Diffusion-weighted MRI in the differential diagnosis of brain meningiomas
Diffusion weighted magnetic resonance imaging (DW MRI) provides information regarding tissue microstructure and can be used to distinguish malignant from benign tumors. The purpose of the study was to compare the ADC of meningiomas with cell density and Ki-67 proliferative index. Material and methods. Diffusion weighted MR images were analyzed in 37 patients with brain meningiomas. The slice with the largest diameter of meningioma was selected for ADC calculation. The region of interest did not include cystic and necrotic areas of the tumor. Tumor grading was classified according to the World Health Organization. The tumor proliferation index was estimated on Ki-67 antigen-stained specimens. Cell density was calculated. Results. In most cases, typical (M I) and atypical (M II) meningiomas were detected (37.8% and 56.7% of patients, respectively). Anaplastic (M III) meningioma was verified in 5.5% of patients. The mean ADC value for M I meningioma was 1375.5 ± 197.5 mm2/s. For M II and M III meningiomas, the mean ADC values were 1113.1±180 mm2/sec and 689±31.1 mm2/s, respectively. Statistically significant differences in the mean ADC values were found between M I and M III meningiomas (p = 0.008) and between M II and M III meningiomas (p = 0.012). No significant differences in cell density between meningioma subgroups were identified (p = 0.834, p = 0.684 and p = 0.766 for M I/M II, M II/M III and M I/M III, respectively). There were statistically significant differences in Ki-67 values between M I and M III meningiomas (p = 0.002) and M II and M III meningiomas (p = 0.007). Statistically significant correlations between ADC values and Ki-67 levels were (r = - 0.699, p = 0.001). Conclusion. Diffusion weighted MRI with ADC maps can be used as an additional non-invasive method for differential diagnosis of brain meningioma.