The DE-CT was interpreted by a radiologist blinded to the clinical outcome, and the attending physicians of the patients were blinded to the interpretation of the DE-CT. DE-CT parameters were then compared between patients who underwent surgery and those who did not. Receiver operating characteristic (ROC) curve analysis was used to find the optimal cut off point to distinguish between patients which did or did not eventually underwent surgery. Based on the cut off points found from the ROC analysis, the negative and positive predictive values were calculated.