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Eppo B. Wolvius

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12 records found

Augmented reality navigation for minimally invasive craniosynostosis surgery

A phantom study

Journal article - Abdullah Thabit, Mohamed Benmahdjoub, Marie Lise C. Van Veelen, W.J. Niessen, W.J. Niessen, W.J. Niessen, Eppo B. Wolvius, T. van Walsum, T. van Walsum

Purpose: In minimally invasive spring-assisted craniectomy, surgeons plan the surgery by manually locating the cranial sutures. However, this approach is prone to error. Augmented reality (AR) could be used to visualize the cranial sutures and assist in the surgery planning. The purpose of our work is to develop an AR-based system to visualize cranial sutures, and to assess the accuracy and usability of using AR-based navigation for surgical guidance in minimally invasive spring-assisted craniectomy. Methods: An AR system was developed that consists of an electromagnetic tracking system linked with a Microsoft HoloLens. The system was used to conduct a study with two skull phantoms. For each phantom, five sutures were annotated and visualized on the skull surface. Twelve participants assessed the system. For each participant, model alignment using six anatomical landmarks was performed, followed by the participant delineation of the visualized sutures. At the end, the participants filled a system usability scale (SUS) questionnaire. For evaluation, an independent optical tracking system was used and the delineated sutures were digitized and compared to the CT-annotated sutures. Results: For a total of 120 delineated sutures, the distance of the annotated sutures to the planning reference was 2.4 ± 1.2 mm. The average delineation time per suture was 13 ± 5 s. For the system usability questionnaire, an average SUS score of 73 was obtained. Conclusion: The developed AR-system has good accuracy (average 2.4 mm distance) and could be used in the OR. The system can assist in the pre-planning of minimally invasive craniosynostosis surgeries to locate cranial sutures accurately instead of the traditional approach of manual palpation. Although the conducted phantom study was designed to closely reflect the clinical setup in the OR, further clinical validation of the developed system is needed and will be addressed in a future work.@en

Biomechanical evaluation of additively manufactured patient-specific mandibular cage implants designed with a semi-automated workflow

A cadaveric and retrospective case study

Journal article - A. van Kootwijk, B. P. Jonker, Eppo B. Wolvius, M. Cruz Saldivar, M.A. Leeflang, J. Zhou, N. Tümer, Mohammad J. Mirzaali, A.A. Zadpoor

Objective: Mandibular reconstruction using patient-specific cage implants is a promising alternative to the vascularized free flap reconstruction for nonirradiated patients with adequate soft tissues, or for patients whose clinical condition is not conducive to microsurgical reconstruction. This study aimed to assess the biomechanical performance of 3D printed patient-specific cage implants designed with a semi-automated workflow in a combined cadaveric and retrospective case series study. Methods: We designed cage implants for two human cadaveric mandibles using our previously developed design workflow. The biomechanical performance of the implants was assessed with the finite element analysis (FEA) and quasi-static biomechanical testing. Digital image correlation (DIC) was used to measure the full-field strains and validate the FE models by comparing the distribution of maximum principal strains within the bone. The retrospective study of a case series involved three patients, each of whom was treated with a cage implant of similar design. The biomechanical performance of these implants was evaluated using the experimentally validated FEA under the scenarios of both mandibular union and nonunion. Results: No implant or screw failure was observed prior to contralateral bone fracture during the quasi-static testing of both cadaveric mandibles. The FEA and DIC strain contour plots indicated a strong linear correlation (r = 0.92) and a low standard error (SE=29.32με), with computational models yielding higher strain values by a factor of 2.7. The overall stresses acting on the case series’ implants stayed well below the yield strength of additively manufactured (AM) commercially pure titanium, when simulated under highly strenuous chewing conditions. Simulating a full union between the graft and remnant mandible yielded a substantial reduction (72.7±1.5%) in local peak stresses within the implants as compared to a non-bonded graft. Conclusions: This study shows the suitability of the developed semi-automated workflow in designing patient-specific cage implants with satisfactory mechanical functioning under demanding chewing conditions. The proposed workflow can aid clinical engineers in creating reconstruction systems and streamlining pre-surgical planning. Nevertheless, more research is still needed to evaluate the osteogenic potential of bone graft insertions.@en

Projection-Wise Disentangling for Fair and Interpretable Representation Learning

Application to 3D Facial Shape Analysis

Conference paper - Xianjing Liu, Bo Li, Esther E. Bron, W.J. Niessen, W.J. Niessen, W.J. Niessen, Eppo B. Wolvius, Gennady V. Roshchupkin

Confounding bias is a crucial problem when applying machine learning to practice, especially in clinical practice. We consider the problem of learning representations independent to multiple biases. In literature, this is mostly solved by purging the bias information from learned ...

Three-Dimensional Stereophotogrammetry in the Evaluation of Craniosynostosis

Current and Potential Use Cases

Journal article - Tareq Abdel-Alim, Rik Iping, Eppo B. Wolvius, Irene M.J. Mathijssen, Clemens M.F. Dirven, W.J. Niessen, W.J. Niessen, W.J. Niessen, Marie Lise C. Van Veelen, Gennady V. Roshchupkin

Three-dimensional (3D) stereophotogrammetry is a novel imaging technique that has gained popularity in the medical field as a reliable, non-invasive, and radiation-free imaging modality. It uses optical sensors to acquire multiple 2D images from different angles which are reconst ...

Three-Dimensional Stereophotogrammetry in the Evaluation of Craniosynostosis

Current and Potential Use Cases

Journal article - Tareq Abdel-Alim, Rik Iping, Eppo B. Wolvius, Irene M.J. Mathijssen, Clemens M.F. Dirven, W.J. Niessen, W.J. Niessen, W.J. Niessen, Marie Lise C. Van Veelen, Gennady V. Roshchupkin

Multimodal markers for technology-independent integration of augmented reality devices and surgical navigation systems

Journal article - Mohamed Benmahdjoub, W.J. Niessen, W.J. Niessen, W.J. Niessen, Eppo B. Wolvius, T. van Walsum

Augmented reality (AR) permits the visualization of pre-operative data in the surgical field of view of the surgeon. This requires the alignment of the AR device’s coordinate system with the used navigation/tracking system. We propose a multimodal marker approach to align an AR d ...

Evaluation of AR visualization approaches for catheter insertion into the ventricle cavity

Journal article - Mohamed Benmahdjoub, Abdullah Thabit, Marie Lise C. Van Veelen, W.J. Niessen, W.J. Niessen, W.J. Niessen, Eppo B. Wolvius, Theo Van Walsum

Augmented reality (AR) has shown potential in computer-aided surgery. It allows for the visualization of hidden anatomical structures as well as assists in navigating and locating surgical instruments at the surgical site. Various modalities (devices and/or visualizations) have b ...

Evaluation of Marker Tracking Using Mono and Stereo Vision in Microsoft HoloLens for Surgical Navigation

Conference paper - Abdullah Thabit, W.J. Niessen, W.J. Niessen, W.J. Niessen, Eppo B. Wolvius, T. van Walsum

Optical-based navigation systems are widely used in surgical interventions. However, despite their great utility and accuracy, they are expensive and require time and effort to setup for surgeries. Moreover, traditional navigation systems use 2D screens to display instrument posi ...

An automatic 3D facial landmarking algorithm using 2D gabor wavelets

Journal article - Markus A. De Jong, Markus A. De Jong, Andreas Wollstein, Andreas Wollstein, Andreas Wollstein, Eppo B. Wolvius, Stefan Böhringer, Clifford Ruff, David Dunaway, Pirro Hysi, Tim Spector, Fan Liu, W.J. Niessen, W.J. Niessen, M.J. Koudstaal, M.J. Koudstaal, Manfred Kayser

In this paper, we present a novel approach to automatic 3D facial landmarking using 2D Gabor wavelets. Our algorithm considers the face to be a surface and uses map projections to derive 2D features from raw data. Extracted features include texture, relief map, and transformation ...

An automatic 3D facial landmarking algorithm using 2D gabor wavelets

Ensemble landmarking of 3D facial surface scans

Journal article - M.A. de Jong, M.A. de Jong, Pirro Hysi, Tim Spector, W.J. Niessen, W.J. Niessen, M.J. Koudstaal, Eppo B. Wolvius, Manfred Kayser, Stefan Böhringer

Landmarking of 3D facial surface scans is an important analysis step in medical and biological applications, such as genome-wide association studies (GWAS). Manual landmarking is often employed with considerable cost and rater dependent variability. Landmarking automatically with ...

Contributed

1 records found

Development of a Workflow for Designing Patient-Specific Mandibular Reconstruction Implants and Predicting their Performance through Experimentally Validated Finite Element Models

Master thesis - A. van Kootwijk, Mohammad J. Mirzaali, N. Tümer, Mohammad Ahmadi, Eppo B. Wolvius, Brend P. Jonker, Siddhant Kumar, Vahid Moosabeiki

Restoration of the normal mandibular form and function is attempted with reconstructive surgery. The current standard procedure to restore continuity defects of the mandible involves free tissue transfer with an autologous bone flap. Even though the success rates are high, several critical drawbacks have been associated with this procedure, including severe donor site morbidity, long hospital stay and recovery process, need for high surgical expertise, insufficient bone graft height, and mechanical failure of the plating system. A systematic approach for the designing and testing of patient-specific implants used as an alternative to the free flap procedure appears to be still lacking. The goal of this thesis project was to develop a semiautomatic workflow for designing patient specific mandibular reconstruction implants and assess the effect of topology optimization on the biomechanical performance of the implant using the finite element analysis (FEA) and experimental validation. Using the proposed workflow, a fully porous implant (lattice implant) and a topology optimized implant (TO implant) were designed according to the anatomy of a synthetic mandible analog subjected to lateral resection, and were additively manufactured using selective laser melting. Both implants were designed in the shape of a cage to allow for the insertion of a bone graft and the integration of dental implants. The mechanical performance of the reconstructed mandibles was predicted with computational FEA and evaluated through quasi-static and cyclic experimental testing. Digital image correlation was used to validate the finite element model through principal strain field comparison. An excellent fit between the implants and mandibles was established, indicating the capability of the workflow to develop customized implants with accurate dimensions. The results obtained with FEA were in agreement with the DIC measurements and quasi-static testing results. No significant differences (P < 0.01) in mean stiffness, mean ultimate load, and mean ultimate displacement were found between the non-implanted control mandibles, lattice-implanted mandibles, and TO-implanted mandibles during quasi-static testing. No implant failure was observed during static nor cyclic testing at loads substantially higher than the average maximum biting force of healthy individuals, indicating the high resistance of the implant designs to mechanical failure. Yet, the lattice implant would likely be preferred over the TO implant for clinical application due to its lower weight (16.5%), higher porosity (17.4%), and shorter workflow time (633.3%). The workflow proposed in this study may offer surgeons and medical engineers the tools to systematically design and evaluate patient-specific reconstruction implants. This would result in more cost-effective and time-effective pre-surgical planning and result in implant designs that can minimize morbidity and maximize aesthetic and functional outcomes.