Sensitivity, specificity, PPV, and NPV of US and US + CEUS, CT, MRI and PET/CT. (A) Sensitivity of US and US + CEUS, CT, MRI, and PET/CT; (B) specificity of US and US + CEUS, CT, MRI, and PET/CT; (C) PPV of US and US + CEUS, CT, MRI, and PET/CT; (D) NPV of US and US + CEUS, CT, MRI, and PET/CT. PPV, positive predictive value; NPV, negative predictive value; US, ultrasound; CEUS, contrast-enhanced ultrasound; CT, computed tomography; MRI, magnetic resonance imaging; PET, positron emission tomography; XGC, xanthogranulomatous cholecystitis.