Christian Hansen

Christian Hansen
Otto-von-Guericke-Universität Magdeburg | OvGU · Department of Simulation and Graphics (ISG)

PhD

About

204
Publications
44,242
Reads
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1,476
Citations
Introduction
I am interested in interdisciplinary and application-oriented research in the following fields of computer science: Human-Machine Interaction, Virtual and Augmented Reality, Illustrative Visualization and Medical Image Computing. In recent years, the application focus of my research has been on interventional radiology, liver surgery and urology.
Additional affiliations
March 2017 - February 2018
Harvard Medical School
Position
  • Research Associate
September 2013 - present
Otto-von-Guericke-Universität Magdeburg
Position
  • Professor
September 2006 - September 2013
Fraunhofer Institute for Digital Medicine MEVIS
Position
  • Researcher
Education
May 2009 - May 2012
Jacobs University
Field of study
  • Computer Science

Publications

Publications (204)
Article
Full-text available
Cancer is a disease which requires a significant amount of careful medical attention. For minimally-invasive thermal ablation procedures, the monitoring of heat distribution is one of the biggest challenges. In this work, three approaches for volumetric heat map reconstruction (Delauney triangulation, minimum volume enclosing ellipsoids (MVEE) and...
Article
Due to the optimisation of conservative treatment, the improvement of imaging methods and the continuous development of surgical techniques, the borders of resectability in liver surgery have changed significantly in recent decades.Thanks to numerous technical developments, in particular three-dimensional segmentation, preoperative planning and ori...
Conference Paper
Full-text available
People with disabilities are often denied the opportunity to obtain a vocational qualification. There is a lack of an appropriate infrastructure for an inclusive education system and recognized degrees. Therefore, didactic methods for inclusive learning situations are needed. This paper describes the user-centered development and evaluation of a se...
Article
Ultrasound is a widely used imaging technique and is appreciated for its non-invasiveness, absence of radiation, widespread availability, and compact equipment. Ergonomic difficulties in manual handling of the probe could be enhanced by a robotic controlled ultrasound. The paper addresses the development of such a system which enables remote operat...
Article
Touchless interaction is popular in the medical domain because it maintains sterility and ensures physicians’ autonomy. Evaluating these technologies, however, proves difficult due to technical and human hurdles. Virtual reality leaves these limitations behind and allows for the exploration of promising concepts by simulating an environment and the...
Article
The rapid development of available hard- and software for computer-assisted or augmented reality (AR) guided interventions creates a need for fast and inexpensive prototyping environments. However, intraoperative tracking systems in particular represent a high cost threshold. Therefore, this work presents a low-cost tracking method based on a conve...
Article
Purpose: Insertion point identification is a major challenge for percutaneous interventions. Planning in 2D slice image data is time-consuming and inefficient. Automated path planning can help to overcome these challenges. However, the setup of the intervention room is difficult to consider. In addition, transferring the insertion point to the ski...
Article
Full-text available
To exploit the potential of virtual reality (VR) in medicine, the input devices must be selected carefully due to their different benefits. In this work, input devices for common interaction tasks in medical VR planning and training are compared. Depending on the specific purpose, different requirements exist. Therefore, an appropriate trade-off be...
Chapter
Due to the growing focus on minimally invasive surgery, there is increasing interest in intraoperative software support. For example, augmented reality can be used to provide additional information. Accurate registration is required for effective support. In this work, we present a manual registration method that aims at mimicking natural manipulat...
Article
Full-text available
Background A multitude of different diseases—benign and malign—can require surgery of the liver. The liver is an especially challenging organ for resection planning due to its unique and interindividually variable anatomy. This demands a high amount of mental imagination from the surgeon in order to plan accordingly - a skill, which takes years of...
Conference Paper
Full-text available
Figure 1: Example of the shape estimation task with the vascular model and Phong visualization. The hand is about to grab and align the arrow. 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 entert...
Preprint
Full-text available
Organ motion poses an unresolved challenge in image-guided interventions. In the pursuit of solving this problem, the research field of time-resolved volumetric magnetic resonance imaging (4D MRI) has evolved. However, current techniques are unsuitable for most interventional settings because they lack sufficient temporal and/or spatial resolution...
Preprint
Full-text available
BackgroundA multitude of different diseases – benign and malign – can require surgery of the liver. The liver is an especially challenging organ for resection planning due to its unique and interindividually variable anatomy. This demands a high amount of mental imagination from the surgeon in order to plan accordingly - a skill, which takes years...
Preprint
Full-text available
Background and Objective: Ultrasound (US) devices are often used in percutanous interventions. Due to their low image quality, the US image slices are aligned with pre-operative Computed Tomography/Magnetic Resonance Imaging (CT/MRI) images to enable better visibilities of anatomies during the intervention. This work aims at improving the deep lear...
Conference Paper
Full-text available
Nowadays, digital competence is required for participation in working life, education, and social activities. Vocational education is the key to teaching and development of digital skills. Technology enhanced learning offers enormous potential for improving equal participation and reducing access barriers. In order to meet the demands for equal acc...
Conference Paper
Full-text available
In this paper, we present an approach based on a combination of convolutional neural networks and analytical algorithms to interpolate between neighboring conebeam projections for upsampling along circular trajectories. More precisely, networks are trained to interpolate the angularly centered projection between the input projections of different a...
Article
Full-text available
Purpose Percutaneous needle insertion is one of the most common minimally invasive procedures. The clinician’s experience and medical imaging support are essential to the procedure’s safety. However, imaging comes with inaccuracies due to artifacts, and therefore sensor-based solutions were proposed to improve accuracy. However, sensors are usually...
Chapter
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 canbe fetched directly from the MR device, reducing th...
Chapter
CT-guided interventions are common practices in interventional radiology to treat oncological conditions. During these interventions, radiologists are exposed to radiation and faced with a non-ergonomic working environment. A robot-guided ultrasound (US) as a complementing imaging method for the purpose of needle guidance could help to overcome the...
Conference Paper
Purpose: Three-dimensional (3D) models of the liver are reported to improve preoperative planning in hepatobiliary surgery. These models can be presented as 3D-PDFs, 3D-printed models or with a recently developed immersive virtual reality (VR) application as a 3D VR model. To date, the quality, feasibility and surgeons’ preference of these 3D prese...
Preprint
Full-text available
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 t...
Article
Full-text available
Minimally invasive interventions, e.g., percutaneous needle interventions, have many advantages compared to traditional surgery. However, they may require complex and time-consuming planning with experience-dependent success. Automated access path planning is faster and more consistent but individual preferences and situational circumstances are no...
Article
Background and Objective Liver tumor ablation is often guided by ultrasound (US). Due to poor image quality, intraoperative US is fused with preoperative computed tomography or magnetic tomography (CT/MR) images to provide visual guidance. As of today, the underlying 2D US to 3D CT/MR registration problem remains a very challenging task. Methods W...
Article
Full-text available
Background: Preoperative three-dimensional (3D) reconstructions for liver surgery planning have been shown to be effective in reduction of blood loss and operation time. However, the role of the 'presentation modality' is not well investigated. We present the first study to compare 3D PDFs, 3D printed models (PR) and virtual reality (VR) 3D models...
Article
We developed a virtual road crossing assessment tool called iVRoad - immersive Virtual Road, which allows to put the patient into realistic road crossing situations and to record various parameters that can be used to quantify unilateral spatial neglect. We present a study with 18 stroke patients in which we evaluate our system with respect to usab...
Article
Surgical planning software is a key component in the treatment of tumor diseases. However, desktop-based systems provide only limited visualization and interaction opportunities. Moreover, collaborative planning among members of a surgical team is only possible to a limited extent. In this work, a collaborative virtual reality (VR) environment to a...
Conference Paper
A high level of motivation and frequent training are relevant in software-based rehabilitation to improve cognitive functioning after acquired brain injury. We evaluated the benefit of tailored user-centered gamification elements in a clinical study with N=83 outpatients undergoing three weeks of cognitive training in their home environment. The us...
Article
Full-text available
Preoperative assessment of the proximity of critical structures to the tumors is crucial in avoiding unnecessary damage during prostate cancer treatment. A patient-specific 3D anatomical model of those structures, namely the neurovascular bundles (NVB) and the external urethral sphincters (EUS), can enable physicians to perform such assessments int...
Article
Vascular structures are assessed, e.g., in tumor surgery to understand the influence of a planned resection on the vascular supply and venous drainage. The understanding of complex branching vascular structures may benefit from immersive virtual reality (VR) visualization. Therefore, the estimation of distance, depth and shape information is a cruc...
Article
Full-text available
The identification of subsurface structures during resection wound repair is a challenge during minimally invasive partial nephrectomy. Specifically, major blood vessels and branches of the urinary collecting system need to be localized under time pressure as target or risk structures during suture placement. This work presents concepts for AR visu...
Article
Full-text available
Purpose Three-dimensional (3D) surgical planning is widely accepted in liver surgery. Currently, the 3D reconstructions are usually presented as 3D PDF data on regular monitors. 3D-printed liver models are sometimes used for education and planning. Methods We developed an immersive virtual reality (VR) application that enables the presentation of...
Chapter
Recent progress in VR and AR hardware enables a wide range of educational applications. Anatomy education, where the complex spatial relations of the human anatomy need to be imagined, may benefit from the immersive experience. Also the integration of virtual information and real information, e.g., muscles and bone overlaid on the user’s body, are...
Conference Paper
Full-text available
Recent studies demonstrated the eligibility of convolutional neural networks (CNNs) for solving the image registration problem. CNNs enable faster transformation estimation and greater generalization capability needed for better support during medical interventions. Conventional fully-supervised training requires a lot of high-quality ground truth...
Preprint
Full-text available
Various convolutional neural network (CNN) based concepts have been introduced for the prostate's automatic segmentation and its coarse subdivision into transition zone (TZ) and peripheral zone (PZ). However, when targeting a fine-grained segmentation of TZ, PZ, distal prostatic urethra (DPU) and the anterior fibromuscular stroma (AFS), the task be...
Article
Full-text available
Purpose Resection site repair during laparoscopic oncological surgery (e.g. laparoscopic partial nephrectomy) poses some unique challenges and opportunities for augmented reality (AR) navigation support. This work introduces an AR registration workflow that addresses the time pressure that is present during resection site repair. Methods We propos...
Article
Full-text available
Various convolutional neural network (CNN) based concepts have been introduced for the prostate's automatic segmentation and its coarse subdivision into transition zone (TZ) and peripheral zone (PZ). However, when targeting a fine-grained segmentation of TZ, PZ, distal prostatic urethra (DPU) and the anterior fibromuscular stroma (AFS), the task be...
Conference Paper
Preoperative planning for liver surgery is a critical procedure to assess a potential resection and it supports surgeons to define the affected vessels and resection volume. Traditional surgical planning systems are widely used to support the planning with the usage of desktop-based 3D and 2D visualizations. However, desktop-based systems offer lim...
Preprint
Full-text available
Recent studies demonstrated the eligibility of convolutional neural networks (CNNs) for solving the image registration problem. CNNs enable faster transformation estimation and greater generalization capability needed for better support during medical interventions. Conventional fully-supervised training requires a lot of high-quality ground truth...
Preprint
Full-text available
We present a Virtual and Augmented Reality multiuser 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 de...
Article
Full-text available
Purpose In laparoscopic surgery training, experts guide novice physicians to desired instrument positions or indicate relevant areas of interest. These instructions are usually given via verbal communication or using physical pointing devices. To facilitate a sterile work flow and to improve training, new guiding methods are needed. This work propo...
Chapter
Nowadays, digital competence is required for participation in working life, education, and social activities. Vocational education is the key to teaching and development of digital skills. Technology enhanced learning offers enormous potential for improving equal participation and reducing access barriers. In order to meet the demands for equal acc...
Article
Full-text available
Augmented reality (AR) may be a useful technique to overcome issues of conventionally used navigation systems supporting medical needle insertions, like increased mental workload and complicated hand-eye coordination. Previous research primarily focused on the development of AR navigation systems designed for specific displaying devices, but differ...
Article
Full-text available
Background and objective: Accurate and reliable segmentation of the prostate gland in MR images can support the clinical assessment of prostate cancer, as well as the planning and monitoring of focal and loco-regional therapeutic interventions. Despite the availability of multi-planar MR scans due to standardized protocols, the majority of segment...
Article
Full-text available
Augmented reality (AR) is a widely researched route for navigation support in laparoscopic surgery. Accurate registration is a crucial component for such AR systems. We introduce two methods for interactive registration that aim to be minimally invasive to the workflow and to mimic natural manipulation of 3D objects. The methods utilise spatially t...
Article
Full-text available
Purpose In this work, a virtual environment for interprofessional team training in laparoscopic surgery is proposed. Our objective is to provide a tool to train and improve intraoperative communication between anesthesiologists and surgeons during laparoscopic procedures. Methods An anesthesia simulation software and laparoscopic simulation softwa...
Conference Paper
Full-text available
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 senso...
Preprint
Full-text available
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....
Preprint
Full-text available
Background and Objective: Accurate and reliable segmentation of the prostate gland in MR images can support the clinical assessment of prostate cancer, as well as the planning and monitoring of focal and loco-regional therapeutic interventions. Despite the availability of multi-planar MR scans due to standardized protocols, the majority of segmenta...
Chapter
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....
Article
Full-text available
Patient handover is an important part for information transfer between medical professionals in a clinical setting. Yet, in current medical education, these conversations are only trained sparsely, since they are costly to perform as they take place in offsite courses and are led by experts over several days. Virtual reality (VR)-based training cou...