Value of color Doppler ultrasound in preoperative typing diagnosis of acute appendicitis

Figure 1 Receiver operating characteristic curves. A: Receiver operating characteristic (ROC) curves of individual ultrasound parameters for diagnosing suppurative appendicitis. Appendix maximum diameter demonstrated the highest diagnostic performance [area under the curve (AUC) = 0.876], with an optimal cut-off value of 9.8 mm, sensitivity of 85.2%, and specificity of 81.7%; followed by appendix wall thickness (AUC = 0.852, cut-off 3.2 mm) and blood flow signal grade (AUC = 0.823, cut-off grade III). Peri-appendiceal fluid showed relatively lower diagnostic performance (AUC = 0.732). The dashed line represents the reference line (AUC = 0.5); B: Comparison of ROC curves between the combined diagnostic model and single ultrasound parameters for diagnosing suppurative appendicitis (n = 328). The combined diagnostic model demonstrated significantly superior diagnostic performance (AUC = 0.924) compared to individual parameters, including appendix maximum diameter (AUC = 0.876), appendix wall thickness (AUC = 0.852), and blood flow signal grade (AUC = 0.823; all P = 0.001). At the optimal cut-off value of 0.52, the combined model achieved a sensitivity of 91.5%, specificity of 87.6%, and overall accuracy of 89.3%. The dashed line represents the reference line (AUC = 0.5). ROC: Receiver operating characteristic; AUC: Area under the curve.