Pasw software version 18

The frequency of each grade in relation to whether or not surgical intervention was performed was assessed with a chi-square test. Kappa (κ) statistics were used to assess inter-reader agreement between the two radiologists for grading of CLSS. The interpretation of the κ values were as follows: poor (κ < 0.1), slight (0.1 ≤ κ ≤ 0.2), fair (0.2 < κ ≤ 0.4), moderate (0.4 < κ ≤ 0.6), substantial (0.6 < κ ≤ 0.8), and almost perfect (0.8 < κ ≤ 1) (4 (link)). Correlation coefficients (r_s) between the grade and operation were acquired with nonparametric correlation analysis (Spearman rank correlation). For analyses of the relationships between MR findings and characteristics of the study group, the association of MRI grades and operations was evaluated in relation to age (≥ 57 years and < 57 years) (3 (link)). Here, we used reference age as 57 years old because Park et al. (3 (link)) reported their study results on the correlation of the grades and neurologic manifestation based on this age originally and we wanted to compare our result to those data. An r_s between 0.1 and 0.3 mean weak correlation; between 0.3 and 0.7, moderate correlation; between 0.7 and 0.9, relatively high correlation; and above 0.9, very high correlation (5 ). We used PASW software version 18.0 (IBM Corp., Armonk, NY, USA) for statistical analyses, and p values ≤ 0.05 were considered statistically significant.

We used chi-square test to evaluate whether the statistical bias exists according to the age and sex. The intra-class correlation coefficient (ICC) was used in the analysis of interobserver agreement between the two radiologists. ICC values < 0.40 indicate poor reproducibility, ICC values of 0.40–0.75 indicate fair-to-good reproducibility, and ICC values > 0.75 indicate excellent reproducibility (9 ). The ADC values were calculated to the arithmetic mean and compared using the Mann-Whitney U test and Friedman's two-way analysis. Interobserver agreement of diagnostic performance was analyzed using kappa statistics. The kappa value interpretation was as follows: poor (k ≤ 0), slight (0 < k ≤ 0.2), fair (0.2 < k ≤ 0.4), moderate (0.4 < k ≤ 0.6), substantial (0.6 < k ≤ 0.8), and nearly perfect (0.8 < k ≤ 1) (10 (link)). The diagnostic performances of the various imaging methods were evaluated using the sensitivity, specificity, and accuracy for differentiating between benign and malignant pathology, as determined by the use of routine sequences with additional DWIs. The pathologic or clinical findings were used as reference standards. The values were analyzed using the McNemar test. Statistical analyses were performed using PASW software version 18.0 (IBM, Armonk, NY, USA). P values ≤ 0.05 were considered statistically significant.

Baseline characteristics were compared using the independent t-test for continuous variables and chi-square test or Fisher exact test for categorical variables. A two-sided p-value of <0.05 was considered statistically significant in all analyses. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy were calculated. All statistical operations were performed using the PASW software version 18.0 (SPSS Inc., Chicago, IL, USA).