The main cardiomyocyte aggregate orientation, represented by the Helix Angle, remains poorly described in vivo during contractionas it is affected by the imaging resolution and thus by a change of wall thickening. This work evaluated the effect of the imaging resolution using a numerical phantom and ex vivoscans on porcine hearts. High-resolution cDTI was acquired in vivoto measure the transmural mobility of Helix Angle at three cardiac phases. A strong steepening of Helix Angle was observed as the resolution decreased in simulation and ex-vivo. A significant change in the Helix Angle distribution was observed during contraction.