Whole-tumor histogram analysis of apparent diffusion coefficient maps in grading diagnosis of ependymoma

Objective: To study the value of whole tumors volume based apparent diffusion coefficient histogram analysis in grading diagnosis of ependymoma. Methods: Seventy-one patients with ependymal tumors were retrospectively analyzed, including 13 cases of WHO I, 28 cases of WHO II, 30 cases of WHO III. Regions of interest (ROI) in the apparent diffusion coefficient maps of three groups on each layer of tumor level were drawn by using MaZda software and were analyzed using the whole tumors gray histogram. The histogram parameters of the three groups all fitted the normal distribution and homogeneity test of variance. The ANOVA analysis was used to compare the three groups. LSD-t test was used to compare the two groups to find out statistical significance of each parameter. Results: Through histogram analysis of 9 parameters, three parameters were statistically significant (P < 0.05), including variance, perc. 01% and perc. 10%. The remaining 6 parameters had no significant difference between the three groups (P > 0.05). Between the WHO I and the WHO II, the sensitivity of perc. 10% was 85.7%, the specificity was 87.7%, the area under the curve was 0.835, and the best cut-off value was 131.33. Between the WHO I and the WHO III, the sensitivity of perc. 10% was 85.7%, the specificity was 100.0%, the area under the curve was 0.872, and the cut-off was 126.5. Between the WHO II and the WHO III, the sensitivity of variance was 68.4%, the specificity was 79.6%, the area under the curve was 0.794, and the cut-off was 2645.7. They had a high identification efficiency. Conclusion: Whole-tumor histogram analysis of apparent diffusion coefficient maps could provide ancillary diagnostic value in grading diagnosis of ependymoma. Perc. 10% and variance had a high diagnostic efficiency. (authors)