A common assumption for phase combination and dynamic distortion correction is that phase offsets ($$$Ф_0$$$), i.e. the phase of coil sensitivities, are temporally stable. We investigate the validity of this assumption at 7T for long measurements (40min) and large head rotations (up to 12°) made with multi-channel coils. We show that changes in separate-channel $$$Ф_{0,ch}$$$ have little effect on the combined phase images (unwarping errors of 0.2 voxel, reduction in phase matching quality by 2%). We thus conclude that the assumption of $$$Ф_0$$$ temporal stability holds and methods based on this assumption should work at 7T with substantial motion.
