The present invention relates to a system (10) for navigating and positioning an instrument (12, 40, 112) in a body (14). The instrument (12, 40, 112) is detectable by the system (10) and the system (10) displays a view to an operator. The instrument (12, 40, 112) is adapted to identify tissue parameters. The system (10) is adapted to display an image being a combined image of the interior of a body (14) and an indication of the tissue parameter at the appropriate earlier locations. The present invention further relates to a method (44) including determining tissue parameters and displaying the parameters in an image of a body (14). The present invention further relates to a software implemented method (44) for being executed on a digital processor. The present invention further relates to an instrument (12, 40, 112).