Endoscopic submucosal dissection with a novel high viscosity injection solution (LiftUp) in an ex vivo model: a prospective randomized study oleh E. Wedi, P. Koehler, J. Hochberger, J. Maiss, S. Milenovic, M. Gromski, N. Ho, C. Gabor, U. Baulain, V. Ellenrieder, C. Jung