Diagnostic accuracy of imaging modalities in differentiating xanthogranulomatous cholecystitis from gallbladder cancer

Background: The aim of this study was to assess the diagnostic performance of radiological imaging in differentiating xanthogranulomatous cholecystitis (XGC) from gallbladder cancer (GBC). Methods: A retrospective analysis of the radiological imaging performed in patients who had pathologically confirmed XGC or GBC between December 2004 to April 2016 was performed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging modality, and combined imaging modalities were calculated. Results: A total of 218 patients (XGC = 109, GBC = 109) were identified; 19 patients received all of abdominal ultrasound (US), contrast-enhanced ultrasound (CEUS), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET/CT); 21 received four of these imaging examination types; 45 received three examinations; 58 received two examinations; and 75 received only one examination. The sensitivity and specificity of CEUS was 90% and 93%, respectively, higher than abdominal US (80%, 86%), CT (71%, 92%), MRI (75%, 90%), and PET/CT (55%, 90%) (all values respective). The sensitivity, specificity, NPV, and PPV of the US combined with CEUS were 91%, 90%, 94%, and 85%, respectively. Although the specificity of CEUS + CT and CEUS + MRI were 100% and 92%, respectively, the sensitivity of CEUS + CT and CEUS + MRI were both only 67%. Conclusions: The Abdominal US is not sufficiently accurate to confidently guide clinical practice, and CEUS showed better diagnostic performance than the other imaging modalities in differentiating XGC from GBC. The combination of abdominal CEUS and CT is helpful for differential diagnosis, as it indicates GBC with better specificity and PPV.