Interstitial fluid pressure is typically raised in solid tumors, which can affect drug delivery. Using magnetic resonance imaging, a technique called convection-MRI was developed that has been used to noninvasively study low-velocity, extravascular fluid flow in tumors. This image shows fluid velocity streamlines, measured in vivo with convection-MRI, that emanate from the tumor center and radiate outwards, and that are consistent with elevated, central fluid pressure. For details, see article by Walker-Samuel and colleagues on page 1859.