A method comprising: creating a dataset (42; 300) that includes a plurality of images (I1 - In) associated with a periodic movement of dynamic anatomy, one of the images (a) depicting a non-tissue internal reference marker, (b) being linked to non-tissue internal reference marker positional information comprising a dataset vector (V1 - Vn), and (c) being at least 2-dimensional; wherein the dataset vector is calculated (72; 260) using (d) a position of an external reference marker received from a tracking system and (e) a position of the non-tissue internal reference marker received from the tracking system; associating (80; 268) a transformation from a tracking space of the tracking system to an image space with an image in the dataset; receiving (70; 94; 258; 354) a current position of the external reference marker from the tracking system; receiving (70; 94; 258; 354) a current position of the non-tissue internal reference marker from the tracking system; calculating (96; 356) a current vector using the current positions of the external reference marker and the non-tissue internal reference marker received from the tracking system; identifying (98, 101; 360) a match dataset vector, MDV, the MDV being the dataset vector most similar to the current vector, the MDV being linked to an image from the dataset; receiving (106; 366) a current position of an instrument reference marker coupled to an instrument from the tracking system; applying (108; 368) the transformation associated with the image linked to the MDV to the current position of the instrument reference marker, thus transforming the current position of the instrument reference marker into image space; and superimposing (110; 370) a representation of the instrument on the image linked to the MDV. creating a dataset (42; 300) that includes a plurality of images (I1 - In) associated with a periodic movement of dynamic anatomy, one of the images (a) depicting a non-tissue internal reference marker, (b) being linked to non-tissue internal reference marker positional information comprising a dataset vector (V1 - Vn), and (c) being at least 2-dimensional; wherein the dataset vector is calculated (72; 260) using (d) a position of an external reference marker received from a tracking system and (e) a position of the non-tissue internal reference marker received from the tracking system; (d) a position of an external reference marker received from a tracking system and (e) a position of the non-tissue internal reference marker received from the tracking system; associating (80; 268) a transformation from a tracking space of the tracking system to an image space with an image in the dataset; receiving (70; 94; 258; 354) a current position of the external reference marker from the tracking system; receiving (70; 94; 258; 354) a current position of the non-tissue internal reference marker from the tracking system; calculating (96; 356) a current vector using the current positions of the external reference marker and the non-tissue internal reference marker received from the tracking system; identifying (98, 101; 360) a match dataset vector, MDV, the MDV being the dataset vector most similar to the current vector, the MDV being linked to an image from the dataset; receiving (106; 366) a current position of an instrument reference marker coupled to an instrument from the tracking system; applying (108; 368) the transformation associated with the image linked to the MDV to the current position of the instrument reference marker, thus transforming the current position of the instrument reference marker into image space; and superimposing (110; 370) a representation of the instrument on the image linked to the MDV.