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10:00   Poster Session 2 (odd numbers) 10:00 0 mins Deep Sylvester Posterior Inference for Adaptive Compressed Sensing in Ultrasound Imaging Simon Penninga, Hans van Gorp, Ruud van Sloun Abstract: Ultrasound images are commonly formed by sequential acquisition of beam-steered scan-lines. Minimizing the number of required scan-lines can significantly enhance frame rate, field of view, energy efficiency, and data transfer speeds. The question we aim to answer is; Can we successfully infer the frames of a video from extreme sparse sampling? Next to this, if we do manage to infer the signal(s), can we exploit this knowledge to drive the sampling scheme, exploiting the gained knowledge? Existing approaches typically use static subsampling schemes in combination with sparsity-based or, more recently, deep-learning-based recovery. In this work, we introduce an adaptive subsampling method that maximizes intrinsic information gain in-situ, employing a Sylvester Normalizing Flow encoder to infer an approximate Bayesian posterior under partial observation in real-time. Using the Bayesian posterior and a deep generative model for future observations, we determine the subsampling scheme that maximizes the mutual information between the subsampled observations, and the next frame of the video. We evaluate our approach using the EchoNet cardiac ultrasound video dataset and demonstrate that our active sampling method outperforms competitive baselines, including uniform and variable-density random sampling, as well as equidistantly spaced scan- lines, improving mean absolute reconstruction error by 15%. Moreover, posterior inference and the sampling scheme generation are performed in just 0.015 seconds (66Hz), making it fast enough for real-time 2D ultrasound imaging applications. While the potential in 2D ultrasound imaging is limited, we hope that demonstrated inference under extreme sparsity will eventually allow for realtime 3D ultrasound linescanning. 10:00 0 mins Imaging behind the plaque: improved ultrasound blood flow quantification using an iterative scheme for active attenuation correction Jelle Plomp, Ashkan Ghanbarzadeh-Dagheyan, Michel Versluis, Guillaume Lajoinie, Erik Groot Jebbink Abstract: Introduction: A clear link exists between local blood flow phenomena and the development of atherosclerosis [1]. High frame rate (HFR), contrast-enhanced ultrasound imaging followed by particle image velocimetry (echoPIV) allows studying these flow phenomena in patients. However, atherosclerotic plaques are often calcified, introducing acoustic shadows where the signal strength received from the contrast agents is strongly reduced, leading to incomplete flow quantification. This occurs in 16 to 56% of the measurements during in vivo studies [2-4]. Resolving this problem would therefore be a major contribution towards the widespread applicability of echoPIV in clinical care. While globally increasing the acoustic pressure during image acquisition would in principle provide an increase in signal strength, it also leads to contrast agent destruction and signal loss. We therefore developed a method that improves the signal intensity in the acoustic shadow region while only locally increasing the pressure where needed. Main research question: to what extent can the accuracy of echoPIV-derived velocity fields in acoustic shadow regions behind arterial plaques be improved by locally increasing the acoustic pressure, while limiting the pressure increase in regions with sufficient signal? Methods: An iterative method was implemented that actively adapts the acoustic pressure transmitted by each transducer element in real-time, based on acquired images. The method uses an iterative controller, coupled to a linear acoustic model. Once optimized, the pressure profile was fixed and used to acquire HFR data. Evaluation was performed in an in vitro setup on 3D printed vessel phantoms that included a wall thickening to induce an acoustic shadow. A fully developed steady laminar flow was used. Results and Conclusions: The transmitted wavefront was actively adapted based on acquired images. In a plaque model with an attenuation of 8.5 dB, errors in the obtained flow velocities were reduced from 35% without adaptation to less than to 10% with the new iterative method. For higher attenuation values, despite being reduced, errors were still larger than 10% after beam adaptation. The developed method can contribute to more widespread applicability of echoPIV in clinical care and potentially also benefits other ultrasound applications that are affected by acoustic shadows. 10:00 0 mins Wavelet Analysis-based Neural Decomposition for Source Separation in MR Spectroscopy and Functional MRI Julian Merkofer, Dennis M. J. van de Sande, Sina Amirrajab, Kyung Min Nam, Alex A. Bhogal, Ruud J. G. van Sloun Abstract: Source separation presents a common challenge in magnetic resonance spectroscopy (MRS) and functional magnetic resonance imaging (fMRI), impacting the accuracy of metabolite quantification and interpretation of functional brain activity [1, 2]. In MRS, overlapping metabolite signals, low signal-to-noise ratios, and artifacts such as residual water and lipid contamination can hinder metabolite quantification [3, 4]. Similarly, separating neuronal activity from physiological noise, such as cardiac and respiratory pulsations, is essential for accurately interpreting brain activation patterns in fMRI [2]. This abstract introduces wavelet analysis-based neural decomposition (WAND), a novel data-driven method for decomposing MR signals into their constituent components. WAND exploits the improved separability of these components within the wavelet domain. It uses a U-Net architecture to predict masks for wavelet coefficients derived from the continuous wavelet transform (CWT). These masks effectively isolate desired signal components, allowing for clean, separated signals to be reconstructed using the inverse CWT. Notably, WAND generates an artifact mask by inverting the sum of all known signal masks, enabling it to capture and remove even unpredictable artifacts. Evaluations using simulated and in-vivo data show that WAND is effective in achieving accurate decomposition and enhancing quantification accuracy in MRS. WAND substantially improves the performance of linear combination model fitting methods, especially in spectra with strong artifacts like residual water and lipid contaminations. Moreover, WAND can be utilized in magnetic resonance spectroscopic imaging (MRSI) to enhance metabolite maps by eliminating artifacts within individual voxels. By integrating spatial information such as voxel correlations and positions, further advancements in MRSI analysis could be achieved. Additionally, WAND shows promise in functional MRS and fMRI for consistently removing artifacts and baseline fluctuations from time-series data. This could lead to more precise dynamic metabolite concentration estimates in fMRS and improve our understanding of brain function and vascular health. [1] R. Faghihi, B. Zeinali-Rafsanjani, M. A. Mosleh-Shirazi, et al., “Magnetic Resonance Spectroscopy and Its Clinical Applications: A Review,” JMIRS, 2017. [2] D. M. Cole, S. M. Smith, C. F. Beckmann, “Advances and pitfalls in the analysis and interpretation of resting-state FMRI data,” Frontiers in Systems Neuroscience, 2010. [3] A. A. Maudsley, O. C. Andronesi, P. B. Barker, et al., “Advanced magnetic resonance spectroscopic neuroimaging: Experts’ consensus recommendations,” NMR in Biomed, 2020. [4] R. E. Hurd, “Artifacts and pitfalls in MR spectroscopy,” in Clinical MR Neuroimaging: Physiological and Functional Techniques, 2009. 10:00 0 mins INVESTIGATING FEATURES FOR RESPIRATORY EFFORT IN OSA PATIENTS THROUGH DIAPHRAGMATIC ELECTROMYOGRAPHY Gabriela Gronska, Elisabetta Peri, Xi Long, Johannes van Dijk, Massimo Mischi Abstract: Introduction: Obstructive sleep apnea (OSA) is a prevalent sleep disorder, which involves recurrent disruptions in airflow due to upper airway collapse, resulting in substantial health risks. Current diagnosis relies on respiratory effort, obtained by placing a catheter in the esophagus to estimate the esophageal pressure. Diaphragmatic electromyography (dEMG) is a non-invasive technique that studies diaphragm muscle activity during respiration, offering the potential for monitoring respiratory effort. However, there is no consensus on the most appropriate dEMG feature to assess respiratory effort. This study explores the sensitivity of different dEMG features to respiratory effort changes between normal breathing and hypopnea/apnea events in OSA patients. Methods: A subset of the SOMNIA dataset [1], including 7 OSA patients, was used. For each patient, we selected dEMG from all the segments related to hypopnea/apnea breathing events (AB), and four windows labeled as normal breathing (NB). This resulted in a total of 23 AB and 28 NB windows. Several features used in the respiration context were extracted from the dEMG envelope, such as the median area under the curve – AUC, median peak to peak - PTP, and variance in the signal – VAR. Furthermore, frequency-domain features from raw dEMG signals, such as mean and median power frequency (MNF, MDF), were explored. The difference in the distributions of features obtained for AB and NB was investigated by using a Wilcoxon signed-rank test. Results and Discussion: The findings from the analysis revealed significantly higher values in both the AUC and VAR when comparing the NB to AB (p < 0.05). In the case of P2P, feature values between NB and AB show no statistically significant difference. The MNF presented significantly lower values for AB (p<0.05). Lastly, results obtained for MDF did not present significant differences. The feature analysis supports the efficacy of AUC, VAR, and MNF in discriminating between AB and NB for dEMG. These findings underscore the potential of utilizing feature-based approaches to characterize heightened respiratory effort observed through dEMG signals, suggesting promising avenues for further research in non-invasive respiratory monitoring techniques. References [1] van Gilst M. M. et al. BMJ Open, 2019, 9 (11) 10:00 0 mins Mechanical evaluation of the KneeReviver device in knee joint distraction for tibiofemoral osteoarthritis treatment – A cadaver study Famke Janssen, Thom Bitter, Nico Verdonschot, Dennis Janssen Abstract: Introduction: Knee joint distraction (KJD) is an innovative treatment for younger patients (ages 45-65) with tibiofemoral osteoarthritis, aimed at unloading cartilage through separation of the femur and tibia. The KneeReviver (KR) is a device specifically developed for this kind of treatment. The KR functions by creating a joint gap, however internal springs and bone pins allow controlled narrowing of this gap during axial loading. While the KR has proven successful for some, the results vary among patients, highlighting the need for a deeper understanding of its mechanical behavior. This study investigated the mechanical principles of the KR under varying axial loads, questioning: 1) to what extent the KR has a pressure relieving effect at the tibiofemoral joint, 2) how the joint gap narrowing during axial loading is affected by the KR, and 3) what is the relative contribution of the KR’s internal springs and bone pins to joint gap narrowing. Methods: An experimental study using five cadaveric knees measured tibiofemoral contact pressures, joint gap narrowing, and spring compression under axial loads of 0, 1.2, 1.5, and 3 times body weight. Axial loading tests were performed with and without the KR. Results: It was found that the KR effectively reduced contact parameters (peak pressure, mean pressure, contact area, and load on cartilage) across all loads in all five cadavers. However, at physiological loading while walking with crutches (1.2 times body weight), the joint gap was not fully maintained. Spring compression increased with loading up to 1.2 times body weight but remained constant at higher loads. These findings confirm the KR's pressure-relieving effect, aligning with KJD principles, while revealing that maintaining the joint gap remains challenging during treatment. Notably, elastic deformation of bone pins plays a more significant role in joint gap narrowing than the compression of internal device springs. A limitation of this study is that the mechanical findings cannot be directly linked to patient outcomes. Although pressure-relieving effects of the KR are confirmed, it is crucial to investigate whether joint gap maintenance correlates with more optimal treatment outcomes. This insight may inform clinical protocols and lead to enhanced treatment strategies. 10:00 0 mins Digital Superphantoms for Thyroid Nodule Imaging using Photoacoustics Max Rietberg, Srirang Manohar Abstract: Background The incidence of thyroid nodules is increasing rapidly due to (over)detection caused by an increase in imaging practices [1]. These nodules require risk assessment since 10-15% are malignant and require treatment [2]. Currently, nodules are examined using ultrasound imaging, which is often insufficient to rule out thyroid cancer. Consequently, invasive diagnostic procedures, such as biopsies or surgery, are required to establish a definitive diagnosis [2]. Photoacoustic imaging (PAI) is a novel technique that combines the detection platform of ultrasound with an illumination source, generating ultrasound by exiting naturally occurring chromophores. PAI adds functional and molecular imaging, e.g. vasculature and oxygen saturation [3], which can be used for the risk stratification of nodules. This could be paramount in reducing unnecessary medical procedures, patient-stress and healthcare costs [4]. Methods To evaluate and optimize the design of a PAI device, we will create and utilize digital phantoms. These phantoms mimic the complex anatomy and optical and acoustic properties of the neck, which is why we call them digital superphantoms. These digital superphantoms enable us to simulate actual measurements on patients. However, while a superphantom can be created to perfectly reflect one person and one lesion, a PAI device must be optimized for a wide range of patients and lesions. Thus, a range of superphantoms must be created. To enable coverage of this biological range and provide control over the phantom design, anatomical structures are generated. This involves both stochastic rule-based models [5] and more advanced models, such as statistical shape models [6]. For example, the former is used for the generation of microvasculature (a potential biomarker), while the latter is used for larger structures such as the thyroid itself. Furthermore, physical properties are generated on a voxel level instead of the structure level. This is necessary to include, for example, a changing tissue oxygen saturation within structures. Results Phantoms based on the Totalsegmentator dataset [7] have been created, where several structures have already been replaced with generated versions. Microvasculature has been realized with a modification of the model from Kreitner et al. [8], and a PAI pipeline was implemented using SIMPA [9].   References 1. Tamhane, S., & Gharib, H. (2016). Thyroid nodule update on diagnosis and management. Clinical Diabetes and Endocrinology, 2(1). https://doi.org/10.1186/s40842-016-0035-7 2. Kamran, S. C., Marqusee, E., Kim, M. I., Frates, M. C., Ritner, J., Peters, H., Benson, C. B., Doubilet, P. M., Cibas, E. S., Barletta, J., Cho, N., Gawande, A., Ruan, D., Moore, F. D., Pou, K., Larsen, P. R., & Alexander, E. K. (2013). Thyroid nodule size and prediction of cancer. The Journal of Clinical Endocrinology & Metabolism, 98(2), 564–570. https://doi.org/10.1210/jc.2012-2968 3. Cox, B., Laufer, J. G., Arridge, S. R., & Beard, P. C. (2012). Quantitative spectroscopic photoacoustic imaging: a review. Journal of Biomedical Optics, 17(6), 061202. https://doi.org/10.1117/1.jbo.17.6.061202 4. Noltes, M. E., Bader, M., Metman, M. J. H., Vonk, J., Steinkamp, P. J., Kukačka, J., Westerlaan, H. E., Dierckx, R. a. J. O., Van Hemel, B. M., Brouwers, A. H., Van Dam, G. M., Jüstel, D., Ntziachristos, V., & Kruijff, S. (2023). Towards in vivo characterization of thyroid nodules suspicious for malignancy using multispectral optoacoustic tomography. European Journal of Nuclear Medicine and Molecular Imaging, 50(9), 2736–2750. https://doi.org/10.1007/s00259-023-06189-1 5. Park, S., Villa, U., Li, F., Cam, R. M., Oraevsky, A. A., & Anastasio, M. A. (2023). Stochastic three-dimensional numerical phantoms to enable computational studies in quantitative optoacoustic computed tomography of breast cancer. Journal of Biomedical Optics, 28(06). https://doi.org/10.1117/1.jbo.28.6.066002 6. Morphomatics. (n.d.). https://morphomatics.github.io/ 7. Wasserthal, N. J. (2023). Dataset with segmentations of 117 important anatomical structures in 1228 CT images [Dataset]. In Zenodo (CERN European Organization for Nuclear Research). https://doi.org/10.5281/zenodo.10047292 8. Kreitner, L., Paetzold, J. C., Rauch, N., Chen, C., Hagag, A. M., Fayed, A. E., Sivaprasad, S., Rausch, S., Weichsel, J., Menze, B. H., Harders, M., Knier, B., Rueckert, D., & Menten, M. J. (2024). Synthetic optical coherence tomography angiographs for detailed retinal vessel segmentation without human annotations. IEEE Transactions on Medical Imaging, 1. https://doi.org/10.1109/tmi.2024.3354408 9. Gröhl, J., Dreher, K. K., Schellenberg, M., Rix, T., Holzwarth, N., Vieten, P., Ayala, L., Bohndiek, S. E., Seitel, A., & Maier-Hein, L. (2022). SIMPA: an open-source toolkit for simulation and image processing for photonics and acoustics. Journal of Biomedical Optics, 27(08). https://doi.org/10.1117/1.jbo.27.8.083010 10:00 0 mins Real-time Football Player Monitoring with Inertial, Global Positioning, Optical and Heart Rate Sensors Bouke Scheltinga, Jasper Reenalda Abstract: Tracking football players throughout training and matches is essential for preventing injuries, and understanding the physiological demands of matches and training. By continuously monitoring players' movements, exertion levels, and recovery times, coaches and sports scientists can adjust training to individual needs and potentially identify injury risks. Football player tracking during training is currently done through a combination of an inertial measurement unit (IMU), global positioning system (GPS), and heart rate monitor, embedded in a single vest. These vests measure in real-time speed, distance, acceleration, deceleration, and changes in direction. Furthermore, heart rate-derived metrics provide insights into cardiovascular responses throughout training. During matches in a stadium, optical tracking systems use multiple cameras around the field to monitor each player’s movement and position. These systems use advanced computer vision and machine learning algorithms to track player position and ball movements. The camera-based systems provide accurate data, however, this data is only available after the match and is not linked to heart rate monitoring. Furthermore, data from an optical system and a vest are not fully comparable. By fusing data from IMUs, GPS, and an optical tracking system, higher accuracy could be achieved in player monitoring, as each data source complements the others. The Fit to Purpose project is collaborating with amateur and professional football teams to develop an accurate real-time football player monitoring system, combining inertial, global positioning, optical and heart rate sensors. The aim is to create a system to monitor biomechanical and physiological parameters during matches, training and rehabilitation. With such a system, the load on players during matches and training could be monitored and training could be adjusted. Additionally, during rehabilitation, it can be objectively assessed to which extent players can return to play. Finally, using collected data, an injury model will be developed based on player characteristics, internal (heart rate) and external loads (speed, distance). Based on patterns in the data related to injuries, the system generates real-time recommendations, alerting coaches and players when an injury risk increases, and allowing for immediate adjustments. 10:00 0 mins Hypnogram and Hypnodensity Analysis of REM Sleep Behavior Disorder using both EEG and HRV-based Sleep Staging Models Jaap F. van der Aar, Merel M. van Gilst, Daan A. van den Ende, Hans van Gorp, Peter Anderer, Angelique Pijpers, Pedro Fonseca, Elisabetta Peri, Sebastiaan Overeem Abstract: Rapid-eye-movement (REM) sleep behavior disorder (RBD) is a primary sleep disorder strongly associated with Parkinson’s disease. Assessing sleep structure in RBD is important for understanding the underlying pathophysiology and for developing diagnostic methods. However, performance of automated sleep stage classification (ASSC) models is considered suboptimal in RBD, for both models utilizing neurological signals (“ExG”: EEG, EOG, and chin EMG) and heart rate variability (HRV) as obtained during polysomnography. Here, we explore this underperformance through the categorical representation of macro sleep structure (i.e., hypnogram) and a representation that leverages the underlying probability distribution of ASSCs (i.e., hypnodensity). By comparing the RBD population (n = 36) to a sex- and age-matched group of OSA patients chosen for their anticipated similar decreased sleep stability, we confirm lower 4-stage classification performance in both ExG-based ASSC (RBD: κ = .74, OSA: κ = .80) and HRV-based ASSC (RBD: κ = .50, OSA: κ = .63). Stages showing lower agreement in RBD, namely N1+N2 and REM sleep, exhibited elevated ambiguity in the hypnodensity, indicating more uncertain classification. Limited differences in bout durations between RBD and OSA suggested sleep instability is not necessarily driving lower agreement in RBD. However, stage transitions in OSA showed more abrupt changes in the underlying probability distribution, while RBD transitions had a more continuous profile, possibly complicating classification. Although both ExG-based and HRV-based automated sleep staging in RBD remains challenging, hypnodensity analysis is informative for the characterization of (RBD) sleep and can capture potential drivers of classification disagreement. 10:00 0 mins Assessing the performance of EVAR endografts on limb hemodynamics, an in-vitro study Hadi Mirgolbabaee, Bob Geelkerken, Michel Versluis, Michel Reijnen, Erik Groot Jebbink Abstract: Background: Endovascular aneurysm repair (EVAR) is the preferred treatment option for most abdominal aortic aneurysms (AAA), reducing hospital stay and recovery time compared to open surgery. However, EVAR suffers from long-term trombo-embolic complications like endograft limb thrombosis (LT) which significantly impact patient’s quality of life and often require reinterventions. Given the complex aetiology of LT, it is important to study the effects of different endograft designs on local hemodynamics, being the focus of this in-vitro study. Method: An in-vitro flow setup was created using five identical AAA flow lumen phantoms, based on the averaged anatomical features of 50 AAA patients. One phantom was left without an endograft acting as a control resembling the pre-operative condition. The other four phantoms were used to implement different EVAR endografts namely TREO, Endurant, Anaconda, and custom-made Anaconda with a gradually flared limb design. Ultrasound particle image velocimetry (echoPIV) was then used to quantify 2D flow fields in the pre-operative and post-operative right and left common iliac arteries (RCIA and LCIA, respectively). Thereafter, hemodynamic parameters, including vector complexity (VC), residence time (RT), and in-plane vortical structures were calculated to identify unfavorable hemodynamic regions. Results: The velocity magnitude at the peak systolic velocity (PSV) timepoint increased in EVAR-treated phantoms compared to the control phantom, with the LCIA of the custom-Anaconda phantom exhibiting the highest velocity magnitude of 118 cm/s. Endurant and TREO showed similar flow patterns during systole, which were also similar to the pre-operative flow patterns, while the two versions of the Anaconda endografts showed similar behavior compared to each other. The custom-made Anaconda grafts had the highest increases (2.4-fold) in VC compared to the control case. Moreover, RT simulations revealed that the Endurant and custom-made Anaconda endografts exhibited more unfavorable hemodynamic regions (n=3 in both) compared to Anaconda (n=1) and TREO (n=1). Conclusion: The findings emphasize that local hemodynamics in endograft limbs are influenced by both AAA anatomy and endograft design. A follow-up in-vitro study using whole blood is necessary to further validate whether the identified unfavorable hemodynamic regions within each endograft limb are associated with enhanced thrombus formation that could lead to LT. 10:00 0 mins Quantification of upper limb function using the powerjar: An exploratory study in healthy subjects and patients with neuromuscular diseases Ingrid S. van den Heuvel, Ingrid W. Koopmans, Marcus P.J. van Diemen, Anil Tarachandani, Ajay Verma, Geert J. Groeneveld, Robert J. Doll Abstract: Neurological disorders affecting muscle strength or coordination are often progressive and characterised by impaired muscle function leading to physical disability. As a result of muscle weakness, daily physical activities can become more complex for these patients. Quantification of their upper limb function in phase two clinical trials is currently done by using handheld dynamometers. However, the clinical relevance of such devices is limited as it is relatively unrelated to daily physical activities. Opening a jar is one of many tasks that patients with an NMD may find difficult to perform. A device which could potentially quantify the upper limb function during such a task is the PowerJar (Usin’Life LLC), a standing bottle with a rotating lid. It measures pressure on the side of the bottle, and the rotation of the lid. Additionally, the torque required to turn the lid can be controlled. Here, we assess the feasibility of using this device in the context of a clinical study. During this exploratory study, 60 healthy subjects and 18 patients with a neurological disorder (Parkinson’s Disease (8), Myasthenia Gravis (5), and Inclusion Body Myositis (5)), performed a series of tasks related to torque and grip strength using the PowerJar. Furthermore, the maximum grip force was measured using a handheld dynamometer (Jamar). Here, we focus on part of the tasks carried out with the PowerJar (e.g., continuous opening of the lid of the bottle and repeating opening and closing of the lid), and assess the inter,- and intra-day repeatability for respectively healthy subjects and patients. Intraclass coefficients are determined for all parameters (e.g. hold time, opening frequency, and maximum grip) to determine the repeatability. Inter, and intra-day repeatability is poor to good depending on the parameter. In this study, we assessed the feasibility of using the PowerJar in a clinical trial including both healthy subjects and patients with NMDs. Repeatability in these specific tasks show promising results, therefore, in future clinical trials, the sensitivity of the PowerJar in clinical drug studies must be investigated. 10:00 0 mins SNR based optimization of EEG source localization: Reducing uncertainty in the source space Ioannis Kyriazis, Frans van der Helm, Alfred Schouten, Mark van de Ruit Abstract: To further understand and quantify dynamical cortical information processing , advancement of EEG methods is required. The 4DEEG framework is being developed to propose an interpretation of cortical information processing that is based upon system identification techniques. Current source localization pipelines do not take into account the maximum signal to noise ratio (SNR) that can be obtained in the source space, introducing uncertainty regarding the true time course of the sources’ current. This study aims to further develop the 4DEEG pipeline, by introducing an SNR specific optimization of the source space. Two thousand evoked potentials were obtained by visual and sensory stimulation from 10 healthy participants, using transient stimuli. The 4DEEG pipeline was decomposed to its core steps and different parameters were tested, including different localization algorithms, source distributions and numbers of trials. The outcome metric was the SNR of the activity at the parcel level, i.e., the current at the different cortical regions of interest. Three source localization algorithms were selected (Variational Bayes, eLORETA & Minimum Norm Estimation), as well as 4 different mappings of distributed cortical sources. Finally, the effect of the number of evoked potentials used for source localisation was explored. Results indicate that eLORETA has a more consistent performance across source mappings, although at the cost of reduced focality, while variational Bayes tends to produce more focal results with variations across source distributions. Moreover, a non-uniform distribution of the cortical space tends to result in a higher SNR. Finally, the average number of evoked potentials needed to achieve optimal SNR was found to be around 1000. Future steps will include the analysis of the interactions between the cortical activity of the parcels with system identification techniques, enabling development of models of signal propagation within the human cortex. 10:00 0 mins Exploring Placebo and Nocebo Effects in Occupational Exoskeleton Use: A SCED Study in Physically Demanding Jobs Daniek van Laar, André Bieleman, Charissa Roossien, Daniel Saakes, Michiel Reneman Abstract: Background: Occupational exoskeletons (OEX) to reduce biomechanical workload and have been suggested to decrease musculoskeletal disorder (MSD; including back, neck and shoulder pain) risks. Many workers with MSDs believe they are directly caused by physical work, such as lifting. Ergonomic messaging can sometimes unintentionally reinforce these beliefs, potentially leading to nocebo effects where negative expectations influence health. Despite decades of research, evidence causally linking occupational load to MSDs is limited. Advances in pain research suggest that multiple dynamically interacting biopsychosocial factors contribute to MSDs. Also, nocebo and placebo effects have not been studied in OEX use, although they are likely relevant in this context. Aims: 1) Investigate placebo and nocebo effects in OEX use during work; 2) Assess novice user experiences and examine how age and sex may influence device acceptance. Method: A three-week A-B-A Single Case Experimental Design (SCED) study. Workers from healthcare and construction, new to OEX, will be assigned to an experimental group (receiving detailed OEX benefits, risks, and uncertainties) or a control group (receiving standard instructions). Phases include a baseline week (regular work), an intervention week (OEX use with varied support), and a reversal week (regular work). Daily and weekly surveys will capture participant experiences of support, reassurance (reduced fears about pain), discomfort, productivity, and usability, followed by a final interview exploring adoption factors. Four passive OEX models for back and shoulder support will be tested, with comprehensive questionnaires collecting user experiences. Analyses will include repeated measures and mixed ANOVAs, paired t-tests, and descriptive statistics. Expected nocebo effects include lower reassurance and baseline discomfort scores in the experimental group, while placebo effects are expected as higher experienced OEX support, productivity, and acceptability scores. Discussion: This innovative study is the first to explore placebo and nocebo effects in OEX use, utilizing a novel SCED approach in OEX research. Findings will advance understanding of biopsychosocial factors in OEX wear, highlighting OEX potential to enhance work sustainability and health in physically demanding roles. 10:00 0 mins Improving early detection of knee osteoarthritis with AI-driven point-of-care ultrasound Lianne Straetemans, Ramon Ottenheijm, Thomas van den Heuvel, Chris de Korte Abstract: Knee osteoarthritis (KOA) is a painful and disabling joint disease. With a prevalence of approximately 9%-14%, it is one of the most prevalent musculoskeletal disorders.1 Diagnosis of KOA is challenging, especially in early or mild stages, because the diagnostic criteria exclude early-stage conditions.2 In doubtful cases, clinical assessment is supplemented by radiographs. However, radiographs are unable to reveal soft tissue damage and inflammation, important for early identification of KOA. Ultrasound (US) has emerged as a promising tool for reliable and accurate detection of KOA-associated features, including osteophytes, meniscal extrusion and synovitis, of which the latter two cannot be seen on radiographs. Furthermore, improving early diagnosis of KOA ideally starts at the general practitioner (GP), where US would enable immediate diagnosis and start of treatment. However, sonographers require extensive training to obtain and interpret the correct image to detect KOA-associated features. . To overcome these challenges, this study aims at creating an AI-based point-of-care US (POCUS) device that enables KOA detection at the GP with minimal training. This study will consist of multiple phases. First, an US acquisition protocol for a smartphone-based US device will be created, consisting of standardized sweeps across the knee. Additionally, a smartphone application will be developed. Standardized US settings will be used, to ensure that all acquisitions are performed with the same scanning parameters. Secondly, GPs with sonography experience will be recruited to acquire data from 400 patients with suspected KOA using their clinical US device and the smartphone-based US device. This data will be used to develop an AI algorithm for automated detection of synovitis, osteophytes and meniscal extrusion. The algorithm will be implemented in the application. Additionally, feedback from users will be collected for further improvement of the application. In the final phase, GPs without US experience will be recruited for evaluation of the application. With this study, we aim to develop and demonstrate the potential and usability of an AI-based POCUS device for detection of KOA by GPs. This AI-based POCUS device could provide an accessible tool, requiring minimal training, to enable earlier detection of KOA and consequently timelier and more personalized treatment. 10:00 0 mins Ultrasound-based velocity imaging in the carotid bifurcation compared to 4D flow MRI Joosje de Bakker, Janna Ruisch, Chris de Korte, Anne Saris Abstract: Stroke is a leading cause of death and major disability. In approximately 20% of the cases it is caused by the rupture of an atherosclerotic plaque in the carotid artery. Complex blood flow seem to play an important role in the initiation, progression and rupture of plaque. Therefore, identification of complex blood flow could aid in better patient-specific risk stratification and treatment planning, however, it cannot be measured by conventional ultrasound systems. The introduction of ultrafast ultrasound, acquiring thousands of images per second, enabled new opportunities for ultrasound-based velocity vector imaging (US-VVI), however in vivo validation is lacking. This study evaluates the performance of US-VVI against 4D flow Magnetic Resonance Imaging (MRI), which is considered the gold standard for in vivo blood flow assessment. 2D US-VVI and 4D flow MRI data were acquired of the carotid bifurcation of twenty healthy volunteers. US-VVI was semi-automatically registered to the 4D flow MRI data based on lumen geometry. In the resulting matching 2D planes, the velocity vector fields of US-VVI and 4D flow MRI were compared based on the cosine similarity for the direction and the root-mean-square error for the velocity magnitude (RMSEmag) at peak systole and end diastole. Furthermore, correspondence of temporal velocity profiles over the cardiac cycle were compared in the common (CCA) and internal carotid artery (ICA) based on similarity and difference in peak systolic velocity. Visually the 2D velocity vector fields matched well between modalities, which was supported by high cosine similarities of 0.86 and 0.70 and low RMSEmag of 19.0 and 6.4 cm/s at peak systole and end diastole, respectively. Temporal velocity profiles showed high resemblance, with similarity indices of 0.87 and 0.80, and mean peak systolic velocity differences of 0.91 and 7.9 cm/s in the CCA and ICA, respectively. In conclusion, this study showed good temporal and spatial agreement between US-VVI and 4D flow MRI. The high spatiotemporal resolution of US-VVI enabled the measurement of small vortices of short duration that remain unrevealed by 4D flow MRI. Therefore, US-VVI is a promising technique to measure complex blood flow potentially relevant in the atherosclerotic disease process. 10:00 0 mins Social navigation in dynamic environments for a healthcare robot Maria Catalina Barcaru, Ming Cao, Elisabeth Wilhelm Abstract: The healthcare system today faces significant strain due to a shortage in nursing staff. To help alleviate this burden, social robots are being introduced in care settings. One key requirement for these robots is to operate autonomously, providing assistance rather than creating additional tasks for the nurses. Additionally, the robot should behave in a way that does not endanger people. This calls for both avoiding obstacles and abiding by social standards, which requires the development and integration of a human-tracking module [1]. This module is critical in social navigation because it predicts human movement and intentions, ultimately assisting in recognizing when there is a potential collision or uncomfortable scenario to avoid. Current research addresses elements of social navigation, although their effectiveness is still constrained by their dependence on sensor hardware and is susceptible to ambient influences like reflective surfaces or low light [2]. Moreover, to ensure safety, most of the models overestimate the risk of collision with people causing the robot to freeze or oscillate when all perceived paths are marked unsafe [3]. The studies also show algorithms designed for dynamic settings, but they are often validated only in simulations or overly simplified environments [4]. As a result, these methods are unable to manage complex scenarios such as sudden human motions, doors that open without warning, or navigating L-shaped corridors. Furthermore, a lot of systems have high computational costs, which can result in dangerous behaviors [3], [5]. The aim of this study is to develop a context-aware social navigation system tailored for highly dynamic environments, such as hospitals. Ideally, the robot will create a map from scratch, without any preloaded environmental map, making it adaptable across various environments, including homes. A human-tracking module will ensure safe, socially-aware movement, and the system will generalize to unexpected scenarios that current research often overlooks. The robot’s performance will be evaluated both in simulations and in field studies, comparing it against state-of-art navigation systems. A specific social score [1] will be used to evaluate social conduct in addition to metrics like path length, time, collision rate, trajectory smoothness, and success rate [2]. References: [1] S. Huang, T. Tanioka, R. Locsin, M. Parker, and O. Masory, "Functions of a caring robot in nursing," 7th Int. Conf. Nat. Lang. Process. Knowl. Eng., pp. 425-429, 2011. [2] P. D. Groves, L. Wang, D. Walter, H. Martin, K. Voutsis, and Z. Jiang, "The four key challenges of advanced multisensor navigation and positioning," IEEE/ION Position, Location and Navigation Symp. (PLANS), pp. 773-792, 2014. [3] C. Mavrogiannis, F. Baldini, A. Wang, D. Zhao, P. Trautman, A. Steinfeld, and J. Oh, "Core challenges of social robot navigation: A survey," ACM Trans. Hum.-Robot Interact., vol. 12, no. 3, pp. 1-39, 2023. [4] Y. Zhou, S. Li, and J. Garcke, "Foresight social-aware reinforcement learning for robot navigation," Proc. 35th Chinese Control and Decision Conf. (CCDC), pp. 3501-3507, 2023. [5] S. Al Mahmud, A. Kamarulariffin, A. M. Ibrahim, and A. J. H. Mohideen, "Advancements and challenges in mobile robot navigation: A review," J. Intell. Robot. Syst., vol. 110, no. 3, p. 120, 2024 10:00 0 mins Investigating the impact of elastic nonlinearity on shear-wave viscoelastographic estimation by the standard k-space method Xueting Li, Marije Zwart, Simona Turco, Massimo Mischi Abstract: Many diseases alter the structure and composition of tissues, which affects their mechanical properties. Shear wave (SW) elastography is a promising tool to assess these properties. For example, the standard k-space method [1] quantifies tissue elasticity and viscosity by focusing on the estimation of the second-order elastic modulus. However, the third-and fourth-order elastic moduli reflecting SW nonlinearity are overlooked, while they might serve as an additional biomarker [2]. Moreover, the impact of nonlinearity on the elasticity and viscosity estimates using the standard k-space method remains unexplored. This study aims to bridge this gap by simulating SW propagation under various nonlinearity conditions using the finite difference method (FDM), before applying the standard k-space method. In SW elastography, a focused ultrasound pulse is used to induce an acoustic radiation force in tissue along the axial direction, generating laterally propagating shear waves. Considering a plane SW with the particle motion restricted to the axial direction, we use the FDM to simulate the axial particle displacement field in the spatiotemporal domain, following the nonlinear SW propagation equation defined in [3]. Four different media were simulated, characterized by different elasticity and viscosity values, with and without nonlinearity. The boundary conditions in the FDM considered a symmetric Gaussian impulse at the origin. We estimated the elasticity and viscosity values by the k-space method: we first applied the two-dimensional Fourier transform on the simulated displacement field to extract the dispersion curve, and then fit it by a Kelvin-Voigt viscoelastic model, which does not include nonlinearity. The fitting is performed within the frequency range where the dispersion curve remained most stable. Finally, we compared the derived elasticity and viscosity values with the true (simulated) values and evaluated the bias caused by ignoring nonlinearity. Our results show that the estimated elasticity and viscosity values closely match the true values when nonlinearity is relatively small. When significant nonlinearity exists, the standard k-space method tends to overestimate both elasticity and viscosity. [1] Nenadic, et al., IEEE IUS, 2014 [2] Rus, et al., Sensors, 2020 [3] Zabolotskaya, et al., J. Acoust. Soc. Am., 2004 10:00 0 mins Zero-D Coupled Hemodynamic and Thermoregulation Modeling for Thermodilution Measurements in Circulatory Systems Noëlle Gerards, Marcel Rutten, Simona Turco, Frans van de Vosse Abstract: Reliable measurement of total circulating blood volume (BV) is important in clinical settings, particularly for managing acute heart failure, trauma and major surgeries. Traditional methods estimating BV status often rely on indirect clinical parameters, which have proven inaccurate. Existing techniques like indicator dilution using radioisotopes, carry potential health risks and time constraints. Thermodilution measurements can enable determination of BV using a fiberoptic sensor integrated with tunable lasers and Fiber Bragg Grating technology, capable of detecting temperature changes with resolution up to 0.1 mK. Previous research demonstrated the feasibility of measuring recirculating thermodilution curves (TDC) on a mock circulatory loop (MCL). To gain further insight into the thermal properties of the MCL and the cardiovascular system, a lumped hemodynamic circulation model was created. A computational model of the MCL was made and an energy balance thermoregulation model was coupled to it. Additionally, the model was expanded to facilitate comparison with thermodilution experiments performed on a porcine model. The model could accurately describe temperature as a result of diffusion in the MCL, including the slow temperature recovery observed during experiments. However, it did not capture the recirculation curves seen in the MCL, as it assumes instantaneous mixing within each compartment due to 0D modeling. This indicates that the heat exchange inside the MCL primarily consists of convective mixing, with a small contribution from diffusive mixing, particularly for the first TDC, which has not yet passed through the left ventricle. The expanded model effectively captures the first TDC and temperature recovery under similar conditions in the porcine experiments. The results from both the MCL and the porcine data provide valuable insights into the dynamic interactions within the cardiovascular system. While the initial computational model configuration successfully described average temperature changes and recovery, it highlighted limitations in capturing detailed recirculation dynamics. The expanded model demonstrates improved performance in capturing the first TDC. Future work involves using a parameter estimation model alongside a sensitivity analysis to identify critical parameters for temperature estimation, enhancing understanding of temperature regulation in the cardiovascular system. Additionally, modeling major vessels in 1D instead of 0D could improve the model. 10:00 0 mins Enhancing speech perception for children in classroom environment with moving speakers Feyisayo Olalere, Kiki van der Heijden, Christiaan H. Stronks, Jeroen Briaire, Johan Frijns, Marcel van Gerven, Yagmur Güçlütürk Abstract: Spatial cues are critical for understanding speech in noisy environments, yet most spatial hearing research focuses on adults, often assuming similar outcomes for children. However, children in noisy classroom environments often struggle to understand speech, especially those using hearing aids, due to their limited access to spatial cues. This study aims to address this gap by enhancing children's speech perception through a deep learning model for speech separation specifically tailored to their acoustics. Our approach simulates realistic data by incorporating room and listener properties, addressing challenges such as poor classroom acoustics and the anatomical differences between children and adults. The dataset includes two types of speaker pairs; child-child and adult-child. We overlaid with children’s babble noise to emulate typical classroom interactions. The model is designed to separate speech signals while preserving spatial cues, ensuring that children can maintain localization ability post-processing. The deep learning model used is designed to take in a two-channel waveform of the noisy speech, and then learn the individual mask for all the speakers present in the mixture. The learned mask is used to estimate the sound of each speaker. We include a post-processing module to further clean the estimated sound. For children using hearing aids, retaining these spatial cues is crucial, as they support the ability to identify and localize multiple speakers in dynamic auditory settings. By preserving these critical cues, the model aids in speaker differentiation, even in overlapping speech scenarios that are particularly challenging for young listeners. Preliminary results suggest that our approach can improve speech perception accuracy for children in simulated noisy environments, which is a step toward enhancing real-world classroom listening experiences. This work makes a unique contribution by addressing the specific needs of children with hearing aids, providing a spatially aware solution that can support effective communication and learning in educational settings. 10:00 0 mins Advancing Fetoscopic Repair of Complex Gastroschisis: Proof of Principle for a Novel Closure Method Nynke Ansems Abstract: Gastroschisis is a congenital abdominal wall defect near the umbilical cord, in which the fetal intestines protrude into the amniotic cavity. Complex gastroschisis (CG), occurring in approximately 10% of cases, is associated with significant morbidity and mortality [1]. Fetoscopic repair of CG has the potential to improve gastrointestinal health at birth, yet no procedure has proven both safe and feasible [2]. This project aimed to establish proof of principle for a novel method enabling the rapid closure of the abdominal wall defect during fetoscopic CG repair. The selected design, a silicone ring with membrane, was intended to close the defect upon insertion into the fetal abdominal cavity. Validation experiments assessed the effects of ring shape (round vs. rusk), diameter (20 mm vs. 30 mm), and stiffness (shore hardness A25 vs. A40) on performance. Prototypes were fabricated by injection-molding liquid silicone rubber in 3D-printed molds. A model of a 24-week CG fetus with defect diameters of 12 mm, 16 mm, and 20 mm was developed to test each ring. During the experiments, intra-abdominal pressure (IAP) was raised to 40 mmHg and then released. Ring retention and defect closure were visually evaluated. The silicone ring remained securely positioned across IAP ranges from 0–40 mmHg for all tested prototypes and defect sizes. For the 12 mm defect, all rings provided complete closure of the defect. For the 16 mm defect, the 20 mm round rings showed superior closure compared to the rusk shape. In the case of the 20 mm defect, the 20 mm rings did not achieve full closure; among the 30 mm rings, round rings achieved better closure than rusk-shaped ones, which showed partial exposure of the intestines in some cases. Ring stiffness did not impact overall performance, although stiffer rings showed a slight advantage in ease of positioning. These results provide initial proof of principle for the silicone ring with membrane as a novel method for rapid defect closure in fetoscopic CG repair. Future work should focus on optimizing ring design parameters to enhance defect closure and on developing a specialized insertion tool, advancing this method toward clinical feasibility. References [1] B. E. Willborg, E. R. Ibirogba, A. T. A. Trad, L. Sbragia, D. Potter, and R. Ruano, “Is there a role for fetal interventions in gastroschisis management? – an updated comprehensive review,” Prenatal Diagnosis, vol. 41, no. 1, pp. 159–176, Aug. 2021. DOI: 10.1002/pd.5820. [2] L.-O. Durmaz, S. E. Brunner, A. Meinzer, T. F. Krebs, and R. Bergholz, “Fetal surgery for gastroschisis— a review with emphasis on minimally invasive procedures,” Children, vol. 9, no. 3, p. 416, Mar. 15, 2022. DOI: 10.3390/children9030416. 10:00 0 mins Feasibility of using virtual reality for stretching exercises of the neck for cervical dystonia patients Luis Felipe García Arias, Martje van Egmond, Marina de Koning-Tijssen, Elisabeth Wilhelm Abstract: Idiopathic Cervical Dystonia (CD) is a movement disorder of the neck causing rare and recurrent movements, postures, or a combination of both [1]. Patients can temporarily improve their symptoms by touching their face or wearing a hat, among other strategies; a sensory trick (ST) [3, 4]. Treatment based on visual feedback has shown positive outcomes for CD patients [2], and immersive virtual reality (VR) could be an option to provide such feedback. However, it is necessary to verify the effect of the VR headset on triggering a ST to quantify the impact of VR-based training for CD properly. This study investigates the feasibility of using immersive virtual reality to support neck muscles stretching and strengthening for cervical dystonia patients. In this feasibility study, we investigate the feasibility of using immersive virtual reality to stretch the neck muscles of CD and the effect of wearing a VR headset on inducing a ST. The study is divided into two parts: the first consists of a one-arm pre-post within-subject test to assess the feasibility of using a VR game to facilitate neck muscle stretching. Participants will be guided by the VR game to execute cervical flexion, cervical extension, and cervical rotation. The directions of the movements will be customized per participant to avoid them activating their dystonic muscles. Each position will be held for 15 seconds, with five repetitions per direction, followed by a 5-second rest period between repetitions. In the second part, we evaluate the VR headset's effect on triggering a sensory trick. During this part of the study, the participants will be required to perform the same movements as in the first part by following visual hints that instruct them to move their head. The participants will repeat the task while wearing a VR. The effect of wearing the VR headset on inducing a ST will be assessed by comparing the root-square-mean value of the EMG signals of the dystonic muscles. In the future, such a game could serve as a tool to facilitate home based training for cervical dystonia. 10:00 0 mins Developing a Circular Workflow for Patient-Specific Surgical Guides in Orthopedic Surgery Guna Shankar Rimmalapudi, Maartje Leemans, Gabriëlle Tuijthof Abstract: The rise of personalized medicine has led to the use of patient-specific surgical guides (PSGs) in orthopedic procedures, improving surgical precision and reducing operation time in complex procedures like osteotomies and implant placement. However, the single-use nature of PSGs contributes to medical waste and negatively affects environmental impact. This study aims to develop a circular workflow that enables the sustainable use of PSGs. We analysed current and future trends to explore sustainable PSG options. First, we identified the five most performed orthopedic procedures in the Netherlands from 2012-2023 using the Health Authority database to extrapolate future PSG use and related waste. Second, we conducted semi-structured interviews with nine 3D Labs and one PSG manufacturer to understand current PSG workflows and sustainability efforts in design and fabrication. Third, we reviewed existing PSG designs in the literature, assessing their suitability for sustainable alternatives. These procedures were selected for their high volumes in the Netherlands (2022-2023), Knee Prosthesis and Arthrosis (100,575), and Tibia & Fibula Procedures (21,762). All 3D labs used PSGs for tibial procedures, aligning with literature indicating their primary use in knee and tibia-related surgeries. Interviews revealed that none practiced sustainability activities and outsourced PSG production due to strict medical device regulation and QMS requirements. Current PSG designs were found to be single-use and lacking sustainability features. Based on these findings and emphasizing reuse and recycling (from the 10R sustainability principles), we developed a circular workflow for PSGs. First, for highly customized or small-sized PSGs, we recommend using recyclable materials like rPLA & rPP, selected for their low glass transition temperatures and consistent diameters. Second, for larger PSG designs involving > 250 grams of material, we propose a hybrid design that minimizes patient-specific shapes while integrating standard reusable components. Design requirements such as material biocompatibility, suitability for EtO sterilization, compatibility with surgical instruments, and diverse patient morphometrics were outlined. Based on these requirements, future research is necessary to develop and evaluate hybrid PSG designs and recyclable materials to ensure patient safety and compliance with medical device regulation. Implementing this approach could reduce PSG waste by 70%, contributing to sustainable medical practices. 10:00 0 mins The LiverTwin: a novel ex-vivo experimental platform for image-guided liver cancer treatment studies Jan van der Hoek, Marleen Krommendijk, Tess Snoeijink, Ata Chizari, Anne Rook, Kyra de Bree, Jaap Greve, Remco Liefers, Wiendelt Steenbergen, Michel Versluis, Jutta Arens, Srirang Manohar, Erik Groot Jebbink Abstract: Introduction: The use of medical imaging modalities for both diagnostic and therapeutic purposes has greatly increased over the last two decades. Many of these imaging technologies have been developed in animal models, however, emerging ethical considerations surrounding these in-vivo studies drive the search for alternative models. Such an alternative is provided by ex-vivo machine perfused organs, which can simulate an in-vivo situation. For research on image-guided interventions of liver cancer, we developed an ex-vivo experimental platform for perfusion of pig livers, focusing on medical imaging compatibility to replicate the clinical setting. Methods: The experimental platform was designed for normothermic perfusion of pig livers with oxygenated pig blood, coined the LiverTwin. Several design choices ensured medical imaging compatibility, including a non-magnetic reservoir for magnetic resonance imaging (MRI), and a height-adjustable organ net to allow organ analysis submerged in blood (MRI) or on top of the reservoir (ultrasound and optical modalities). The medical imaging compatibility was explored using a variety of imaging modalities. MRI (FLASH and T1-weighted contrast-enhanced sequences) and two dynamic light scattering imaging methods (laser speckle and laser Doppler imaging) were used to collect detailed and locoregional information on the liver perfusion. To replicate interventional treatments such as transarterial radioembolisation (TARE), cone-beam computed tomography (CBCT) and X-ray angiography were used to visualise the vasculature. Concurrently, microbubbles and dynamic contrast enhanced ultrasound (DCE-US) were used to improve targeting in TARE by the development of a novel DCE-US guided TARE approach. Results: Magnetic resonance imaging could distinguish between healthy and ischemic regions at several time instances of perfusion. Using dynamic light scattering imaging, the deterioration of the liver microperfusion over time was captured. A TARE treatment was replicated, where angiograms served as roadmaps for catheter navigation, and intermittent CBCT scans provided 3D information on the liver vasculature. Using these scans, multiple catheter positions could be analysed with DCE-US to improve targeting in the replicated TARE treatment. Conclusion: The LiverTwin platform showed excellent compatibility with medical imaging and was deemed successful in replicating the clinical setting, providing a unique experimental setup for medical imaging-related research on liver cancer. 10:00 0 mins Characterizing electrode performance in cochlear implant users: an EEG and reaction-time study using direct electrical stimulation Elisabeth Noordanus, John van Opstal Abstract: Cochlear implants (CIs) restore auditory perception in individuals with severe-to-profound hearing loss. However, considerable variability in CI users' spatial and temporal auditory selectivity significantly impacts their speech perception abilities. This study investigates how neurophysiological and behavioral responses to direct electrical stimulation can uncover electrode-specific and individual differences in auditory processing. We employed two novel assessment techniques: the Electrode Interaction Auditory Steady State Response (ELI-ASSR) and the Electrode Interaction Reaction Time (ELI-RT) paradigms. These methods measure auditory responses through EEG recordings and reaction times, respectively, using direct stimulation of two adjacent CI electrodes with amplitude-modulated pulse trains at a fixed rate and varied modulation frequencies. Sixteen unilateral CI users participated in the study. In the neurophysiological ELI-ASSR paradigm, we analyzed EEG responses at beat frequencies to assess electrode interactions. All participants demonstrated significant beat responses, achieving reliable, artifact-free recordings. A weak correlation was noted between EEG beat signal-to-noise ratios (SNRs) and stimulation level, while a positive correlation emerged between beat SNRs and electrically evoked compound action potential (eCAP) amplitudes, suggesting partially consistent electrode response patterns. The behavioral ELI-RT paradigm evaluated reaction times to changes in electrode position or modulation frequency, with interference from adjacent-electrode stimulation. Reaction times varied by participant, electrode location, and task type (electrode change vs. modulation frequency change). Notably, faster reaction times to modulation frequency changes were associated with superior speech-in-noise performance, indicating enhanced temporal selectivity. Additionally, ELI-ASSR EEG beat SNRs for a specific electrode set consistently correlated with reaction times to modulation frequency changes for the same electrode set (r ≈ 0.25), while no significant relationship was observed with reaction times prompted by electrode changes. These findings indicate that ELI-ASSR offers robust, objective measurements of electrode interactions, while ELI-RT captures individualized spatial and temporal selectivity within the electrode array. Together, these methods provide complementary insights into CI users' neural processing capabilities, potentially guiding optimized CI programming to enhance auditory perception, especially in challenging speech-in-noise environments. 10:00 0 mins Comparison of rMMN paradigms to study sensory neuroplasticity in healthy humans Annika A. de Goede, Alissa Haj Yahya, Soma Makai-Bölöni, Robert J. Doll Abstract: Neuroplasticity refers to the ability of the nervous system to alter its function and structure in response to stimuli. It is essential for normal brain development, memory, and recovery. The mismatch negativity (MMN) test is believed to assess short-term sensory neuroplasticity at the network level. A modified version is the roving paradigm (rMMN) which focuses on two MMN subcomponents: the repetition positivity (RP) and deviance negativity (DN). RP reflects the formation of a memory trace for the repeated standard stimuli, while DN reflects the detection of changes generated by a deviant stimulus. This study aims to evaluate the repeatability and optimal rMMN test settings in terms of 1) maximizing MMN and 2) minimizing test duration. Instead of applying a single deviant tone, the rMMN test consists of several sequences of identical stimuli that vary in tone frequency and duration. The last stimulus of each sequence is referred to as RP and the first stimulus of a new sequence as DN. Seventeen healthy subjects participated four times in two configurations of the rMMN test. Configuration 1 consisted of short (n=4), medium (n=8), and long (n=16) sequences, and configuration 2 of short (n=3), medium (n=6), and long (n=12) sequences. rMMN endpoints were manually scored between 100-200 ms and analyzed using linear mixed models. For both configurations, the rMMN endpoints showed the formation of a memory trace. Configuration 1 resulted in significantly larger MMN, RP and DN amplitudes compared to configuration 2 (p < .001), indicating a stronger memory trace for longer sequences. Although, amplitudes were smaller for configuration 2, they were still comparable to literature. RP and DN showed good to excellent repeatability (ICC > .75) over the day for both configurations when combining all sequence lengths, while MMN showed moderate repeatability (ICC = .65). Both configurations are suitable for use in clinical studies or early-phase drug development. Within-day test repeatability is moderate to excellent. Configuration 1 resulted in significantly larger rMMN amplitudes, while test duration was shorter for configuration 2. The fact that configuration 2 reduces test duration, while still performing consistently with literature, makes it more suitable for future use. 10:00 0 mins Impact of Medical Technology on Intraoperative Nurses' Workload and Work Enjoyment Anneke Schouten, Rick Butler, Carlijn Vrins, Steven Flipse, Frank Willem Jansen, Anne van der Eijk, John van den Dobbelsteen Abstract: Background The integration of technology in the operating room (OR) aims to improve patient safety, efficiency, and surgeon well-being. However, its impact on intraoperative nurses’ tasks remains underexplored. Addressing this is vital, especially amid a severe nurse shortage, to help reduce workload and enhance job satisfaction. Aim This study examines the effects of medical technology on intraoperative nurses' workload and job satisfaction at the Leiden University Medical Center. Method Data were collected through interviews, questionnaires, video recordings, and hospital records for procedures with varying technological complexity: open surgery (OS), minimally invasive surgery (MIS), and robot-assisted surgery (RAS). Factors affecting workload and job satisfaction were identified via interviews and the SURG-TLX questionnaire. Video analysis tracked staff movements and locations in 35 gynecological surgeries (4 OS, 25 MIS, 6 RAS), marking interactions around the operating table as active involvement. Results SURG-TLX results showed minimal differences across procedures, with OS yielding the highest job satisfaction. Key positive factors included teamwork, effective preparation, functional technology, freedom of movement, adequate lighting, and active involvement. Workload was influenced by surgery duration and the requirement for nurses to remain in static positions for extended periods. The video analysis revealed movement patterns by procedure type: movement around the surgical table was minimal overall (<10%), with RAS showing lower movement and interaction percentages than MIS and OS. Hospital data indicated that lights remained on throughout OS but were off for an average of 71 minutes in MIS and 188 minutes in RAS. Average surgery times were 236 minutes for OS, 134 minutes for MIS, and 249 minutes for RAS. Conclusions Intraoperative nurses reported the highest job satisfaction with OS and the lowest with RAS. This difference likely results from longer RAS procedures, extended periods with the lights off, restricted movement, and less active involvement in the surgery. 10:00 0 mins Minimally invasive sacroiliac joint fusion revision using a patient specific surgical guide for implant placement A.D. Smelt, J.M. Nellensteijn, N.F.B. Kampkuiper, M. Haenen, M. Leemans, E.E.G. Hekman, F.F. Schröder, M.A. Koenrades Abstract: Objective: Minimally invasive surgical revision of sacroiliac joint fusion (SIJF) requires accurate placement of implants to reobtain or increase stability after implant loosening, implant malposition or pelvic fracture to relief pain. Current management using fluoroscopy and standard instruments challenges accurate placement and does not allow non-parallel implant configurations, which is desirable due to limited space for additional implants. The objective of this study was to develop and evaluate the use of patient specific surgical guides in SIJ fusion revision. Methods: A patient specific guide (PSG) was developed to be fixated in in situ implants or sacroiliac screws by use of Kirschner wires, not requiring any bone seating, and to accurately guide placement of additional implants (iFuse Implant System, SI-Bone, Santa Clara, CA, USA). PSGs comprised a 3D printed main body (polyamide 12, powder bed fusion) and guidance tubes (polyamide 12, fiberglass or stainless steel). Thirteen patients (all female, median age 52 years) underwent SIJ fusion revision in a prone position lateral approach from 2021 to 2024 using a PSG. One to three additional implants were placed resulting in a total of 22 implants. Positional and angular deviations were evaluated from postoperative CTs. Results: All implants were successfully placed without malpositioning complications. A mean total 3D positional deviation of 6.2 ± 2.0 mm (polyamide 12: 7.9-8.3 mm; fiberglass 5.9 ± 1.9; stainless steel: 6.1 ± 2.3) and a total mean 3D angular deviation of 4.2 ± 2.3⁰ (polyamide 12: 1.8-2.0⁰; fiberglass: 5.1 ± 2.7⁰; stainless steel: 3.7 ± 1.6⁰ ) was found. Conclusion: This study suggests that PSGs can facilitate accurate implant placement in minimally invasive SIJ fusion revision even with trans-articular non-parallel implant configurations. This may improve clinical outcome after revision with adequate pain relief and reduce malpositioning and implant loosening complications. 10:00 0 mins Reducing Late Night Snacking: Exploring the Potential of Ambient Tangible Interfaces Jonathan Jeuring, Champika Ranasinghe, Marcus Gerhold Abstract: Background: Late-night snacking is an unhealthy behavior that can cause weight gain, reduce sleep quality and cause psychological issues, headaches, and digestive problems that can increase the risk of Non Communicable Diseases (NCDs) [1,2]. Existing approaches focus mainly on making people aware of the consequences of late-night snacking and diet tracking and nudging, often using apps on mobile devices. Despite the increased awareness, late-night snacking is a habit that people find difficult to quit. This research explored the potential of utilizing ambient, tangible and multisensory user interfaces that can be embedded into everyday spaces to stimulate a behavior towards discouraging unhealthy late-night snacking. Solution: We designed NightSnakie, a snack dispenser that can be integrated easily into real-world living spaces (e.g., kitchen or living room). Based on existing behavior change techniques and theories, NightSnakie does not try to stop late-night snacking completely. Instead, it is aimed at discouraging unhealthy late-night snacking by replacing it with a small healthy snack at a regular time between the dinner and bedtime. It uses smell and audio based ambient stimulation to discourage further eating. Methods: (a) Design Methods - We adopted a user-centered, design-thinking driven iterative methodology to design NightSnakie. (b) Evaluation Methods- To understand the pragmatic and hedonic stimulative qualities of NightSnakie, and to gain insights for detailing the design, we evaluated NightSnakie using AttractDiff. We conducted a design focus group (N=6) based on 1-2-4-all Liberating Structure method to gain insights for detailing the design of NightSnakie along five dimensions: type of snack, location, rewards (short-term reward, long-term), refill options, and user interaction. Results: AttractDiff results indicate that the overall impression of the product's pragmatic quality and hedonic stimulation is positive. Attractiveness of the product is average indicating that it should be improved. We derived design guidelines for detailing the NightSnakie design based on the focus group results. Conclusion: NightSnakie shows potential for reducing and discouraging unhealthy late-night snacking. The design guidelines derived from the focus group design session can guide the detailed design of NightSnakie. 10:00 0 mins Toward Interaction-Aware Soft Robotic Endoscopes Using In-Situ Force Sensing Venkata Rithwick Puranam, Mostafa A Atalla, Gijs Krijnen, Giulio Dagnino, Momen Abayazid Abstract: Minimally invasive surgery (MIS) has revolutionized diagnostics and therapeutic procedures by providing patients with less invasive alternatives to traditional open surgeries. By using flexible instruments such as endoscopes, clinicians can perform complex procedures through smaller incisions and natural orifices, reducing recovery times and enhancing patient outcomes. Despite these advantages, endoscopes still face limitations, particularly due to the lack of sensory feedback at the distal end of the scope, which is crucial for navigating the anatomy accurately and safely. This absence of sensory capability can lead to complications including unintentional scope looping, discomfort for the patient and tissue damage due to excessive interaction forces, impacting the overall effectiveness and precision of the procedure. Recent studies showed that looping occurs in 54.3% of colonoscopy cases with perforation and bleeding rates up to 7.3 and 23.1 per 10000 procedures, signifying the necessity for sensory feedback integration. In this work, we propose integrating flexible capacitive sensors directly at the distal end of the colonoscopes to provide force sensory feedback, allowing for real-time monitoring of contact forces exerted by the tip on the intestine wall. These sensors are designed to detect pressure variations, which can provide valuable insights into the amount of force applied to sensitive tissues. This sensory data can then potentially be supplied to the interventionist in the form of haptic feedback to guide the navigation process or be used to guide robotic-guided endoscopes to stay within safe tissue interaction limits. This integrated sensing modality promises to enhance the functionality of existing colonoscopes, paving the way for safer interaction-aware endoscopic procedures. 10:00 0 mins Making light work of surgical instrument counting: a matrixed multiple case study on the fidelity of weighing systems in the operating room Anton Kooijmans, Maarten van der Elst, John van den Dobbelsteen Abstract: Background Surgical instrument counting is a labour-intensive task of operating room (OR) nurses. Around 20 years ago, weighing scales were proposed as a solution to relieve their workload [1]. A recent survey among Dutch hospitals shows that while a quarter of hospitals still use such a system, several noted that it cannot be relied upon for instrument counting [2]. The current study aims to identify factors that influence how weighing systems are used in different hospitals using the Matrixed Multiple Case Study (MMCS) method [3]. Methods We conducted interviews among OR and sterilisation department professionals of four hospitals that use weighing systems. After content analysis, we designated each hospital as high fidelity (weighing is used for instrument counting) or low fidelity (weighing is used for instrument counting). We identified relevant factors for each site, the extent of their presence, and the type of influence they had on fidelity (enabling/neutral/hindering). We organised this data in a sortable matrix and assessed fidelity-related trends across hospitals. Results Two hospitals were high fidelity, and two were assigned a low fidelity status. Eighteen factors were identified, of which three were present in all hospitals regardless of fidelity status: Physical properties of instruments and materials and Nurse experience with a hindering influence, and Being able to weigh in the operating room with an enabling experience. Four factors exhibited strong strends by fidelity status. They were Trust in technology, Interdisciplinary coordination, and Presence of facilitator being more present with an enabling influence in high fidelity hospitals, and Size and complexity of instrument inventory being more present with a hindering influence in low fidelity hospitals. Conclusions All hospitals experience limitations of the weighing system. However, these limitations can be overcome in hospitals where the above-mentioned factors are present, thereby relieving staff workload. MMCS can be used to investigate fidelity-related factors of current labour-saving innovations in the OR.

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