Differentiation of Posterior Fossa Schwannomas from Meningiomas Using ADC Values

Objective: To assess the diagnostic efficiency of apparent diffusion coefficient (ADC) values in differentiating posterior fossa schwannomas and meningiomas.
Methods: A total of 55 patients who were referred for magnetic resonance imaging (MRI) of posterior fossa extra-axial lesions were retrospectively enrolled in our study. Tumors were classified based on the patients’ conventional MRI findings. The mean ADC values of the tumor and reference value from contralateral cerebellar parenchyma were obtained by using region of interest from ADC maps by two radiologists in consensus. ADC ratios were calculated. Differences between schwannomas and meningiomas in mean ADC, and ADC ratio values were statistically analyzed.
Results: 52.7% of patients were male, 47.3% were female with a mean age of 53.4. Based on conventional MRI features, 29 were interpreted as schwannoma, 26 as meningioma. Mean ADC values (×10-3 mm2/s) of schwannomas and meningiomas were 1.087±0.224 and 0.729±0.130, respectively. Mean ADC ratios were 1.56±0.34 for schwannomas and 1.08±0.17 for meningiomas. Mean ADC values and ADC ratios of schwannomas were significantly greater than meningiomas (p<0.001). The area under the curve (AUC) of ADC value for differentiating schwannomas from meningiomas was 0.957, and the sensitivity and specificity were 92% and 89%, respectively (p<0.001). The AUC of ADC ratios was 0.932, and the sensitivity and specificity were 92% and 79%, respectively (p<0.001).
Conclusion: The ADC value and ADC ratios may helpful in discriminating schwannomas and meningiomas. Although diagnosis of schwannoma and meningioma is based on typical imaging features, ADC value and ratio can provide a clue for a discrepancy in controversial cases.