Correlation Between Aquaporin 4 Expression and Different DWI Parameters in Grade I Meningioma

Diffusion-weighted imaging (DWI) measures water diffusion in biological tissues. Cellular water transport depends on aquaporins (AQPs). The expression of aquaporins might differ in several pathologic disorders. Therefore, the aim of this study was to evaluate the associations between AQP4 expression and different DWI parameters in meningioma.

Twenty-three patients with meningioma grade I were included in this retrospective study. DWI was obtained with three b values (0; 500; 1000) using a 1.5-T device. ADC_mean, ADC_min, ADC_max, and true diffusion coefficients (D) were obtained in every patient. Aquaporin 4 expression was quantified immunohistochemically in four immunoreactivity levels.

The estimated DWI parameters (mean value ± standard deviation, 10^-3 mm² s^-1) of the tumors were as follows: ADC_min 0.67 ± 0.16, ADC_mean 0.94 ± 0.23, ADC_max 1.29 ± 0.50, and D 0.65 ± 0.23. The mean level of the AQP4 expression was 2.02 ± 0.75 points. A statistically significant correlation between AQP4 expression and ADC_max was identified (r = 0.508, p = 0.013). No significant correlations between AQP4 and other DWI parameters were found.

A clear correlation between AQP4 expression and ADC_max values in grade I meningioma was identified. There were no significant correlations between AQP4 expression and other DWI parameters, such as ADC_min, ADC_mean, and D.