THE DIAGNOSTIC VALUE OF THE ACOUSTIC SHADOW OF THE RENAL STONES: MULTIDEDECTOR CT AS A REFERENCE STANDARD

Introduction: In this study, we aimed to investigate the relationships between sonographic acoustic shadow

and density and, size of renal calculi with multidetector CT as the reference standard.

Materials and Methods: Fifty patients with suspected renal stone disease were prospectively examined.

Two staff radiologists performed real time sonography and were blinded to each other and two other

radiologists evaluated the CT images. For both imaging modality diagnosis of nephrolithiasis were made by

certain criteria. Cohen’s Kappa test was used to assess interobserver variability. Spearman’s rho analysis and

chi-square tests were used to assess the relationship between the density and size of the renal stones on noncontrast

CT and acoustic shadow on US examination.

Results: Eighty seven renal stones were identified in 36 (72%) of all patients on non-contrast CT. Of the

87 stones, the first radiologist diagnosed only 36 stones (41.3%), whereas the second radiologist diagnosed 41

(47.1) stones on US. Strong correlation was found between the density and size of the renal stones on noncontrast

CT images (p<0.001). Stones larger than 3 mm in diameter and denser than 300 HU on non-contrast

CT had acoustic shadows on US examination.

Conclusion: This study found a strong correlation between presence of acoustic shadow on US

examination and, size and density of renal stones on non-contrast CT examination.