A computational model for real-time calculation of electric field due to transcranial magnetic stimulation in clinics

The aim of this paper is to propose an approach for an accurate and fast (real-time) computation of the electric field induced inside the whole brain volume during a transcranial magnetic stimulation (TMS) procedure. The numerical solution implements the admittance method for a discretized realistic brain model derived from Magnetic Resonance Imaging (MRI). Results are in a good agreement with those obtained using commercial codes and require much less computational time. An integration of the developed codewith neuronavigation toolswill permit real-time evaluation of the stimulated brain regions during the TMSdelivery, thus improving the efficacy of clinical applications

Analysis of the 'Endoworm' prototype's ability to grip the bowel in in vitro and ex vivo models

[EN] Access to the small bowel by means of an enteroscope is difficult, even using current devices such as single-balloon or double-balloon enteroscopes. Exploration time and patient discomfort are the main drawbacks. The prototype 'Endoworm' analysed in this paper is based on a pneumatic translation system that, gripping the bowel, enables the endoscope to move forward while the bowel slides back over its most proximal part. The grip capacity is related to the pressure inside the balloon, which depends on the insufflate volume of air. Different materials were used as in vitro and ex vivo models: rigid polymethyl methacrylate, flexible silicone, polyester urethane and ex vivo pig small bowel. On measuring the pressure-volume relationship, we found that it depended on the elastic properties of the lumen and that the frictional force depended on the air pressure inside the balloons and the lumen's elastic properties. In the presence of a lubricant, the grip on the simulated intestinal lumens was drastically reduced, as was the influence of the lumen's properties. This paper focuses on the Endoworm's ability to grip the bowel, which is crucial to achieving effective endoscope forward advance and bowel foldingThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was funded by the Spanish Ministry of Economy and Competitiveness through Project (PI18/01365) and by the UPV/IIS LA Fe through the (Endoworm 3.0) Project. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development FundTobella, J.; Pons-Beltrán, V.; Santonja, A.; Sánchez-Diaz, C.; Campillo Fernandez, AJ.; Vidaurre, A. (2020). Analysis of the 'Endoworm' prototype's ability to grip the bowel in in vitro and ex vivo models. Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine. 234(5):1-10. https://doi.org/10.1177/09544119209014141102345Iddan, G., Meron, G., Glukhovsky, A., & Swain, P. (2000). Wireless capsule endoscopy. Nature, 405(6785), 417-417. doi:10.1038/35013140Yamamoto, H., Sekine, Y., Sato, Y., Higashizawa, T., Miyata, T., Iino, S., … Sugano, K. (2001). Total enteroscopy with a nonsurgical steerable double-balloon method. Gastrointestinal Endoscopy, 53(2), 216-220. doi:10.1067/mge.2001.112181Arnott, I. D. R., & Lo, S. K. (2004). REVIEW: The Clinical Utility of Wireless Capsule Endoscopy. Digestive Diseases and Sciences, 49(6), 893-901. doi:10.1023/b:ddas.0000034545.58486.e6Hosoe, N., Takabayashi, K., Ogata, H., & Kanai, T. (2019). Capsule endoscopy for small‐intestinal disorders: Current status. 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H. (2006). Experimental investigation of frictional and viscoelastic properties of intestine for microendoscope application. Tribology Letters, 22(2), 143-149. doi:10.1007/s11249-006-9073-0Lyle, A. B., Luftig, J. T., & Rentschler, M. E. (2013). A tribological investigation of the small bowel lumen surface. Tribology International, 62, 171-176. doi:10.1016/j.triboint.2012.11.018De Simone, A., & Luongo, A. (2013). Nonlinear viscoelastic analysis of a cylindrical balloon squeezed between two rigid moving plates. International Journal of Solids and Structures, 50(14-15), 2213-2223. doi:10.1016/j.ijsolstr.2013.03.028Sliker, L. J., Ciuti, G., Rentschler, M. E., & Menciassi, A. (2016). Frictional resistance model for tissue-capsule endoscope sliding contact in the gastrointestinal tract. Tribology International, 102, 472-484. doi:10.1016/j.triboint.2016.06.003Zhang, C., Liu, H., & Li, H. (2014). 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Preliminary Mechanical Characterization of the Small Bowel for In Vivo Robotic Mobility. Journal of Biomechanical Engineering, 133(9). doi:10.1115/1.400516

Active flexible concentric ring electrode for non-invasive surface bioelectrical recordings

Bioelectrical surface recordings are usually performed by unipolar or bipolar disc electrodes even though they entail the serious disadvantage of having poor spatial resolution. Concentric ring electrodes give improved spatial resolution, although this type of electrode has so far only been implemented in rigid substrates and as they are not adapted to the curvature of the recording surface may provide discomfort to the patient. Moreover, the signals recorded by these electrodes are usually lower in amplitude than conventional disc electrodes. The aim of this work was thus to develop and test a new modular active sensor made up of concentric ring electrodes printed on a flexible substrate by thick-film technology together with a reusable battery-powered signal-conditioning circuit. Simultaneous ECG recording with both flexible and rigid concentric ring electrodes was carried out on ten healthy volunteers at rest and in motion. The results show that flexible concentric ring electrodes not only present lower skin electrode contact impedance and lower baseline wander than rigid electrodes but are also less sensitive to interference and motion artefacts. We believe these electrodes, which allow bioelectric signals to be acquired non-invasively with better spatial resolution than conventional disc electrodes, to be a step forward in the development of new monitoring systems based on Laplacian potential recordings.This research was supported in part by the Ministerio de Ciencia y Tecnologia de Espana (TEC2010-16945) and by the Universitat Politecnica de Valencia (PAID 2009/10-2298). The proof-reading of this paper was funded by the Universitat Politecnica de Valencia, Spain.Prats Boluda, G.; Ye Lin, Y.; García Breijo, E.; Ibáñez Civera, FJ.; Garcia Casado, FJ. (2012). Active flexible concentric ring electrode for non-invasive surface bioelectrical recordings. 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Improvement of spatial selectivity and decrease of mutual information of tri-polar concentric ring electrodes. Journal of Neuroscience Methods, 165(2), 216-222. doi:10.1016/j.jneumeth.2007.06.007Prats-Boluda, G., Garcia-Casado, J., Martinez-de-Juan, J. L., & Ye-Lin, Y. (2011). Active concentric ring electrode for non-invasive detection of intestinal myoelectric signals. Medical Engineering & Physics, 33(4), 446-455. doi:10.1016/j.medengphy.2010.11.009He, B., & Cohen, R. J. (1992). Body surface Laplacian mapping of cardiac electrical activity. The American Journal of Cardiology, 70(20), 1617-1620. doi:10.1016/0002-9149(92)90471-aBesio, W., Aakula, R., Koka, K., & Dai, W. (2006). Development of a Tri-polar Concentric Ring Electrode for Acquiring Accurate Laplacian Body Surface Potentials. Annals of Biomedical Engineering, 34(3), 426-435. doi:10.1007/s10439-005-9054-8Ye-Lin, Y., Garcia-Casado, J., Prats-Boluda, G., Ponce, J. L., & Martinez-de-Juan, J. L. (2009). 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Brain Topography, 8(4), 355-366. doi:10.1007/bf01186911Farina, D., & Cescon, C. (2001). Concentric-ring electrode systems for noninvasive detection of single motor unit activity. IEEE Transactions on Biomedical Engineering, 48(11), 1326-1334. doi:10.1109/10.959328G. Besio, C. C. Lu, P. P. Tarjan, W. (2001). A Feasibility Study for Body Surface Cardiac Propagation Maps of Humans from Laplacian Moments of Activation. Electromagnetics, 21(7-8), 621-632. doi:10.1080/027263401752246243Li, G., Wang, Y., Lin, L., Jiang, W., Wang, L. L., Lu, S. C.-Y., & Besio, W. G. (2005). Active Laplacian electrode for the data-acquisition system of EHG. Journal of Physics: Conference Series, 13, 330-335. doi:10.1088/1742-6596/13/1/077Engel, J., Chen, J., & Liu, C. (2003). Development of polyimide flexible tactile sensor skin. Journal of Micromechanics and Microengineering, 13(3), 359-366. doi:10.1088/0960-1317/13/3/302Papakostas, T. V., Lima, J., & Lowe, M. (s. f.). A large area force sensor for smart skin applications. Proceedings of IEEE Sensors. doi:10.1109/icsens.2002.1037366Stieglitz, T. (2001). Flexible biomedical microdevices with double-sided electrode arrangements for neural applications. Sensors and Actuators A: Physical, 90(3), 203-211. doi:10.1016/s0924-4247(01)00520-9Hamilton, P. S., & Tompkins, W. J. (1986). Quantitative Investigation of QRS Detection Rules Using the MIT/BIH Arrhythmia Database. IEEE Transactions on Biomedical Engineering, BME-33(12), 1157-1165. doi:10.1109/tbme.1986.325695Besio, W., & Chen, T. (2007). Tripolar Laplacian electrocardiogram and moment of activation isochronal mapping. Physiological Measurement, 28(5), 515-529. doi:10.1088/0967-3334/28/5/006Besio, G., Koka, K., Aakula, R., & Weizhong Dai. (2006). Tri-polar concentric ring electrode development for Laplacian electroencephalography. IEEE Transactions on Biomedical Engineering, 53(5), 926-933. doi:10.1109/tbme.2005.863887Setti, L., Fraleoni-Morgera, A., Ballarin, B., Filippini, A., Frascaro, D., & Piana, C. (2005). An amperometric glucose biosensor prototype fabricated by thermal inkjet printing. Biosensors and Bioelectronics, 20(10), 2019-2026. doi:10.1016/j.bios.2004.09.022Reddy, A. S. G., Narakathu, B. B., Atashbar, M. Z., Rebros, M., Rebrosova, E., & Joyce, M. K. (2011). Gravure Printed Electrochemical Biosensor. Procedia Engineering, 25, 956-959. doi:10.1016/j.proeng.2011.12.235Gruetzmann, A., Hansen, S., & Müller, J. (2007). Novel dry electrodes for ECG monitoring. Physiological Measurement, 28(11), 1375-1390. doi:10.1088/0967-3334/28/11/005LI, G., LIAN, J., SALLA, P., CHENG, J., RAMACHANDRA, I., SHAH, P., … HE, B. (2003). Body Surface Laplacian Electrocardiogram of Ventricular Depolarization in Normal Human Subjects. 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Model estimation of cerebral hemodynamics between blood flow and volume changes: a data-based modeling approach

It is well known that there is a dynamic relationship between cerebral blood flow (CBF) and cerebral blood volume (CBV). With increasing applications of functional MRI, where the blood oxygen-level-dependent signals are recorded, the understanding and accurate modeling of the hemodynamic relationship between CBF and CBV becomes increasingly important. This study presents an empirical and data-based modeling framework for model identification from CBF and CBV experimental data. It is shown that the relationship between the changes in CBF and CBV can be described using a parsimonious autoregressive with exogenous input model structure. It is observed that neither the ordinary least-squares (LS) method nor the classical total least-squares (TLS) method can produce accurate estimates from the original noisy CBF and CBV data. A regularized total least-squares (RTLS) method is thus introduced and extended to solve such an error-in-the-variables problem. Quantitative results show that the RTLS method works very well on the noisy CBF and CBV data. Finally, a combination of RTLS with a filtering method can lead to a parsimonious but very effective model that can characterize the relationship between the changes in CBF and CBV