AQP1 and neoplasm: 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.