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  1. Article ; Online: Multi-network approach for image segmentation in non-contrast enhanced cardiac 3D MRI of arrhythmic patients.

    Vernikouskaya, Ina / Bertsche, Dagmar / Metze, Patrick / Schneider, Leonhard M / Rasche, Volker

    Computerized medical imaging and graphics : the official journal of the Computerized Medical Imaging Society

    2024  Volume 113, Page(s) 102340

    Abstract: Left atrial appendage (LAA) is the source of thrombi formation in more than 90% of strokes in patients with nonvalvular atrial fibrillation. Catheter-based LAA occlusion is being increasingly applied as a treatment strategy to prevent stroke. Anatomical ... ...

    Abstract Left atrial appendage (LAA) is the source of thrombi formation in more than 90% of strokes in patients with nonvalvular atrial fibrillation. Catheter-based LAA occlusion is being increasingly applied as a treatment strategy to prevent stroke. Anatomical complexity of LAA makes percutaneous occlusion commonly performed under transesophageal echocardiography (TEE) and X-ray (XR) guidance especially challenging. Image fusion techniques integrating 3D anatomical models derived from pre-procedural imaging into the live XR fluoroscopy can be applied to guide each step of the LAA closure. Cardiac magnetic resonance (CMR) imaging gains in importance for radiation-free evaluation of cardiac morphology as alternative to gold-standard TEE or computed tomography angiography (CTA). Manual delineation of cardiac structures from non-contrast enhanced CMR is, however, labor-intensive, tedious, and challenging due to the rather low contrast. Additionally, arrhythmia often impairs the image quality in ECG synchronized acquisitions causing blurring and motion artifacts. Thus, for cardiac segmentation in arrhythmic patients, there is a strong need for an automated image segmentation method. Deep learning-based methods have shown great promise in medical image analysis achieving superior performance in various imaging modalities and different clinical applications. Fully-convolutional neural networks (CNNs), especially U-Net, have become the method of choice for cardiac segmentation. In this paper, we propose an approach for automatic segmentation of cardiac structures from non-contrast enhanced CMR images of arrhythmic patients based on CNNs implemented in a multi-stage pipeline. Two-stage implementation allows subdividing the task into localization of the relevant cardiac structures and segmentation of these structures from the cropped sub-regions obtained from previous step leading to efficient and effective way of automated cardiac segmentation.
    MeSH term(s) Humans ; Atrial Appendage/anatomy & histology ; Magnetic Resonance Imaging ; Atrial Fibrillation/therapy ; Tomography, X-Ray Computed ; Angiography
    Language English
    Publishing date 2024-01-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 639451-6
    ISSN 1879-0771 ; 0895-6111
    ISSN (online) 1879-0771
    ISSN 0895-6111
    DOI 10.1016/j.compmedimag.2024.102340
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  2. Article ; Online: 3D localization from 2D X-ray projection.

    Bertsche, Dagmar / Rasche, Volker / Rottbauer, Wolfgang / Vernikouskaya, Ina

    International journal of computer assisted radiology and surgery

    2022  Volume 17, Issue 9, Page(s) 1553–1558

    Abstract: Purpose: Most cardiology procedures are guided using X-ray (XR) fluoroscopy. However, the projective nature of the XR fluoroscopy does not allow for true depth perception as required for safe and efficient intervention guidance in structural heart ... ...

    Abstract Purpose: Most cardiology procedures are guided using X-ray (XR) fluoroscopy. However, the projective nature of the XR fluoroscopy does not allow for true depth perception as required for safe and efficient intervention guidance in structural heart diseases. For improving guidance, different methods have been proposed often being radiation-intensive, time-consuming, or expensive. We propose a simple 3D localization method based on a single monoplane XR projection using a co-registered centerline model.
    Methods: The method is based on 3D anatomic surface models and corresponding centerlines generated from preprocedural imaging. After initial co-registration, 2D working points identified in monoplane XR projections are localized in 3D by minimizing the angle between the projection lines of the centerline points and the working points. The accuracy and reliability of the located 3D positions were assessed in 3D using phantom data and in patient data projected to 2D obtained during placement of embolic protection system in interventional procedures.
    Results: With the proposed methods, 2D working points identified in monoplane XR could be successfully located in the 3D phantom and in the patient-specific 3D anatomy. Accuracy in the phantom (3D) resulted in 1.6 mm (± 0.8 mm) on average, and 2.7 mm (± 1.3 mm) on average in the patient data (2D).
    Conclusion: The use of co-registered centerline models allows reliable and accurate 3D localization of devices from a single monoplane XR projection during placement of the embolic protection system in TAVR. The extension to different vascular interventions and combination with automatic methods for device detection and registration might be promising.
    MeSH term(s) Algorithms ; Fluoroscopy/methods ; Humans ; Imaging, Three-Dimensional/methods ; Phantoms, Imaging ; Reproducibility of Results ; X-Rays
    Language English
    Publishing date 2022-07-11
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2365628-1
    ISSN 1861-6429 ; 1861-6410
    ISSN (online) 1861-6429
    ISSN 1861-6410
    DOI 10.1007/s11548-022-02709-w
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  3. Article ; Online: Deep learning-based framework for motion-compensated image fusion in catheterization procedures.

    Vernikouskaya, Ina / Bertsche, Dagmar / Rottbauer, Wolfgang / Rasche, Volker

    Computerized medical imaging and graphics : the official journal of the Computerized Medical Imaging Society

    2022  Volume 98, Page(s) 102069

    Abstract: Objective: Augmenting X-ray (XR) fluoroscopy with 3D anatomic overlays is an essential technique to improve the guidance of the catheterization procedures. Unfortunately, cardiac and respiratory motion compromises the augmented fluoroscopy. Motion ... ...

    Abstract Objective: Augmenting X-ray (XR) fluoroscopy with 3D anatomic overlays is an essential technique to improve the guidance of the catheterization procedures. Unfortunately, cardiac and respiratory motion compromises the augmented fluoroscopy. Motion compensation methods can be applied to update the overlay of a static model with regard to respiratory and cardiac motion. We investigate the feasibility of motion detection between two fluoroscopic frames by applying a convolutional neural network (CNN). Its integration in the existing open-source software framework 3D-XGuide is demonstrated, such extending its functionality to automatic motion detection and compensation.
    Methods: The CNN is trained on reference data generated from tracking of the rapid pacing catheter tip by applying template matching with normalized cross-correlation (CC). The developed CNN motion compensation model is packaged in a standalone web service, allowing for independent use via a REST API. For testing and demonstration purposes, we have extended the functionality of 3D-XGuide navigation framework by an additional motion compensation module, which uses the displacement predictions of the standalone CNN model service for motion compensation of the static 3D model overlay. We provide the source code on GitHub under BSD license.
    Results: The performance of the CNN motion compensation model was evaluated on a total of 1690 fluoroscopic image pairs from ten clinical datasets. The CNN model-based motion compensation method clearly overperformed the tracking of the rapid pacing catheter tip with CC with prediction frame rates suitable for live application in the clinical setting.
    Conclusion: A novel CNN model-based method for automatic motion compensation during fusion of 3D anatomic models with XR fluoroscopy is introduced and its integration with a real software application demonstrated. Automatic motion extraction from 2D XR images using a CNN model appears as a substantial improvement for reliable augmentation during catheter interventions.
    MeSH term(s) Catheterization ; Deep Learning ; Fluoroscopy/methods ; Motion ; Neural Networks, Computer
    Language English
    Publishing date 2022-05-13
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 639451-6
    ISSN 1879-0771 ; 0895-6111
    ISSN (online) 1879-0771
    ISSN 0895-6111
    DOI 10.1016/j.compmedimag.2022.102069
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  4. Article ; Online: Impact of cardiac and respiratory motion on the 3D accuracy of image-guided interventions on monoplane systems.

    Bertsche, Dagmar / Metze, Patrick / Schneider, Leonhard-Moritz / Vernikouskaya, Ina / Rasche, Volker

    International journal of computer assisted radiology and surgery

    2023  Volume 19, Issue 2, Page(s) 367–374

    Abstract: Purpose: Image-guided intervention (IGI) systems have the potential to increase the efficiency in interventional cardiology but face limitations from motion. Even though motion compensation approaches have been proposed, the resulting accuracy has ... ...

    Abstract Purpose: Image-guided intervention (IGI) systems have the potential to increase the efficiency in interventional cardiology but face limitations from motion. Even though motion compensation approaches have been proposed, the resulting accuracy has rarely been quantified using in vivo data. The purpose of this study is to investigate the potential benefit of motion-compensation in IGS systems.
    Methods: Patients scheduled for left atrial appendage closure (LAAc) underwent pre- and postprocedural non-contrast-enhanced cardiac magnetic resonance imaging (CMR). According to the clinical standard, the final position of the occluder device was routinely documented using x-ray fluoroscopy (XR). The accuracy of the IGI system was assessed retrospectively based on the distance of the 3D device marker location derived from the periprocedural XR data and the respective location as identified in the postprocedural CMR data.
    Results: The assessment of the motion-compensation depending accuracy was possible based on the patient data. With motion synchronization, the measured accuracy of the IGI system resulted similar to the estimated accuracy, with almost negligible distances of the device marker positions identified in CMR and XR. Neglection of the cardiac and/or respiratory phase significantly increased the mean distances, with respiratory motion mainly reducing the accuracy with rather low impact on the precision, whereas cardiac motion decreased the accuracy and the precision of the image guidance.
    Conclusions: In the presented work, the accuracy of the IGI system could be assessed based on in vivo data. Motion consideration clearly showed the potential to increase the accuracy in IGI systems. Where the general decrease in accuracy in non-motion-synchronized data did not come unexpected, a clear difference between cardiac and respiratory motion-induced errors was observed for LAAc data. Since sedation and intervention location close to the large vessels likely impacts the respiratory motion contribution, an intervention-specific accuracy analysis may be useful for other interventions.
    MeSH term(s) Humans ; Retrospective Studies ; Heart ; Motion
    Language English
    Publishing date 2023-07-21
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2365628-1
    ISSN 1861-6429 ; 1861-6410
    ISSN (online) 1861-6429
    ISSN 1861-6410
    DOI 10.1007/s11548-023-02998-9
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  5. Article ; Online: Cryo-balloon catheter localization in X-Ray fluoroscopy using U-net.

    Vernikouskaya, Ina / Bertsche, Dagmar / Dahme, Tillman / Rasche, Volker

    International journal of computer assisted radiology and surgery

    2021  Volume 16, Issue 8, Page(s) 1255–1262

    Abstract: Purpose: Automatic identification of interventional devices in X-ray (XR) fluoroscopy offers the potential of improved navigation during transcatheter endovascular procedures. This paper presents a prototype implementation of fully automatic 3D ... ...

    Abstract Purpose: Automatic identification of interventional devices in X-ray (XR) fluoroscopy offers the potential of improved navigation during transcatheter endovascular procedures. This paper presents a prototype implementation of fully automatic 3D reconstruction of a cryo-balloon catheter during pulmonary vein isolation (PVI) procedures by deep learning approaches.
    Methods: We employ convolutional neural networks (CNN) to automatically identify the cryo-balloon XR marker and catheter shaft in 2D fluoroscopy during PVI. Training data are generated exploiting established semiautomatic techniques, including template-matching and analytical graph building. A first network of U-net architecture uses a single grayscale XR image as input and yields the mask of the XR marker. A second network of the similar architecture is trained using the mask of the XR marker as additional input to the grayscale XR image for the segmentation of the cryo-balloon catheter shaft mask. The structures automatically identified in two 2D images with different angulations are then used to reconstruct the cryo-balloon in 3D.
    Results: Automatic identification of the XR marker was successful in 78% of test cases and in 100% for the catheter shaft. Training of the model for prediction of the XR marker mask was successful with 3426 training samples. Incorporation of the XR marker mask as additional input for the model predicting the catheter shaft allowed to achieve good training result with only 805 training samples. The average prediction time per frame was 14.47 ms for the XR marker and 78.22 ms for the catheter shaft. Localization accuracy for the XR marker yielded on average 1.52 pixels or 0.56 mm.
    Conclusions: In this paper, we report a novel method for automatic detection and 3D reconstruction of the cryo-balloon catheter shaft and marker from 2D fluoroscopic images. Initial evaluation yields promising results thus indicating the high potential of CNNs as alternatives to the current state-of-the-art solutions.
    MeSH term(s) Catheters ; Cryosurgery/instrumentation ; Fluoroscopy/methods ; Humans ; Image Processing, Computer-Assisted/methods ; Neural Networks, Computer ; Surgery, Computer-Assisted
    Language English
    Publishing date 2021-04-20
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2365628-1
    ISSN 1861-6429 ; 1861-6410
    ISSN (online) 1861-6429
    ISSN 1861-6410
    DOI 10.1007/s11548-021-02366-5
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  6. Article ; Online: 3D-XGuide: open-source X-ray navigation guidance system.

    Vernikouskaya, Ina / Bertsche, Dagmar / Rottbauer, Wolfgang / Rasche, Volker

    International journal of computer assisted radiology and surgery

    2020  Volume 16, Issue 1, Page(s) 53–63

    Abstract: Purpose: With the growing availability and variety of imaging modalities, new methods of intraoperative support have become available for all kinds of interventions. The basic principles of image fusion and image guidance have been widely adopted and ... ...

    Abstract Purpose: With the growing availability and variety of imaging modalities, new methods of intraoperative support have become available for all kinds of interventions. The basic principles of image fusion and image guidance have been widely adopted and are commercialized through a number of platforms. Although multimodal systems have been found to be useful for guiding interventional procedures, they all have their limitations. The integration of more advanced guidance techniques into the product functionality is, however, not easy due to the proprietary solutions of the vendors. Therefore, the purpose of this work is to introduce a software system for image fusion, real-time navigation, and working points documentation during transcatheter interventions performed under X-ray (XR) guidance.
    Methods: An interactive software system for cross-modal registration and image fusion of XR fluoroscopy with CT or MRI-derived anatomic 3D models is implemented using Qt application framework and VTK visualization pipeline. DICOM data can be imported in retrospective mode. Live XR data input is realized by a video capture card application interface.
    Results: The actual software release offers a graphical user interface with basic functionality including data import and handling, calculation of projection geometry and transformations between related coordinate systems, rigid 3D-3D registration, and template matching-based tracking and motion compensation algorithms in 2D and 3D. The link to the actual software release on GitHub including source code and executable is provided to support independent research and development in the field of intervention guidance.
    Conclusion: The introduced system provides a common foundation for the rapid prototyping of new approaches in the field of XR fluoroscopic guidance. As a pure software solution, the developed system is potentially vendor-independent and can be easily extended to be used with the XR systems of different manufacturers.
    MeSH term(s) Algorithms ; Fluoroscopy/methods ; Humans ; Imaging, Three-Dimensional/methods ; Magnetic Resonance Imaging ; Motion ; Software ; Tomography, X-Ray Computed
    Language English
    Publishing date 2020-10-15
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2365628-1
    ISSN 1861-6429 ; 1861-6410
    ISSN (online) 1861-6429
    ISSN 1861-6410
    DOI 10.1007/s11548-020-02274-0
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  7. Article: Cardiac magnetic resonance imaging for preprocedural planning of percutaneous left atrial appendage closure.

    Bertsche, Dagmar / Metze, Patrick / Luo, Erfei / Dahme, Tillman / Gonska, Birgid / Rottbauer, Wolfgang / Vernikouskaya, Ina / Rasche, Volker / Schneider, Leonhard M

    Frontiers in cardiovascular medicine

    2023  Volume 10, Page(s) 1132626

    Abstract: Introduction: Percutaneous closure of the left atrial appendage (LAA) facilitates stroke prevention in patients with atrial fibrillation. Optimal device selection and positioning are often challenging due to highly variable LAA shape and dimension and ... ...

    Abstract Introduction: Percutaneous closure of the left atrial appendage (LAA) facilitates stroke prevention in patients with atrial fibrillation. Optimal device selection and positioning are often challenging due to highly variable LAA shape and dimension and thus require accurate assessment of the respective anatomy. Transesophageal echocardiography (TEE) and x-ray fluoroscopy (XR) represent the gold standard imaging techniques. However, device underestimation has frequently been observed. Assessment based on 3-dimensional computer tomography (CTA) has been reported as more accurate but increases radiation and contrast agent burden. In this study, the use of non-contrast-enhanced cardiac magnetic resonance imaging (CMR) to support preprocedural planning for LAA closure (LAAc) was investigated.
    Methods: CMR was performed in thirteen patients prior to LAAc. Based on the 3-dimensional CMR image data, the dimensions of the LAA were quantified and optimal C-arm angulations were determined and compared to periprocedural data. Quantitative figures used for evaluation of the technique comprised the maximum diameter, the diameter derived from perimeter and the area of the landing zone of the LAA.
    Results: Perimeter- and area-based diameters derived from preprocedural CMR showed excellent congruency compared to those measured periprocedurally by XR, whereas the respective maximum diameter resulted in significant overestimation (
    Discussion: This small pilot study demonstrates the potential of non-contrast-enhanced CMR to support preprocedural planning of LAAc. Diameter measurements based on LAA area and perimeter correlated well with the actual device selection parameters. CMR-derived determination of landing zones facilitated accurate C-arm angulation for optimal device positioning.
    Language English
    Publishing date 2023-06-23
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2781496-8
    ISSN 2297-055X
    ISSN 2297-055X
    DOI 10.3389/fcvm.2023.1132626
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  8. Article ; Online: MRI-based training model for left atrial appendage closure.

    Bertsche, Dagmar / Pfisterer, Mona / Dahme, Tillman / Schneider, Leonhard-Moritz / Metze, Patrick / Vernikouskaya, Ina / Rasche, Volker

    International journal of computer assisted radiology and surgery

    2023  Volume 18, Issue 11, Page(s) 2111–2116

    Abstract: Purpose: Percutaneous closure of the left atrial appendage (LAA) reduces the risk of embolic stroke in patients with atrial fibrillation. Thereby, the optimal transseptal puncture (TSP) site differs due to the highly variable anatomical shape of the LAA, ...

    Abstract Purpose: Percutaneous closure of the left atrial appendage (LAA) reduces the risk of embolic stroke in patients with atrial fibrillation. Thereby, the optimal transseptal puncture (TSP) site differs due to the highly variable anatomical shape of the LAA, which is rarely considered in existing training models. Based on non-contrast-enhanced magnetic resonance imaging (MRI) volumes, we propose a training model for LAA closure with interchangeable and patient-specific LAA enabling LAA-specific identification of the TSP site best suited.
    Methods: Based on patient-specific MRI data, silicone models of the LAAs were produced using a 3D-printed cast model. In addition, an MRI-derived 3D-printed base model was set up, including the right and left atrium with predefined passages in the septum, mimicking multiple TSP sites. The various silicone models and a tube mimicking venous access were connected to the base model. Empirical use of the model allowed the demonstration of its usability.
    Results: Patient-specific silicone models of the LAA could be generated from all LAA patient MRI datasets. The influence of various combinations regarding TSP sites and LAA shapes could be demonstrated as well as the technical functionality of the occluder system. Via the attached tube mimicking the venous access, the correct handling of the deployment catheter even in case of not optimal puncture site could be practiced.
    Conclusion: The proposed contrast-agent and radiation-free MRI-based training model for percutaneous LAA closure enables the pre-interventional assessment of the influence of the TSP site on the access of patient-specific LAA shapes. A straightforward replication of this work is measured by using clinically available imaging protocols and a widespread 3D printer technique to build the model.
    Language English
    Publishing date 2023-03-30
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2365628-1
    ISSN 1861-6429 ; 1861-6410
    ISSN (online) 1861-6429
    ISSN 1861-6410
    DOI 10.1007/s11548-023-02870-w
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  9. Article ; Online: How to improve navigation during cardioband transcatheter tricuspid annuloplasty.

    Bertsche, Dagmar / Keßler, Mirjam / Buckert, Dominik / Schneider, Leonhard-Moritz / Rottbauer, Wolfgang / Rasche, Volker / Markovic, Sinisa / Vernikouskaya, Ina

    European heart journal. Cardiovascular Imaging

    2021  Volume 22, Issue 6, Page(s) 611–613

    MeSH term(s) Cardiac Valve Annuloplasty ; Heart Valve Prosthesis Implantation ; Humans ; Mitral Valve/surgery ; Mitral Valve Annuloplasty ; Treatment Outcome ; Tricuspid Valve/diagnostic imaging ; Tricuspid Valve/surgery ; Tricuspid Valve Insufficiency/diagnostic imaging ; Tricuspid Valve Insufficiency/surgery
    Language English
    Publishing date 2021-01-19
    Publishing country England
    Document type Journal Article
    ZDB-ID 2638345-7
    ISSN 2047-2412 ; 2047-2404
    ISSN (online) 2047-2412
    ISSN 2047-2404
    DOI 10.1093/ehjci/jeab002
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  10. Article: Computed tomography angiography/magnetic resonance imaging-based preprocedural planning and guidance in the interventional treatment of structural heart disease.

    Bertsche, Dagmar / Rottbauer, Wolfgang / Rasche, Volker / Buckert, Dominik / Markovic, Sinisa / Metze, Patrick / Gonska, Birgid / Luo, Erfei / Dahme, Tillman / Vernikouskaya, Ina / Schneider, Leonhard M

    Frontiers in cardiovascular medicine

    2022  Volume 9, Page(s) 931959

    Abstract: Preprocedural planning and periprocedural guidance based on image fusion are widely established techniques supporting the interventional treatment of structural heart disease. However, these two techniques are typically used independently. Previous works ...

    Abstract Preprocedural planning and periprocedural guidance based on image fusion are widely established techniques supporting the interventional treatment of structural heart disease. However, these two techniques are typically used independently. Previous works have already demonstrated the benefits of integrating planning details into image fusion but are limited to a few applications and the availability of the proprietary tools used. We propose a vendor-independent approach to integrate planning details into periprocedural image fusion facilitating guidance during interventional treatment. In this work, we demonstrate the feasibility of integrating planning details derived from computer tomography and magnetic resonance imaging into periprocedural image fusion with open-source and commercially established tools. The integration of preprocedural planning details into periprocedural image fusion has the potential to support safe and efficient interventional treatment of structural heart disease.
    Language English
    Publishing date 2022-10-17
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2781496-8
    ISSN 2297-055X
    ISSN 2297-055X
    DOI 10.3389/fcvm.2022.931959
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