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Real-time QRS detection using integrated variance for ECG gated cardiac MRI

  • Marcus Schmidt EMAIL logo , Johannes W. Krug and Georg Rose
Published/Copyright: September 30, 2016
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Current Directions in Biomedical Engineering
From the journal Current Directions in Biomedical Engineering Volume 2 Issue 1

Abstract

During magnetic resonance imaging (MRI), a patient’s vital signs are required for different purposes. In cardiac MRI (CMR), an electrocardiogram (ECG) of the patient is required for triggering the image acquisition process. However, a reliable QRS detection of an ECG signal acquired inside an MRI scanner is a challenging task due to the magnetohydrodynamic (MHD) effect which interferes with the ECG. The aim of this work was to develop a reliable QRS detector usable inside the MRI which also fulfills the standards for medical devices (IEC 60601-2-27). Therefore, a novel real-time QRS detector based on integrated variance measurements is presented. The algorithm was trained on ANSI/AAMI EC13 test waveforms and was then applied to two databases with 12-lead ECG signals recorded inside and outside an MRI scanner. Reliable results for both databases were achieved for the ECG signals recorded inside (DBMRI: sensitivity Se = 99.94%, positive predictive value +P = 99.84%) and outside (DBInCarT: Se = 99.29%, +P = 99.72%) the MRI. Due to the accurate R-peak detection in real-time this can be used for monitoring and triggering in MRI exams.

Keywords: ECG; MRI; QRS detection; variance

1 Introduction

Magnetic resonance imaging (MRI) gain more and more importance in clinical routine because of its high image quality and the absence of ionizing radiation. To detect cardiovascular diseases, cardiovascular MRI (CMR) is an increasing used, noninvasive diagnostic method [1]. In clinical practice, MR scanners with field strength up to 3T are used [2], [3]. The electrocardiogram (ECG) is used to synchronize the cardiac phase with the CMR image acquisition process. Another use of the ECG during MRI applications is the monitoring of the vital sign to ensure the safety of the patient. For both, gating and patient monitoring, the ECG’s R-wave or QRS-complex has to be detected accurately. However, QRS detection is hampered due to the magnetohydrodynamic (MHD) effect and the fast switching gradient magnetic fields inside the MRI scanner [4]. Methods to reduce gradient and RF-induced artifacts were proposed in [5]. Methods for filtering the MHD effect were presented in [6].

QRS detectors used in certified clinical monitoring systems need to be able to cope with different pathological test ECG signals according to the IEC 60601-2-27 standard [7]. This standard can be tested using ANSI/AAMI EC13 test waveforms. In the past, different QRS detection algorithms for MRI were developed [5], [8], [9]. However, most of these methods required multiple leads and were not tested according to the IEC standard.

This work proposes a new real-time QRS detector for MRI applications which fulfills the IEC standard. We have previously shown that the statistical central moments can be used for a reliable QRS detection in MRI [10]. We propose to use an approach based on integrated variance to fulfill the IEC standard and to provide a reliable QRS detection during MRI. The technique was trained using the ANSI/AAMI EC13 test waveforms and tested with ECG signal recorded outside [11] and inside [10] the MRI.

2 Material and methods

2.1 Database

For the development and evaluation of the novel QRS detector one training and two test databases were used. The training database DBTraining consists of the ANSI/AAMI E13 test waveforms (sampling rate: 720 Hz, resolution: 12 bit) [12]. The aim with these test waveforms is to detect the average heart rate, i e. no QRS-complexes were annotated but only an average heart rate is given. In the datasets a ventricular bigeminy (VB, aami3a), slow alternating VB (aami3b) as well as a rapid alternating VB (aami3c) and bidirectional systoles (aami3d) are available. Further the heart rate during a ventricular tachycardia (aami4a: 1 mV peak-to-valley, aami4b: 2 mV peak-to-valley) has to be estimated correctly. Further the amplitude in aami4a and aami4b was halved (aami4a_h and aami4b_h) and doubled (aami4a_d and aami4b_d). For three datasets (aami3a, aami3b, aami3d), two acceptable HR were given as reference which means that some arrhythmic peaks are allowed to be missed by the QRS detector. Further a difference of 10% or 5 beats (what shows the higher difference) were allowed for a correct HR estimation.

The first test database (DBInCarT) [12] consisted of 12 lead ECG data in 75 records sampled with 257 Hz with over 175,000 annotated beats. The datasets were recorded from 15 female and 17 male patients ranged from 18 to 80 years (mean age: 58 years). 3 datasets (54, 57 and 58) were rejected because of a missing signal. A total of 168,341 annotated QRS complexes were used for the evaluation of the QRS detector.

The second test database (DBMRI) consisted of ECG signals acquired inside a 3T MRI (Siemens, Skyra, Germany) in head first and feet first position. The ECG data were recorded using a 12-lead Holter ECG (CardioMem CM3000-12, GETEMED, Germany) with a sampling frequency (fs) of 1024 Hz and a resolution of 12 bit. The overall length of the database was 2.25 h with 9421 annotated QRS complexes.

2.2 Algorithm

The ECG signals were bandpass filtered (5th order, 45 Hz Butterworth low-pass and 3rd order, 0.5 Hz Butterworth high-pass filter) to reduce noise and baseline wander. The variance of a vector X = [x1, x2, …, xL] was computed as

(1)V⁢a⁢r=1L⁢∑i=1L(xi−x¯)2.

in a sliding window L = 0.02 s ⋅ fs with a step width of 1 sample where fs is the sampling frequency of the ECG. This window length was chosen to fit into the upslope or downslope of the QRS complex. A step width of 1 sample preserved the original sampling frequency. The result of the variance was integrated in a sliding window of S = 0.05 s ⋅ fs. The threshold for QRS detection was defined as the median of the last 10 maxima of the integrated variance of the QRS complexes multiplied with a factor of 0.31. This factor was empirically determined using the training database. The different steps are pictured in Figure 1.

Figure 1 Different steps for calculating the integrated variance. (A) Filtered ECG signal recorded inside the MRI. (B) Variance resulted from the ECG signal in (A). (C) Integrated variance (blue) and the threshold (dashed, red).
Figure 1

Different steps for calculating the integrated variance. (A) Filtered ECG signal recorded inside the MRI. (B) Variance resulted from the ECG signal in (A). (C) Integrated variance (blue) and the threshold (dashed, red).

Finally, a decision rule was applied to further improve the QRS detection. If the slope of the integrated variance and the QRS-complex was positive, the detected value was set on the R-peak. If the slopes had different signs, the detected position was chosen.

2.3 Evaluation metric

To evaluate the new QRS detector (M1) the sensitivity (Se) and the positive predictive value (+P) were calculated according to the ANSI/AAMI EC57 standard [13]. These statistical parameter can be written as:

(2)S⁢e=T⁢PT⁢P+F⁢N

and

(3)+P=T⁢PT⁢P+F⁢P.

The true positive detected beats are presented by TP, the false negative detected beats are presented by FN and FP represents the false positive detected beats. The detection error rate (DER) was calculated and defined as:

(4)D⁢E⁢R=F⁢P+F⁢NT⁢P+F⁢N.

As presented in [10], [11] only the precordial lead V4 was used for data evaluation. The precordial leads exhibit high R-peak amplitude due to their myocardium close proximity [14]. Further the highest R-peak was represented by V4. The reason is the location near to the apex of the heart.

The proposed method was compared to other state-of-the-art QRS detectors. These detectors were based on the 4th order central moments (M2) [10], the 5th order cumulants (M3) [11] the Pan/Tompkins-based algorithm (M4) [15] and on ICA (M5) [9]. All methods used an adaptive threshold.

3 Results

The results of DBTraining used for threshold selection are presented in Table 1. It shows that all limits for a correct HR estimation for arrhythmias as well as for tachycardia were satisfied. Further all arrhythmia peaks except in aami3a could be detected. In aami3a the small arrhythmia peaks were ignored by the algorithm.

Table 1

Estimated heart rates (HR) for DBTraining computed from the detected R-peaks using the variance-based method (M1).

DatasetAccepted HR (Bpm)HR M1 (Bpm)
aami3a40/8040
aami3b30/6060
aami3c120118
aami3d45/9090
aami4a206198
aami4a_h206198
aami4a_d206198
aami4b195195
aami4b_h195195
aami4b_d195195

The results of the proposed QRS detector (M1) and the other approaches (M2–M5) for DBMRI and DBInCarT are presented in Table 2 and in Table 3.

Table 2

QRS detection results using methods M1–M5 applied to DBMRI.

MethodBeatsTPFPFN+P (%)Se (%)DER (%)Delay (ms)Jitter (ms)
M19241923715699.8499.940.233.822.35
M29241924037199.6099.990.417.772.89
M39241924036199.6199.990.409.272.90
M4924192261031398.8999.861.264.197.88
M59241923431799.6699.920.4110.325.90
Table 3

QRS detection results using methods M1–M5 applied to DBInCarT.

MethodBeatsTPFPFN+P (%)Se (%)DER (%)Delay (ms)Jitter (ms)
M1168,341167,146472119599.7299.291.0125.5710.23
M2168,341167,38115796099.9199.430.6612.167.17
M3138,341167,38116976599.9099.550.5513.677.24
M4168,341166,378158174499.9198.961.139.339.26
M5168,341167,72529261699.8399.630.5414.4012.60

As shown in Table 2, method M1 showed best results concerning to the DER (0.23%) for DBMRI, the mean delay (3.82 ms) as well as the jitter (2.35 ms). Further M1 reached the best +P with 99.84%. Methods M2 and M3 achieved the best Se (99.99%). Worse results were achieved for M4 with a DER of 1.26% together with the highest jitter of 7.88 ms. Method M5 showed the highest mean delay (10.32 ms).

In contrast to DBMRI, the detection quality of M1 was lower when applied to database DBInCarT. Results are given in Table 3. Here M1 shows a DER of 1.01% together with a the highest mean delay of 25.57%. The best DER (0.54%) shows M5 as well best Se (99.63%).

4 Discussion

A novel QRS detector based on integrated variance was developed on ANSI/AAMI test waveforms and evaluated using 12-lead ECG different databases. Considering the QRS detection for the ECGs acquired in a 3T MRI scanner, high Se and +P values as well as a low mean delay (< 20 ms) and jitter (< 15 ms) were obtained. Due to the low mean delay, the proposed can be used for real time CMR covering the complete systolic cardiac phase [16]. The low jitter prevents a blurring of the CMR images [17].

In this study, the superior quality of ECG lead V4 was used to ensure a reliable QRS detection. These ECGs were acquired using non MR-safe hardware which makes this approach currently not usable in clinical practice. However, standard devices were modified previously and were successfully used during MRI scanning [18]. This means that the high quality of a 12-lead ECG and especially of lead V4 could be used during MRI exams in the future.

Despite the training using ECG signals acquired outside the MRI (ANSI/AAMI EC13 waveforms), the proposed variance based detection technique (M1) shows best results concerning DER as well as mean delay and jitter when applied to the ECGs acquired during MRI. This shows the high robustness of this technique to distinguish arrhythmias from the MHD effect.

In conclusion, the proposed method could be used for gating in CMR and for patient monitoring during MRI examinations. In future works, the proposed algorithm will be applied to ECG signals with arrhythmias which were recorded during MRI exams.

Author’s Statement

Research funding: Marcus Schmidt and Johannes W. Krug are funded by the Federal Ministry for Economic Affairs and Energy (BMWi, Germany) under grant number KF3172301JL3. Conflict of interest: Authors state no conflict of interest. Material and Methods: Informed consent: Informed consent has been obtained from all individuals included in this study. Ethical approval: The research related to human use complies with all the relevant national regulations, institutional policies and was performed in accordance with the tenets of the Helsinki Declaration, and has been approved by the authors’ institutional review board or equivalent committee.

References

[1] Lima JAC, Desai MY. Cardiovascular magnetic resonance imaging: current and emerging applications. J Am Coll Cardiol. 2004;44:1164–71.10.1016/j.jacc.2004.06.033Search in Google Scholar

[2] Schick F. Whole-body MRI at high field: technical limits and clinical potential. Eur Radiol. 2005;15:946–59.10.1007/s00330-005-2678-0Search in Google Scholar

[3] Schmitt F, Grosu D, Mohr C, Purdy D, Salem K, Scott KT, et al. 3 Tesla-MRT: Der Erfolg höherer Feldstärken. Radiologie. 2004;44:31–48.10.1007/s00117-003-1000-xSearch in Google Scholar

[4] Nijm GM , Swiryn S, Larson AC, Sahakian AV. Extraction of the magnetohydrodynamic blood flow potential from the surface electrocardiogram in magnetic resonance imaging. Med Biol Eng Comput. 2008;46:729–33.10.1007/s11517-008-0307-1Search in Google Scholar

[5] Oster J, Pietquin O, Kraemer M, Felblinger J. Bayesian framework for artifact reduction on ECG in MRI. International Conference on Acoustics, Speech, and Signal Processing : Proceedings (ICASSP) 2010;489–92.10.1109/ICASSP.2010.5495684Search in Google Scholar

[6] Krug JW. Improved cardiac gating and patient monitoring in high field magnetic resonance imaging by means of electrocardiogram signal processing [Phd thesis]. Germany: Otto-von-Guericke-University; 2015.Search in Google Scholar

[7] IEC 60601-2-27: Medical electrical equipment – Part 2–27: Particular requirements for the basic safety and essential performance of electrocardiographic monitoring equipment. International Electrotechnical Commission 3;2011.Search in Google Scholar

[8] Fischer SE, Wickline SA, Lorenz CH. Novel real-time R-wave detection algorithm based on the vectorcardiogram for accurate gated magnetic resonance acquisitions. Magn Reson Med. 1999;42:361–70.10.1002/(SICI)1522-2594(199908)42:2<361::AID-MRM18>3.0.CO;2-9Search in Google Scholar

[9] Krug JW, Rose G, Clifford GD, Oster J. ECG-based gating in ultra-high field cardiovascular magnetic resonance using an independent component analysis approach. J. Cardiovasc. Magn. Reson. 2013;15:104.10.1186/1532-429X-15-104Search in Google Scholar

[10] Schmidt M, Krug JW, Rose G. A real-time QRS detector based on higher-order statistics for ECG gated cardiac MRI. Comput Cardiol. 2014;41:733–6.Search in Google Scholar

[11] Schmidt M, Krug JW, Rose G. QRS detection using 5th order cumulants for ECG gated cardiac MRI. In Proc BMT, Hannover, Germany, 2014;59:180.Search in Google Scholar

[12] Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, et al. PhysioBank, PhysioToolkit, PhysioNet: components of a new research resource for complex physiologic signals. Circulation. 2000;101:e215–20.10.1161/01.CIR.101.23.e215Search in Google Scholar

[13] Testing and Reporting Performance Results of Cardiac Rhythm and ST-Segment Measurement Algorithm. ANSI/AAMI:EC57 1998/(R)2003.Search in Google Scholar

[14] von Olshausen KE. EKG-Information. Germany: Steinkopff Verlag Darmstadt; 2005;8:19.10.1007/3-7985-1551-4Search in Google Scholar

[15] Clifford GD. Signal processing methods for heart rate variability [Phd thesis]. England: University of Oxford; 2002.Search in Google Scholar

[16] Lentner C. Geigy scientific tables: vol5. Heart and circulation. 8th ed. Ciba-Geigy; 1990.Search in Google Scholar

[17] Thompson RB, McVeigh ER. Flow-gated phase-contrast MRI using radial acquisitions. Magnet Reson Med. 2004;52:598–604.10.1002/mrm.20187Search in Google Scholar

[18] Tse Z, Dumoulin C, Clifford G, Jerosch-Herald M, Kacher D, Kwong R, et al. MRI-compatible 12-lead ECGs with MHD separation: application to cardiac MRI gating, physiological monitoring and noninvasive cardiac-output estimation. Proc Intl Soc Mag Reson Med. 2010;18:286.10.1186/1532-429X-12-S1-O95Search in Google Scholar

Published Online: 2016-9-30
Published in Print: 2016-9-1

©2016 Marcus Schmidt et al., licensee De Gruyter.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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https://doi.org/10.1515/cdbme-2016-0057
Keywords for this article
ECG; MRI; QRS detection; variance
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BY-NC-ND 4.0

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  32. Prediction of immediately occurring microsleep events from brain electric signals
  33. Determining cardiac vagal threshold from short term heart rate complexity
  34. Classification of cardiac excitation patterns during atrial fibrillation
  35. An algorithm to automatically determine the cycle length coverage to identify rotational activity during atrial fibrillation – a simulation study
  36. Deriving respiration from high resolution 12-channel-ECG during cycling exercise
  37. Reducing of gradient induced artifacts on the ECG signal during MRI examinations using Wilcoxon filter
  38. Automatic detection and mapping of double potentials in intracardiac electrograms
  39. Modeling the pelvic region for non-invasive pelvic intraoperative neuromonitoring
  40. Postprocessing algorithm for automated analysis of pelvic intraoperative neuromonitoring signals
  41. Best practice: surgeon driven application in pelvic operations
  42. Vasomotor assessment by camera-based photoplethysmography
  43. Classification of morphologic changes in photoplethysmographic waveforms
  44. Novel computation of pulse transit time from multi-channel PPG signals by wavelet transform
  45. Efficient design of FIR filter based low-pass differentiators for biomedical signal processing
  46. Nonlinear causal influences assessed by mutual compression entropy
  47. Comparative study of methods for solving the correspondence problem in EMD applications
  48. fNIRS for future use in auditory diagnostics
  49. Semi-automated detection of fractional shortening in zebrafish embryo heart videos
  50. Blood pressure measurement on the cheek
  51. Derivation of the respiratory rate from directly and indirectly measured respiratory signals using autocorrelation
  52. Left cardiac atrioventricular delay and inter-ventricular delay in cardiac resynchronization therapy responder and non-responder
  53. An automatic systolic peak detector of blood pressure waveforms using 4th order cumulants
  54. Real-time QRS detection using integrated variance for ECG gated cardiac MRI
  55. Preprocessing of unipolar signals acquired by a novel intracardiac mapping system
  56. In-vitro experiments to characterize ventricular electromechanics
  57. Continuous non-invasive monitoring of blood pressure in the operating room: a cuffless optical technology at the fingertip
  58. Application of microwave sensor technology in cardiovascular disease for plaque detection
  59. Artificial blood circulatory and special Ultrasound Doppler probes for detecting and sizing gaseous embolism
  60. Detection of microsleep events in a car driving simulation study using electrocardiographic features
  61. A method to determine the kink resistance of stents and stent delivery systems according to international standards
  62. Comparison of stented bifurcation and straight vessel 3D-simulation with a prior simulated velocity profile inlet
  63. Transient Euler-Lagrange/DEM simulation of stent thrombosis
  64. Automated control of the laser welding process of heart valve scaffolds
  65. Automation of a test bench for accessing the bendability of electrospun vascular grafts
  66. Influence of storage conditions on the release of growth factors in platelet-rich blood derivatives
  67. Cryopreservation of cells using defined serum-free cryoprotective agents
  68. New bioreactor vessel for tissue engineering of human nasal septal chondrocytes
  69. Determination of the membrane hydraulic permeability of MSCs
  70. Climate retainment in carbon dioxide incubators
  71. Multiple factors influencing OR ventilation system effectiveness
  72. Evaluation of an app-based stress protocol
  73. Medication process in Styrian hospitals
  74. Control tower to surgical theater
  75. Development of a skull phantom for the assessment of implant X-ray visibility
  76. Surgical navigation with QR codes
  77. Investigation of the pressure gradient of embolic protection devices
  78. Computer assistance in femoral derotation osteotomy: a bottom-up approach
  79. Automatic depth scanning system for 3D infrared thermography
  80. A service for monitoring the quality of intraoperative cone beam CT images
  81. Resectoscope with an easy to use twist mechanism for improved handling
  82. In vitro simulation of distribution processes following intramuscular injection
  83. Adjusting inkjet printhead parameters to deposit drugs into micro-sized reservoirs
  84. A flexible standalone system with integrated sensor feedback for multi-pad electrode FES of the hand
  85. Smart control for functional electrical stimulation with optimal pulse intensity
  86. Tactile display on the remaining hand for unilateral hand amputees
  87. Effects of sustained electrical stimulation on spasticity assessed by the pendulum test
  88. An improved tracking framework for ultrasound probe localization in image-guided radiosurgery
  89. Improvement of a subviral particle tracker by the use of a LAP-Kalman-algorithm
  90. Learning discriminative classification models for grading anal intraepithelial neoplasia
  91. Regularization of EIT reconstruction based on multi-scales wavelet transforms
  92. Assessing MRI susceptibility artefact through an indicator of image distortion
  93. EyeGuidance – a computer controlled system to guide eye movements
  94. A framework for feedback-based segmentation of 3D image stacks
  95. Doppler optical coherence tomography as a promising tool for detecting fluid in the human middle ear
  96. 3D Local in vivo Environment (LivE) imaging for single cell protein analysis of bone tissue
  97. Inside-Out access strategy using new trans-vascular catheter approach
  98. US/MRI fusion with new optical tracking and marker approach for interventional procedures inside the MRI suite
  99. Impact of different registration methods in MEG source analysis
  100. 3D segmentation of thyroid ultrasound images using active contours
  101. Designing a compact MRI motion phantom
  102. Cerebral cortex classification by conditional random fields applied to intraoperative thermal imaging
  103. Classification of indirect immunofluorescence images using thresholded local binary count features
  104. Analysis of muscle fatigue conditions using time-frequency images and GLCM features
  105. Numerical evaluation of image parameters of ETR-1
  106. Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV) experimentation
  107. Effect of the number of electrodes on the reconstructed lung shape in electrical impedance tomography
  108. Hardware dependencies of GPU-accelerated beamformer performances for microwave breast cancer detection
  109. Computer assisted assessment of progressing osteoradionecrosis of the jaw for clinical diagnosis and treatment
  110. Evaluation of reconstruction parameters of electrical impedance tomography on aorta detection during saline bolus injection
  111. Evaluation of open-source software for the lung segmentation
  112. Automatic determination of lung features of CF patients in CT scans
  113. Image analysis of self-organized multicellular patterns
  114. Effect of key parameters on synthesis of superparamagnetic nanoparticles (SPIONs)
  115. Radiopacity assessment of neurovascular implants
  116. Development of a desiccant based dielectric for monitoring humidity conditions in miniaturized hermetic implantable packages
  117. Development of an artifact-free aneurysm clip
  118. Enhancing the regeneration of bone defects by alkalizing the peri-implant zone – an in vitro approach
  119. Rapid prototyping of replica knee implants for in vitro testing
  120. Protecting ultra- and hyperhydrophilic implant surfaces in dry state from loss of wettability
  121. Advanced wettability analysis of implant surfaces
  122. Patient-specific hip prostheses designed by surgeons
  123. Plasma treatment on novel carbon fiber reinforced PEEK cages to enhance bioactivity
  124. Wear of a total intervertebral disc prosthesis
  125. Digital health and digital biomarkers – enabling value chains on health data
  126. Usability in the lifecycle of medical software development
  127. Influence of different test gases in a non-destructive 100% quality control system for medical devices
  128. Device development guided by user satisfaction survey on auricular vagus nerve stimulation
  129. Empirical assessment of the time course of innovation in biomedical engineering: first results of a comparative approach
  130. Effect of left atrial hypertrophy on P-wave morphology in a computational model
  131. Simulation of intracardiac electrograms around acute ablation lesions
  132. Parametrization of activation based cardiac electrophysiology models using bidomain model simulations
  133. Assessment of nasal resistance using computational fluid dynamics
  134. Resistance in a non-linear autoregressive model of pulmonary mechanics
  135. Inspiratory and expiratory elastance in a non-linear autoregressive model of pulmonary mechanics
  136. Determination of regional lung function in cystic fibrosis using electrical impedance tomography
  137. Development of parietal bone surrogates for parietal graft lift training
  138. Numerical simulation of mechanically stimulated bone remodelling
  139. Conversion of engineering stresses to Cauchy stresses in tensile and compression tests of thermoplastic polymers
  140. Numerical examinations of simplified spondylodesis models concerning energy absorption in magnetic resonance imaging
  141. Principle study on the signal connection at transabdominal fetal pulse oximetry
  142. Influence of Siluron® insertion on model drug distribution in the simulated vitreous body
  143. Evaluating different approaches to identify a three parameter gas exchange model
  144. Effects of fibrosis on the extracellular potential based on 3D reconstructions from histological sections of heart tissue
  145. From imaging to hemodynamics – how reconstruction kernels influence the blood flow predictions in intracranial aneurysms
  146. Flow optimised design of a novel point-of-care diagnostic device for the detection of disease specific biomarkers
  147. Improved FPGA controlled artificial vascular system for plethysmographic measurements
  148. Minimally spaced electrode positions for multi-functional chest sensors: ECG and respiratory signal estimation
  149. Automated detection of alveolar arches for nasoalveolar molding in cleft lip and palate treatment
  150. Control scheme selection in human-machine- interfaces by analysis of activity signals
  151. Event-based sampling for reducing communication load in realtime human motion analysis by wireless inertial sensor networks
  152. Automatic pairing of inertial sensors to lower limb segments – a plug-and-play approach
  153. Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor
  154. Interactive monitoring system for visual respiratory biofeedback
  155. Development of a low-cost senor based aid for visually impaired people
  156. Patient assistive system for the shoulder joint
  157. A passive beating heart setup for interventional cardiology training
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