Image-guided surgery near anatomical or functional risk structures poses a challenging
task for surgeons. To this end, surgical navigation systems that visualize the spatial
relation between patient anatomy (represented by 3D images) and surgical instruments
have been described. The provided 3D visualizations of these navigation systems are
often complex and thus might increase the mental effort for surgeons. Therefore, an
appropriate intraoperative visualization of spatial relations between surgical instruments
and risk structures poses a pressing need. We propose three visualization methods
to improve spatial perception in navigated surgery. A pointer ray encodes the distance
between a tracked instrument tip and risk structures along the tool's main axis. A
side-looking radar visualizes the distance between the instrument tip and nearby structures
by a ray rotating around the tool. Virtual lighthouses visualize the distances between
the instrument tip and predefined anatomical landmarks as color-coded lights flashing
between the instrument tip and the landmarks. Our methods aim to encode distance information
with low visual complexity. To evaluate our concepts' usefulness, we conducted a user
study with 16 participants. During the study, the participants were asked to insert
a pointer tool into a virtual target inside a phantom without touching nearby risk
structures or boundaries. Results showed that our concepts were perceived as useful
and suitable to improve distance assessment and spatial awareness of risk structures
and surgical instruments. Participants were able to safely maneuver the instrument
while our navigation cues increased participant confidence of successful avoidance
of risk structures.
