Startseite Medizin Introducing a frequency-tunable magnetic particle spectrometer
Artikel Open Access

Introducing a frequency-tunable magnetic particle spectrometer

  • André Behrends EMAIL logo , Matthias Graeser und Thorsten M. Buzug
Veröffentlicht/Copyright: 12. September 2015
Artikel downloaden (PDF)
Veröffentlichen auch Sie bei De Gruyter Brill
Informationen für Autor*innen Erkunden Sie dieses Fachgebiet
Current Directions in Biomedical Engineering
Aus der Zeitschrift Current Directions in Biomedical Engineering Band 1 Heft 1

Abstract

Image quality in the new imaging modality magnetic particle imaging (MPI) heavily relies on the quality of the magnetic nanoparticles in use. Therefore, it is crucial to understand the behaviour of such particles. A common technique to analyze the behaviour of the particles is magnetic particle spectrometry (MPS). However, most spectrometers are limited to measurements at a single or multiple discrete excitation frequencies. This paper introduces a frequency-tunable spectrometer, able to perform measurements in the range of 100 Hz - 24kHz.

Keywords: magnetic particle imaging; magnetic particle spectroscopy; tunable-frequency; magnetic nanoparticles; particle parameters; image quality

1 Introduction

In 2005 the upcoming imaging modality magnetic particle imaging (MPI) was presented by Weizenecker and Gleich [1]. Until now, a lot of effort has been made to improve the imaging systems. Sensitivity enhanced systems like field-free line imaging, as well as better signal processing techniques are just two of the many aspects that have been adressed. Nevertheless image quality in MPI not only depends on the quality of the imaging system, but likewise on the quality of the magnetic nanoparticles. The influence of magnetic nanoparticle properties on imaging quality has been discussed for example by Ferguson et al. [2]. A common method to determine the properties of magnetic nanoparticles is magnetic particle spectroscopy (MPS) as presented by Biederer [3]. However, modern MPS systems are only capable of measuring at discrete frequency steps. Most systems are limited to one excitation frequency, others to multiple discrete frequencies [3][4]. The following sections describe a measurement setup which is capable of carrying out MPS measurements with a freely tunable excitation frequency in the range of 100 Hz - 24 kHz. This reveals the possibility to determine different properties of the nanoparticles, such as: the influence of Brownian and Néel rotation on signal quality, the frequency-dependent hysteresis and its related dissipation losses, the hydrodynamic volume of the particles, the temperature of the sample or the viscosity of the medium surrounding the nanoparticles [5][6][7].

2 The basic setup for MPS

The most published signal chain of an MPS system is shown in Figure 1. It consists of a personal computer (PC) which generates the excitation signal. This signal is amplified by a power amplifier to supply the necessary current to produce a specific field strength. The excitation signal has to be filtered by a bandpass-filter to eliminate unwanted signal frequencies, which may couple into the system by induction. Those frequencies can be hard to distinguish from the harmonics produced by the particles. The send coil’s impedance is matched by a set of capacitors to compensate the reactance of the coil and match the resulting load to the power amplifier’s optimal load. This ensures a high efficiency of the power amplifier. Due to the fact that the excitation field induces a signal orders of magnitude higher than the particle signal, a bandstop-filter has to be used to reduce the excitation signal. The filtered signal is amplified by a low-noise amplifier and finally fed back to the PC for further analysis. This setup is limited to a single excitation frequency due to the bandpass and lowpass filtering stages, which have to be made of passive electrical components to avoid nonlinear effects and prevent the distortion of the particle signal. To overcome this limitation the send and receive chain have to be modified. These modifications are presented in the upcoming section.

Figure 1 The basic setup of a MPS system adapted from [3]. It consists of a PC for signal generation, controlling and measurement, as well as a power amplifier (AC Amp), a bandpass-filter (BPF), the transmission (Tx) and send (Rx) coils, a bandstop-filter (BSF) and a low-noise amplifier (LNA). The nanoparticles are depicted as dots between the send and receive coils.
Figure 1

The basic setup of a MPS system adapted from [3]. It consists of a PC for signal generation, controlling and measurement, as well as a power amplifier (AC Amp), a bandpass-filter (BPF), the transmission (Tx) and send (Rx) coils, a bandstop-filter (BSF) and a low-noise amplifier (LNA). The nanoparticles are depicted as dots between the send and receive coils.

3 Modification of the basic MPS setup

To allow a free choice of the excitation frequency in a given frequency range, it is required to get rid of frequency limiting structures like lumped filters and the concept of an ideal impedance matching. The two major issues which have to be adressed are: distribution of the required current in the send coil, which is equal to restraining the power amplifiers load to a specific range and elimination of the excitation signal in the receive chain, allowing the measurement of the particle signal.

3.1 Receive chain modifications

For a frequency-independent elimination of the excitation signal a cancellation technique described by Graeser et al. [8] has been implemented. The idea is to build two identical measurement chambers. During the measurement process, in one of the chambers the particles are inserted and the other one is left empty. The send coils of the chambers are connected in series, providing the same current in the coils and accordingly the same excitation field. The receive coils are connected in series as well, but with subtractive polarity, thus the excitation signal cancels out. As the particle signal is only induced in one receive coil it is unaffected by the cancellation and is the only signal left. The setup is shown in Figure 2. The dots next to the coils denote the same instantaneous polarity of the coils. In a real setup the cancellation is not ideal as the chambers will differ slightly due to manufacturing inequalities. Additionally, environmental influences might vary in the chambers. The cancellation is best when the magnetic flux of the excitation signal is equal in both receive coils. Maximal attenuation can be achieved by adjusting the coupling factors of send and receive coil in one chamber to match the coupling factors of the second.

Figure 2 The basic setup for the cancellation method: The dots next to the coils depict the same instantaneous polarity. If the send coils produce the same field, the induced signals in the receive coils will cancel out. Since the particle signal is only induced in one chamber, it is not affected by this cancellation. Idealy the particle signal is the only signal left.
Figure 2

The basic setup for the cancellation method: The dots next to the coils depict the same instantaneous polarity. If the send coils produce the same field, the induced signals in the receive coils will cancel out. Since the particle signal is only induced in one chamber, it is not affected by this cancellation. Idealy the particle signal is the only signal left.

3.2 Send chain modifications

The limiting factor of an amplifier is its output power. To produce a sufficient current and a desired field strength, an apparent power given by

(1)|S|=I2⋅|Z|=12ι^2⋅|Z|

is required. Here I is the root mean square value of the current, Z is the complex load impedance and î is the current amplitude. The load of two coils in series is given by the absolute value of the sum of their complex impedances

(2)|Z|=|(RL1+RL2)+jw(L1+L2)|,

where RL1 and RL2 are the equivalent series resistances L1 and L2 are the inductivities of the two send coils respectively. The frequency f of the signal is related to the angular frequency ω by ω = 2πf. The electrical parameters of the send coils are measured and the required current to produce a magnetic field amplitude of 10 mT is determined by simulation. The values are shown in Table 1. The frequency range is split into four measurement ranges. For one frequency in each of the measurement range the system’s apparent power is minimized by a capacitor in series connection to the coils. The measurement ranges, the frequencies for which the apparent power minimization is done and the corresponding capacitor values are shown

Table 1

Parameters of the send coils and the required current

ParameterCoil 1Coil 2
Inductivity37.5µH37.5µH
Equivalent series resistance34.5mΩ28.7 mΩ
Required current amplitude13 A

in Table 2. In Figure 3 the logarithmic apparent power of the different setups over the full frequency range is shown and the related measurement ranges are highlighted. As it can be seen the apparent power stays below 500 V A for every measurement range. The minimization frequencies are chosen to low. This is done to ensure the resulting load is inductive for most measured frequencies, because capacitive loads may lead to instabilites in the amplifier’s operation [9]. The power amplifier used to drive the coils is an AE Techron 7224 amplifier with a maximum power output of 1000 W into an optimal load of8 [10]. It is necessary to oversize the amplifier concerning the power, as the stated load impedance is almost never the optimal load to achieve the maximum output. In addition, the load is reactive for most frequencies, which means the signal from the amplifier is partially reflected back to the amplifier, leading to increased heating of the amplifier and limiting the maximum applicable power to the load.

Table 2

The measurement ranges, as well as the frequencies for which the apparent power minimization is done and the corresponding capacitor values are shown.

rangefrequenciesminimized frequencycapacitance
1100 Hz – 8.5 kHz--
28.5 kHz – 14 kHz9160 Hz4µF
314 kHz – 19 kHz14 700 Hz1.5µF
419 kHz – 24 kHz19875 Hz0.83 µF
Figure 3 The logarithmic apparent power to produce a current of 13A over the full frequency range is shown for the different measurement setups. The corresponding measurement range for each setup is highlighted.
Figure 3

The logarithmic apparent power to produce a current of 13A over the full frequency range is shown for the different measurement setups. The corresponding measurement range for each setup is highlighted.

3.3 Full setup of the spectrometer

The resulting setup of the spectrometer is presented in Figure 4. The capacitors are connected in series right after the power amplifier, each with the possibility to be bypassed with a short connection. The send coils are connected in series as well, whereas the voltage over one coil is measured using a voltage divider. If the voltage differs from the expected value, the excitation voltage is adapted accordingly. The receive coils are connected in a subtractive polarity manner such that the excitation signal cancels out. Then the particle signal is amplified by the SR560 low-noise amplifier and measured by the PC.

Figure 4 The schematic of the full setup shows the different capacitors for each measurement setup. The coils form a cancellation unit and the current of the coils is verified by measuring the voltage over one of the send coils. Since the voltages are too high for a direct measurement, a voltage divider is used.
Figure 4

The schematic of the full setup shows the different capacitors for each measurement setup. The coils form a cancellation unit and the current of the coils is verified by measuring the voltage over one of the send coils. Since the voltages are too high for a direct measurement, a voltage divider is used.

4 Results

The spectrums of two exemplary particle measurements are shown in Figure 5. The amplitudes have been normalized and plotted against the k-th harmonic of the excitation frequency. Measurements have been carried out for 49 frequencies starting at 100 Hz, 500 Hz and continuing in steps of 500 Hz to 24kHz. The particle signals have been measured succesfully for every frequency and every particle measurement has been corrected by a preceding empty measurement.

Figure 5 The spectrum of two exemplary excitation frequencies are plotted against the k-th harmonic of the excitation frequency. All measurements are compensated by a preceding empty measurement.
Figure 5

The spectrum of two exemplary excitation frequencies are plotted against the k-th harmonic of the excitation frequency. All measurements are compensated by a preceding empty measurement.

5 Conclusion

In conclusion a setup for a frequency-tunable spectrometer in the range of 100 Hz - 24kHz has been introduced. Based on particle measurements it could be shown that the spectrometer is working as intended and is able to determine the particle spectrums accurately. This allows for further investigations such as: particle performance, relaxation effects or dissipation losses.

Funding

We acknowledge the support of the Federal Ministry of Education and Research, Germany (BMBF) under the grant numbers 13GW0069A and 13N11090.

Author's Statement

  1. 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 has been complied with all the relevant national regulations, institutional policies and in accordance the tenets of the Helsinki Declaration, and has been approved by the authors’ institutional review board or equivalent committee.

References

[1] Gleich B, Weizenecker J. Tomographic imaging using the nonlinear response of magnetic particles. Nature 2005; 435(7046): 1214–121710.1038/nature03808Suche in Google Scholar

[2] Ferguson RM, Khandhar AP, Hamed A, Loc H, Hovorka O, Krishnan KM. Tailoring the magnetic and pharmacokinetic properties of iron oxide magnetic particle imaging tracers. Biomedical Engineering/Biomedizinische Technik 2013; 58(6): 493–50710.1515/bmt-2012-0058Suche in Google Scholar

[3] Biederer S, Sattel T, Knopp T, Lüdtke-Buzug K, Gleich B, Weizenecker J, Borgert J, Buzug TM. A Spectrometer for Magnetic Particle Imaging. IFMBE Proceedings 2008; 22: 2313–231610.1007/978-3-540-89208-3_555Suche in Google Scholar

[4] Wawrzik T, Ludwig F, Schilling M. Perspectives of Magnetic Particle Spectroscopy for magnetic nanoparticle characterization. Springer Proceedings in Physics 2012; 140: 41–4510.1007/978-3-642-24133-8_7Suche in Google Scholar

[5] Rosensweig RE. Heating magnetic fluid with alternating magnetic field. Journal of Magnetism and Magnetic Materials (2002); 252: 370–37410.1016/S0304-8853(02)00706-0Suche in Google Scholar

[6] Weaver JB, Rauwerdink AM, Hansen EW. Magnetic nanoparticle estimation. Medical Physics 2009; 36(5): 1822–182910.1118/1.3106342Suche in Google Scholar

[7] Rauwerdink AM, Weaver JB. Viscous effects on nanoparticle magnetization harmonics. Journal of Magnetism and Magnetic Materials 2009; 322(2010) 609–61310.1016/j.jmmm.2009.10.024Suche in Google Scholar

[8] Graeser M, Knopp T, Grüttner M, Sattel TF, Buzug TM. Analog receive signal processing for magnetic particle imaging. Medical Physics 2013; 40: 04230310.1118/1.4794482Suche in Google Scholar

[9] Linear Technology. Application Note 148 - Does Your Op Amp Oscillate?. http://cds.linear.com/docs/en/application-note/an148fa.pdf accessed: 26.03.2015Suche in Google Scholar

[10] AETechron Inc. AETechron 7224 - Operator’s Manual.http://www.aetechron.com/pdf/7224_OperatorManual.pdf accessed: 29.11.2014Suche in Google Scholar

Published Online: 2015-9-12
Published in Print: 2015-9-1

© 2015 by Walter de Gruyter GmbH, Berlin/Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Artikel in diesem Heft

  1. Research Article
  2. Development and characterization of superparamagnetic coatings
  3. Research Article
  4. The development of an experimental setup to measure acousto-electric interaction signal
  5. Research Article
  6. Stability analysis of ferrofluids
  7. Research Article
  8. Investigation of endothelial growth using a sensors-integrated microfluidic system to simulate physiological barriers
  9. Research Article
  10. Energy harvesting for active implants: powering a ruminal pH-monitoring system
  11. Research Article
  12. New type of fluxgate magnetometer for the heart’s magnetic fields detection
  13. Research Article
  14. Field mapping of ballistic pressure pulse sources
  15. Research Article
  16. Development of a new homecare sleep monitor using body sounds and motion tracking
  17. Research Article
  18. Noise properties of textile, capacitive EEG electrodes
  19. Research Article
  20. Detecting phase singularities and rotor center trajectories based on the Hilbert transform of intraatrial electrograms in an atrial voxel model
  21. Research Article
  22. Spike sorting: the overlapping spikes challenge
  23. Research Article
  24. Separating the effect of respiration from the heart rate variability for cases of constant harmonic breathing
  25. Research Article
  26. Locating regions of arrhythmogenic substrate by analyzing the duration of triggered atrial activities
  27. Research Article
  28. Combining different ECG derived respiration tracking methods to create an optimal reconstruction of the breathing pattern
  29. Research Article
  30. Atrial and ventricular signal averaging electrocardiography in pacemaker and cardiac resynchronization therapy
  31. Research Article
  32. Estimation of a respiratory signal from a single-lead ECG using the 4th order central moments
  33. Research Article
  34. Compressed sensing of multi-lead ECG signals by compressive multiplexing
  35. Research Article
  36. Heart rate monitoring in ultra-high-field MRI using frequency information obtained from video signals of the human skin compared to electrocardiography and pulse oximetry
  37. Research Article
  38. Synchronization in wireless biomedical-sensor networks with Bluetooth Low Energy
  39. Research Article
  40. Automated classification of stages of anaesthesia by populations of evolutionary optimized fuzzy rules
  41. Research Article
  42. Effects of sampling rate on automated fatigue recognition in surface EMG signals
  43. Research Article
  44. Closed-loop transcranial alternating current stimulation of slow oscillations
  45. Research Article
  46. Cardiac index in atrio- and interventricular delay optimized cardiac resynchronization therapy and cardiac contractility modulation
  47. Research Article
  48. The role of expert evaluation for microsleep detection
  49. Research Article
  50. The impact of baseline wander removal techniques on the ST segment in simulated ischemic 12-lead ECGs
  51. Research Article
  52. Metal artifact reduction by projection replacements and non-local prior image integration
  53. Research Article
  54. A novel coaxial nozzle for in-process adjustment of electrospun scaffolds’ fiber diameter
  55. Research Article
  56. Processing of membranes for oxygenation using the Bellhouse-effect
  57. Research Article
  58. Inkjet printing of viable human dental follicle stem cells
  59. Research Article
  60. The use of an icebindingprotein out of the snowflea Hypogastrura harveyi as a cryoprotectant in the cryopreservation of mesenchymal stem cells
  61. Research Article
  62. New NIR spectroscopy based method to determine ischemia in vivo in liver – a first study on rats
  63. Research Article
  64. QRS and QT ventricular conduction times and permanent pacemaker therapy after transcatheter aortic valve implantation
  65. Research Article
  66. Adopting oculopressure tonometry as a transient in vivo rabbit glaucoma model
  67. Research Article
  68. Next-generation vision testing: the quick CSF
  69. Research Article
  70. Improving tactile sensation in laparoscopic surgery by overcoming size restrictions
  71. Research Article
  72. Design and control of a 3-DOF hydraulic driven surgical instrument
  73. Research Article
  74. Evaluation of endourological tools to improve the diagnosis and therapy of ureteral tumors – from model development to clinical application
  75. Research Article
  76. Frequency based assessment of surgical activities
  77. Research Article
  78. “Hands free for intervention”, a new approach for transoral endoscopic surgery
  79. Research Article
  80. Pseudo-haptic feedback in medical teleoperation
  81. Research Article
  82. Feasibility of interactive gesture control of a robotic microscope
  83. Research Article
  84. Towards structuring contextual information for workflow-driven surgical assistance functionalities
  85. Research Article
  86. Towards a framework for standardized semantic workflow modeling and management in the surgical domain
  87. Research Article
  88. Closed-loop approach for situation awareness of medical devices and operating room infrastructure
  89. Research Article
  90. Kinect based physiotherapy system for home use
  91. Research Article
  92. Evaluating the microsoft kinect skeleton joint tracking as a tool for home-based physiotherapy
  93. Research Article
  94. Integrating multimodal information for intraoperative assistance in neurosurgery
  95. Research Article
  96. Respiratory motion tracking using Microsoft’s Kinect v2 camera
  97. Research Article
  98. Using smart glasses for ultrasound diagnostics
  99. Research Article
  100. Measurement of needle susceptibility artifacts in magnetic resonance images
  101. Research Article
  102. Dimensionality reduction of medical image descriptors for multimodal image registration
  103. Research Article
  104. Experimental evaluation of different weighting schemes in magnetic particle imaging reconstruction
  105. Research Article
  106. Evaluation of CT capability for the detection of thin bone structures
  107. Research Article
  108. Towards contactless optical coherence elastography with acoustic tissue excitation
  109. Research Article
  110. Development and implementation of algorithms for automatic and robust measurement of the 2D:4D digit ratio using image data
  111. Research Article
  112. Automated high-throughput analysis of B cell spreading on immobilized antibodies with whole slide imaging
  113. Research Article
  114. Tissue segmentation from head MRI: a ground truth validation for feature-enhanced tracking
  115. Research Article
  116. Video tracking of swimming rodents on a reflective water surface
  117. Research Article
  118. MR imaging of model drug distribution in simulated vitreous
  119. Research Article
  120. Studying the extracellular contribution to the double wave vector diffusion-weighted signal
  121. Research Article
  122. Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields
  123. Research Article
  124. Introducing a frequency-tunable magnetic particle spectrometer
  125. Research Article
  126. Imaging of aortic valve dynamics in 4D OCT
  127. Research Article
  128. Intravascular optical coherence tomography (OCT) as an additional tool for the assessment of stent structures
  129. Research Article
  130. Simple concept for a wide-field lensless digital holographic microscope using a laser diode
  131. Research Article
  132. Intraoperative identification of somato-sensory brain areas using optical imaging and standard RGB camera equipment – a feasibility study
  133. Research Article
  134. Respiratory surface motion measurement by Microsoft Kinect
  135. Research Article
  136. Improving image quality in EIT imaging by measurement of thorax excursion
  137. Research Article
  138. A clustering based dual model framework for EIT imaging: first experimental results
  139. Research Article
  140. Three-dimensional anisotropic regularization for limited angle tomography
  141. Research Article
  142. GPU-based real-time generation of large ultrasound volumes from freehand 3D sweeps
  143. Research Article
  144. Experimental computer tomograph
  145. Research Article
  146. US-tracked steered FUS in a respiratory ex vivo ovine liver phantom
  147. Research Article
  148. Contribution of brownian rotation and particle assembly polarisation to the particle response in magnetic particle spectrometry
  149. Research Article
  150. Preliminary investigations of magnetic modulated nanoparticles for microwave breast cancer detection
  151. Research Article
  152. Construction of a device for magnetic separation of superparamagnetic iron oxide nanoparticles
  153. Research Article
  154. An IHE-conform telecooperation platform supporting the treatment of dementia patients
  155. Research Article
  156. Automated respiratory therapy system based on the ARDSNet protocol with systemic perfusion control
  157. Research Article
  158. Identification of surgical instruments using UHF-RFID technology
  159. Research Article
  160. A generic concept for the development of model-guided clinical decision support systems
  161. Research Article
  162. Evaluation of local alterations in femoral bone mineral density measured via quantitative CT
  163. Research Article
  164. Creating 3D gelatin phantoms for experimental evaluation in biomedicine
  165. Research Article
  166. Influence of short-term fixation with mixed formalin or ethanol solution on the mechanical properties of human cortical bone
  167. Research Article
  168. Analysis of the release kinetics of surface-bound proteins via laser-induced fluorescence
  169. Research Article
  170. Tomographic particle image velocimetry of a water-jet for low volume harvesting of fat tissue for regenerative medicine
  171. Research Article
  172. Wireless medical sensors – context, robustness and safety
  173. Research Article
  174. Sequences for real-time magnetic particle imaging
  175. Research Article
  176. Speckle-based off-axis holographic detection for non-contact photoacoustic tomography
  177. Research Article
  178. A machine learning approach for planning valve-sparing aortic root reconstruction
  179. Research Article
  180. An in-ear pulse wave velocity measurement system using heart sounds as time reference
  181. Research Article
  182. Measuring different oxygenation levels in a blood perfusion model simulating the human head using NIRS
  183. Research Article
  184. Multisegmental fusion of the lumbar spine a curse or a blessing?
  185. Research Article
  186. Numerical analysis of the biomechanical complications accompanying the total hip replacement with NANOS-Prosthetic: bone remodelling and prosthesis migration
  187. Research Article
  188. A muscle model for hybrid muscle activation
  189. Research Article
  190. Mathematical, numerical and in-vitro investigation of cooling performance of an intra-carotid catheter for selective brain hypothermia
  191. Research Article
  192. An ideally parameterized unscented Kalman filter for the inverse problem of electrocardiography
  193. Research Article
  194. Interactive visualization of cardiac anatomy and atrial excitation for medical diagnosis and research
  195. Research Article
  196. Virtualizing clinical cases of atrial flutter in a fast marching simulation including conduction velocity and ablation scars
  197. Research Article
  198. Mesh structure-independent modeling of patient-specific atrial fiber orientation
  199. Research Article
  200. Accelerating mono-domain cardiac electrophysiology simulations using OpenCL
  201. Research Article
  202. Understanding the cellular mode of action of vernakalant using a computational model: answers and new questions
  203. Research Article
  204. A java based simulator with user interface to simulate ventilated patients
  205. Research Article
  206. Evaluation of an algorithm to choose between competing models of respiratory mechanics
  207. Research Article
  208. Numerical simulation of low-pulsation gerotor pumps for use in the pharmaceutical industry and in biomedicine
  209. Research Article
  210. Numerical and experimental flow analysis in centifluidic systems for rapid allergy screening tests
  211. Research Article
  212. Biomechanical parameter determination of scaffold-free cartilage constructs (SFCCs) with the hyperelastic material models Yeoh, Ogden and Demiray
  213. Research Article
  214. FPGA controlled artificial vascular system
  215. Research Article
  216. Simulation based investigation of source-detector configurations for non-invasive fetal pulse oximetry
  217. Research Article
  218. Test setup for characterizing the efficacy of embolic protection devices
  219. Research Article
  220. Impact of electrode geometry on force generation during functional electrical stimulation
  221. Research Article
  222. 3D-based visual physical activity assessment of children
  223. Research Article
  224. Realtime assessment of foot orientation by Accelerometers and Gyroscopes
  225. Research Article
  226. Image based reconstruction for cystoscopy
  227. Research Article
  228. Image guided surgery innovation with graduate students - a new lecture format
  229. Research Article
  230. Multichannel FES parameterization for controlling foot motion in paretic gait
  231. Research Article
  232. Smartphone supported upper limb prosthesis
  233. Research Article
  234. Use of quantitative tremor evaluation to enhance target selection during deep brain stimulation surgery for essential tremor
  235. Research Article
  236. Evaluation of adhesion promoters for Parylene C on gold metallization
  237. Research Article
  238. The influence of metallic ions from CoCr28Mo6 on the osteogenic differentiation and cytokine release of human osteoblasts
  239. Research Article
  240. Increasing the visibility of thin NITINOL vascular implants
  241. Research Article
  242. Possible reasons for early artificial bone failure in biomechanical tests of ankle arthrodesis systems
  243. Research Article
  244. Development of a bending test procedure for the characterization of flexible ECoG electrode arrays
  245. Research Article
  246. Tubular manipulators: a new concept for intracochlear positioning of an auditory prosthesis
  247. Research Article
  248. Investigation of the dynamic diameter deformation of vascular stents during fatigue testing with radial loading
  249. Research Article
  250. Electrospun vascular grafts with anti-kinking properties
  251. Research Article
  252. Integration of temperature sensors in polyimide-based thin-film electrode arrays
  253. Research Article
  254. Use cases and usability challenges for head-mounted displays in healthcare
  255. Research Article
  256. Device- and service profiles for integrated or systems based on open standards
  257. Research Article
  258. Risk management for medical devices in research projects
  259. Research Article
  260. Simulation of varying femoral attachment sites of medial patellofemoral ligament using a musculoskeletal multi-body model
  261. Research Article
  262. Does enhancing consciousness for strategic planning processes support the effectiveness of problem-based learning concepts in biomedical education?
  263. Research Article
  264. SPIO processing in macrophages for MPI: The breast cancer MPI-SNLB-concept
  265. Research Article
  266. Numerical simulations of airflow in the human pharynx of OSAHS patients
https://doi.org/10.1515/cdbme-2015-0062
Schlagwörter für diesen Artikel
magnetic particle imaging; magnetic particle spectroscopy; tunable-frequency; magnetic nanoparticles; particle parameters; image quality
Creative Commons
BY-NC-ND 3.0

Artikel in diesem Heft

  1. Research Article
  2. Development and characterization of superparamagnetic coatings
  3. Research Article
  4. The development of an experimental setup to measure acousto-electric interaction signal
  5. Research Article
  6. Stability analysis of ferrofluids
  7. Research Article
  8. Investigation of endothelial growth using a sensors-integrated microfluidic system to simulate physiological barriers
  9. Research Article
  10. Energy harvesting for active implants: powering a ruminal pH-monitoring system
  11. Research Article
  12. New type of fluxgate magnetometer for the heart’s magnetic fields detection
  13. Research Article
  14. Field mapping of ballistic pressure pulse sources
  15. Research Article
  16. Development of a new homecare sleep monitor using body sounds and motion tracking
  17. Research Article
  18. Noise properties of textile, capacitive EEG electrodes
  19. Research Article
  20. Detecting phase singularities and rotor center trajectories based on the Hilbert transform of intraatrial electrograms in an atrial voxel model
  21. Research Article
  22. Spike sorting: the overlapping spikes challenge
  23. Research Article
  24. Separating the effect of respiration from the heart rate variability for cases of constant harmonic breathing
  25. Research Article
  26. Locating regions of arrhythmogenic substrate by analyzing the duration of triggered atrial activities
  27. Research Article
  28. Combining different ECG derived respiration tracking methods to create an optimal reconstruction of the breathing pattern
  29. Research Article
  30. Atrial and ventricular signal averaging electrocardiography in pacemaker and cardiac resynchronization therapy
  31. Research Article
  32. Estimation of a respiratory signal from a single-lead ECG using the 4th order central moments
  33. Research Article
  34. Compressed sensing of multi-lead ECG signals by compressive multiplexing
  35. Research Article
  36. Heart rate monitoring in ultra-high-field MRI using frequency information obtained from video signals of the human skin compared to electrocardiography and pulse oximetry
  37. Research Article
  38. Synchronization in wireless biomedical-sensor networks with Bluetooth Low Energy
  39. Research Article
  40. Automated classification of stages of anaesthesia by populations of evolutionary optimized fuzzy rules
  41. Research Article
  42. Effects of sampling rate on automated fatigue recognition in surface EMG signals
  43. Research Article
  44. Closed-loop transcranial alternating current stimulation of slow oscillations
  45. Research Article
  46. Cardiac index in atrio- and interventricular delay optimized cardiac resynchronization therapy and cardiac contractility modulation
  47. Research Article
  48. The role of expert evaluation for microsleep detection
  49. Research Article
  50. The impact of baseline wander removal techniques on the ST segment in simulated ischemic 12-lead ECGs
  51. Research Article
  52. Metal artifact reduction by projection replacements and non-local prior image integration
  53. Research Article
  54. A novel coaxial nozzle for in-process adjustment of electrospun scaffolds’ fiber diameter
  55. Research Article
  56. Processing of membranes for oxygenation using the Bellhouse-effect
  57. Research Article
  58. Inkjet printing of viable human dental follicle stem cells
  59. Research Article
  60. The use of an icebindingprotein out of the snowflea Hypogastrura harveyi as a cryoprotectant in the cryopreservation of mesenchymal stem cells
  61. Research Article
  62. New NIR spectroscopy based method to determine ischemia in vivo in liver – a first study on rats
  63. Research Article
  64. QRS and QT ventricular conduction times and permanent pacemaker therapy after transcatheter aortic valve implantation
  65. Research Article
  66. Adopting oculopressure tonometry as a transient in vivo rabbit glaucoma model
  67. Research Article
  68. Next-generation vision testing: the quick CSF
  69. Research Article
  70. Improving tactile sensation in laparoscopic surgery by overcoming size restrictions
  71. Research Article
  72. Design and control of a 3-DOF hydraulic driven surgical instrument
  73. Research Article
  74. Evaluation of endourological tools to improve the diagnosis and therapy of ureteral tumors – from model development to clinical application
  75. Research Article
  76. Frequency based assessment of surgical activities
  77. Research Article
  78. “Hands free for intervention”, a new approach for transoral endoscopic surgery
  79. Research Article
  80. Pseudo-haptic feedback in medical teleoperation
  81. Research Article
  82. Feasibility of interactive gesture control of a robotic microscope
  83. Research Article
  84. Towards structuring contextual information for workflow-driven surgical assistance functionalities
  85. Research Article
  86. Towards a framework for standardized semantic workflow modeling and management in the surgical domain
  87. Research Article
  88. Closed-loop approach for situation awareness of medical devices and operating room infrastructure
  89. Research Article
  90. Kinect based physiotherapy system for home use
  91. Research Article
  92. Evaluating the microsoft kinect skeleton joint tracking as a tool for home-based physiotherapy
  93. Research Article
  94. Integrating multimodal information for intraoperative assistance in neurosurgery
  95. Research Article
  96. Respiratory motion tracking using Microsoft’s Kinect v2 camera
  97. Research Article
  98. Using smart glasses for ultrasound diagnostics
  99. Research Article
  100. Measurement of needle susceptibility artifacts in magnetic resonance images
  101. Research Article
  102. Dimensionality reduction of medical image descriptors for multimodal image registration
  103. Research Article
  104. Experimental evaluation of different weighting schemes in magnetic particle imaging reconstruction
  105. Research Article
  106. Evaluation of CT capability for the detection of thin bone structures
  107. Research Article
  108. Towards contactless optical coherence elastography with acoustic tissue excitation
  109. Research Article
  110. Development and implementation of algorithms for automatic and robust measurement of the 2D:4D digit ratio using image data
  111. Research Article
  112. Automated high-throughput analysis of B cell spreading on immobilized antibodies with whole slide imaging
  113. Research Article
  114. Tissue segmentation from head MRI: a ground truth validation for feature-enhanced tracking
  115. Research Article
  116. Video tracking of swimming rodents on a reflective water surface
  117. Research Article
  118. MR imaging of model drug distribution in simulated vitreous
  119. Research Article
  120. Studying the extracellular contribution to the double wave vector diffusion-weighted signal
  121. Research Article
  122. Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields
  123. Research Article
  124. Introducing a frequency-tunable magnetic particle spectrometer
  125. Research Article
  126. Imaging of aortic valve dynamics in 4D OCT
  127. Research Article
  128. Intravascular optical coherence tomography (OCT) as an additional tool for the assessment of stent structures
  129. Research Article
  130. Simple concept for a wide-field lensless digital holographic microscope using a laser diode
  131. Research Article
  132. Intraoperative identification of somato-sensory brain areas using optical imaging and standard RGB camera equipment – a feasibility study
  133. Research Article
  134. Respiratory surface motion measurement by Microsoft Kinect
  135. Research Article
  136. Improving image quality in EIT imaging by measurement of thorax excursion
  137. Research Article
  138. A clustering based dual model framework for EIT imaging: first experimental results
  139. Research Article
  140. Three-dimensional anisotropic regularization for limited angle tomography
  141. Research Article
  142. GPU-based real-time generation of large ultrasound volumes from freehand 3D sweeps
  143. Research Article
  144. Experimental computer tomograph
  145. Research Article
  146. US-tracked steered FUS in a respiratory ex vivo ovine liver phantom
  147. Research Article
  148. Contribution of brownian rotation and particle assembly polarisation to the particle response in magnetic particle spectrometry
  149. Research Article
  150. Preliminary investigations of magnetic modulated nanoparticles for microwave breast cancer detection
  151. Research Article
  152. Construction of a device for magnetic separation of superparamagnetic iron oxide nanoparticles
  153. Research Article
  154. An IHE-conform telecooperation platform supporting the treatment of dementia patients
  155. Research Article
  156. Automated respiratory therapy system based on the ARDSNet protocol with systemic perfusion control
  157. Research Article
  158. Identification of surgical instruments using UHF-RFID technology
  159. Research Article
  160. A generic concept for the development of model-guided clinical decision support systems
  161. Research Article
  162. Evaluation of local alterations in femoral bone mineral density measured via quantitative CT
  163. Research Article
  164. Creating 3D gelatin phantoms for experimental evaluation in biomedicine
  165. Research Article
  166. Influence of short-term fixation with mixed formalin or ethanol solution on the mechanical properties of human cortical bone
  167. Research Article
  168. Analysis of the release kinetics of surface-bound proteins via laser-induced fluorescence
  169. Research Article
  170. Tomographic particle image velocimetry of a water-jet for low volume harvesting of fat tissue for regenerative medicine
  171. Research Article
  172. Wireless medical sensors – context, robustness and safety
  173. Research Article
  174. Sequences for real-time magnetic particle imaging
  175. Research Article
  176. Speckle-based off-axis holographic detection for non-contact photoacoustic tomography
  177. Research Article
  178. A machine learning approach for planning valve-sparing aortic root reconstruction
  179. Research Article
  180. An in-ear pulse wave velocity measurement system using heart sounds as time reference
  181. Research Article
  182. Measuring different oxygenation levels in a blood perfusion model simulating the human head using NIRS
  183. Research Article
  184. Multisegmental fusion of the lumbar spine a curse or a blessing?
  185. Research Article
  186. Numerical analysis of the biomechanical complications accompanying the total hip replacement with NANOS-Prosthetic: bone remodelling and prosthesis migration
  187. Research Article
  188. A muscle model for hybrid muscle activation
  189. Research Article
  190. Mathematical, numerical and in-vitro investigation of cooling performance of an intra-carotid catheter for selective brain hypothermia
  191. Research Article
  192. An ideally parameterized unscented Kalman filter for the inverse problem of electrocardiography
  193. Research Article
  194. Interactive visualization of cardiac anatomy and atrial excitation for medical diagnosis and research
  195. Research Article
  196. Virtualizing clinical cases of atrial flutter in a fast marching simulation including conduction velocity and ablation scars
  197. Research Article
  198. Mesh structure-independent modeling of patient-specific atrial fiber orientation
  199. Research Article
  200. Accelerating mono-domain cardiac electrophysiology simulations using OpenCL
  201. Research Article
  202. Understanding the cellular mode of action of vernakalant using a computational model: answers and new questions
  203. Research Article
  204. A java based simulator with user interface to simulate ventilated patients
  205. Research Article
  206. Evaluation of an algorithm to choose between competing models of respiratory mechanics
  207. Research Article
  208. Numerical simulation of low-pulsation gerotor pumps for use in the pharmaceutical industry and in biomedicine
  209. Research Article
  210. Numerical and experimental flow analysis in centifluidic systems for rapid allergy screening tests
  211. Research Article
  212. Biomechanical parameter determination of scaffold-free cartilage constructs (SFCCs) with the hyperelastic material models Yeoh, Ogden and Demiray
  213. Research Article
  214. FPGA controlled artificial vascular system
  215. Research Article
  216. Simulation based investigation of source-detector configurations for non-invasive fetal pulse oximetry
  217. Research Article
  218. Test setup for characterizing the efficacy of embolic protection devices
  219. Research Article
  220. Impact of electrode geometry on force generation during functional electrical stimulation
  221. Research Article
  222. 3D-based visual physical activity assessment of children
  223. Research Article
  224. Realtime assessment of foot orientation by Accelerometers and Gyroscopes
  225. Research Article
  226. Image based reconstruction for cystoscopy
  227. Research Article
  228. Image guided surgery innovation with graduate students - a new lecture format
  229. Research Article
  230. Multichannel FES parameterization for controlling foot motion in paretic gait
  231. Research Article
  232. Smartphone supported upper limb prosthesis
  233. Research Article
  234. Use of quantitative tremor evaluation to enhance target selection during deep brain stimulation surgery for essential tremor
  235. Research Article
  236. Evaluation of adhesion promoters for Parylene C on gold metallization
  237. Research Article
  238. The influence of metallic ions from CoCr28Mo6 on the osteogenic differentiation and cytokine release of human osteoblasts
  239. Research Article
  240. Increasing the visibility of thin NITINOL vascular implants
  241. Research Article
  242. Possible reasons for early artificial bone failure in biomechanical tests of ankle arthrodesis systems
  243. Research Article
  244. Development of a bending test procedure for the characterization of flexible ECoG electrode arrays
  245. Research Article
  246. Tubular manipulators: a new concept for intracochlear positioning of an auditory prosthesis
  247. Research Article
  248. Investigation of the dynamic diameter deformation of vascular stents during fatigue testing with radial loading
  249. Research Article
  250. Electrospun vascular grafts with anti-kinking properties
  251. Research Article
  252. Integration of temperature sensors in polyimide-based thin-film electrode arrays
  253. Research Article
  254. Use cases and usability challenges for head-mounted displays in healthcare
  255. Research Article
  256. Device- and service profiles for integrated or systems based on open standards
  257. Research Article
  258. Risk management for medical devices in research projects
  259. Research Article
  260. Simulation of varying femoral attachment sites of medial patellofemoral ligament using a musculoskeletal multi-body model
  261. Research Article
  262. Does enhancing consciousness for strategic planning processes support the effectiveness of problem-based learning concepts in biomedical education?
  263. Research Article
  264. SPIO processing in macrophages for MPI: The breast cancer MPI-SNLB-concept
  265. Research Article
  266. Numerical simulations of airflow in the human pharynx of OSAHS patients
Jetzt anmelden und 20% sparen
Institutioneller Zugang
Wie funktioniert Authentifizierung?
Gewinner des OpenAthens UX Award 2026
Gewinner des OpenAthens UX Award 2026
Haben Sie eine Idee, wie wir unsere Website verbessern können?
Bitte schreiben Sie uns.
© 2026 De Gruyter Brill
Heruntergeladen am 6.3.2026 von https://www.degruyterbrill.com/document/doi/10.1515/cdbme-2015-0062/html
Button zum nach oben scrollen