NIMG-20PREOPERATIVE MRI-BASED FRACTAL DIMENSIONS AS A PREDICTOR OF ATYPICAL MENINGIOMA (NOVEL TECHNIQUE).

BACKGROUND: To date no preoperative objective imaging method is available to predict meningioma grade. We propose the use of fractal analysis, which describes the complexity of a structure or image, as a way to differentiate Grade I from Grade II meningiomas. METHODS: A group of 27 patients diagnosed with atypical (WHO Grade II) and another group of 27 patients with a benign (WHO Grade I) meningioma were retrospectively reviewed after obtaining IRB approval. Preoperative brain MRIs (T1W, post-gadolinium) were processed to determine the average (FDa) and maximum (FDm) fractal dimension of the contrast enhancing part of the tumour. Box-count method and ImageJ 1.49 software were used. FDa and FDm as well as volume of the peritumoral edema, incomplete peritumoral band, male sex and skull base localisation were included into the logistic regression model as possible predictors of the malignancy. RESULTS: There were 34 women and 20 men in the study group; mean age was 62 ± 15 years. Ki-67 was significantly higher in the atypical (10.0; IQR, 7.0) than in the benign group (3.0; IQR, 3; P 0.70). Both FDa and FDm were significantly higher in atypical groups (P 1.31 (OR, 12.30; 95%CI, 1.14-132.50; P = .039) and skull base location (OR, .052; 95%CI, .005-.567; P = .015) were confirmed to be statistically significant predictors of the atypical phenotype. CONCLUSION: Tumor fractal dimension of the preoperative MRI has a tendency to correlate with atypical histopathology in meningiomas. Further studies of a wide prospective cohort are warranted.