The glymphatic system may play a critical role in the parenchymal clearance of amyloid beta, a leading molecular candidate to initiate Alzheimer’s disease. Clinical investigation, however, is currently hindered by an absence of non-invasive techniques for assessment. The movement of fluid in the perivascular space represents a central component of the glymphatic pathway. Here, we present the first non-invasive evaluation of glymphatic function by using an ultra-long echo-time, low b-value, diffusion-tensor sequence targeted to the perivascular space of the rat brain. We demonstrate that this novel technique is sensitive to the fluid movement along perivascular channels that drives glymphatic inflow.