Prof. Dr. Christian Hansen

@inproceedings{klank2026,

title = {Testing before Building? Strengths and Weaknesses of VR-Based Usability Testing of a Gesture Interface},

author = {R Klank and F Heinrich and D Schott and C Hansen and F Joeres },

year  = {2026},

date = {2026-11-16},

urldate = {2026-11-16},

booktitle = {ACM Symposium on Virtual Reality Software and Technology (VRST)},

keywords = {},

pubstate = {forthcoming},

tppubtype = {inproceedings}

}

@inproceedings{schwenderling2026,

title = {Augmented Reality Training of Attention Allocation in Medical Dual-Task Learning Applications},

author = {L Schwenderling and M Schotte and F Joeres and F Heinrich and C Hansen},

year  = {2026},

date = {2026-08-31},

urldate = {2026-08-31},

booktitle = {ACM International Conference on Mobile Human-Computer Interaction 2026 (MobileHCI 2026)},

journal = {The ACM International Conference on Mobile Human-Computer Interaction 2026 (MobileHCI 2026)},

key = {selected},

keywords = {},

pubstate = {forthcoming},

tppubtype = {inproceedings}

}

@inproceedings{schreiter2026,

title = {Touch-Based Interaction and Clutching Strategies in Collaborative Robotics across Task Types},

author = {J Schreiter and P Pandi and R Klank and C Hansen and F Heinrich},

year  = {2026},

date = {2026-06-30},

urldate = {2026-06-30},

booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)},

keywords = {},

pubstate = {forthcoming},

tppubtype = {inproceedings}

}

@inproceedings{urrutia2026,

title = {Where Is the Needle Tip? Vibroacoustic Sensing Reveals Hidden Needle-Tissue Transitions During Ultrasound Guidance},

author = {R Urrutia and N Esmaeili and S Matinfar and A Boese and N Davaris and C Arens and C Hansen and A Illanes},

url = {https://link.springer.com/10.1007/978-3-032-38236-8_59},

doi = {10.1007/978-3-032-38236-8_59},

isbn = {978-3-032-38235-1},

year  = {2026},

date = {2026-09-26},

urldate = {2026-09-26},

booktitle = {Medical Image Computing and Computer Assisted Intervention – MICCAI 2026},

issuetitle = {Medical Image Computing and Computer Assisted Intervention (MICCAI)},

volume = {16893},

publisher = {Springer},

address = {Cham},

series = {Lecture Notes in Computer Science},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{esmaeili2026,

title = {When Tissue Speaks: Vibroacoustic Monitoring of Tissue Response during Electrosurgery},

author = {N Esmaeili and R Urrutia and D Espejo and A Boese and P Horvath and C Hansen and J Hagenah and A Illanes},

url = {https://link.springer.com/10.1007/978-3-032-38236-8_58},

doi = {10.1007/978-3-032-38236-8_58},

isbn = {978-3-032-38235-1},

year  = {2026},

date = {2026-09-26},

urldate = {2026-09-26},

booktitle = {Medical Image Computing and Computer Assisted Intervention – MICCAI 2026},

volume = {16893},

pages = {606–615},

publisher = {Springer},

address = {Cham},

series = {Lecture Notes in Computer Science},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{holonote,

title = {HoloNote: Exploring Augmented Reality Notifications for Ergonomic Feedback in Laparoscopic Training},

author = {F Heinrich and T Mielke and R Klank and F Ortega and C Hansen and T Huber and F Huettl},

url = {https://dl.acm.org/doi/10.1145/3772363.3799086},

doi = {10.1145/3772363.3799086},

year  = {2026},

date = {2026-04-13},

urldate = {2026-04-13},

booktitle = {Extended Abstracts of the CHI Conference on Human Factors in Computing Systems (CHI EA)},

number = {368},

abstract = {Laparoscopic surgery is a physically demanding task that can lead to ergonomic strain. While notification-based approaches have been used to support ergonomics in other domains, their application in laparoscopic surgery remains limited.

Therefore, an augmented reality (AR) notification concept was implemented using lightweight optical see-through AR glasses, examining their suitability for laparoscopic training.

A pilot study with ten surgeons was conducted using a laparoscopic simulator, where participants performed a stitching and knot-tying task with and without AR-based notifications.

All participants were able to complete the tasks while wearing the AR glasses. While task completion times were longer in the AR condition, no conclusive differences in perceived workload were observed. User experience and wearing comfort were rated positively, whereas the notifications were perceived as useful but not consistently effective. The findings suggest that lightweight AR glasses are a feasible platform for ergonomic feedback in laparoscopic training and motivate further investigation.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{nokeyd,

title = {Enhancing Gesture-Based Human–Robot Interaction: Investigating the Role of Force Automation},

author = {T Mielke and M Georgiades and O Grosser and M Pech and C Hansen and F Heinrich},

doi = {10.1145/3757279.3785568},

year  = {2026},

date = {2026-03-16},

urldate = {2026-03-16},

booktitle = {ACM/IEEE International Conference on Human-Robot Interaction (HRI)},

pages = {619-628},

abstract = {Directly controlling robot motion through human–robot interaction enables the integration of human expertise into robot control. However, this requires efficient interaction methods. While previous work has shown that hand gestures offer potential for natural control, the lack of haptic feedback remains a key challenge. One solution is partial automation, in which the contact force is autonomously controlled. We implemented force automation enhanced gesture control, as well as the state-of-the-art baseline of hand-guiding, to systematically investigate hand gesture interaction for robot control. A user study (n=28) was conducted to investigate the efficiency and workload of these interaction concepts. As the interaction method efficiency may depend on task demands, two tasks with different precision requirements were evaluated in the context of robotic ultrasound. The results indicate that force automation significantly reduces perceived workload and task duration when using hand gestures. Moreover, gesture-based interaction can match the efficiency of hand-guiding for broad tasks and even outperform it in precise tasks. These findings highlight the potential of gesture-based interaction for robot control, particularly when the absence of haptic feedback is compensated by partial automation.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{mielke_gesturing_2025,

title = {Gesturing Towards Efficient Robot Control: Exploring Sensor Placement and Control Modes for Mid-Air Human-Robot Interaction},

author = {T Mielke and F Heinrich and C Hansen},

doi = {10.1109/ICRA55743.2025.11127519},

year  = {2025},

date = {2025-09-02},

urldate = {2025-09-02},

booktitle = {2025 IEEE International Conference on Robotics and Automation (ICRA)},

publisher = {IEEE},

abstract = {While collaborative robots effectively combine robotic precision with human capabilities, traditional control methods such as button presses or hand guidance can be slow and physically demanding. This has led to an increasing interest in natural user interfaces that integrate hand gesturebased interactions for more intuitive and flexible robot control. Therefore, this paper systematically explores mid-air robot control by comparing position and rate control modes with different state-of-the-art and novel sensor placements. A user study was conducted to evaluate each combination in terms of accuracy, task duration, perceived workload, and physical exertion. Our results indicate that position control is more efficient than rate control. Traditional desk-mounted sensors can provide a good balance between accuracy and comfort. However, robot-mounted sensors are a viable alternative for short-term, accurate control with less spatial requirements. Legmounted sensors, while comfortable, pose challenges to handeye coordination. Based on these findings, we provide design implications for improving the usability and comfort of midair human-robot interaction. Future research should extend this evaluation to a wider range of tasks and environments.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{mielke_enhancing_2025,

title = {Enhancing AR-to-Robot Registration Accuracy: A Comparative Study of Marker Detection Algorithms and Registration Parameters},

author = {T Mielke and F Heinrich and C Hansen},

doi = {10.1109/ICRA55743.2025.11128039},

year  = {2025},

date = {2025-09-02},

urldate = {2025-09-02},

booktitle = {2025 IEEE International Conference on Robotics and Automation (ICRA)},

publisher = {IEEE},

abstract = {Augmented Reality (AR) offers potential for enhancing human-robot collaboration by enabling intuitive interaction and real-time feedback. A crucial aspect of AR-robot integration is accurate spatial registration to align virtual content with the physical robotic workspace. This paper systematically investigates the effects of different tracking techniques and registration parameters on AR-to-robot registration accuracy, focusing on paired-point methods. We evaluate four marker detection algorithms - ARToolkit, Vuforia, ArUco, and retroreflective tracking - analyzing the influence of viewing distance, angle, marker size, point distance, distribution, and quantity. Our results show that ARToolkit provides the highest registration accuracy. While larger markers and positioning registration point centroids close to target locations consistently improved accuracy, other factors such as point distance and quantity were highly dependent on the tracking techniques used. Additionally, we propose an effective refinement method using point cloud registration, significantly improving accuracy by integrating data from points recorded between registration locations. These findings offer practical guidelines for enhancing AR-robot registration, with future work needed to assess the transferability to other AR devices and robots.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{heinrich_you_2025,

title = {Do You See What I See? Evaluating Relative Depth Judgments Between Real and Virtual Projections},

author = {F Heinrich and D Schott and L Schwenderling and C Hansen},

url = {https://doi.org/10.1145/3706599.3720157},

doi = {10.1145/3706599.3720157},

year  = {2025},

date = {2025-04-01},

urldate = {2025-04-01},

booktitle = {Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

series = {CHI EA '25},

abstract = {Projector-based augmented reality (AR) is promising in different domains with less issues in discomfort or shortage of space. However, due to limitations like high costs and cumbersome calibration, this AR modality remains underused. To address this problem, a stereoscopic projector-based AR simulation was implemented for a cost-effective video see-through AR headset. To evaluate the validity of this simulation, a relative depth judgment experiment was conducted to compare this method with a physical projection system. Consistent results suggest that a known interaction effect between visualization and disparity mode could be successfully reproduced using both the physical projection and the virtual simulation. In addition, first findings indicate that there are no significant differences between these projection modalities. The results indicate that other perception-related effects observed for projector-based AR may also be applicable to virtual projection simulations and that future findings determined using only these simulations may also be applicable to real projections.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schwenderling_teach_2025,

title = {Teach Me Where to Look: Dual-Task Attention Training in Augmented Reality},

author = {L Schwenderling and M Schotte and F Joeres and F Heinrich and L Hanke and F Huettl and T Huber and C Hansen},

url = {https://dl.acm.org/doi/10.1145/3706599.3720198},

doi = {10.1145/3706599.3720198},

year  = {2025},

date = {2025-04-01},

urldate = {2025-04-01},

booktitle = {Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {ACM},

address = {Yokohama Japan},

abstract = {Regular eye contact is essential in medicine to recognize signs of pain. However, it is difficult to remember this during training as attention is tied up in learning. While augmented reality (AR) has shown promising results for medical education, there is no training for attention allocation yet. Therefore, three auditory and three visual attention guidance tools in AR are evaluated for their use in medical dual-task training settings. In expert reviews with six participants in human-computer interaction and medical didactics, advantages, disadvantages, and refinements for the cues were developed. For visual cues, an overt but less occluding cue was preferred for constant visibility of the primary task. A more diegetic cue design was proposed for the auditory cues to use a patient simulation as a reminder of the regular face glance. In general, several cues were found to be suitable for gaze guidance training, requiring only minor changes for improvement.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{mielke_virtual_2025,

title = {Virtual Studies, Real Results? Assessing the Impact of Virtualization on Human-Robot Interaction},

author = {T Mielke and M Allgaier and D Schott and C Hansen and F Heinrich},

url = {https://dl.acm.org/doi/10.1145/3706599.3719724},

doi = {10.1145/3706599.3719724},

year  = {2025},

date = {2025-04-01},

urldate = {2025-04-01},

booktitle = {Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {ACM},

address = {Yokohama Japan},

abstract = {Extended Reality (XR) shows potential for human-centered evaluation of real-world scenarios and could improve efficiency and safety in robotic research. However, the validity of XR Human-Robot Interaction (HRI) studies remains underexplored. This paper investigates the transferability of HRI studies across virtualization levels for three tasks. Our results indicate XR study validity is task-specific, with task virtualization as a key influencing factor. Partially virtualized settings with virtual tasks and a real robot, as well as fully virtualized setups with a simulated robot, yielded results comparable to real setups for pick-and-place and robotic ultrasound. However, for precision-dependent peg-in-hole, differences were observed between real and virtualized conditions regarding completion time, perceived workload, and ease. Demonstrating the task dependency of XR transferability and comparing virtualization levels, our work takes an important step in assessing XR study validity. Future work should isolate factors affecting transferability and assess relative validity in the absence of absolute validity.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schreiter_exploring_2025,

title = {Exploring Interaction Concepts for the Manipulation of a Collaborative Robot: A Comparative Study},

author = {J Schreiter and T Mielke and M Georgiades and M Pech and C Hansen and F Heinrich},

url = {https://ieeexplore.ieee.org/document/10974113},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

booktitle = {ACM/IEEE International Conference on Human-Robot Interaction},

pages = {55–64},

publisher = {IEEE Press},

address = {Melbourne, Australia},

series = {HRI '25},

abstract = {Robotic systems have the potential to enhance a wide range of domains, such as medical workflows, by automating individual steps of complex processes. However, human-robot interaction (HRI) is of critical importance, as effective collaboration between humans and robots is essential even in highly automated environments. Recent research has predominantly focused on the development of interaction methods rather than systematically comparing existing approaches. Therefore, we conducted a user study (n=20) to compare different HRI concepts for end effector manipulation combined with clutching mechanisms for manipulation activation in an alignment task using the example of robotic ultrasound (US). Manipulation methods included hand-guiding, teleoperation, and touchless interaction, while clutching mechanisms were realized through hand, voice, and foot interaction. The results indicate advantages of hand-guiding for manipulation. While no significant differences were observed between clutching mechanisms, strong evidence suggests comparable performance across these modalities. Notably, significant interaction effects on perceived workload reveal that the optimal clutching mechanism depends on the selected manipulation technique. This work underscores the critical importance of selecting appropriate HRI concepts and understanding the dependencies of manipulation techniques with clutching mechanisms. While our study included the usage of a robotic US, the insights gained are broadly transferable across various domains involving robotic manipulation tasks in human-robot collaboration.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schott_stand_2024,

title = {Stand Alone or Stay Together: An In-Situ Experiment of Mixed-Reality Applications in Embryonic Anatomy Education},

author = {D Schott and M Kunz and F Heinrich and J Mandel and A Albrecht and R Braun-Dullaeus and C Hansen},

url = {https://dl.acm.org/doi/10.1145/3641825.3687706},

doi = {10.1145/3641825.3687706},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Proceedings of the 30th ACM Symposium on Virtual Reality Software and Technology},

series = {VRST '24},

abstract = {Where traditional media and methods reach their limits in anatomy education, mixed-reality (MR) environments can provide effective learning support because of their high interactivity and spatial visualization capabilities. However, the underlying design and pedagogical requirements are as diverse as the technologies themselves. This paper examines the effectiveness of individual- and collaborative learning environments for anatomy education, using embryonic heart development as an example. Both applications deliver the same content using identical visualizations and hardware but differ in interactivity and pedagogical approach. The environments were evaluated in a user study with medical students (n = 90) during their examination phase, assessing usability, user experience, social interaction/co-presence, cognitive load, and personal preference. Additionally, we conducted a knowledge test before and after an MR learning session to determine educational effects compared to a conventional anatomy seminar. Results indicate that the individual learning environment was generally preferred. However, no significant difference in learning effectiveness could be shown between the conventional approach and the MR applications. This suggests that both can effectively complement traditional seminars despite their different natures. Our study contributes to understanding how different MR settings could be tailored for anatomical education.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{allgaier_gamification_2024,

title = {Gamification Concepts for a VR-Based Visuospatial Training for Intraoperative Liver Ultrasound},

author = {M Allgaier and F Huettl and L Hanke and T Huber and B Preim and S Saalfeld and C Hansen},

url = {https://doi.org/10.1145/3613905.3650736},

doi = {10.1145/3613905.3650736},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

series = {CHI EA '24},

abstract = {Gamification is widely used due to its positive influence on learning by adding emotions and steering behavior. In medical VR training applications, the use of gamification is rare, and when it is implemented, it often lacks thoughtful design decisions and empirical evaluation. Using a VR-based training for intraoperative ultrasound for liver surgery, we analyzed game elements regarding their suitability and examined two in more detail: difficulty levels and a kit, where the user has to assemble a virtual liver using US. In a broad audience study, levels achieved significantly better results regarding enjoyment. Qualitative feedback from medical students directly comparing the elements revealed that they prefer the kit as well as levels for training. Our studies indicate that levels and the more interactive kit improve the learning experience, which could also be taken as a basis for similar VR-based medical training applications.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{polenz_simulating_2024,

title = {Simulating Projective Augmented Reality Visualizations in Virtual Reality: Is VR a Feasible Environment for Medical AR Evaluations?},

author = {L Polenz and F Joeres and C Hansen and F Heinrich},

url = {https://doi.org/10.1145/3613905.3650843},

doi = {10.1145/3613905.3650843},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

series = {CHI EA '24},

abstract = {Augmented Reality (AR) has demonstrated potential in medical applications, such as enhancing surgical navigation. However, evaluating medical AR visualizations entails high costs and effort to provide suitable hardware solutions. This is particularly crucial in projective AR, as these systems require several error-prone calibration and registration steps. This work investigates the suitability of Virtual Reality (VR) as a cost-effective and controlled study environment for evaluating projective AR visualizations. A virtual twin of a real laboratory environment was created, and a user study comparing two needle navigation visualizations was conducted. The study simulated identical experiments in both AR and VR to assess if similar results would emerge. Our findings indicate that both AR and VR experiments exhibited comparable effects in terms of performance and workload of both needle insertion visualizations. This study serves as a preliminary step in demonstrating the feasibility of using VR as an evaluation environment for projective AR visualizations.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schott_is_2023,

title = {Is This the vReal Life? Manipulating Visual Fidelity of Immersive Environments for Medical Task Simulation},

author = {D Schott and F Heinrich and L Stallmeister and J Moritz and B Hensen and C Hansen},

url = {https://ieeexplore.ieee.org/document/10316533/},

doi = {10.1109/ISMAR59233.2023.00134},

year  = {2023},

date = {2023-10-01},

urldate = {2023-10-01},

booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)},

pages = {1171–1180},

publisher = {IEEE},

address = {Sydney, Australia},

abstract = {Recent developments and research advances contribute to an ever-increasing trend towards quality levels close to what we experience in reality. In this work, we investigate how different degrees of these quality characteristics affect user performance, qualia of user experience (UX), and sense of presence in an example medical task. To this end, a two-way within-subjects design user study was conducted, in which three different levels of visual fidelity were compared. In addition, two different interaction modalities were considered: (1) the use of conventional VR controllers and (2) natural hand interaction using 3D-printed, spatially-registered replicas of medical devices, to interact with their virtual representations. Consistent results indicate that higher degrees of visual fidelity evoke a higher sense of presence and UX. However, user performance was less affected. Moreover, no differences were detected between both interaction modalities for the examined task. Future work should investigate the discovered interaction effects between quality levels and interaction modalities in more detail and examine whether these results can be reproduced in tasks that require more precision. This work provides insights into the implications to consider when studying interactions in VR and paves the way for investigations into early phases of medical product development and workflow analysis.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{allgaier_livrsono_2023,

title = {LiVRSono - Virtual Reality Training with Haptics for Intraoperative Ultrasound},

author = {M Allgaier and F Huettl and L Hanke and H Lang and T Huber and B Preim and S Saalfeld and C Hansen},

url = {https://ieeexplore.ieee.org/document/10316488/},

doi = {10.1109/ISMAR59233.2023.00114},

year  = {2023},

date = {2023-10-01},

urldate = {2023-10-01},

booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)},

pages = {980–989},

publisher = {IEEE},

address = {Sydney, Australia},

abstract = {One of the biggest challenges in using ultrasound (US) is learning to create a spatial mental model of the interior of the scanned object based on the US image and the probe position. As intraoperative ultrasound (IOUS) cannot be easily trained on patients, we present LiVRSono, an immersive VR application to train this skill. The immersive environment, including an US simulation with patientspecific data as well as haptics to support hand-eye coordination, provides a realistic setting. Four clinically relevant training scenarios were identified based on the described learning goal and the workflow of IOUS for liver. The realism of the setting and the training scenarios were evaluated with eleven physicians, of which six participants are experts in IOUS for liver and five participants are potential users of the training system. The setting, handling of the US probe, and US image were considered realistic enough for the learning goal. Regarding the haptic feedback, a limitation is the restricted workspace of the input device. Three of the four training scenarios were rated as meaningful and effective. A pilot study regarding learning outcome shows positive results, especially with respect to confidence and perceived competence. Besides the drawbacks of the input device, our training system provides a realistic learning environment with meaningful scenarios to train the creation of a mental 3D model when performing IOUS. We also identified important improvements to the training scenarios to further enhance the training experience.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{heinrich_2d_2022,

title = {2D Versus 3D: A Comparison of Needle Navigation Concepts between Augmented Reality Display Devices},

author = {F Heinrich and L Schwenderling and F Joeres and C Hansen},

url = {https://ieeexplore.ieee.org/document/9756753},

doi = {10.1109/VR51125.2022.00045},

year  = {2022},

date = {2022-03-01},

urldate = {2022-03-01},

booktitle = {2022 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)},

pages = {260–269},

abstract = {Surgical procedures requiring needle navigation assistance suffer from complicated hand-eye coordination and are mentally demanding. Augmented reality (AR) can help overcome these issues. How-ever, only an insufficient amount of fundamental research has focused on the design and hardware selection of such AR needle navigation systems. This work contributes to this research area by presenting a user study (n=24) comparing three state-of-the-art navigation concepts displayed by an optical see-through head-mounted display and a stereoscopic projection system. A two-dimensional glyph visualization resulted in higher targeting accuracy but required more needle insertion time. In contrast, punctures guided by a three-dimensional see-through vision concept were less accurate but faster and were favored in a qualitative interview. The third concept, a static representation of the correctly positioned needle, showed too high target errors for clinical accuracy needs. This concept per-formed worse when displayed by the projection system. Besides that, no meaningful differences between the evaluated AR display devices were detected. User preferences and use case restrictions, e.g., sterility requirements, seem to be more crucial selection criteria. Future work should focus on improving the accuracy of the see-through vision concept. Until then, the glyph visualization is recommended.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{hombeck_evaluating_2022,

title = {Evaluating Perceptional Tasks for Medicine: A Comparative User Study Between a Virtual Reality and a Desktop Application},

author = {J Hombeck and M Meuschke and L Zyla and A Heuser and J Toader and F Popp and C Bruns and C Hansen and R Datta and K Lawonn},

url = {https://ieeexplore.ieee.org/abstract/document/9756759},

doi = {10.1109/VR51125.2022.00071},

year  = {2022},

date = {2022-03-01},

urldate = {2022-03-01},

booktitle = {2022 IEEE Conference on Virtual Reality and 3D User Interfaces (VR)},

pages = {514–523},

abstract = {Since for most consumers the Virtual Reality (VR) experience exceeds that of desktop applications, an increasing number of applications is being transferred from desktop to VR. Industrial and entertainment applications primarily expect for a richer consumer experience, while others, such as surgical applications, seek for improved precision over their desktop counterparts. One way to improve the performance of precision-based VR applications is to provide suitable visualizations. Today, these "suitable" visualizations are mostly transferred from desktop to VR without considering their spatial and temporal performance might change in VR. This may not lead to an optimal solution, which can be crucial for precision-based tasks. Misinterpretation of shape or distance in a surgical or pre-operative simulation can affect the chosen treatment and thus directly impact the outcome. Therefore, we evaluate the performance differences of multiple visualizations for 3D surfaces based on their shape and distance estimation for desktop and VR applications. We conducted a quantitative user study with 56 participants evaluating seven visualizations (Phong, Toon, Fresnel, Pseudo-Chromadepth, Heatmap, Isolines, and Arrow Glyphs). Our results show that the performance of each visualization varies depending on the task, system, and surface type, with VR generally providing improved results. While Isolines are able to improve distance estimation, Phong and Heatmaps are beneficial for shape estimation.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schott_vrar_2021,

title = {A VR/AR Environment for Multi-User Liver Anatomy Education},

author = {D Schott and P Saalfeld and G Schmidt and F Joeres and C Boedecker and F Huettl and H Lang and T Huber and B Preim and C Hansen},

url = {https://ieeexplore.ieee.org/document/9417662/},

doi = {10.1109/VR50410.2021.00052},

year  = {2021},

date = {2021-03-01},

urldate = {2021-03-01},

booktitle = {2021 IEEE Virtual Reality and 3D User Interfaces (VR)},

pages = {296–305},

publisher = {IEEE},

address = {Lisboa, Portugal},

abstract = {We present a Virtual and Augmented Reality multi-user prototype of a learning environment for liver anatomy education. Our system supports various training scenarios ranging from small learning groups to classroom-size education, where students and teachers can participate in virtual reality, augmented reality, or via desktop PCs. In an iterative development process with surgeons and teachers, a virtual organ library was created. Nineteen liver data sets were used comprising 3D surface models, 2D image data, pathology information, diagnosis and treatment decisions. These data sets can interactively be sorted and investigated individually regarding their volumetric and meta information. The three participation modes were evaluated within a user study with surgery lecturers (5) and medical students (5). We assessed the usability and presence using questionnaires. Additionally, we collected qualitative data with semistructured interviews. A total of 435 individual statements were recorded and summarized to 49 statements. The results show that our prototype is usable, induces presence, and potentially support the teaching of liver anatomy and surgery in the future.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{alpers_25d_2021,

title = {2.5D Thermometry Maps for MRI-Guided Tumor Ablation},

author = {J Alpers and D Reimert and M Rötzer and T Gerlach and M Gutberlet and F Wacker and B Hensen and C Hansen},

url = {http://arxiv.org/abs/2108.05734},

doi = {10.1007/978-3-030-87202-1_30},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

booktitle = {Medical Image Computing and Computer Assisted Intervention (MICCAI)},

pages = {311–320},

abstract = {Fast and reliable monitoring of volumetric heat distribution during MRI-guided tumor ablation is an urgent clinical need. In this work, we introduce a method for generating 2.5D thermometry maps from uniformly distributed 2D MRI phase images rotated around the applicator's main axis. The images can be fetched directly from the MR device, reducing the delay between image acquisition and visualization. For reconstruction, we use a weighted interpolation on a cylindric coordinate representation to calculate the heat value of voxels in a region of interest. A pilot study on 13 ex vivo bio protein phantoms with flexible tubes to simulate a heat sink effect was conducted to evaluate our method. After thermal ablation, we compared the measured coagulation zone extracted from the post-treatment MR data set with the output of the 2.5D thermometry map. The results show a mean Dice score of 0.75+-0.07, a sensitivity of 0.77+-0.03, and a reconstruction time within 18.02ms+-5.91ms. Future steps should address improving temporal resolution and accuracy, e.g., incorporating advanced bioheat transfer simulations.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{martel_feasibility_2020,

title = {Feasibility Check: Can Audio Be a Simple Alternative to Force-Based Feedback for Needle Guidance?},

author = {A Illanes and A Boese and M Friebe and C Hansen},

url = {https://link.springer.com/10.1007/978-3-030-59716-0_3},

doi = {10.1007/978-3-030-59716-0_3},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

booktitle = {Medical Image Computing and Computer Assisted Intervention (MICCAI)},

pages = {24–33},

abstract = {Accurate needle placement is highly relevant for puncture of anatomical structures. The clinician’s experience and medical imaging are essential to complete these procedures safely. However, imaging may come with inaccuracies due to image artifacts. Sensor-based solutions have been proposed for acquiring additional guidance information. These sensors typically require to be embedded in the instrument tip, leading to direct tissue contact, sterilization issues, and added device complexity, risk, and cost. Recently, an audio-based technique has been proposed for ”listening” to needle tip-tissue interactions by an externally placed sensor. This technique has shown promising results for different applications. But the relation between the interaction event and the generated audio excitation is still not fully understood. This work aims to study this relationship, using a force sensor as a reference, by relating events and dynamical characteristics occurring in the audio signal with those occurring in the force signal. We want to show that dynamical information that a well-known sensor as force can provide could also be extracted from a low-cost and simple sensor such as audio. In this aim, the Pearson coefficient was used for signal-to-signal correlation between extracted audio and force indicators. Also, an event-to-event correlation between audio and force was performed by computing features from the indicators. Results show high values of correlation between audio and force indicators in the range of 0.53 to 0.72. These promising results demonstrate the usability of audio sensing for tissue-tool interaction and its potential to improve telemanipulated and robotic surgery in the future.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{martel_interacting_2020,

title = {Interacting with Medical Volume Data in Projective Augmented Reality},

author = {F Heinrich and K Bornemann and K Lawonn and C Hansen},

url = {https://link.springer.com/10.1007/978-3-030-59716-0_41},

doi = {10.1007/978-3-030-59716-0_41},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

booktitle = {Medical Image Computing and Computer Assisted Intervention (MICCAI)},

pages = {429–439},

abstract = {Medical volume data is usually explored on monoscopic monitors. Displaying this data in three-dimensional space facilitates the development of mental maps and the identification of anatomical structures and their spatial relations. Using augmented reality (AR) may further enhance these effects by spatially aligning the volume data with the patient. However, conventional interaction methods, e.g. mouse and keyboard, may not be applicable in this environment. Appropriate interaction techniques are needed to naturally and intuitively manipulate the image data. To this end, a user study comparing four gestural interaction techniques with respect to both clipping and windowing tasks was conducted. Image data was directly displayed on a phantom using stereoscopic projective AR and direct volume visualization. Participants were able to complete both tasks with all interaction techniques with respectively similar clipping accuracy and windowing efficiency. However, results suggest advantages of gestures based on motion-sensitive devices in terms of reduced task completion time and less subjective workload. This work presents an important first step towards a surgical AR visualization system enabling intuitive exploration of volume data. Yet, more research is required to assess the interaction techniques’ applicability for intraoperative use.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{heinrich_augmented_2019,

title = {Augmented Reality Visualisation Concepts to Support Intraoperative Distance Estimation},

author = {F Heinrich and G Schmidt and F Jungmann and C Hansen},

url = {https://doi.org/10.1145/3359996.3364818},

doi = {10.1145/3359996.3364818},

year  = {2019},

date = {2019-11-01},

urldate = {2019-11-01},

booktitle = {Proceedings of the 25th ACM Symposium on Virtual Reality Software and Technology},

series = {VRST '19},

abstract = {The estimation of distances and spatial relations between surgical instruments and surrounding anatomical structures is a challenging task for clinicians in image-guided surgery. Using augmented reality (AR), navigation aids can be displayed directly at the intervention site to support the assessment of distances and reduce the risk of damage to healthy tissue. To this end, four distance-encoding visualisation concepts were developed using a head-mounted optical see-through AR setup and evaluated by conducting a comparison study. Results suggest the general advantage of the proposed methods compared to a blank visualisation providing no additional information. Using a Distance Sensor concept signalising the proximity of nearby structures resulted in the least time the instrument was located below 5mm to surrounding risk structures and yielded the least amount of collisions with them.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{heinrich_depth_2019,

title = {Depth Perception in Projective Augmented Reality: An Evaluation of Advanced Visualization Techniques},

author = {F Heinrich and K Bornemann and K Lawonn and C Hansen},

url = {https://doi.org/10.1145/3359996.3364245},

doi = {10.1145/3359996.3364245},

year  = {2019},

date = {2019-11-01},

urldate = {2019-11-01},

booktitle = {Proceedings of the 25th ACM Symposium on Virtual Reality Software and Technology},

series = {VRST '19},

abstract = {Augmented reality (AR) is a promising tool to convey useful information at the place where it is needed. However, perceptual issues with augmented reality visualizations affect the estimation of distances and depth and thus can lead to critically wrong assumptions. These issues have been successfully investigated for video see-through modalities. Moreover, advanced visualization methods encoding depth information by displaying additional depth cues were developed. In this work, state-of-the-art visualization concepts were adopted for a projective AR setup. We conducted a user study to assess the concepts’ suitability to convey depth information. Participants were asked to sort virtual cubes by using the provided depth cues. The investigated visualization concepts consisted of conventional Phong shading, a virtual mirror, depth-encoding silhouettes, pseudo-chromadepth rendering and an illustrative visualization using supporting line depth cues. Besides different concepts, we altered between a monoscopic and a stereoscopic display mode to examine the effects of stereopsis. Consistent results across variables show a clear ranking of examined concepts. The supporting lines approach and the pseudo-chromadepth rendering performed best. Stereopsis was shown to provide significant advantages for depth perception, while the current visualization technique had only little effect on investigated measures in this condition. However, similar results were achieved using the supporting lines and the pseudo-chromadepth concepts in a monoscopic setup. Our study showed the suitability of advanced visualization concepts for the rendering of virtual content in projective AR. Specific depth estimation results contribute to the future design and development of applications for these systems.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{shen_cnn-based_2019,

title = {A CNN-Based Framework for Statistical Assessment of Spinal Shape and Curvature in Whole-Body MRI Images of Large Populations},

author = {P Ernst and G Hille and C Hansen and K Tönnies and M Rak},

url = {https://link.springer.com/10.1007/978-3-030-32251-9_1},

doi = {10.1007/978-3-030-32251-9_1},

year  = {2019},

date = {2019-01-01},

urldate = {2019-01-01},

booktitle = {Medical Image Computing and Computer Assisted Intervention (MICCAI)},

pages = {3–11},

abstract = {The extraction of spines from medical records in a fast yet accurate way is a challenging task, especially for large data sets. Addressing this issue, we present a framework based on convolutional neural networks for the reconstruction of the spinal shape and curvature, making statistical assessments feasible on epidemiological scale. Our method uses a two-step strategy. First, anchor vertebrae and the spinal centerline in between them get extracted. Second, the centerlines are transformed into a common coordinate system to enable comparisons and statistical assessments across subjects. Our networks were trained on 103 subjects, where we achieved accuracies of 3.3 mm on average, taking at most 1 s per record, which eases the handling of even very large cohorts. Without any further training, we validated our model on study data of about 3400 subjects with only 10 cases of failure, which demonstrates the robustness of our method with respect to the natural variability in spinal shape and curvature. A thorough statistical analysis of the results underpins the importance of our work. Specifically, we show that the spinal curvature is significantly influenced by the body mass index of a subject. Moreover, we show that the same findings arise when Cobb angles are considered instead of direct curvature measures. To this end, we propose a generalization of classical Cobb angles that can be evaluated algorithmically and can also serve as a useful (visual) tool for physicians in everyday clinical practice.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{navab_illustrative_2015,

title = {Illustrative Visualization of Vascular Models for Static 2D Representations},

author = {K Lawonn and M Luz and B Preim and C Hansen},

url = {http://link.springer.com/10.1007/978-3-319-24571-3_48},

doi = {10.1007/978-3-319-24571-3_48},

year  = {2015},

date = {2015-01-01},

urldate = {2015-01-01},

booktitle = {Medical Image Computing and Computer Assisted Intervention (MICCAI)},

pages = {399–406},

abstract = {Depth assessment of 3D vascular models visualized on 2D displays is often difficult, especially in complex workspace conditions such as in the operating room. To address these limitations, we propose a new visualization technique for 3D vascular models. Our technique is tailored to static monoscopic 2D representations, as they are often used during surgery. To improve depth assessment, we propose a combination of supporting lines, view-aligned quads, and illustrative shadows. In addition, a hatching scheme that uses different line styles depending on a distance measure is applied to encode vascular shape as well as the distance to tumors. The resulting visualization can be displayed on monoscopic 2D monitors and on 2D printouts without the requirement to use color or intensity gradients. A qualitative study with 15 participants and a quantitative study with 50 participants confirm that the proposed visualization technique significantly improves depth assessment of complex 3D vascular models.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}