asked to: (1) identify the ones that corresponded to CHDs; (2) describe the findings; and (3) provide the possible diagnosis. Each center disclosed the diagnosis of volume data sets only during the analysis phase of the study.
Inclusion criteria were: (1) signed Institutional Review Board–approved consent forms; (2) gestational ages at ultrasonographic examination between 18 and 26 weeks; and (3) volume data sets should have been obtained with the STIC technique using either B mode or color Doppler ultrasonography. Only 1 volume data set per case was included in the study.
Diagnostic indices of 4DUS in the identification of CHDs were calculated, including sensitivity, specificity, positive and negative predictive values, and false-positive and -negative rates. Intercenter agreement was determined using a generalized k statistic for multiple raters developed by Jason King, PhD, and colleagues (available online at http://www.ccitonline.org/jking/homepage/interrater.html) as well as by comparing the receiver operating characteristic curves for the identification of CHDs. The statistical packages used were SPSS v