The DWI statistical analysis
The inter-observer variability between the wo radiologists was evaluated using inter-rater agreement (Kappa coefficient). As described,(16) the results were interpreted as follows: values ≤0 indicate no agreement; 0.01–0.20 indicate none to slight agreement, 0.21–0.40 = fair agreement, 0.41–0.60 = moderate, 0.61–0.80 = substantial, and 0.81–1.00 = almost perfect agreement.(17) The ADC values of the parathyroid lesions, thyroid glands, and cervical lymph nodes were analyzed using the Friedman test with Bonferroni correction, and the scores of structure identification and geometric distortion on SS-EPI and RS-EPI were compared using the median test. In both tests, p-values <0.05 were accepted as significant. All statistical analyses were performed with EZR (Saitama Medical Center, Jichi Medical University), which is a graphical user interface for R (The R Foundation for Statistical Computing, Vienna, Austria, ver. 2.13.0).(18)