Maria Luz

Automation in surgery: the impact of navigated-control assistance on performance, workload, situation awareness, and acquisition of surgical skills.

Objective: Human performance consequences of a new technology of image-guided navigation (IGN) support for surgeons are investigated. Background: Navigated control (NC) represents an advancement of IGN technology. In contrast to currently available pointer-based systems, it represents a higher degree of automation that supports processes not only of information analysis and integration but also of intraoperative decision making. Method: In the first experiment, 14 surgical novices performed a simulated mastoidectomy with and without NC support. Effects of provision of the system were analyzed with respect to different measures of surgical performance and outcome, workload, and situation awareness. In the second experiment, 21 advanced medical students were trained to perform a mastoidectomy by practicing it either with or without NC support. It was investigated to what extent the provision of the system during practice would affect the acquisition of surgical skills. Results: The results reveal that NC support can reduce both the risk of intraoperative injuries and complications as well as the physiological effort of surgeons. “Cost effects” compared to a conventional (i.e., not supported) surgery emerged with respect to the time needed for the surgery, increased subjective workload, reduced spare capacity, and a reduced level of situation awareness. However, no significant effects on processes of skill acquisition were found. Conclusion: NC systems can contribute to improved patient safety. Most of the cost effects seem to be related not to the basic principle of NC but to its current technological implementation. Application: The results have consequences for the design and clinical use of automated navigation support.

Illustrative Visualization of Vascular Models for Static 2D Representations

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.

Impact of navigated-control assistance on performance, workload and situation awareness of experienced surgeons performing a simulated mastoidectomy

Navigated control (NC) is an advanced image‐guided navigation system that provides an additional control function to enhance patient safety. It automatically stops the surgical instrument if it comes close to critical anatomical structures that need to be protected during surgery. The purpose of this study was to explore the human performance consequences of computer‐based navigated control assistance.

Comparison of gesture and conventional interaction techniques for interventional neuroradiology

PurposeInteraction with radiological image data and volume renderings within a sterile environment is a challenging task. Clinically established methods such as joystick control and task delegation can be time-consuming and error-prone and interrupt the workflow. New touchless input modalities may have the potential to overcome these limitations, but their value compared to established methods is unclear.MethodsWe present a comparative evaluation to analyze the value of two gesture input modalities (Myo Gesture Control Armband and Leap Motion Controller) versus two clinically established methods (task delegation and joystick control). A user study was conducted with ten experienced radiologists by simulating a diagnostic neuroradiological vascular treatment with two frequently used interaction tasks in an experimental operating room. The input modalities were assessed using task completion time, perceived task difficulty, and subjective workload.ResultsOverall, the clinically established method of task delegation performed best under the study conditions. In general, gesture control failed to exceed the clinical input approach. However, the Myo Gesture Control Armband showed a potential for simple image selection task.ConclusionNovel input modalities have the potential to take over single tasks more efficiently than clinically established methods. The results of our user study show the relevance of task characteristics such as task complexity on performance with specific input modalities. Accordingly, future work should consider task characteristics to provide a useful gesture interface for a specific use case instead of an all-in-one solution.

Auditory feedback to support image-guided medical needle placement

PurposeDuring medical needle placement using image-guided navigation systems, the clinician must concentrate on a screen. To reduce the clinician’s visual reliance on the screen, this work proposes an auditory feedback method as a stand-alone method or to support visual feedback for placing the navigated medical instrument, in this case a needle.MethodsAn auditory synthesis model using pitch comparison and stereo panning parameter mapping was developed to augment or replace visual feedback for navigated needle placement. In contrast to existing approaches which augment but still require a visual display, this method allows view-free needle placement. An evaluation with 12 novice participants compared both auditory and combined audiovisual feedback against existing visual methods.ResultsUsing combined audiovisual display, participants show similar task completion times and report similar subjective workload and accuracy while viewing the screen less compared to using the conventional visual method. The auditory feedback leads to higher task completion times and subjective workload compared to both combined and visual feedback.ConclusionAudiovisual feedback shows promising results and establishes a basis for applying auditory feedback as a supplement to visual information to other navigated interventions, especially those for which viewing a patient is beneficial or necessary.

Improving spatial perception of vascular models using supporting anchors and illustrative visualization

We provide supporting anchors for depth assessment.We describe an algorithm that place the anchors optimal in a view-dependent manner.We introduce a novel and fast real-time hatching scheme that outperforms state-of-the-art methods regarding computation time and memory usage. Display Omitted Incorrect spatial interpretation of 3D vascular models is a main perceptional problem in medical visualization. For improved depth perception, we propose supporting anchors between vascular trees and a cylindrical cutaway that serves as an insight for a virtual resection surface or a path for a tumor ablation. The supporting anchors are optimally arranged in a circular manner such that the depth can be perceived without time-consuming interaction. For improved shape perception and distance-encoding, we additionally employ a novel and fast hatching approach that produces results comparable to state-of-the-art techniques. The advantages of our new visualization approach are demonstrated using the example of laparoscopic liver surgery and confirmed in a quantitative user study with 81 participants. The results show that participants were able to assess relative distances more precisely and were most confident using our illustrative visualization approach.

Foot Interaction Concepts to Support Radiological Interventions

Abstract During neuroradiological interventions, physicians need to interact with medical image data, which cannot be done while the hands are occupied. We propose foot input concepts with one degree of freedom, which matches a common interaction task in the operating room. We conducted a study to compare our concepts in regards to task completion time, subjective workload and user experience. Relative input performed significantly better than absolute or rate-based input. Our findings may enable more effective computer interactions in the operating room and similar domains where the hands are not available.

GazeTap: towards hands-free interaction in the operating room

During minimally-invasive interventions, physicians need to interact with medical image data, which cannot be done while the hands are occupied. To address this challenge, we propose two interaction techniques which use gaze and foot as input modalities for hands-free interaction. To investigate the feasibility of these techniques, we created a setup consisting of a mobile eye-tracking device, a tactile floor, two laptops, and the large screen of an angiography suite. We conducted a user study to evaluate how to navigate medical images without the need for hand interaction. Both multimodal approaches, as well as a foot-only interaction technique, were compared regarding task completion time and subjective workload. The results revealed comparable performance of all methods. Selection is accomplished faster via gaze than with a foot only approach, but gaze and foot easily interfere when used at the same time. This paper contributes to HCI by providing techniques and evaluation results for combined gaze and foot interaction when standing. Our method may enable more effective computer interactions in the operating room, resulting in a more beneficial use of medical information.

Semiautomatic neck curve reconstruction for intracranial aneurysm rupture risk assessment based on morphological parameters

PurposeMorphological parameters of intracranial aneurysms (IAs) are well established for rupture risk assessment. However, a manual measurement is error-prone, not reproducible and cumbersome. For an automatic extraction of morphological parameters, a 3D neck curve reconstruction approach to delineate the aneurysm from the parent vessel is required.MethodsWe present a 3D semiautomatic aneurysm neck curve reconstruction for the automatic extraction of morphological parameters which was developed and evaluated with an experienced neuroradiologist. We calculate common parameters from the literature and include two novel angle-based parameters: the characteristic dome point angle and the angle difference of base points.ResultsWe applied our method to 100 IAs acquired with rotational angiography in clinical routine. For validation, we compared our approach to manual segmentations yielding highly significant correlations. We analyzed 95 of these datasets regarding rupture state. Statistically significant differences were found in ruptured and unruptured groups for maximum diameter, maximum height, aspect ratio and the characteristic dome point angle. These parameters were also found to statistically significantly correlate with each other.ConclusionsThe new 3D neck curve reconstruction provides robust results for all datasets. The reproducibility depends on the vessel tree centerline and the user input for the initial dome point and parameters characterizing the aneurysm neck region. The characteristic dome point angle as a new metric regarding rupture risk assessment can be extracted. It requires less computational effort than the complete neck curve reconstruction.

Guidelines for Quantitative Evaluation of Medical Visualizations on the Example of 3D Aneurysm Surface Comparisons

Medical visualizations are highly adapted to a specific medical application scenario. Therefore, many researchers conduct qualitative evaluations with a low number of physicians or medical experts to assess the benefits of their visualization technique. Although this type of research has advantages, it is difficult to reproduce and can be subjectively biased. This makes it problematic to quantify the benefits of a new visualization technique. Quantitative evaluation can objectify research and help bringing new visualization techniques into clinical practice. To support researchers, we present guidelines to quantitatively evaluate medical visualizations, considering specific characteristics and difficulties. We demonstrate the adaptation of these guidelines on the example of comparative aneurysm surface visualizations. We developed three visualization techniques to compare aneurysm volumes. The visualization techniques depict two similar, but not identical aneurysm surface meshes. In a user study with 34 participants and five aneurysm data sets, we assessed objective measures (accuracy and required time) and subjective ratings (suitability and likeability). The provided guidelines and presentation of different stages of the evaluation allow for an easy adaptation to other application areas of medical visualization.