  Working with organs and tissue blocks is an essential task in medical
environments. In order to prepare specimens for further analysis, wet-bench
workers must dissect tissue and collect spatial metadata. The Registration User
Interface (RUI) was developed to allow stakeholders in the Human Biomolecular
Atlas Program (HuBMAP) to register tissue blocks by size, position, and
orientation. The RUI has been used by tissue mapping centers across the HuBMAP
consortium to register a total of 45 kidney, spleen, and colon tissue blocks.
In this paper, we compare three setups for registering one 3D tissue block
object to another 3D reference organ (target) object. The first setup is a 2D
Desktop implementation featuring a traditional screen, mouse, and keyboard
interface. The remaining setups are both virtual reality (VR) versions of the
RUI: VR Tabletop, where users sit at a physical desk; VR Standup, where users
stand upright. We ran a user study involving 42 human subjects completing 14
increasingly difficult and then 30 identical tasks and report position
accuracy, rotation accuracy, completion time, and satisfaction. We found that
while VR Tabletop and VR Standup users are about three times as fast and about
a third more accurate in terms of rotation than 2D Desktop users, there are no
significant differences for position accuracy. The performance values for the
2D Desktop version (22.6 seconds per task, 5.9 degrees rotation, and 1.32 mm
position accuracy) confirm that the 2D Desktop interface is well-suited for
registering tissue blocks at a speed and accuracy that meets the needs of
experts performing tissue dissection. In addition, the 2D Desktop setup is
cheaper, easier to learn, and more practical for wet-bench environments than
the VR setups. All three setups were implemented using the Unity game engine,
and study materials were made available, alongside videos documenting our
setups.
