This article presents a solution for continuous monitoring of both respiratory rate (RR) and heart rate (HR) inside Magnetic Resonance Imaging (MRI) environments by a novel ballistocardiography (BCG) fiber-optic sensor. We designed and created a sensor based on the Fiber Bragg Grating (FBG) probe encapsulated inside fiberglass (fiberglass is a composite material made up of glass fiber, fabric, and cured synthetic resin). Due to this, the encapsulation sensor is characterized by very small dimensions (30 × 10 × 0.8 mm) and low weight (2 g). We present original results of real MRI measurements (conventionally most used 1.5 T MR scanner) involving ten volunteers (six men and four women) by performing conventional electrocardiography (ECG) to measure the HR and using a Pneumatic Respiratory Transducer (PRT) for RR monitoring. The acquired sensor data were compared against real measurements using the objective Bland⁻Altman method, and the functionality of the sensor was validated (95.36% of the sensed values were within the ±1.96 SD range for the RR determination and 95.13% of the values were within the ±1.96 SD range for the HR determination) by this means. The accuracy of this sensor was further characterized by a relative error below 5% (4.64% for RR and 4.87% for HR measurements). The tests carried out in an MRI environment demonstrated that the presence of the FBG sensor in the MRI scanner does not affect the quality of this imaging modality. The results also confirmed the possibility of using the sensor for cardiac triggering at 1.5 T (for synchronization and gating of cardiovascular magnetic resonance) and for cardiac triggering when a Diffusion Weighted Imaging (DWI) is used.

Department of Cybernetics and Biomedical Engineering Faculty of Electrical Engineering and Computer Science VSB Technical University of Ostrava 17 Listopadu 15 70833 Ostrava Czech Republic

Department of Metallurgical Materials and Biomedical Engineering University of Texas El Paso 500 W University Ave El Paso TX 79968 USA

Department of Telecommunications Faculty of Electrical Engineering and Computer Science VSB Technical University of Ostrava 17 Listopadu 15 70833 Ostrava Czech Republic

Zobrazit více v PubMed

Weckesser M., Posse S., Olthoff U., Kemna L., Dager S., Müller-Gärtner H.W. Functional imaging of the visual cortex with bold-contrast MRI: Hyperventilation decreases signal response. Mag. Res. Med. 1999;41:213–216. doi: 10.1002/(SICI)1522-2594(199901)41:1<213::AID-MRM31>3.0.CO;2-S. PubMed DOI

Giardino N.D., Friedman S.D., Dager S.R. Anxiety, respiration, and cerebral blood flow: Implications for functional brain imaging. Compr. Psychiatry. 2007;48:103–112. doi: 10.1016/j.comppsych.2006.11.001. PubMed DOI PMC

Tamaki S., Yamada T., Okuyama Y., Morita T., Sanada S., Tsukamoto Y. Cardiac iodine-123 metaiodobenzylguanidine imaging predicts sudden cardiac death independently of left ventricular ejection fraction in patients with chronic heart failure and left ventricular systolic dysfunction: results from a comparative study with signal-averaged electrocardiogram, heart rate variability, and QT dispersion. J. Am. Coll. Cardiol. 2009;53:426–435. PubMed

Zabel M., Acar B., Klingenheben T., Franz M.R., Hohnloser S.H., Malik M. Analysis of 12-lead T-wave morphology for risk stratification after myocardial infarction. Circulation. 2000;102:1252–1257. doi: 10.1161/01.CIR.102.11.1252. PubMed DOI

Ogura R., Hiasa Y., Takahashi T., Yamaguchi K., Fujiwara K., Ohara Y., Hosokawa S. Specific findings of the standard 12-lead ECG in patients with takotsubo’ cardiomyopathy. Circ. J. 2003;67:687–690. doi: 10.1253/circj.67.687. PubMed DOI

Chakeres D.W., Kanarlu A., Boudoulas H., Young D.C. Effect of static magnetic field exposure of up to 8 Tesla on sequential human vital sign measurements. J. Magn. Reson. Imaging. 2003;18:346–352. doi: 10.1002/jmri.10367. PubMed DOI

Jekic M., Ding Y., Dzwonczyk R. Magnetic field threshold for accurate electrocardiography in the MRI environment. Magn. Reson. Med. 2010;64:1586–1591. doi: 10.1002/mrm.22419. PubMed DOI PMC

Krug J.W., Rose G. Magnetohydrodynamic distortions of the ECG in different MR scanner configurations; Proceedings of the 2011 Computing in Cardiology; Hangzhou, China. 18–21 September 2011; pp. 769–772.

Lanzer P., Barta C., Botvinick E.H., Wiesendanger H.U., Modin G., Higgins C.B. ECG-synchronized cardiac MR imaging: Method and evaluation. Radiology. 1985;155:681–686. doi: 10.1148/radiology.155.3.4001369. PubMed DOI

Weissler A.M., Harris W.S., Schoenfeld C.D. Systolic Time Intervals in Heart Failure in Man. Circulation. 1968;37:149–159. doi: 10.1161/01.CIR.37.2.149. PubMed DOI

Berne R.M., Levy M.N. Cardiovascular Physiology. Mosby; St. Louis, MO, USA: 1997.

Brau A.C., Wheeler C.T., Hedlund L.W., Johnson G.A. Fiber-optic stethoscope: A cardiac monitoring and gating system for magnetic resonance microscopy. Magn. Reson. Med. 2002;47:314–321. doi: 10.1002/mrm.10049. PubMed DOI

Baliyan V., Das C.J., Sharma R., Gupta A.K. Diffusion weighted imaging: Technique and applications. World J. Radiol. 2016;8:785–798. doi: 10.4329/wjr.v8.i9.785. PubMed DOI PMC

Biel L., Pettersson O., Philipson L., Wide P. ECG analysis: A new approach in human identification. IEEE Trans. Ind. Meas. 2001;50:808–812. doi: 10.1109/19.930458. DOI

Zhang Y., Hou Z. An algorithm for evaluating the ECG signal quality in 12 lead ECG monitoring system; Proceedings of the IEEE International Conference on Software Engineering and Service Sciences (ICSESS); Beijing, China. 23–25 September 2015; pp. 453–456.

Bousseljot R., Kreiseler D. ECG signal analysis by pattern comparison. Comput. Cardiol. 1998;0:349–352. PubMed

Araoye M.A., Omotoso A.B., Opadijo G.O. The orthogonal and 12 lead ECG in adult negroes with systemic hypertension: comparison with age-matched control. West Afr. J. med. 1998;17:157–164. PubMed

Tse Z.T.H., Dumoulin C.L., Clifford G.D., Schweitzer J., Qin L., Oster J., Jerosch-Herold M., Kwong R.Y., Michaud G., Stevenson W.G., et al. 1.5 Tesla MRI-Conditional 12-lead ECG for MR Imaging and Intra-MR Intervention. Mag. Reson. Med. 2014;71:1336–1347. doi: 10.1002/mrm.24744. PubMed DOI PMC

Dabaghyan M., Zhang S.H., Ward J., Kwong R.Y., Stevenson W.G., Watkins R.D., Zion T.T., Schmidt E.J. 3 T cardiac imaging with on-line 12-lead ECG monitoring. J. Cardiovasc. Mag. Reson. 2016;18:212. doi: 10.1186/1532-429X-18-S1-P212. DOI

Frauenrath T., Hezel F., Renz W., D’Orth T., Dieringer M., Von Knobelsdorff-Brenkenhoff F., Prothmann M., Schulz-Menger J., Niendorf T. Acoustic cardiac triggering: A practical solution for synchronization and gating of cardiovascular magnetic resonance at 7 Tesla. J. Cardiovasc. Mag. Reson. 2010;12 doi: 10.1186/1532-429X-12-67. PubMed DOI PMC

Maderwald S., Orzada S., Lin Z., Schäfer L.C., Bitz A.K., Kraff O., Brote I., Häring L., Czylwik A., Zenge M.O., et al. 7 Tesla Cardiac Imaging with a Phonocardiogram Trigger Device. Proc. Int. Soc. Mag. Reson. Med. 2011;19:201.

Frauenrath T., Hezel F., Heinrichs U., Kozerke S., Utting J.F., Kob M., Butenweg C., Boesiger P., Niendorf T. Feasibility of cardiac gating free of interference with electro-magnetic fields at 1.5 Tesla, 3.0 Tesla and 7.0 Tesla using an MR-stethoscope. Investig. Radiol. 2009;44 doi: 10.1097/RLI.0b013e3181b4c15e. PubMed DOI

Rotariu C., Cristea C., Arotaritei D., Bozomitu R.G., Pasarica A. Continuous respiratory monitoring device for detection of sleep apnea episodes; Proceedings of the 2016 IEEE 22nd International Symposium for Design and Technology in Electronic Packaging (SIITME); Oradea, Romania. 20–23 Octorber 2016; pp. 106–109.

Vasanawala S.S., Jackson E. A method of rapid robust respiratory synchronization for MRI. Pediatr. Radiol. 2010;40:1690–1692. doi: 10.1007/s00247-010-1755-y. PubMed DOI PMC

Yoon J.-W., Noh Y.-S., Kwon Y.-S., Kim W.-K., Yoon H.-R. Improvement of dynamic respiration monitoring through sensor fusion of accelerometer and gyro-sensor. J. Electr. Eng. Technol. 2014;9:334–343. doi: 10.5370/JEET.2014.9.1.334. DOI

Favero F.C., Villatoro J., Pruneri V. Microstructured optical fiber interferometric breathing sensor. J. Biomed. Opt. 2012;17 doi: 10.1117/1.JBO.17.3.037006. PubMed DOI

Sprager S., Donlagic D., Zazula D. Monitoring of basic human vital functions using optical interferometer; Proceedings of the IEEE 10th International Conference on Signal Processing (ICSP); Beijing, China. 24–28 October 2010; pp. 1738–1741.

Sprager S., Donlagic D., Zazula D. Estimation of heart rate, respiratory rate and motion by using optical interferometer as body sensor; Proceedings of the IASTED International Conference on Signal and Image Processing; Honolulu, HI, USA. 14–16 December 2011; pp. 280–287.

Sprager S., Zazula D. Detection of heartbeat and respiration from optical interferometric signal by using wavelet transform. Comput. Methods Prog. Biomed. 2013;111:41–51. doi: 10.1016/j.cmpb.2013.03.003. PubMed DOI

Will C., Shi K., Lurz F., Weigel R., Koelpin A. Intelligent signal processing routine for instantaneous heart rate detection using a Six-Port microwave interferometer; Proceedings of the 2015 International Symposium on Intelligent Signal Processing and Communication Systems (ISPACS); Nusa Dua, Bali. 9–12 November 2015; pp. 483–487.

Zazula D., Sprager S. Detection of the first heart sound using fibre-optic interferometric measurements and neural networks; Proceedings of the Symposium on Neural Network Applications in Electrical Engineering; Belgrade, Serbia. 20–22 September 2012; pp. 171–176.

Byeong H.L., Young H.K., Kwan S.P., Joo B.E., Myoung J.K., Byung S.R., Hae Y.C. Interferometric Fiber Optic Sensors. Sensors. 2012;12:2467–2486. PubMed PMC

Hsieh Y.H., Chen N.K. Micro tapered Mach–Zehnder fiber interferometer for monitoring pressure fluctuation and its applications in pulse rate detection; Proceedings of the 2013 6th IEEE/International Conference on Advanced Infocomm Technology (ICAIT); Taiwan, China. 6–9 July 2013; pp. 113–115.

Roriz P., Carvalho L., Frazão O., Santos J.L., Simoes A.J. From conventional sensors to fibre optic sensors for strain and force measurements in biomechanics applications: A review. J. Biomech. 2014;47:1251–1261. doi: 10.1016/j.jbiomech.2014.01.054. PubMed DOI

Dziuda L. Fiber-optic sensors for monitoring patient physiological parameters: A review of applicable technologies and relevance to use during magnetic resonance imaging procedures. J. Biomech. 2015;20:010901. doi: 10.1117/1.JBO.20.1.010901. PubMed DOI

Chethana K., Guru Prasad A.S., Omkar S.N., Asokan S. Fiber bragg grating sensor-based device for simultaneous measurement of respiratory and cardiac activities. J. Biophotonics. 2016;10:278–285. doi: 10.1002/jbio.201500268. PubMed DOI

Dzuida L., Skibniewski F.W., Krej M., Lewandowski J. Monitoring respiration and cardiac activity using fiber Bragg grating-based sensor. IEEE Trans. Biomed. Eng. 2012;59:1934–1942. doi: 10.1109/TBME.2012.2194145. PubMed DOI

Dziuda L., Krej M., Skibniewski F.W. Fiber Bragg grating strain sensor incorporated to monitor patient vital signs during MRI. IEEE Sens. J. 2013;13:4986–4991. doi: 10.1109/JSEN.2013.2279160. DOI

Emamian M., Hasanian S.M., Tayefi M., Bijari M., Movahedian far F., Shafiee M., Avan A., Heidari-Bakavoli A., Moohebati M., Ebrahimi M., et al. Association of hematocrit with blood pressure and hypertension. J. Clin. Lab. Anal. 2017;31 doi: 10.1002/jcla.22124. PubMed DOI PMC

Hang-yin L. Experimental study of non-uniform strains in composites with embedded fiber bragg grating. Meas. Sci. Technol. 2005;16 doi: 10.1088/0957-0233/16/12/003. DOI

Anoshkin A.N., Shipunov G.S., Voronkov A.A., Shardakov I.N. Effect of temperature on the spectrum of fiber Bragg grating sensors embedded in polymer composite. AIP Conf. Proc. 1909 doi: 10.1063/1.5013688. DOI

Zhang Y. The Packaging Technology Study on Smart Composite Structure Based on the Embedded FBG Sensor. IOP Conf. Ser. Mater. Sci. Eng. 2018;322 doi: 10.1088/1757-899X/322/2/022059. DOI

Fajkus M., Nedoma J., Martinek R., Vasinek V., Nazeran H., Siska P. A Non-invasive Multichannel Hybrid Fiber-optic Sensor System for Vital Sign Monitoring. Sensors. 2017;17:111. doi: 10.3390/s17010111. PubMed DOI PMC

Nedoma J., Kepak S., Fajkus M., Cubik J., Siska P., Martinek R., Krupa P. Magnetic Resonance Imaging Compatible Non-Invasive Fibre-Optic Sensors Based on the Bragg Gratings and Interferometers in the Application of Monitoring Heart and Respiration Rate of the Human Body: A Comparative Study. Sensors. 2018;18:3713. doi: 10.3390/s18113713. PubMed DOI PMC

Yang X., Chen Z., Elvin C.S.M., Janice L.H.Y., Ng S.H., Teo J.T., Wu R. Textile Fiber Optic Microbend Sensor Used for Heartbeat and Respiration Monitoring. IEEE Sens. J. 2015;15:757–761. doi: 10.1109/JSEN.2014.2353640. DOI

Grilett A., Kinet D., Witt J., Schukar M., Krebber K., Pirotte F., Depre A. Optical fiber sensors embedded into medical textiles for healthcare monitoring. IEEE Sens. J. 2008;8:1215–1222. doi: 10.1109/JSEN.2008.926518. DOI

Chen D., Lau J.T., Teo S.H., Ng X., Yang P., Kei L. Simultaneous measurement of breathing rate and heart rate using a microbend multimode fiber optic sensor. J. Biomed. Opt. 2014;19:57001. doi: 10.1117/1.JBO.19.5.057001. PubMed DOI

Krehel M., Schmid M., Rossi R.M., Boesel F.L., Bona G.L., Scherer L.J. An optical fibre-based sensor for respiratory monitoring. Sensors. 2014;14:13088–13101. doi: 10.3390/s140713088. PubMed DOI PMC

Leal-Junior A.G., Díaz C.R., Leitão C., Pontes M.J., Marques C., Frizera A. Polymer optical fiber-based sensor for simultaneous measurement of breath and heart rate under dynamic movements. Opt. Laser Technol. 2018;109:429–436. doi: 10.1016/j.optlastec.2018.08.036. DOI

Taffoni F., Formica D., Saccomandi P., Di Pino G., Schena E. Optical fiber-based MR-compatible sensors for medical applications: An overview. Sensors. 2013;13:14105–14120. doi: 10.3390/s131014105. PubMed DOI PMC

Grillet A., Kinet D., Witt J., Schukar M., Krebber K., Pirotte F., Depré A. Optical fibre sensors embedded into medical textiles for monitoring of respiratory movements in MRI environment; Proceedings of the Third European Workshop on Optical Fibre Sensors; Napoli, Italy. 4–6 July 2007.

Moerman K.M., Sprengers A.M.J., Nederveen A.J., Simms C.K. A novel MRI compatible soft tissue indentor and fibre Bragg grating force sensor. Med. Eng. Phys. 2013;35:486–499. doi: 10.1016/j.medengphy.2012.06.014. PubMed DOI

Tan U.-X., Yang B., Gullapalli R., Desai J.P. Triaxial MRI-compatible fiber-optic force sensor IEEE. Trans. Robot. 2011;27:65–74. doi: 10.1109/TRO.2010.2090061. PubMed DOI PMC

Yoo W.J., Jang K.W., Seo J.K., Heo J.Y., Moon J.S., Park J.Y., Lee B. Development of respiration sensors using plastic optical fiber for respiratory monitoring inside MRI system. J. Opt. Soc. Korea. 2010;14:235–239. doi: 10.3807/JOSK.2010.14.3.235. DOI

Kam W., Mohammed W.S., Leen G., O’Sullivan K., O’Keeffe M., O’Keeffe S., Lewis E. All plastic optical fiber-based respiration monitoring sensor; Proceedings of the IEEE Sensors; New Delhi, India. 29–31 December 2017; pp. 1–3.

Filograno M.L., Pisco M., Catalano A., Forte E., Aiello M., Cavaliere C., Soricelli A., Davino D., Visone C., Cutolo A., et al. Triaxial Fiber Optic Magnetic Field Sensor for Magnetic Resonance Imaging. J. Lightw. Technol. 2017;35:3924–3933. doi: 10.1109/JLT.2017.2722545. DOI

Nedoma J., Fajkus M., Novak M., Strbikova N., Vasinek V., Nazeran H., Vanus J., Perecar F., Martinek R. Validation of a novel fiber-optic sensor system for monitoring cardiorespiratory activities during mri examinations. Adv. Electr. Electron. Eng. 2017;15:536–543. doi: 10.15598/aeee.v15i3.2194. DOI

Su H., Shang W., Li G., Patel N., Fischer G.S. An MRI-Guided Telesurgery System Using a Fabry-Perot Interferometry Force Sensor and a Pneumatic Haptic Device. Ann. Biomed. Eng. 2017;45:1917–1928. doi: 10.1007/s10439-017-1839-z. PubMed DOI PMC

Dziuda L., Skibniewski F.W. A new approach to ballistocardiographic measurements using fibre Bragg grating-based sensors. Biocybern. Biomed. Eng. 2014;34:101–106. doi: 10.1016/j.bbe.2014.02.001. DOI

Agarwal R.P., O’Regan D. Ordinary and Partial Differential Equations. Springer; New York, NY, USA: 2009. Two-Dimensional Wave Equation.

Kersay A.D., Davis M.A., Patrick H.J., LeBlanc M., Koo K.P., Askins C.G., Putnam M.A., Friebele E.J. Fiber grating sensors. J. Lightw. Technol. 1997;15:1442–1463. doi: 10.1109/50.618377. DOI

Pinheiro E., Postolache O., Girao P. Theory and Developments in an Unobtrusive Cardiovascular System Representation: Ballistocardiography. Open Biomed. Eng. J. 2010;4 doi: 10.2174/1874120701004010201. PubMed DOI PMC

Lindqvist A., Pihlajamäki K., Jalonen J., Laaksonen V., Alihanka J. Static-charge-sensitive bed ballistocardiography in cardiovascular monitoring. Clin. Physiol. 1996;16:23–30. doi: 10.1111/j.1475-097X.1996.tb00553.x. PubMed DOI

Inan O.T. Novel Technologies for Cardiovascular Monitoring Using Ballistocardiography and Electrocardiography. Proquest; Ann Arbor, MI, USA: 2011.

Wiard R.M., Inan O.T., Giovangrandi L., Cuttino C.M., Kovacs G.T.A. Preliminary results from standing ballistocardiography measurements in microgravity; Proceedings of the 2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC); Osaka, Japan. 3–7 July 2013. PubMed

Zhu Y., Zhang H., Jayachandran M., Ng A.K., Biswas J., Chen Z. Ballistocardiography with fiber optic sensor in headrest position: A feasibility study and a new processing algorithm; Proceedings of the 2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC); Osaka, Japan. 3–7 July 2013. PubMed

Jiao C., Lyons P., Zare A., Rosales L., Skubic M. Heart beat characterization from ballistocardiogram signals using extended functions of multiple instances; Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBS; Lake Buena Vista, FL, USA. 16–20 August 2016. PubMed

Product FBGuard. [(accessed on 6 December 2018)]; Available online: http://www.safibra.cz/en/fbguard-interrogation-unit.

Product TSD221-MRI. [(accessed on 6 December 2018)]; Available online: https://www.biopac.com/wp-content/uploads/TSD221-MRI.pdf.

Bland J.M., Altman D.G. Measuring agreement in method comparison studies. Stat. Methods Med. Res. 1999;8:135–160. doi: 10.1177/096228029900800204. PubMed DOI

Yang L., Xu L., Schoepf U.J., Wichmann J.L., Fox M.A., Yan J., Fan Z., Zhang Z. Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: Influence of heart rate on image quality and evaluation of diagnostic accuracy. PLoS ONE. 2015;10 doi: 10.1371/journal.pone.0134194. PubMed DOI PMC

Stäb D., Roessler J., O’Brien K., Hamilton-Craig C., Barth M. ECG Triggering in Ultra-High Field Cardiovascular MRI. Tomography. 2016;2:167–174. doi: 10.18383/j.tom.2016.00193. PubMed DOI PMC

Dziuda L., Skibniewski F.W., Krej M., Baran P.M. Fiber Bragg grating-based sensor for monitoring respiration and heart activity during magnetic resonance imaging examinations. J. Biomed. Opt. 2013;18:057006. doi: 10.1117/1.JBO.18.5.057006. PubMed DOI