Method and system for guiding a diagnostic or therapeutic instrument towards a target region inside the patient's body

Method and system are presented for guiding a diagnostic or therapeutic instrument towards a correct target inside the patient's body. A combined image obtained by registering structural and functional images of at least a portion of the patient's body including the target is used together with a guiding device. The guiding device has an indicator associated with the instrument, and is operable for presenting data indicative of a position of a location on the instrument relative to any other point in the at least portion of the patient's body. The guiding device is connectable to a computer device displaying the combined image and operable thereby for guiding the instrument towards the target.