Accuracy of sonography for detecting renal stone: comparison with CT

Abstract

Purpose: To determine the diagnostic accuracy values of sonography in the detection of renal stones using noncontrast CT as the gold standard. In addition, we correlated the accuracy of sonography with stone size, the kidney affected (right versus left), and body mass index (BMI).

Methods: Fifty patients underwent 2 separate sonographic examinations performed by 2 radiologists. CT scans were evaluated by another 2 radiologists, and the diagnosis was made by consensus. We compared the sonograms and CT scans and the sonographic detection of stones in the left and right kidneys. All sonographic findings were correlated with the BMI groups.

Results: The sensitivity of sonography for any stone in a patient was 52-57% for the right kidney (radiologist 1 and 2) and 32-39% for the left kidney (radiologist 1 and 2). The overall accuracy of sonography in detecting a stone in the right kidney by radiologists 1 and 2 was 67% and 77%, respectively. The corresponding accuracy values for the left kidney were 53% and 54%, respectively.

Conclusion: Sonography is of limited value for detecting renal stones. The sonographic detection of a renal stone is dependent on the side of the kidney involved but is independent of BMI.