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  1. Article ; Online: Spatially Variant Ultrasound Attenuation Mapping Using a Regularized Linear Least-Squares Approach.

    Birdi, Jasleen / D'hooge, Jan / Bertrand, Alexander

    IEEE transactions on ultrasonics, ferroelectrics, and frequency control

    2022  Volume 69, Issue 5, Page(s) 1596–1609

    Abstract: Quantitative ultrasound methods aim to estimate the acoustic properties of the underlying medium, such as the attenuation and backscatter coefficients, and have applications in various areas including tissue characterization. In practice, tissue ... ...

    Abstract Quantitative ultrasound methods aim to estimate the acoustic properties of the underlying medium, such as the attenuation and backscatter coefficients, and have applications in various areas including tissue characterization. In practice, tissue heterogeneity makes the coefficient estimation challenging. In this work, we propose a computationally efficient algorithm to map spatial variations of the attenuation coefficient. Our proposed approach adopts a fast, linear least-squares strategy to fit the signal model to data from pulse-echo measurements. As opposed to existing approaches, we directly estimate the attenuation map, that is, the local attenuation coefficient at each axial location by solving a joint estimation problem. In particular, we impose a physical model that couples all these local estimates and combine it with a smooth regularization to obtain a smooth map. Compared to the conventional spectral log difference method and the more recent ALGEBRA approach, we demonstrate that the attenuation estimates obtained by our method are more accurate and better correlate with the ground-truth attenuation profiles over a wide range of spatial and contrast resolutions.
    MeSH term(s) Acoustics ; Algorithms ; Least-Squares Analysis ; Phantoms, Imaging ; Ultrasonography/methods
    Language English
    Publishing date 2022-04-27
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1525-8955
    ISSN (online) 1525-8955
    DOI 10.1109/TUFFC.2022.3157949
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: The Sobering Sting: Oleoyl Serotonin Is a Novel

    An, Dongchen / Carrazoni, Guilherme Salgado / Souto das Neves, Ben-Hur / D'Hooge, Rudi / Peigneur, Steve / Tytgat, Jan

    Biomedicines

    2024  Volume 12, Issue 2

    Abstract: Cannabinoid receptors (CB1 and CB2) are promising targets for a better understanding of neurological diseases. Nevertheless, only a few ligands of CB have reached clinical application so far. Venoms are considered as interesting sources of novel ... ...

    Abstract Cannabinoid receptors (CB1 and CB2) are promising targets for a better understanding of neurological diseases. Nevertheless, only a few ligands of CB have reached clinical application so far. Venoms are considered as interesting sources of novel biologically active compounds. Here, we describe an endocannabinoid-like molecule, oleoyl serotonin (OS), present in the venom of Stephanoconus snails. Using electrophysiological assays, it was shown that OS inhibits CB1 and CB2. Structure-activity relationship studies using a chimeric CB1/2 revealed that the domain encompassing the transmembrane helix V (TMHV)- intracellular loop 3 (ICL3)-TMHVI of the CB2 is critical for the binding and function of OS. We concluded that OS binds to sites of the CB2 that are different from the binding sites of the non-selective CB agonist WIN55,212-2. Behavioral assays in mice showed that OS counteracted learning and memory deficits caused by WIN55,212-2. Furthermore, a selectivity screening of OS showed high selectivity for CB over various ion channels and receptors. Overall, OS may represent a new approach to the prevention and treatment of learning and memory cognition impairment in neurological diseases.
    Language English
    Publishing date 2024-02-18
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2720867-9
    ISSN 2227-9059
    ISSN 2227-9059
    DOI 10.3390/biomedicines12020454
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Concepts and applications of ultrafast cardiac ultrasound imaging.

    Petrescu, Aniela / D'hooge, Jan / Voigt, Jens-Uwe

    Echocardiography (Mount Kisco, N.Y.)

    2021  Volume 38, Issue 1, Page(s) 7–15

    Abstract: The concept of ultrafast echocardiographic imaging has been around for decades. However, only recent progress in ultrasound machine hardware and computer technology allowed to apply this concept to echocardiography. High frame rate echocardiography can ... ...

    Abstract The concept of ultrafast echocardiographic imaging has been around for decades. However, only recent progress in ultrasound machine hardware and computer technology allowed to apply this concept to echocardiography. High frame rate echocardiography can visualize phenomena that have never been captured before. It enables a wide variety of potential new applications, including shear wave imaging, speckle tracking, ultrafast Doppler imaging, and myocardial perfusion imaging. The principles of these applications and their potential clinical use will be presented in this manuscript.
    MeSH term(s) Echocardiography ; Humans ; Myocardial Perfusion Imaging ; Ultrasonography ; Ultrasonography, Doppler
    Language English
    Publishing date 2021-01-20
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 843645-9
    ISSN 1540-8175 ; 0742-2822
    ISSN (online) 1540-8175
    ISSN 0742-2822
    DOI 10.1111/echo.14971
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  4. Article ; Online: Fast linear least-squares method for ultrasound attenuation and backscatter estimation.

    Birdi, Jasleen / Muraleedharan, Arun / D'hooge, Jan / Bertrand, Alexander

    Ultrasonics

    2021  Volume 116, Page(s) 106503

    Abstract: The ultrasonic attenuation and backscatter coefficients of tissues are relevant acoustic parameters due to their wide range of clinical applications. In this paper, a linear least-squares method for the estimation of these coefficients in a homogeneous ... ...

    Abstract The ultrasonic attenuation and backscatter coefficients of tissues are relevant acoustic parameters due to their wide range of clinical applications. In this paper, a linear least-squares method for the estimation of these coefficients in a homogeneous region of interest based on pulse-echo measurements is proposed. The method efficiently fits an ultrasound backscattered signal model to the measurements in both the frequency and depth dimension simultaneously at a low computational cost. It is demonstrated that the inclusion of depth information has a positive effect particularly on the accuracy of the estimated attenuation. The sensitivity of the attenuation and backscatter coefficients' estimates to several predefined parameters such as the window length, window overlap and usable bandwidth of the spectrum is also studied. Comparison of the proposed method with a benchmark approach based on dynamic programming highlights better performance of our method in estimating these coefficients, both in terms of accuracy and computation time. Further analysis of the computation time as a function of the predefined parameters indicates our method's potential to be used in real-time clinical settings.
    Language English
    Publishing date 2021-06-17
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 200839-7
    ISSN 1874-9968 ; 0041-624X
    ISSN (online) 1874-9968
    ISSN 0041-624X
    DOI 10.1016/j.ultras.2021.106503
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Non-rigid image registration using a modified fuzzy feature-based inference system for 3D cardiac motion estimation.

    Hosseini, Monire Sheikh / Moradi, Mahammad Hassan / Tabassian, Mahdi / D'hooge, Jan

    Computer methods and programs in biomedicine

    2021  Volume 205, Page(s) 106085

    Abstract: Background and objective: Non-rigid image registration is a well-established method for estimating cardiac motion on 3D echocardiographic images. However, such images have relatively poor spatio-temporal resolution making registration challenging. Some ... ...

    Abstract Background and objective: Non-rigid image registration is a well-established method for estimating cardiac motion on 3D echocardiographic images. However, such images have relatively poor spatio-temporal resolution making registration challenging. Some of the main challenges are extracting features relevant to the registration problem and defining a suitable geometrical transformation to be applied. The latter can be tackled using a fuzzy inference system considering its potential in transformation modeling. From this point of view, feature-based image registration can be considered an identification problem in which the transformation parameters are computed through an optimization process. This study, thus, aims to estimate cardiac motion on 3D echocardiographic images based on feature-based non-rigid image registration through sets of modified fuzzy rules.
    Methods: The 3D volume features were extracted with the popular scale-invariant feature transform (SIFT) descriptors in 3D space. Sets of fuzzy rules were generated according to the extracted features to register every two consecutive frames. Finally, some supplementary rules modified the registration rule for estimating cardiac motion.
    Results: Applying the fuzzy feature-based inference system on the STRAUS synthetic database showed the proposed method to be competitive with other well-established registration algorithms in terms of tracking error and accuracy of strain estimates. The proposed algorithm yielded a tracking error of 1 mm and a relative circumferential strain error of 0.82±4.69%. In addition, the potential of the proposed algorithm for clinical applications was confirmed by evaluating its performance on an in-vivo database called CETUS.
    Conclusion: This paper proposes a novel registration method based on fuzzy logic which was shown to enable tracking complex cardiac deformations in 3D echocardiographic images with high accuracy.
    MeSH term(s) Algorithms ; Echocardiography ; Fuzzy Logic ; Heart/diagnostic imaging ; Imaging, Three-Dimensional ; Motion
    Language English
    Publishing date 2021-04-06
    Publishing country Ireland
    Document type Journal Article
    ZDB-ID 632564-6
    ISSN 1872-7565 ; 0169-2607
    ISSN (online) 1872-7565
    ISSN 0169-2607
    DOI 10.1016/j.cmpb.2021.106085
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Ultrasound Shear Wave Elastography in Cardiology.

    Caenen, Annette / Bézy, Stéphanie / Pernot, Mathieu / Nightingale, Kathryn R / Vos, Hendrik J / Voigt, Jens-Uwe / Segers, Patrick / D'hooge, Jan

    JACC. Cardiovascular imaging

    2023  Volume 17, Issue 3, Page(s) 314–329

    Abstract: The advent of high-frame rate imaging in ultrasound allowed the development of shear wave elastography as a noninvasive alternative for myocardial stiffness assessment. It measures mechanical waves propagating along the cardiac wall with speeds that are ... ...

    Abstract The advent of high-frame rate imaging in ultrasound allowed the development of shear wave elastography as a noninvasive alternative for myocardial stiffness assessment. It measures mechanical waves propagating along the cardiac wall with speeds that are related to stiffness. The use of cardiac shear wave elastography in clinical studies is increasing, but a proper understanding of the different factors that affect wave propagation is required to correctly interpret results because of the heart's thin-walled geometry and intricate material properties. The aims of this review are to give an overview of the general concepts in cardiac shear wave elastography and to discuss in depth the effects of age, hemodynamic loading, cardiac morphology, fiber architecture, contractility, viscoelasticity, and system-dependent factors on the measurements, with a focus on clinical application. It also describes how these factors should be considered during acquisition, analysis, and reporting to ensure an accurate, robust, and reproducible measurement of the shear wave.
    MeSH term(s) Humans ; Elasticity Imaging Techniques ; Predictive Value of Tests ; Ultrasonography ; Cardiology ; Myocardium
    Language English
    Publishing date 2023-12-21
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 2491503-8
    ISSN 1876-7591 ; 1936-878X
    ISSN (online) 1876-7591
    ISSN 1936-878X
    DOI 10.1016/j.jcmg.2023.12.007
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Comparing Myocardial Shear Wave Propagation Velocity Estimation Methods Based on Tissue Displacement, Velocity and Acceleration Data.

    Seliverstova, Ekaterina / Caenen, Annette / Bézy, Stephanie / Nooijens, Sjoerd / Voigt, Jens-Uwe / D'hooge, Jan

    Ultrasound in medicine & biology

    2022  Volume 48, Issue 11, Page(s) 2207–2216

    Abstract: Shear wave elastography (SWE) is a promising technique used to assess cardiac function through the evaluation of cardiac stiffness non-invasively. However, in the literature, SWE varies in terms of tissue motion data (displacement, velocity or ... ...

    Abstract Shear wave elastography (SWE) is a promising technique used to assess cardiac function through the evaluation of cardiac stiffness non-invasively. However, in the literature, SWE varies in terms of tissue motion data (displacement, velocity or acceleration); method used to characterize mechanical wave propagation (time domain [TD] vs. frequency domain [FD]); and the metric reported (wave speed [WS], shear or Young's modulus). This variety of reported methodologies complicates comparison of reported findings and sheds doubt on which methodology better approximates the true myocardial properties. We therefore conducted a simulation study to investigate the accuracy of various SWE data analysis approaches while varying cardiac geometry and stiffness. Lower WS values were obtained by the TD method compared with the FD method. Acceleration-based WS estimates in the TD were systematically larger than those based on velocity (∼10% difference). These observations were confirmed by TD analysis of 32 in vivo SWE mechanical wave measurements. In vivo data quality is typically too low for accurate FD analysis. Therefore, our study suggests using acceleration-based TD analysis for in vivo SWE to minimize underestimation of the true WS and, thus, to maximize the sensitivity of SWE to detect stiffness changes resulting from pathology.
    MeSH term(s) Acceleration ; Elastic Modulus ; Elasticity Imaging Techniques/methods ; Heart/diagnostic imaging ; Motion
    Language English
    Publishing date 2022-08-11
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 186150-5
    ISSN 1879-291X ; 0301-5629
    ISSN (online) 1879-291X
    ISSN 0301-5629
    DOI 10.1016/j.ultrasmedbio.2022.06.003
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: High-Frame-Rate Speckle Tracking for Echocardiographic Stress Testing.

    Orlowska, Marta / Bézy, Stéphanie / Ramalli, Alessandro / Voigt, Jens-Uwe / D'hooge, Jan

    Ultrasound in medicine & biology

    2022  Volume 48, Issue 8, Page(s) 1644–1651

    Abstract: Stress echocardiography helps to diagnose cardiac diseases that cannot easily be detected or do not even manifest at rest. In clinical practice, assessment of the stress test is usually performed visually and, therefore, in a qualitative and subjective ... ...

    Abstract Stress echocardiography helps to diagnose cardiac diseases that cannot easily be detected or do not even manifest at rest. In clinical practice, assessment of the stress test is usually performed visually and, therefore, in a qualitative and subjective way. Although speckle tracking echocardiography (STE) has been proposed for the quantification of function during stress, its time resolution is inadequate at high heart rates. Recently, high-frame-rate (HFR) imaging approaches have been proposed together with dedicated STE algorithms capable of handling small interframe displacements. The aim of this study was to determine if HFR STE is effective in assessing strain and strain rate parameters during echocardiographic stress testing. Specifically, stress echocardiography, at four different workload intensities, was performed in 25 healthy volunteers. At each stress level, HFR images from the apical four-chamber view were recorded using the ULA-OP 256 experimental scanner. Then, the myocardium was tracked with HFR STE, and strain and strain rate biomarkers were extracted to further analyze systolic and diastolic (early and late) peaks, as well as a short-lived isovolumic relaxation peak during stress testing. The global systolic strain response was monophasic, revealing a significant (p < 0.001) increase at low stress but then reaching a plateau. In contrast, all strain rate indices linearly increased (p < 0.001) with increasing stress level. These findings are in line with those reported using tissue Doppler imaging and, thus, indicate that HFR STE can be a useful tool in assessing cardiac function during stress echocardiography.
    MeSH term(s) Diastole ; Echocardiography/methods ; Exercise Test ; Heart Rate/physiology ; Heart Ventricles/diagnostic imaging ; Humans ; Reproducibility of Results ; Systole/physiology
    Language English
    Publishing date 2022-05-28
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 186150-5
    ISSN 1879-291X ; 0301-5629
    ISSN (online) 1879-291X
    ISSN 0301-5629
    DOI 10.1016/j.ultrasmedbio.2022.04.009
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  9. Article ; Online: Use of 3D anatomical models in mock circulatory loops for cardiac medical device testing.

    Rocchi, Maria / Ingram, Marcus / Claus, Piet / D'hooge, Jan / Meyns, Bart / Fresiello, Libera

    Artificial organs

    2022  Volume 47, Issue 2, Page(s) 260–272

    Abstract: Introduction: Mock circulatory loops (MCLs) are mechanical representations of the cardiovascular system largely used to test the hemodynamic performance of cardiovascular medical devices (MD). Thanks to 3 dimensional (3D) printing technologies, MCLs can ...

    Abstract Introduction: Mock circulatory loops (MCLs) are mechanical representations of the cardiovascular system largely used to test the hemodynamic performance of cardiovascular medical devices (MD). Thanks to 3 dimensional (3D) printing technologies, MCLs can nowadays also incorporate anatomical models so to offer enhanced testing capabilities. The aim of this review is to provide an overview on MCLs and to discuss the recent developments of 3D anatomical models for cardiovascular MD testing.
    Methods: The review first analyses the different techniques to develop 3D anatomical models, in both rigid and compliant materials. In the second section, the state of the art of MCLs with 3D models is discussed, along with the testing of different MDs: implantable blood pumps, heart valves, and imaging techniques. For each class of MD, the MCL is analyzed in terms of: the cardiovascular model embedded, the 3D model implemented (the anatomy represented, the material used, and the activation method), and the testing applications.
    Discussions and conclusions: MCLs serve the purpose of testing cardiovascular MDs in different (patho-)physiological scenarios. The addition of 3D anatomical models enables more realistic connections of the MD with the implantation site and enhances the testing capabilities of the MCL. Current attempts focus on the development of personalized MCLs to test MDs in patient-specific hemodynamic and anatomical scenarios. The main limitation of MCLs is the impossibility to assess the impact of a MD in the long-term and at a biological level, for which animal experiments are still needed.
    MeSH term(s) Heart Valves ; Hemodynamics ; Printing, Three-Dimensional ; Lung ; Models, Anatomic ; Models, Cardiovascular
    Language English
    Publishing date 2022-11-12
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 441812-8
    ISSN 1525-1594 ; 0160-564X
    ISSN (online) 1525-1594
    ISSN 0160-564X
    DOI 10.1111/aor.14433
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  10. Article ; Online: Solvent electrospinning amorphous solid dispersions with high itraconazole, celecoxib, mebendazole and fenofibrate drug loading and release potential.

    Becelaere, Jana / Frateur, Olmo / Schoolaert, Ella / Vanhoorne, Valérie / D'hooge, Dagmar R / Vervaet, Chris / Hoogenboom, Richard / De Clerck, Karen

    Journal of controlled release : official journal of the Controlled Release Society

    2023  Volume 362, Page(s) 268–277

    Abstract: In this work, the feasibility of ultra-high drug loaded amorphous solid dispersions (ASDs) for the poorly soluble itraconazole, mebendazole and celecoxib via solvent electrospinning in combination with poly(2-ethyl-2-oxazoline) and fenofibrate in ... ...

    Abstract In this work, the feasibility of ultra-high drug loaded amorphous solid dispersions (ASDs) for the poorly soluble itraconazole, mebendazole and celecoxib via solvent electrospinning in combination with poly(2-ethyl-2-oxazoline) and fenofibrate in combination with polyvinylpyrrolidone is demonstrated. By lowering the polymer concentration in the electrospinning solution below its individual spinnable limit, ASDs with a drug content of up to 80 wt% are obtained. This is attributed to drug-polymer interactions not being limited by default to hydrogen bonds, as also Van der Waals interactions can result in high drug loadings. The theoretically predicted miscibility by the Flory-Huggins theory is corroborated by the experimental findings based on (modulated) differential scanning calorimetry and x-ray diffraction. Globally, the maximally obtained amorphous drug loadings are higher compared to the loadings found in literature. Additionally, non-sink dissolution tests demonstrate an increase in solubility of up to 50 times compared to their crystalline counterparts. Moreover, due to the lack of precipitation biocompatible PEtOx succeeds in stabilizing the dissolved drug and inhibiting its instant precipitation. The current work thus demonstrates the broader applicability of the electrospinning technique for the production of physically stable ASDs with ultra-high drug loadings, a result which has been validated for several Biopharmaceutics Classification System class II drugs.
    Language English
    Publishing date 2023-09-01
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 632533-6
    ISSN 1873-4995 ; 0168-3659
    ISSN (online) 1873-4995
    ISSN 0168-3659
    DOI 10.1016/j.jconrel.2023.08.054
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