Statistical analysis
The Pearson Chi-squared test (χ2) was used to compare radiological and pathological stages. The concordance between the radiological and pathological stages was evaluated by using the к statistic, which is a measure of agreement between observers that corrects for chance agreement. The grade of concordance has been defined as ‘fair’, for a of 0–0.2, moderate for 0.21–0.45, substantial for 0.46–0.75 and almost perfect for 0.76–0.99 [9]. Statistical analysis was performed using SPSS software package version 22.0 (Statistical Package for Social ScienceTM, Chicago, IL, USA) and p < 0.05 was considered to indicate statistical significance.