Institut für Medizintechnik und Medizininformatik
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- PublikationTracking of a magnetically navigated millirobot with a magnetic-field camera(IEEE, 10.04.2024) Vergne, Céline; Pinto Inácio, José Miguel; Quirin, Thomas; Sargent, David; Madec, Morgan; Pascal, Joris [in: IEEE Sensors Journal]A significant progress has been made in the development of magnetic micromanipulation for minimally invasive surgery. The development of systems to localize millimeter-sized robots during magnetic manipulation without line-of-sight detection remains, however, a challenging task. In this study, we focused on the development of a tracking system aiming to fill this gap. A robot, which consists of a cylindrical magnet of 1-mm diameter, is localized using a 2-D array of 3-D magnetoresistive sensors. The system, also called magnetic-field camera (MFC), provides tracking of the robot with a refresh rate of 2 Hz. The developed tracking algorithm reaches a mean absolute error (MAE) for the position and the orientation of, respectively, 0.56 mm and 5.13° in 2-D. This system can be added to the existing magnetic manipulation systems (MMSs) allowing closed-loop control of the navigation. The performances of the MFC are not affected by an exposure to strong magnetic fields. Exposures up to 3 T have been validated. Increasing the integrability of the MFC into MMSs. The presented tracking system makes it possible to target applications, such as minimally invasive eye surgery or drug delivery. The high spatial and magnetic resolutions allow the tracking of magnetic particles, down to 200- μm diameter, when placed close to the surface. The system could also be suitable for the localization of small objects for 2-D biomanipulation.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationGeometric cuts by an autonomous laser osteotome increase stability in mandibular reconstruction with free fibula grafts. A cadaver study(Elsevier, 2024) Gottsauner, Maximilian; Morawska, Marta M.; Tempel, Simon; Müller-Gerbl, Magdalena; Dalcanale, Federico; de Wild, Michael; Ettl, Tobias [in: Journal of Oral and Maxillofacial Surgery]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationGeometric cuts by an autonomous laser osteotome increase stability in mandibular reconstruction with free fibula grafts. A cadaver study(Elsevier, 2024) Gottsauner, Maximilian; Morawska, Marta M.; Tempel, Simon; Müller-Gerbl, Magdalena; Dalcanale, Federico; de Wild, Michael; Ettl, Tobias [in: Journal of Oral and Maxillofacial Surgery]Background Nonunion and plate exposure represent a major complication after mandibular reconstruction with free fibula flaps. These drawbacks may be resolved by geometric osteotomies increasing intersegmental bone contact area and stability. Purpose The aim of this study was to compare intersegmental bone contact and stability of geometric osteotomies to straight osteotomies in mandibular reconstructions with free fibula grafts performed by robot-guided erbium-doped yttrium aluminum garnet laser osteotomy.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationLow-coercivity perpendicular spin transfer torque magnetic tunnel junctions as nanoscale magnetic sensors(IEEE, 09/2023) Nicolas, Hugo; Sousa, Ricardo C.; Mora-Hernández, Ariam; Prejbeanu, Ioan-Lucian; Hebrard, Luc; Kammerer, Jean-Baptiste; Pascal, Joris [in: 2023 IEEE International Magnetic Conference - Short Papers (INTERMAG Short Papers)]This paper presents the use of the spin transfer torque effect in perpendicular magnetic tunnel junctions to operate the devices as magnetic sensors. The junctions, specifically designed for sensing applications exhibit close to low-coercivity, allowing the sensitivity to be as high as 25 mV/mT for a large dynamic range of 20 mT. In addition, the junctions have diameters ranging from 20 to 100 nanometers, making them among the smallest magnetic sensing elements ever reported to our knowledge. A single operational amplifier operates the junction and outputs a voltage proportional to the external magnetic field. This paper opens the way to a monolithic integration of both the conditioning electronics and the perpendicular magnetic tunnel junction.04B - Beitrag Konferenzschrift
- PublikationParameter optimization in a finite element mandibular fracture fixation model using the design of experiments approach(Elsevier, 08/2023) Maintz, Michaela; Msallem, Bilal; de Wild, Michael; Seiler, Daniel; Herrmann, Sven; Feiler, Stefanie; Sharma, Neha; Dalcanale, Federico; Cattin, Philippe; Thieringer, Florian Markus [in: Journal of the Mechanical Behavior of Biomedical Materials]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationSolving the explainable AI conundrum by bridging clinicians’ needs and developers’ goals(Nature, 22.05.2023) Bienefeld, Nadine; Boss, Jens Michael; Lüthy, Rahel; Brodbeck, Dominique; Azzati, Jan; Blaser, Mirco; Willms, Jan; Keller, Emanuela [in: npj Digital Medicine]Explainable artificial intelligence (XAI) has emerged as a promising solution for addressing the implementation challenges of AI/ML in healthcare. However, little is known about how developers and clinicians interpret XAI and what conflicting goals and requirements they may have. This paper presents the findings of a longitudinal multi-method study involving 112 developers and clinicians co-designing an XAI solution for a clinical decision support system. Our study identifies three key differences between developer and clinician mental models of XAI, including opposing goals (model interpretability vs. clinical plausibility), different sources of truth (data vs. patient), and the role of exploring new vs. exploiting old knowledge. Based on our findings, we propose design solutions that can help address the XAI conundrum in healthcare, including the use of causal inference models, personalized explanations, and ambidexterity between exploration and exploitation mindsets. Our study highlights the importance of considering the perspectives of both developers and clinicians in the design of XAI systems and provides practical recommendations for improving the effectiveness and usability of XAI in healthcare.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationHow sample size impacts probabilistic stimulation maps in deep brain stimulation(MDPI, 03.05.2023) Nordin, Teresa; Blomstedt, Patric; Hemm-Ode, Simone; Wårdell, Karin [in: Brain Sciences]Probabilistic stimulation maps of deep brain stimulation (DBS) effect based on voxel-wise statistics (p-maps) have increased in literature over the last decade. These p-maps require correction for Type-1 errors due to multiple testing based on the same data. Some analyses do not reach overall significance, and this study aims to evaluate the impact of sample size on p-map computation. A dataset of 61 essential tremor patients treated with DBS was used for the investigation. Each patient contributed with four stimulation settings, one for each contact. From the dataset, 5 to 61 patients were randomly sampled with replacement for computation of p-maps and extraction of high- and low-improvement volumes. For each sample size, the process was iterated 20 times with new samples generating in total 1140 maps. The overall p-value corrected for multiple comparisons, significance volumes, and dice coefficients (DC) of the volumes within each sample size were evaluated. With less than 30 patients (120 simulations) in the sample, the variation in overall significance was larger and the median significance volumes increased with sample size. Above 120 simulations, the trends stabilize but present some variations in cluster location, with a highest median DC of 0.73 for n = 57. The variation in location was mainly related to the region between the high- and low-improvement clusters. In conclusion, p-maps created with small sample sizes should be evaluated with caution, and above 120 simulations in single-center studies are probably required for stable results.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationA survey of practice patterns for real-time intrafractional motion-management in particle therapy(Elsevier, 26.04.2023) Zhang, Ye; Trnkova, Petra; Toshito, Toshiyuki; Heijmen, Ben; Richter, Christian; Aznar, Marianne; Albertini, Francesca; Bolsi, Alexandra; Daartz, Juliane; Bertholet, Jenny; Knopf, Antje [in: Physics and Imaging in Radiation Oncology]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationA survey of practice patterns for adaptive particle therapy for interfractional changes(Elsevier, 04/2023) Trnkova, Petra; Zhang, Ye; Toshito, Toshiyuki; Heijmen, Ben; Richter, Christian; Aznar, Marianne C.; Albertini, Francesca; Bolsi, Alessandra; Daartz, Juliane; Knopf, Antje; Bertholet, Jenny [in: Physics and Imaging in Radiation Oncology]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationTest-re-test reliability and dynamics of the Fukuda–Unterberger stepping test(Frontiers Research Foundation, 29.03.2023) Hemm-Ode, Simone; Baumann, Denise; Duarte da Costa, Vasco; Tarnutzer, Alexander Andrea [in: Frontiers in Neurology]The Fukuda-stepping-test (FST), i.e., repetitive walking on the spot while blindfolded, has been proposed as a means to assess the integrity of the vestibular pathways. While its sensitivity to detect abnormalities in patients is limited, it may be useful in studying the physiology of the subjective-straight-ahead (SSA). Considering reported systematic shifts in SSA in humans, we hypothesize that such asymmetries arise from individual differences in the orientation/configuration of the macular organs and in central processing of vestibular input. We hypothesize that such asymmetries are stable over time in individual subjects. Alternatively, such asymmetries may arise from random noise in the sensory/motor systems involved, demonstrating low reproducibility over time. Materials and methods: Twenty-four subjects walked on the spot over 60 s while blindfolded. Using an inertial measurement unit (IMU) placed at the chest, angular deviations were recorded and compared to manually-measured final positions. Both static (direction, magnitude) and dynamic (time-to-onset of deviation, pattern of deviations) parameters were retrieved from the yaw slopes. Significant deviations were found in 15/24 participants for the manual measurements (leftwards = 8; rightwards = 7), whereas when using the IMU-sensor 13/24 participants showed significant shifts (leftwards = 9; rightwards = 4). There was a high correlation (0.98) between manually measured rotation angles (average absolute deviations = 58.0 deg ± 48.6 deg; intra-individual variability = 39 deg ± 24 deg) and sensor-based yaw slopes (1.00 deg/s ± 0.88 deg/s; 0.67 deg/s ± 0.41 deg/s). Relevant yaw deviation was detected 22.1 s ± 12.3 s (range = 5.6 s-59.2 s) after the onset of marching (no relevant yaw-deviation in 15/139 measurements), showing a mostly linear behavior over time. Conclusion: We observed significant inter-individual variability in task performance in the FST, reproducing findings from previous studies. With test-re-test reliability being moderate only, but at the same time observing a preference in the side of shifts in most trials and subjects, we conclude that likely both individually varying estimates of straight-ahead and random noise contribute to the pattern of angular deviations observed. Using an IMU-sensory based approach, additional dynamic parameters could be retrieved, emphasizing the value of such a quantitative approach over manual measurements. Such an approach may provide useful additional information to distinguish patients from healthy controls.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationWear estimation of hip implants with varying chamfer geometry at the trunnion junction. A finite element analysis(IOP Publishing, 01.03.2023) Gutmann, Celine; Shaikh, Numa; Shenoy, B. Satish; Bhat, Shaymasunder N.; Keni, Laxmikant G.; K. N., Chetan [in: Biomedical Physics & Engineering Express]The hip joint helps the upper body to transfer its weight to lower body. Along with age, there are various reasons for the degeneration of the hip joint. The artificial hip implant replaces the degenerated hip. Wear between the joints is the primary cause of the hip implant becoming loose. The wear can occur due to various reasons. Due to this revision surgery are most common in young and active patients. In the design phase of the implant if this is taken care then life expectancy of the implant can be improved. Small design changes can significantly enhance the implant’s life. In this work, elliptical-shaped hip implant stem is designed, and linear wear is estimated at trunnion junction. In this work, a 28 mm diameter femoral head with a 4 mm thick acetabular cup and a 2 mm thick backing cup is used. The top surface taper radiuses are changed. Solid works was used to create the models. Ansys was used to perform the analysis. It was found that as the radius of the TTR decreased, the wear rate decreased. The least wear rate was found in 12/14 mm taper with a value of 1.15E for the first material combination and with a value of 1.23E for the second material combination. In the comparison between the models with 1 mm chamfer and no chamfer, it was found that the wear rate was lower for the models with 1 mm chamfer. When the chamfer was increased (more than 1 mm), the linear wear increased. Wear is the main reason for the loosening of hip implants, which leads to a revision of an implant. It was found that with a decrease in TTR, there was a small increase in the linear wear rate. Overall, the implant with TTR 6 mm and a chamfer of 1 mm was found to have the least wear rate. To validate these results, the implant can be 3D printed and tested on a hip simulator.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationLow-field electromagnetic tracking using 3-D magnetometer for assisted surgery(IEEE, 02/2023) Vergne, Céline; Féry, Corentin; Quirin, Thomas; Nicolas, Hugo; Madec, Morgan; Hemm-Ode, Simone; Pascal, Joris [in: IEEE Transactions on Magnetics]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationEffect of printing parameters on mechanical performance of material-extrusion 3D-printed PEEK specimens at the point-of-care(MDPI, 17.01.2023) Zarean, Paridokht; Zarean, Parichehr; de Wild, Michael; Thieringer, Florian M.; Sharma, Neha; Seiler, Daniel; Malgaroli, Patrick [in: Applied Sciences]Additive manufacturing (AM) of polyetheretherketone (PEEK) biomaterials using the material-extrusion (MEX) method has been studied for years. Because of the challenging manufacturing process, precisely controlling printing parameters is crucial. This study aimed to investigate the effects of printing parameters such as orientation and position of printing on mechanical properties. Thus, 34 samples were printed using PEEK filament and the MEX process. Samples were divided into two main groups (A,B) according to their printing orientations (A: groups 1–3) and positions on the build plate (B: groups 4–8). Mechanical tensile tests were performed to evaluate the effects of different printing orientations and positions on mechanical properties. The means of the tensile modulus in samples 3D-printed in XY (group 1), XZ (group 2), and ZX (group 3) orientations were not significantly different (p-value = 0.063). Groups 1 and 2 had smaller distributions than group 3 in the means of tensile strength. The t-test showed that the overall means of the measurements in groups 4–8 did not differ significantly (p-value = 0.315). The tensile tests indicated that printing in vertical and horizontal orientations had no significant influence on mechanical properties. There were no significant differences in mechanical strength between top/bottom printed samples in five different lateral positions. Reliability of printing with good mechanical properties could be a step forward to manufacturing patient-specific implants.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationTowards a novel cost-effective and versatile bioink for 3D-bioprinting in tissue engineering(MDPI, 09.01.2023) Züger, Fabian; Berner, Natascha; Gullo, Maurizio [in: Biomimetics]3D-bioprinting for tissue regeneration relies on, among other things, hydrogels with favorable rheological properties. These include shear thinning for cell-friendly extrusion, post-printing structural stability as well as physiologically relevant elastic moduli needed for optimal cell attachment, proliferation, differentiation and tissue maturation. This work introduces a cost-efficient gelatin-methylcellulose based hydrogel whose rheological properties can be independently optimized for optimal printability and tissue engineering. Hydrogel viscosities were designed to present three different temperature regimes: low viscosity for eased cell suspension and printing with minimal shear stress, form fidelity directly after printing and long term structural stability during incubation. Enzymatically crosslinked hydrogel scaffolds with stiffnesses ranging from 5 to 50 kPa were produced, enabling the hydrogel to biomimic cell environments for different types of tissues. The bioink showed high intrinsic cytocompatibility and tissues fabricated by embedding and bioprinting NIH 3T3 fibroblasts showed satisfactory viability. This novel hydrogel uses robust and inexpensive technology, which can be adjusted for implementation in tissue regeneration, e.g., in myocardial or neural tissue engineering.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMonitoring the exposure to magnetic fields of MRI workers using goggles integrating magnetometers(2023) Jeker, Dominic; Quirin, Thomas; Pascal, Joris [in: 2023 IEEE International Symposium on Medical Measurements and Applications (MeMeA)]04B - Beitrag Konferenzschrift
- PublikationReal-time feature extraction from electrocochleography with impedance measurements during cochlear implantation using linear state-space models(IEEE, 2023) Andonie, Raphael R.; Wimmer, Wilhelm; Wildhaber, Reto; Caversaccio, Marco; Weder, Stefan [in: IEEE Transactions on Biomedical Engineering]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAssessment of the impact of static field inhomogeneity on the performance of miniaturized NMR devices(IEEE, 2023) Baumgarten, Guilherme; Madec, Morgan; Nguyen, Duc-Vinh; Werling, Lucas; Pascal, Joris; Gajendramurthy, Chunchesh Malangi; Bertani, Philippe; Djukic, Jean-Pierre; Hebrard, Luc [in: IEEE Transactions on Magnetics]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationGradiometer-based magnetic localization for medical tools(IEEE, 2023) Fischer, Cedric; Quirin, Thomas; Chautems, Christophe; Boehler, Quentin; Pascal, Joris; Nelson, Bradley J. [in: IEEE Transactions on Magnetics]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationExtraction of canine gait characteristics using a mobile gait analysis system based on inertial measurement units(Elsevier, 2023) Altermatt, Matthias; Kalt, Denise; Blättler, P.; Schkommodau, Erik [in: Veterinary and Animal Science]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAn origami 3D patterned cellulose-based scaffold for bioengineering cardiovascular applications(Springer, 2023) Gullo, Maurizio; Melo Rodriguez, Gabriela; Trueb, Donata; Schoelkopf, Joachim; Köser, Joachim [in: Cellulose]01A - Beitrag in wissenschaftlicher Zeitschrift