Nephrocalcinosis in premature infants: variability in ultrasound detection.

Objective: To measure variability among radiologists in the ultrasound diagnosis of nephrocalcinosis in premature infants.

Methodology: In this prospective multicenter study, renal ultrasounds were performed on 54 very low birth weight infants using a 5.0- and 7.5-MHz transducer, and these ultrasounds were read independently by three radiologists. kappa coefficients were calculated to assess variability in identification of nephrocalcinosis among the radiologists.

Results: The kappa coefficient (+/- confidence intervals) using a 5.0-MHz transducer was 0.143 (0.108, 0.178); using the 7.5-MHz transducer, the kappa coefficient was 0.268 (0.243, 0.293). All three radiologists agreed in their identification of nephrocalcinosis on 3 of 54 ultrasounds using a 5.0-MHz transducer; a total of 6 of 54 ultrasounds obtained using a 7.5-MHz transducer were read as positive by all three radiologists.

Conclusion: There is significant variability among radiologists in the ultrasound identification of nephrocalcinosis in premature infants; a 7.5-MHz ultrasound transducer is associated with less variability in recognizing this lesion.