Receiver operating characteristic curve for the volumetric impedance phase shift spectroscopy (VIPS) device to differentiate subjects with severe stroke from subjects suffering small strokes. Receiver operating characteristic curve for the volumetric impedance phase shift spectroscopy (VIPS) device to differentiate subjects with severe stroke from subjects suffering small strokes. Christopher P Kellner et al. J NeuroIntervent Surg doi:10.1136/neurintsurg-2017-013690 Copyright © Society of NeuroInterventional Surgery. All rights reserved.