A method is provided for planning a position and/or a movement trajectory of a medical instrument in a heterogeneous body structure. The method includes providing at least one of a) body structure data corresponding to mechanical properties of the heterogeneous body structure, wherein said mechanical properties influence a movement of the instrument through the heterogeneous body structure due to the mechanical interaction between the instrument and the heterogeneous body structure, b) instrument data concerning mechanical and/or geometric properties of the instrument, or c) movement data concerning mechanical properties that are intended to cause and/or describe a movement of the instrument through the heterogeneous body structure. The position and/or movement trajectory-of the instrument or a probability that said position and/or movement trajectory will be achieved then is determined based on at least one of the movement data, the body structure data or the instrument data.
