Wahrend einer neurochirurgischen Intervention muss es dem Operateur moglich sein diagnostische Bi... more Wahrend einer neurochirurgischen Intervention muss es dem Operateur moglich sein diagnostische Bilder zu aktualisieren. Bei dem hier verwendeten neurochirurgischen Mikroskop konnen diagnostische Bilder als virtuelle Modelle und Schnittbilder eingeblendet werden, um einen Sichtwechsel zwischen Patient und externen Bildschirmen zu vermeiden. Um eine intraoperative Aktualisierung der Modelle zu ermoglichen, wurde im Rahmen dieser Arbeit das Mikroskop an eine C-Arm-Angiographieanlage uber einen PACS-Server angebunden. Auserdem wird ein effizienter Workflow vorgestellt, der u. a. die Modellgenerierung aus den DICOM-Bildern mit Hilfe der Entwicklungsumgebung MeVisLab vorsieht. Unter Laborbedingungen durchgefuhrte Experimente ergaben eine mittlere Dauer der Modellaktualisierung von maximal 18,5 ± 2,5 min. Die Abweichung der virtuellen Uberlagerung von realen Strukturen im Mikroskop liegt im Wesentlichen im Submillimeterbereich. Das Mikroskopsystem bildet mit diesem Workflow eine solide For...
In life-threatening diseases and in several clinical interventions, monitoring of vital parameter... more In life-threatening diseases and in several clinical interventions, monitoring of vital parameters is essential to guarantee the safety of patients. Besides monitoring the electrocardiogram (ECG), it is helpful to assess respiratory activity. If the respiration signal itself is not recorded, it can be extracted from the ECG (i.e. ECG derived respiration, EDR). In the present paper, we compared six EDR approaches, namely RS-decline quantified by central moments, respiratory sinus arrhythmia (RSA), R-wave amplitude, QRS area, RS-distance and maximum RS-slope. In order to evaluate the performance of each approach, we applied each method to a database of ECGs and reference respiration signals of 41 healthy subjects. All considered methods revealed relatively small absolute mean errors of the breathing rate (BR) at rest (0.75-1.3 Bpm). The method based on higher order central moments revealed a minimum mean absolute error of 0.75Bpm (4.40%) and a maximum correlation and concordance with the reference BR (rp=0.97, rc=0.97). Using this technique, we analyzed changes of respiration in patients suffering from acute schizophrenia. An increased respiration rate of about 4Bpm was found. Additionally, alteration of respiratory ratio and reduced respiratory sinus arrhythmia was demonstrated. We conclude that a precise dynamic monitoring of breathing and the investigation of changes in breathing patterns is possible without recording respiration per se.
In life-threatening diseases and in several clinical interventions, monitoring of vital parameter... more In life-threatening diseases and in several clinical interventions, monitoring of vital parameters is essential to guarantee the safety of patients. Besides monitoring the electrocardiogram (ECG), it is helpful to assess respiratory activity. If the respiration signal itself is not recorded, it can be extracted from the ECG (i.e. ECG derived respiration, EDR). In the present paper, we compared six EDR approaches, namely RS-decline quantified by central moments, respiratory sinus arrhythmia (RSA), R-wave amplitude, QRS area, RS-distance and maximum RS-slope. In order to evaluate the performance of each approach, we applied each method to a database of ECGs and reference respiration signals of 41 healthy subjects. All considered methods revealed relatively small absolute mean errors of the breathing rate (BR) at rest (0.75-1.3 Bpm). The method based on higher order central moments revealed a minimum mean absolute error of 0.75Bpm (4.40%) and a maximum correlation and concordance with ...
Current Directions in Biomedical Engineering, 2021
Performing minimal invasive interventions under real-time image guidance proves problematic in a ... more Performing minimal invasive interventions under real-time image guidance proves problematic in a closed-bore magnetic resonance imaging scanner. To enable better usability in MRI guided interventions, robotic systems could be used for additional assistance. However, the integration of such devices into the clinical workflow relates to many technical challenges in order to increase precision of the procedure while ensuring the overall safety. In this work, an MR compatible, compact, ultra-light and remotely controllable micropositioning system called μRIGS is presented. The instrument positioning unit can be operated in a 5-DoF range within a working volume of 2100 cm3with an instrument feed of 120 mm. The kinematics are actuated with a combination of non-metallic Bowden cables and electric stepper motors from a safe distance inside the scanner room, while their control is initiated from the control room via a custom-fitted GUI. Thereby, the precision of the positioning reproducibili...
Current Directions in Biomedical Engineering, 2018
Conventional computed tomography (CT) systems are encapsulated in hardware and software. Integrat... more Conventional computed tomography (CT) systems are encapsulated in hardware and software. Integration of further imaging modalities and sensors which can acquire prior knowledge for dose saving image acquisition and reconstruction techniques are barely possible. Within the scope of our research project, an open interface and freely configurable CT system is now being developed. The integration of further modalities and sensors into this system is a main target. A subproject deals with a multi sensor patient table, which provides additional information through integrated sensors. In particular, force sensors are installed inside the patient table to determine the patient’s mass. This value can be used to specify the required tube voltage, so that a more precise setting can be made in comparison to today‘s clinical practice. Studys show that a more precise kVp estimation can significantly reduce patient dose. Sensors for the monitoring of respiration and pulse are also integrated into ...
Current Directions in Biomedical Engineering, 2016
The arterial blood pressure (ABP) holds a lot of information about the cardiovascular system. To ... more The arterial blood pressure (ABP) holds a lot of information about the cardiovascular system. To analyse the ABP signal, at first the pulse wave has to be detected correctly. Due to influences, e.g. of noise, an accurate beat detection is a challenging task. In this work, a novel real-time ABP detector based on higher-order statistics is presented. The method uses the 4
Electromagnetic tracking systems (EMTS) are utilized to track surgical instruments during navigat... more Electromagnetic tracking systems (EMTS) are utilized to track surgical instruments during navigated interventions. Compared to optical tracking technologies, the non-line-of-sight feature is the biggest advantage of EMTS. However, significant distortions due to nearby metallic objects and a small working volume are serious drawbacks preventing ETMS from being widely used. We worked on developing new methods to improve the accuracy of EMTS even in the vicinity of large metal objects while speeding up the position estimation frame rate. Therefore, we proposed a method to realize frequency deviation multiplexing (FDM) for EMTS in order to speed up the frame rate, and a quadratic-rectangular (QR) excitation method to remove the distorted voltage induced by the nearby conductive distorter. The results show that the measurement speed and robustness to nearby metal objects of our EMTS were improved by the FDM and QR method. Keyword: Electromagnetic Tracking, Image-guided Interventions, Nav...
Functional electrical stimulation and robot-assisted gait training are techniques which are used ... more Functional electrical stimulation and robot-assisted gait training are techniques which are used in a clinical routine to enhance the rehabilitation process of stroke patients. By combining these technologies, therapy effects could be further improved and the rehabilitation process can be supported. In order to combine these technologies, a novel algorithm was developed, which aims to extract gait events based on movement data recorded with inertial measurement units. In perspective, the extracted gait events can be used to trigger functional electrical stimulation during robot-assisted gait training. This approach offers the possibility of equipping a broad range of potential robot-assisted gait trainers with functional electrical stimulation. In particular, the aim of this study was to test the robustness of the previously developed algorithm in a clinical setting with patients who suffered a stroke. A total amount of N = 10 stroke patients participated in the study, with written ...
Technologies such as robot-assisted gait trainers or functional electrical stimulation can improv... more Technologies such as robot-assisted gait trainers or functional electrical stimulation can improve the rehabilitation process of people affected with gait disorders due to stroke or other neurological defects. By combining both technologies, the potential disadvantages of each technology could be compensated and simultaneously, therapy effects could be improved. Thus, an algorithm was designed that aims to detect the gait cycle of a robot-assisted gait trainer. Based on movement data recorded with inertial measurement units, gait events can be detected. These events can further be used to trigger functional electrical stimulation. This novel setup offers the possibility of equipping a broad range of potential robot-assisted gait trainers with functional electrical stimulation. The aim of this paper in particular was to test the feasibility of a system using inertial measurement units for gait event detection during robot-assisted gait training. Thus, a 39-year-old healthy male adult...
Wahrend einer neurochirurgischen Intervention muss es dem Operateur moglich sein diagnostische Bi... more Wahrend einer neurochirurgischen Intervention muss es dem Operateur moglich sein diagnostische Bilder zu aktualisieren. Bei dem hier verwendeten neurochirurgischen Mikroskop konnen diagnostische Bilder als virtuelle Modelle und Schnittbilder eingeblendet werden, um einen Sichtwechsel zwischen Patient und externen Bildschirmen zu vermeiden. Um eine intraoperative Aktualisierung der Modelle zu ermoglichen, wurde im Rahmen dieser Arbeit das Mikroskop an eine C-Arm-Angiographieanlage uber einen PACS-Server angebunden. Auserdem wird ein effizienter Workflow vorgestellt, der u. a. die Modellgenerierung aus den DICOM-Bildern mit Hilfe der Entwicklungsumgebung MeVisLab vorsieht. Unter Laborbedingungen durchgefuhrte Experimente ergaben eine mittlere Dauer der Modellaktualisierung von maximal 18,5 ± 2,5 min. Die Abweichung der virtuellen Uberlagerung von realen Strukturen im Mikroskop liegt im Wesentlichen im Submillimeterbereich. Das Mikroskopsystem bildet mit diesem Workflow eine solide For...
In life-threatening diseases and in several clinical interventions, monitoring of vital parameter... more In life-threatening diseases and in several clinical interventions, monitoring of vital parameters is essential to guarantee the safety of patients. Besides monitoring the electrocardiogram (ECG), it is helpful to assess respiratory activity. If the respiration signal itself is not recorded, it can be extracted from the ECG (i.e. ECG derived respiration, EDR). In the present paper, we compared six EDR approaches, namely RS-decline quantified by central moments, respiratory sinus arrhythmia (RSA), R-wave amplitude, QRS area, RS-distance and maximum RS-slope. In order to evaluate the performance of each approach, we applied each method to a database of ECGs and reference respiration signals of 41 healthy subjects. All considered methods revealed relatively small absolute mean errors of the breathing rate (BR) at rest (0.75-1.3 Bpm). The method based on higher order central moments revealed a minimum mean absolute error of 0.75Bpm (4.40%) and a maximum correlation and concordance with the reference BR (rp=0.97, rc=0.97). Using this technique, we analyzed changes of respiration in patients suffering from acute schizophrenia. An increased respiration rate of about 4Bpm was found. Additionally, alteration of respiratory ratio and reduced respiratory sinus arrhythmia was demonstrated. We conclude that a precise dynamic monitoring of breathing and the investigation of changes in breathing patterns is possible without recording respiration per se.
In life-threatening diseases and in several clinical interventions, monitoring of vital parameter... more In life-threatening diseases and in several clinical interventions, monitoring of vital parameters is essential to guarantee the safety of patients. Besides monitoring the electrocardiogram (ECG), it is helpful to assess respiratory activity. If the respiration signal itself is not recorded, it can be extracted from the ECG (i.e. ECG derived respiration, EDR). In the present paper, we compared six EDR approaches, namely RS-decline quantified by central moments, respiratory sinus arrhythmia (RSA), R-wave amplitude, QRS area, RS-distance and maximum RS-slope. In order to evaluate the performance of each approach, we applied each method to a database of ECGs and reference respiration signals of 41 healthy subjects. All considered methods revealed relatively small absolute mean errors of the breathing rate (BR) at rest (0.75-1.3 Bpm). The method based on higher order central moments revealed a minimum mean absolute error of 0.75Bpm (4.40%) and a maximum correlation and concordance with ...
Current Directions in Biomedical Engineering, 2021
Performing minimal invasive interventions under real-time image guidance proves problematic in a ... more Performing minimal invasive interventions under real-time image guidance proves problematic in a closed-bore magnetic resonance imaging scanner. To enable better usability in MRI guided interventions, robotic systems could be used for additional assistance. However, the integration of such devices into the clinical workflow relates to many technical challenges in order to increase precision of the procedure while ensuring the overall safety. In this work, an MR compatible, compact, ultra-light and remotely controllable micropositioning system called μRIGS is presented. The instrument positioning unit can be operated in a 5-DoF range within a working volume of 2100 cm3with an instrument feed of 120 mm. The kinematics are actuated with a combination of non-metallic Bowden cables and electric stepper motors from a safe distance inside the scanner room, while their control is initiated from the control room via a custom-fitted GUI. Thereby, the precision of the positioning reproducibili...
Current Directions in Biomedical Engineering, 2018
Conventional computed tomography (CT) systems are encapsulated in hardware and software. Integrat... more Conventional computed tomography (CT) systems are encapsulated in hardware and software. Integration of further imaging modalities and sensors which can acquire prior knowledge for dose saving image acquisition and reconstruction techniques are barely possible. Within the scope of our research project, an open interface and freely configurable CT system is now being developed. The integration of further modalities and sensors into this system is a main target. A subproject deals with a multi sensor patient table, which provides additional information through integrated sensors. In particular, force sensors are installed inside the patient table to determine the patient’s mass. This value can be used to specify the required tube voltage, so that a more precise setting can be made in comparison to today‘s clinical practice. Studys show that a more precise kVp estimation can significantly reduce patient dose. Sensors for the monitoring of respiration and pulse are also integrated into ...
Current Directions in Biomedical Engineering, 2016
The arterial blood pressure (ABP) holds a lot of information about the cardiovascular system. To ... more The arterial blood pressure (ABP) holds a lot of information about the cardiovascular system. To analyse the ABP signal, at first the pulse wave has to be detected correctly. Due to influences, e.g. of noise, an accurate beat detection is a challenging task. In this work, a novel real-time ABP detector based on higher-order statistics is presented. The method uses the 4
Electromagnetic tracking systems (EMTS) are utilized to track surgical instruments during navigat... more Electromagnetic tracking systems (EMTS) are utilized to track surgical instruments during navigated interventions. Compared to optical tracking technologies, the non-line-of-sight feature is the biggest advantage of EMTS. However, significant distortions due to nearby metallic objects and a small working volume are serious drawbacks preventing ETMS from being widely used. We worked on developing new methods to improve the accuracy of EMTS even in the vicinity of large metal objects while speeding up the position estimation frame rate. Therefore, we proposed a method to realize frequency deviation multiplexing (FDM) for EMTS in order to speed up the frame rate, and a quadratic-rectangular (QR) excitation method to remove the distorted voltage induced by the nearby conductive distorter. The results show that the measurement speed and robustness to nearby metal objects of our EMTS were improved by the FDM and QR method. Keyword: Electromagnetic Tracking, Image-guided Interventions, Nav...
Functional electrical stimulation and robot-assisted gait training are techniques which are used ... more Functional electrical stimulation and robot-assisted gait training are techniques which are used in a clinical routine to enhance the rehabilitation process of stroke patients. By combining these technologies, therapy effects could be further improved and the rehabilitation process can be supported. In order to combine these technologies, a novel algorithm was developed, which aims to extract gait events based on movement data recorded with inertial measurement units. In perspective, the extracted gait events can be used to trigger functional electrical stimulation during robot-assisted gait training. This approach offers the possibility of equipping a broad range of potential robot-assisted gait trainers with functional electrical stimulation. In particular, the aim of this study was to test the robustness of the previously developed algorithm in a clinical setting with patients who suffered a stroke. A total amount of N = 10 stroke patients participated in the study, with written ...
Technologies such as robot-assisted gait trainers or functional electrical stimulation can improv... more Technologies such as robot-assisted gait trainers or functional electrical stimulation can improve the rehabilitation process of people affected with gait disorders due to stroke or other neurological defects. By combining both technologies, the potential disadvantages of each technology could be compensated and simultaneously, therapy effects could be improved. Thus, an algorithm was designed that aims to detect the gait cycle of a robot-assisted gait trainer. Based on movement data recorded with inertial measurement units, gait events can be detected. These events can further be used to trigger functional electrical stimulation. This novel setup offers the possibility of equipping a broad range of potential robot-assisted gait trainers with functional electrical stimulation. The aim of this paper in particular was to test the feasibility of a system using inertial measurement units for gait event detection during robot-assisted gait training. Thus, a 39-year-old healthy male adult...
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