artifact may rather be more indicative of the presence of calculi somewhere within the kidney, rather than at a specific location.