In addition, high-grade gliomas have been shown to upregulate aquaporin channels, notably AQP4 and AQP1, limiting the ability of ADC to truly capture restricted diffusion in a hypercellular environment.37–39 Moreover, ADC is a scalar quantity that measures isotropic diffusion of water and therefore lacks information regarding anisotropy, precluding ADC from accurately differentiating areas of tumor infiltration from peritumoral edema and healthy nervous tissue. This evidence concerns the gene AQP4 and central nervous system cancer.