The present invention proposes an apparatus and method for assisting a user to plan a puncture trajectory within a region-of-interest of a subject. The apparatus comprises: a data interface (211) configured to receive anatomical data of the region-of-interest of the subject and to output the at least one candidate puncture trajectory, and a data processor (213) for calculating at least one candidate puncture trajectory on basis of the anatomical data, multiple criteria, and a tradeoff among the multiple criteria. The anatomical data of the subject comprises three-dimensional data of the region of interest. The data processor (213) is further configured, upon receiving a first user input for adjusting the tradeoff among the multiple criteria, to adjust the tradeoff among the multiple criteria on basis of the first user input, and to calculate the at least one candidate puncture trajectory on basis of the anatomical data, the multiple criteria and the adjusted tradeoff among the multiple criteria. Different from conventional automatic planning tools which tend to offer a universal best tradeoff among multiple criteria for all cases, the proposed apparatus allows the user to tailor the tradeoff and thus tailor the automatic calculation of the candidate puncture trajectories so as to better meet the actual clinical needs.
