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)