{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T02:37:07Z","timestamp":1782959827662,"version":"3.54.5"},"reference-count":57,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2020,6,1]],"date-time":"2020-06-01T00:00:00Z","timestamp":1590969600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>During the last years, Electrocardiographic Imaging (ECGI) has emerged as a powerful and promising clinical tool to support cardiologists. Starting from a plurality of potential measurements on the torso, ECGI yields a noninvasive estimation of their causing potentials on the epicardium. This unprecedented amount of measured cardiac signals needs to be conditioned and adapted to current knowledge and methods in cardiac electrophysiology in order to maximize its support to the clinical practice. In this setting, many cardiac indices are defined in terms of the so-called bipolar electrograms, which correspond with differential potentials between two spatially close potential measurements. Our aim was to contribute to the usefulness of ECGI recordings in the current knowledge and methods of cardiac electrophysiology. For this purpose, we first analyzed the basic stages of conventional cardiac signal processing and scrutinized the implications of the spatial-temporal nature of signals in ECGI scenarios. Specifically, the stages of baseline wander removal, low-pass filtering, and beat segmentation and synchronization were considered. We also aimed to establish a mathematical operator to provide suitable bipolar electrograms from the ECGI-estimated epicardium potentials. Results were obtained on data from an infarction patient and from a healthy subject. First, the low-frequency and high-frequency noises are shown to be non-independently distributed in the ECGI-estimated recordings due to their spatial dimension. Second, bipolar electrograms are better estimated when using the criterion of the maximum-amplitude difference between spatial neighbors, but also a temporal delay in discrete time of about 40 samples has to be included to obtain the usual morphology in clinical bipolar electrograms from catheters. We conclude that spatial-temporal digital signal processing and bipolar electrograms can pave the way towards the usefulness of ECGI recordings in the cardiological clinical practice. The companion paper is devoted to analyzing clinical indices obtained from ECGI epicardial electrograms measuring waveform variability and repolarization tissue properties.<\/jats:p>","DOI":"10.3390\/s20113131","type":"journal-article","created":{"date-parts":[[2020,6,2]],"date-time":"2020-06-02T09:19:27Z","timestamp":1591089567000},"page":"3131","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Spatial-Temporal Signals and Clinical Indices in Electrocardiographic Imaging (I): Preprocessing and Bipolar Potentials"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0125-485X","authenticated-orcid":false,"given":"Ra\u00fal","family":"Caulier-Cisterna","sequence":"first","affiliation":[{"name":"Department of Signal Theory and Communications, Telematics and Computing Systems, Rey Juan Carlos University, Fuenlabrada, 28943 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5966-881X","authenticated-orcid":false,"given":"Margarita","family":"Sanrom\u00e1n-Junquera","sequence":"additional","affiliation":[{"name":"Department of Signal Theory and Communications, Telematics and Computing Systems, Rey Juan Carlos University, Fuenlabrada, 28943 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1356-2646","authenticated-orcid":false,"given":"Sergio","family":"Mu\u00f1oz-Romero","sequence":"additional","affiliation":[{"name":"Department of Signal Theory and Communications, Telematics and Computing Systems, Rey Juan Carlos University, Fuenlabrada, 28943 Madrid, Spain"},{"name":"Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, Boadilla, 28223 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6593-1517","authenticated-orcid":false,"given":"Manuel","family":"Blanco-Velasco","sequence":"additional","affiliation":[{"name":"Department of Signal Theory and Communications, Universidad de Alcal\u00e1, Alcal\u00e1 de Henares, 28805 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0402-8487","authenticated-orcid":false,"given":"Rebeca","family":"Goya-Esteban","sequence":"additional","affiliation":[{"name":"Department of Signal Theory and Communications, Telematics and Computing Systems, Rey Juan Carlos University, Fuenlabrada, 28943 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1928-865X","authenticated-orcid":false,"given":"Arcadi","family":"Garc\u00eda-Alberola","sequence":"additional","affiliation":[{"name":"Arrhythmia Unit, Hospital Cl\u00ednico Universitario Virgen de la Arrixaca de Murcia, El Palmar, 30120 Murcia, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0426-8912","authenticated-orcid":false,"given":"Jos\u00e9 Luis","family":"Rojo-\u00c1lvarez","sequence":"additional","affiliation":[{"name":"Department of Signal Theory and Communications, Telematics and Computing Systems, Rey Juan Carlos University, Fuenlabrada, 28943 Madrid, Spain"},{"name":"Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, Boadilla, 28223 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,1]]},"reference":[{"key":"ref_1","unstructured":"Arunachalam, S.P. (2017). Novel Approaches for Quantitative Electrogram Analysis for Rotor Identification: Implications for Ablation in Patients with Atrial Fibrillation. [Ph.D. Thesis, University of Minnesota]."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"940","DOI":"10.1016\/j.hrthm.2005.06.029","article-title":"Identification of successful catheter ablation sites in patients with ventricular tachycardia based on electrogram characteristics during sinus rhythm","volume":"2","author":"Zeppenfeld","year":"2005","journal-title":"Heart Rhythm"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.hrthm.2017.08.001","article-title":"Electrogram signature of specific activation patterns: Analysis of atrial tachycardias at high-density endocardial mapping","volume":"15","author":"Frontera","year":"2018","journal-title":"Heart Rhythm"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"e000215","DOI":"10.1161\/JAHA.113.000215","article-title":"Direct comparison of adjacent endocardial and epicardial electrograms: Implications for substrate mapping","volume":"2","author":"Tokuda","year":"2013","journal-title":"J. Am. Heart Assoc."},{"key":"ref_5","first-page":"215","article-title":"The inverse problem in electrocardiography: Solutions in terms of epicardial potentials","volume":"16","author":"Rudy","year":"1988","journal-title":"Crit. Rev. Biomed. Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1016\/S0022-0736(98)80005-8","article-title":"Noninvasive imaging and catheter imaging of potentials, electrograms, and isochrones on the ventricular surfaces","volume":"30","author":"Rudy","year":"1998","journal-title":"J. Electrocardiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0022-0736(99)90025-0","article-title":"Electrocardiographic imaging: A noninvasive imaging modality for characterization of intramural myocardial activation","volume":"32","author":"Rudy","year":"1999","journal-title":"J. Electrocardiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1515\/bmte.2001.46.s2.201","article-title":"Electrocardiographic Imaging: Noninvasive Reconstruction of Epicardial Measures of Dispersion of Repolarization","volume":"46","author":"Ghanem","year":"2001","journal-title":"Biomed. Tech. Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2152","DOI":"10.1161\/01.CIR.102.17.2152","article-title":"A noninvasive imaging modality for cardiac arrhythmias","volume":"102","author":"Burnes","year":"2000","journal-title":"Circulation"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"981","DOI":"10.1114\/1.1588655","article-title":"Noninvasive electrocardiographic imaging (ECGI): Application of the generalized minimal residual (GMRes) method","volume":"31","author":"Ramanathan","year":"2003","journal-title":"Ann. Biomed. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"422","DOI":"10.1038\/nm1011","article-title":"Noninvasive electrocardiographic imaging for cardiac electrophysiology and arrhythmia","volume":"10","author":"Ramanathan","year":"2004","journal-title":"Nat. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"6309","DOI":"10.1073\/pnas.0601533103","article-title":"Activation and repolarization of the normal human heart under complete physiological conditions","volume":"103","author":"Ramanathan","year":"2006","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.ccep.2014.11.004","article-title":"Noninvasive mapping to guide atrial fibrillation ablation","volume":"7","author":"Lim","year":"2015","journal-title":"Card. Electrophysiol. Clin."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"966","DOI":"10.1016\/j.jelectrocard.2015.08.028","article-title":"Non-invasive cardiac mapping in clinical practice: Application to the ablation of cardiac arrhythmias","volume":"48","author":"Dubois","year":"2015","journal-title":"J. Electrocardiol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/j.ijcard.2017.02.104","article-title":"Noninvasive ECG imaging (ECGI): Mapping the arrhythmic substrate of the human heart","volume":"237","author":"Rudy","year":"2017","journal-title":"Int. J. Cardiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1070","DOI":"10.1016\/j.hrthm.2018.03.011","article-title":"Role for electrocardiographic imaging in cardiac resynchronization therapy?","volume":"15","author":"Rudy","year":"2018","journal-title":"Heart Rhythm"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1016\/j.hrthm.2018.10.010","article-title":"Performance and limitations of noninvasive cardiac activation mapping","volume":"16","author":"Duchateau","year":"2019","journal-title":"Heart Rhythm"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1109\/TBME.2009.2024928","article-title":"Resolution Strategies for the Finite-Element-Based Solution of the ECG Inverse Problem","volume":"57","author":"Wang","year":"2010","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.3389\/fphys.2018.01305","article-title":"Validation and Opportunities of Electrocardiographic Imaging: From Technical Achievements to Clinical Applications","volume":"9","author":"Cluitmans","year":"2018","journal-title":"Front. Physiol."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Duchateau, J., Coudi\u00e8re, Y., Ha\u00efssaguerre, M., and Dubois, R. (2015, January 6\u20139). Virtual Bipolar and Laplacian Electrodes for Activation Map Construction in ECGi. Proceedings of the 2015 Computing in Cardiology Conference (CinC), Nice, France.","DOI":"10.1109\/CIC.2015.7411069"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Shenasa, M., Hindricks, G., Callans, D.J., Miller, J.M., and Josephson, M.E. (2019). Cardiac Mapping, John Wiley & Sons.","DOI":"10.1002\/9781119152637"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3070","DOI":"10.3390\/s20113070","article-title":"Spatial-temporal Signals and Clinical Indices in Electrocardiographic Imaging (II): Electrogram Clustering, Fragmentation, and T-wave Alternans","volume":"20","year":"2020","journal-title":"Sensors"},{"key":"ref_23","unstructured":"Rojo-\u00c1lvarez, J.L., Goya-Esteban, R., Mu\u00f1oz-Romero, S., Garc\u00eda-Alberola, A., Melgarejo-Meseguer, F.M., and Blanco-Velasco, M. (2018, January 23\u201326). T-Wave Alternans Analysis with Electrocardiographic Imaging. Proceedings of the 2018 Computing in Cardiology Conference (CinC), Maastricht, The Netherlands."},{"key":"ref_24","unstructured":"Villabriga, B., and Romaniega, T. (2010). Manual de Arritmias y Electrofisiolog\u00eda Card\u00edaca, Pulso Ediciones."},{"key":"ref_25","unstructured":"Josephson, M.E. (2016). Josephson\u2019s Clinical Cardiac Electrophysiology, Wolters Kluwer."},{"key":"ref_26","unstructured":"Mont, L. (2011). Manual de Electrofisiolog\u00eda cl\u00ednica y Ablaci\u00f3n, Marge M\u00e9dica Books."},{"key":"ref_27","unstructured":"Rudy, Y., Ramanathan, C., Ghosh, S., and Zipes, D. (2009). Noninvasive electrocardiographic imaging (ECGI): Methodology and excitation of the normal human heart. Cardiac Electrophysiology: From Cell to Bedside, Saunders Elsevier. [5th ed.]."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1496","DOI":"10.1161\/01.CIR.97.15.1496","article-title":"Electrocardiographic imaging: Noninvasive characterization of intramural myocardial activation from inverse-reconstructed epicardial potentials and electrograms","volume":"97","author":"Oster","year":"1998","journal-title":"Circulation"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1161\/01.CIR.101.5.533","article-title":"Noninvasive ECG imaging of electrophysiologically abnormal substrates in infarcted hearts: A model study","volume":"101","author":"Burnes","year":"2000","journal-title":"Circulation"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1016\/j.hrthm.2004.12.022","article-title":"Noninvasive electrocardiographic imaging (ECGI): Comparison to intraoperative mapping in patients","volume":"2","author":"Ghanem","year":"2005","journal-title":"Heart Rhythm"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"98ra84","DOI":"10.1126\/scitranslmed.3002152","article-title":"Noninvasive electroanatomic mapping of human ventricular arrhythmias with electrocardiographic imaging","volume":"3","author":"Wang","year":"2011","journal-title":"Sci. Transl. Med."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2045","DOI":"10.1016\/j.jacc.2006.08.019","article-title":"Single-beat noninvasive imaging of cardiac electrophysiology of ventricular pre-excitation","volume":"48","author":"Berger","year":"2006","journal-title":"J. Am. Coll. Cardiol."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Berger, T., Pfeifer, B., Hanser, F.F., Hintringer, F., Fischer, G., Netzer, M., Trieb, T., Stuehlinger, M., Dichtl, W., and Baumgartner, C. (2011). Single-beat noninvasive imaging of ventricular endocardial and epicardial activation in patients undergoing CRT. PLoS ONE, 6.","DOI":"10.1371\/journal.pone.0016255"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"e005105","DOI":"10.1161\/CIRCEP.116.005105","article-title":"Electrical and Structural Substrate of Arrhythmogenic Right Ventricular Cardiomyopathy Determined Using Noninvasive Electrocardiographic Imaging and Late Gadolinium Magnetic Resonance Imaging","volume":"10","author":"Andrews","year":"2017","journal-title":"Circ. Arrhythm. Electrophysiol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"2325","DOI":"10.1056\/NEJMoa1613773","article-title":"Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia","volume":"377","author":"Cuculich","year":"2017","journal-title":"N. Engl. J. Med."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"e006108","DOI":"10.1161\/CIRCEP.117.006108","article-title":"How Accurate Is Inverse Electrocardiographic Mapping?: A Systematic In Vivo Evaluation","volume":"11","author":"Bear","year":"2018","journal-title":"Circ. Arrhythm. Electrophysiol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e007484","DOI":"10.1161\/CIRCEP.119.007484","article-title":"Electromechanics of the Normal Human Heart In Situ","volume":"12","author":"Andrews","year":"2019","journal-title":"Circ. Arrhythmia Electrophysiol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1936","DOI":"10.1161\/CIRCULATIONAHA.114.011359","article-title":"Electrophysiologic substrate in congenital long QT syndrome: Noninvasive mapping with electrocardiographic imaging (ECGI)","volume":"130","author":"Vijayakumar","year":"2014","journal-title":"Circulation"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1111\/pace.12882","article-title":"Electrophysiologic Scar Substrate in Relation to VT: Noninvasive High-Resolution Mapping and Risk Assessment with ECGI","volume":"39","author":"Zhang","year":"2016","journal-title":"PACE"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"894","DOI":"10.1016\/j.jacep.2016.12.017","article-title":"The Electrophysiological Substrate of Early Repolarization Syndrome: Noninvasive Mapping in Patients","volume":"3","author":"Zhang","year":"2017","journal-title":"JACC. Clin. Electrophysiol."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Everss-Villalba, E., Melgarejo-Meseguer, F.M., Blanco-Velasco, M., Gimeno-Blanes, F.J., Sala-Pla, S., Rojo-\u00c1lvarez, J.L., and Garc\u00eda-Alberola, A. (2017). Noise Maps for Quantitative and Clinical Severity Towards Long-Term ECG Monitoring. Sensors, 17.","DOI":"10.3390\/s17112448"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"644","DOI":"10.1016\/j.hrthm.2009.02.018","article-title":"Infarct architecture and characteristics on delayed enhanced magnetic resonance imaging and electroanatomic mapping in patients with postinfarction ventricular arrhythmia","volume":"6","author":"Desjardins","year":"2009","journal-title":"Heart Rhythm"},{"key":"ref_43","unstructured":"Josephson, M.E. (2008). Clinical Cardiac Electrophysiology: Techniques and Interpretations, Lippincott Williams & Wilkins."},{"key":"ref_44","unstructured":"Kenneth, A., and Ellenbogen, M.D. (2015). Essential Concepts of Electrophysiology through Case Studies: Intracardiac EGMs, CardioText."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"20130761","DOI":"10.1098\/rsif.2013.0761","article-title":"An automated algorithm for online detection of fragmented QRS and identification of its various morphologies","volume":"10","author":"Maheshwari","year":"2013","journal-title":"J. R. Soc. Interface"},{"key":"ref_46","first-page":"201","article-title":"The electrocardiogram and its relationship to excitation of the heart","volume":"151","author":"Rudy","year":"1995","journal-title":"Dev. Cardiovasc. Med."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"e004104","DOI":"10.1161\/CIRCEP.116.004104","article-title":"Experimental Validation of Noninvasive Epicardial and Endocardial Activation Imaging","volume":"9","author":"Oosterhoff","year":"2016","journal-title":"Circ. Arrhythm. Electrophysiol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1161\/01.RES.46.2.283","article-title":"A comparison of volume conductor and source geometry effects on body surface and epicardial potentials","volume":"46","author":"Rudy","year":"1980","journal-title":"Circulation"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"902","DOI":"10.1007\/s10439-009-9665-6","article-title":"Application of L1-norm regularization to epicardial potential solution of the inverse electrocardiography problem","volume":"37","author":"Ghosh","year":"2009","journal-title":"Ann. Biomed. Eng."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1109\/10.108129","article-title":"The use of temporal information in the regularization of the inverse problem of electrocardiography","volume":"39","author":"Oster","year":"1992","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.compbiomed.2015.04.027","article-title":"Techniques for automated local activation time annotation and conduction velocity estimation in cardiac mapping","volume":"65","author":"Cantwell","year":"2015","journal-title":"Comput. Biol. Med."},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Liang, J.J., and Callans, D.J. (2017). Electrophysiologic Testing and Cardiac Mapping. Cardiac Arrhythmias, Pacing and Sudden Death, Springer.","DOI":"10.1007\/978-3-319-58000-5_7"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1111\/jce.13163","article-title":"Novel mapping technique for localization of focal and reentrant activation during atrial fibrillation","volume":"28","author":"Takahashi","year":"2017","journal-title":"J. Cardiovasc. Electrophysiol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1111\/j.1540-8167.1997.tb00807.x","article-title":"Noncontact endocardial mapping: Reconstruction of electrograms and isochrones from intracavitary probe potentials","volume":"8","author":"Liu","year":"1997","journal-title":"J. Cardiovasc. Electrophysiol."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"887","DOI":"10.1161\/01.CIR.98.9.887","article-title":"Simultaneous endocardial mapping in the human left ventricle using a noncontact catheter: Comparison of contact and reconstructed electrograms during sinus rhythm","volume":"98","author":"Schilling","year":"1998","journal-title":"Circulation"},{"key":"ref_56","unstructured":"Harlev, D., Greenfield, P., and Amariglio, L. (2016). Cardiac mapping with catheter shape information. (9,526,434), US Patent."},{"key":"ref_57","unstructured":"Yeo, C., Lemery, R., and Green, M. (2017). Contributions of Noncontact Mapping to the Understanding of Normal Atrial Activation. Interatrial Block and Supraventricular Arrhythmias: Clinical Implications of Bay\u00e9s\u2019 Syndrome, Cardiotext."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/11\/3131\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:34:43Z","timestamp":1760175283000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/11\/3131"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,6,1]]},"references-count":57,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2020,6]]}},"alternative-id":["s20113131"],"URL":"https:\/\/doi.org\/10.3390\/s20113131","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,6,1]]}}}