980 research outputs found

    A Deep Learning-Based Fully Automated Pipeline for Regurgitant Mitral Valve Anatomy Analysis From 3D Echocardiography

    Get PDF
    Three-dimensional transesophageal echocardiography (3DTEE) is the recommended imaging technique for the assessment of mitral valve (MV) morphology and lesions in case of mitral regurgitation (MR) requiring surgical or transcatheter repair. Such assessment is key to thorough intervention planning and to intraprocedural guidance. However, it requires segmentation from 3DTEE images, which is timeconsuming, operator-dependent, and often merely qualitative. In the present work, a novel workflow to quantify the patient-specific MV geometry from 3DTEE is proposed. The developed approach relies on a 3D multi-decoder residual convolutional neural network (CNN) with a U-Net architecture for multi-class segmentation of MV annulus and leaflets. The CNN was trained and tested on a dataset comprising 55 3DTEE examinations of MR-affected patients. After training, the CNN is embedded into a fully automatic, and hence fully repeatable, pipeline that refines the predicted segmentation, detects MV anatomical landmarks and quantifies MV morphology. The trained 3D CNN achieves an average Dice score of 0.82 +/- 0.06, mean surface distance of 0.43 +/- 0.14 mm and 95% Hausdorff Distance (HD) of 3.57 +/- 1.56 mm before segmentation refinement, outperforming a state-of-the-art baseline residual U-Net architecture, and provides an unprecedented multi-class segmentation of the annulus, anterior and posterior leaflet. The automatic 3D linear morphological measurements of the annulus and leaflets, specifically diameters and lengths, exhibit differences of less than 1.45 mm when compared to ground truth values. These measurements also demonstrate strong overall agreement with analyses conducted by semi-automated commercial software. The whole process requires minimal user interaction and requires approximately 15 seconds

    Funktionelle Herzklappen-Stent Designs für zukünftige autologe, transkatheter Klappenprothesen in pulmonaler Position

    Get PDF
    Background Transcatheter pulmonary valve replacement (TPVR) has asserted its position as a cornerstone in cardiology and become a nonsurgical alternative for patients with a dysfunctional right ventricular outflow tract (RVOT), demonstrating excellent early and late clinical outcomes. Short- and long-term complications of TPVR include stent fracture and migration, coronary compression, and valve regurgitation. Objective The purpose of this study is to describe methodology for developing Nitinol stents by conducting a computational design and finite element analysis in conjunction with 3D reconstruction of animal cardiac CT for TPVR. Methods 3D cardiac CT reconstruction was achieved using 3D Slicer, from which the RVOT + pulmonary artery (PA) was exported for blood flow simulation and hoop force acquisition with the stents. Functional stents were designed using Autodesk Fusion 360 and divided into three morphological geometries: group 1–straight tubular stents, group 2–corollaceous stents, and group 3–corollaceous stents with an elliptic geometry. Stent simulations for stent life and radial force, and the hoop force of the stent during expansion with the RVOT+PA model were obtained in Ansys. The blood flow simulation of RVOT+PA was performed using Ansys with the velocity-based coupled solver. Results 3D cardiac CT reconstructions were obtained in STL format, from which the right ventricle (RV) +PA model was performed for the blood flow simulation and the hoop force was obtained with the stents. Twelve functional stents were successfully designed and exported in SAT and STP formats for simulation. All stent life (Times)/radial force (N) were achieved: Group 1 comprised the stents DGS 3 (3219.2/1.88E+05), DGS 5 (16406/1.94E+05), DGS 7 (1.00E+06/1.89E+05), DGS 8B (0/3.74E+05), DGS-10B (8370.1/2.41E+05), DGS 12D (1.00E+06/2.41E+08); Group 2 comprised the stents DGS 8A (0/3.60E+05), DGS 9A (0/3.60E+05), DGS 10A (46093/2.28E+05), DGS 12C (2.50E+005/1.69E+05); Group 3 comprised the stents DGS 12A (1.00E+06/2.38E+08), DGS 12B (54509/2.20E+05). Hoop force (N) was obtained from the 12 stents: Group 1–DGS 5 (57802), DGS 7 (54647), DGS 8B (53248), DGS 10B (56650), DGS 12D (46297). Group 2–DGS 8A (50490), DGS 9A (60393), DGS 10A (23639), DGS 12C (29802). Group 3–DGS 12A (16368), DGS 12B (16368). The RV+PA blood flow simulation demonstrated that the anterior part of the PA wall had the largest shear force. Conclusions DGS 12C, DGS 12D, DGS 10A, DGS 10B, DGS 7, and DGS 5 can be subsequently tested in vitro. Autologous pulmonary valves could be sutured onto the functional stents to maintain their original geometry prior to implantation. Pre-implantation 3D CT reconstruction and stent simulation can be performed for better evaluation and visualization. The RV+PA blood flow simulation may serve as a significant input for the design of stents and pulmonary valve to determine the shear force throughout the cardiac cycle.Hintergrund Der katheterbasierte Pulmonalklappenersatz ist ein Eckpfeiler der Kardiologie und bietet zudem eine nicht-chirurgische Alternative für die Behandlung funktionsgestörter rechtsventrikulärer Ausflusstrakte oder bioprothetischer Klappen mit hervorragenden frühen und späten klinischen Ergebnissen. Kurz- und langfristige Komplikationen von TPVR umfassen Stentfraktur/-migration, Komprimierung der Koronararterien und Klappeninsuffizienz. Ziel Ziel dieser Studie ist es, die Methodik und das Konzept für Nitinol-Stents mithilfe rechnerischer Entwürfe und Finite-Elemente-Analysen anhand von 3D-Rekonstruktionen kardialer CT-Untersuchungen in Tieren für die Anwendung von TPVR zu beschreiben. Methoden Die 3D-Rekonstruktion der CT-Untersuchungen erfolgte mit der Software 3D Slicer, aus der die RVOT und Pulmonalarterie (PA) in Verbindung mit den Stents für die Blutflusssimulation und die Umfangsspannung exportiert wurde. Die funktionellen Stents wurden mit Fusion 360 entworfen und danach in die Formate SAT und STP exportiert. Simulationen für die Lebensdauer und Radialkraft sowie für die Umfangsspannung der Stents bei der Freisetzung mit dem RVOT+PA-Modell wurden in Ansys berechnet. Die Blutflusssimulation von RVOT+PA wurde in Ansys mit dem geschwindigkeitsbasierten gekoppelten Solver durchgeführt. Ergebnisse Zwölf funktionelle Stents wurden mithilfe von Fusion 360 generiert. SAT- und STP-Dateien wurden zur Simulation in Ansys exportiert. 3D Kardio-CT-Rekonstruktionen wurden mithilfe im STL-Format kreiert, aus dem das RVOT+PA-Modell des Prä-CT ausgewählt wurde, um die Blutflusssimulation durchzuführen und die Ringkraft der Stents zu erhalten. Die Lebensdauer (Anzahl) und Radialkraft (N) der Stents wurden wie folgt berechnet: DGS-3 (3219.2/1.88E+05), DGS-5 (16406/1.94E+05), DGS-7 (1.00E+06/1.89E+05), DGS-8A (0/3.60E+05), DGS-8B (0/3.74E+05), DGS-9A (0/3.60E+05), DGS-10A (46093/2.28E+05), DGS-10B (8370.1/2.41E+05), DGS-12A (1.00E+06/2.38E+08), DGS-12B (54509/2.20E+05), DGS-12D (1.00E+06/2.41E+08), DGS-12C (2.50E+005/1.69E+05). Die jeweilige Umspannungskraft (N) wurde wie folgt berechnet: DGS-5 (57802), DGS-7 (54647), DGS-8A (50490), DGS-8B (53248), DGS-9A (60393), DGS-10A (23639), DGS-10B (56650), DGS-12A (16368), DGS-12B (16368), DGS-12C (29802), DGS-12D (46297). Die RV+PA-Blutflusssimulation zeigte, dass der vordere Teil der PA-Wand die größte Scherkraft aufwies. Schlussfolgerungen DGS-12C, DGS-12D, DGS-10A, DGS-10B, DGS-7 und DGS-5 können nachfolgend in vitro getestet werden. Autologe Pulmonalklappen können zur Erhaltung der ursprünglichen Geometrie vor der Implantation auf funktionelle Stents aufgenäht werden. Vor der Implantation können Kardio-CT 3D-Rekonstruktion und Stentsimulationen zur besseren Bewertung und Visualisierung durchgeführt werden. Die Blutflusssimulation von RVOT+PA kann einen bedeutsamen Beitrag zur Gestaltung von Stents und Pulmonalklappen leisten, um die Scherkraft während des gesamten Herzzyklus zu erhalten

    Characterisation and State Estimation of Magnetic Soft Continuum Robots

    Get PDF
    Minimally invasive surgery has become more popular as it leads to less bleeding, scarring, pain, and shorter recovery time. However, this has come with counter-intuitive devices and steep surgeon learning curves. Magnetically actuated Soft Continuum Robots (SCR) have the potential to replace these devices, providing high dexterity together with the ability to conform to complex environments and safe human interactions without the cognitive burden for the clinician. Despite considerable progress in the past decade in their development, several challenges still plague SCR hindering their full realisation. This thesis aims at improving magnetically actuated SCR by addressing some of these challenges, such as material characterisation and modelling, and sensing feedback and localisation. Material characterisation for SCR is essential for understanding their behaviour and designing effective modelling and simulation strategies. In this work, the material properties of commonly employed materials in magnetically actuated SCR, such as elastic modulus, hyper-elastic model parameters, and magnetic moment were determined. Additionally, the effect these parameters have on modelling and simulating these devices was investigated. Due to the nature of magnetic actuation, localisation is of utmost importance to ensure accurate control and delivery of functionality. As such, two localisation strategies for magnetically actuated SCR were developed, one capable of estimating the full 6 degrees of freedom (DOFs) pose without any prior pose information, and another capable of accurately tracking the full 6-DOFs in real-time with positional errors lower than 4~mm. These will contribute to the development of autonomous navigation and closed-loop control of magnetically actuated SCR

    4D FLOW CMR in congenital heart disease

    Get PDF
    This thesis showed that the use of a cloud-based reconstruction applicationwith advanced eddy currents correction, integrated with interactiveimaging evaluation tools allowed for remote visualization and interpretationof 4D flow data and that was sufficient for gross visualizationof aortic valve regurgitation. Further, this thesis demonstrated that bulkflow and pulmonary regurgitation can be accurately quantified using 4Dflow imaging analyzed. Peak systolic velocity over the pulmonary valvemay be underestimated. However, the measurement of peak systolicvelocity can be optimized if measured at the level of highest velocity inthe pulmonary artery. Also correlated against invasive measurements (inan animal model), this thesis shows that aorta flow and pulmonary flowcan be accurately and simultaneously measured by 4D flow MRI.When applied in clinical practice, 4D flow has extra advantages, of beingable to visualize flow pattern, vorticity and to predict aortic growth. InASD patients it can measure shunt volume directly following the septumframe by frame. In Fontan patients in can visualize better than standardMRI the Fontan circuit and it can measure flow at multiple points alongthe Fontan circuit. We observed in our Fontan population that shunt lesionswere very common, most of the time via veno-venous collaterals.Further using advanced computations, we showed that WSS angle wasthe only independent predictor of aortic growth in BAV patients. We alsoshowed the feasibility of GLS analysis on 4D flow MRI and presented anintegrative approach in which flow and functional data are acquired inone sequence.From the technical point of view, 4D flow MRI has proved to complementthe traditional components of the standard cardiac MR exams, enablingin-depth insights into hemodynamics. At this moment it proved its addedvalue, but in most of the cases it is not able yet to replace the standardexam. This is still due to long scanning times and relatively longpost-processing times.<br/

    Stem Cells in Domestic Animals

    Get PDF
    Stem cells are an attractive tool for cell-based therapies in regenerative medicine, both for humans and animals. The research and review articles published in this first book of the Collection “Stem Cells in Domestic Animals: Applications in Health and Production” are excellent examples of the recent advances made in the field of stem/stromal cell research in veterinary medicine. In this field, sophisticated and new treatments are now required for improving patients’ quality of life; in livestock animals, the goal of regenerative medicine is to improve not only animal welfare but also the quality of production, aiming to preserve human health. The contributions collected in this book concern both laboratory research and clinical applications of mesenchymal stem/stromal cells. The increasing knowledge of cell-based therapies may constitute an opportunity for researchers, veterinary practitioners, and animal owners to contribute to animal and human health and well-being

    Measurement of left ventricular deformation using 3D echocardiography

    Get PDF
    Bakgrunn: 3D speckle tracking ekkokardiografi (STE) er en hjerteultralydmetode som gir mulighet for måling av deformasjonsparametere, som strain, rotasjon, tvist og torsjon. Den største begrensningen for 3D STE er lav tids- og romlig oppløsning. Økes den ene oppløsingen vil den andre bli redusert. I tillegg vil andre faktorer som antall flettede bilder, sektorstørrelse og dybde påvirke begge oppløsningene. Denne avhandlingen har hatt som mål å finne tilstander og opptaksinnstillinger for å optimalisere nøyaktigheten til 3D STE-parametere i et kontrollert miljø. Videre har det vært som mål å finne regional deformasjon fra 3D STE i en klinisk studie på pasienter med aortaklaffestenose (AS) ved bruk av optimaliserte innstillinger. Materiale og metode: Studie 1 og 2 utforsket nøyaktigheten til 3D STE ved bruk av et in vitro-oppsett med et fantom av venstre ventrikkel. Studie 1 sammenlignet 3D STE strain mot sonomikromertri som gullstandard i longitudinell, sirkumferensiell og radiell retning. Ved å bruke et annet fantom i studie 2 ble 3D STE tvist sammenlignet mot sonomikrometri tvist for å finne nøyaktigheten til 3D STE tvistmålinger. Studie 3 inkluderte 85 pasienter med variabel grad av AS i en tverrsnittstudie. 3D ekkokardiografi ble utført og 3D STE-parametere ble sammenlignet mellom grupper av pasienter med mild, moderat og alvorlig AS. Resultater: Studie 1 fant godt samsvar mellom 3D STE og sonomikrometri med optimalt volum rate på 36,6 volumer per sekund (VPS) ved bruk av 6 sammenflettede bilder. I studie 2 hadde 3D STE godt samsvar ved bruk av både 4 og 6 sammenflettede bilder med volum rater på henholdsvis 20,3 og 17,1 VPS. Studie 3 fant lavere global longitudinal strain i pasienter med alvorlig AS sammenlignet med mild AS. Basal og midtre longitudinal strain var også lavere i alvorlig sammenlignet med mild AS. Apikal-basal ratio var høyere for moderat i forhold til mild AS. Maks apikal-basal tvist var høyere hos pasienter med alvorlig sammenlignet med mild og moderat AS. Konklusjon: Måling av venstre ventrikkelfunksjon med 3D STE er mest nøyaktig med volum rater < 40 VPS. Høy romlig oppløsning virker å være mer viktig enn tidsoppløsning. Pasienter med alvorlig AS har lavere global, basal og midtre longitudinal strain enn pasienter med mild AS, ved bruk av 3D STE. De har også høyere tvist enn mild og moderat AS. Områder som involverer apeks, har høyere spredning av data og har antagelig lavere nøyaktighet ved bruk av 3D STE.Background: 3D speckle tracking echocardiography (STE) enables measurement of multiple parameters of deformation, such as strain, rotation, twist and torsion. The main limitation of 3D STE is low temporal and spatial resolution. Increasing resolution in time will decrease resolution in space, and vice versa. In addition, other factors such as number of stitched images, sector size and depth, influence the resolution. This thesis aimed to find conditions and acquisition settings to optimize accuracy for 3D STE parameters in a controlled in vitro environment. Secondly, it aimed to evaluate regional deformation by 3D STE in a clinical study on patients with aortic valve stenosis (AS) using optimized settings. Materials and methods: Study 1 and 2 explored the accuracy of 3D STE using an in vitro setup with a left ventricle (LV) phantom. Study 1 compared 3D STE strain to strain by sonomicrometry as the gold standard. Measurements were compared in both longitudinal, circumferential and radial direction. Using a different twisting phantom in study 2, 3D STE twist was compared to twist by sonomicrometry to evaluate the accuracy of 3D STE twist. Study 3 was a cross-sectional analysis of 85 patients with variable degree of AS in a cross-sectional study. 3D echocardiography was done, and 3D STE parameters were compared between groups of patients with mild, moderate and severe AS. Results: Study 1 found 3D STE strain to have good agreement with sonomicrometry. Optimal acquisition settings were found to be volume rate 36.6 volumes per second (VPS) obtained by 6 stitched images. Study 2 found 3D STE twist to have good agreement with sonomicrometry when using both 4 and 6 stitched images with volume rates 20.3 and 17.1 VPS, respectively. Study 3 found global longitudinal strain to be lower in patients with severe AS compared to those with mild AS. Basal and mid longitudinal strains were also lower in severe AS than in mild AS. Apical basal ratio was higher for moderate than mild AS. Peak apical-basal twist was higher in patients with severe AS than in those with mild and moderate AS. Conclusion: Assessment of LV function by 3D STE is most accurate at volume rates < 40 VPS. High spatial resolution seems to be more important than temporal resolution. Patients with severe AS have lower global, as well as lower regional basal and mid longitudinal strain compared to patients with mild AS, assessed with 3D STE. They also have higher twist than mild and moderate AS. Segments involving the apex have high dispersion and probably lower accuracy in 3D STE.Doktorgradsavhandlin

    Magnetic Resonance Imaging of the fetal cardiovascular system and congenital heart disease

    Get PDF
    An early diagnosis of congenital heart diseases (CHD) has important prognostic impact. Prenatal echocardiography is an indispensable part of prenatal screening in many countries. However, it might provide poor diagnostic quality in some cases. Complementary diagnostic methods for postnatal life are missing prenatally. This work aims to investigate the use of fetal cardiovascular magnetic resonance imaging (MRI) as an adjunct to fetal echocardiography. This manuscript is divided into the anatomical visualization of CHD and the quantification of the impact of fetal motion on cardiovascular flow-measurements. 101 singleton pregnant women carrying fetus with suspected CHD in fetal echocardiography were prospectively recruited for fetal cardiac MRI. In 85 participants 2D and 3D MRI data could be reconstructed successfully and compared to echocardiographic and postnatal data. Furthermore, 10 pregnant women from the first sub study and 10 adult volunteers were recruited. The impact of simulated fetal motion in the adult volunteers was investigated. The artifacts observed during this study were compared to the artefacts in fetal flow-measurements by a three-point scoring system. MRI reconstructions of vascular structures showed a good agreement with 2D-echocardiography, while 3D-MRI reconstructions were superior to 2D-MRI data regarding their quality and diagnostic accuracy. Additional anatomic structures were identified in 10 cases with MRI and could be confirmed postnatally. Flow-measurements corrupted by simulated fetal motion within the middle third of an acquisition showed significant errors in contrast to measurements under motion corruption during the first and last third of the acquisition. The velocity of motion did not have a major impact. A three-point scoring system could readily identify the amount and impact of fetal motion on the later acquisition. 3D fetal cardiac MRI is a reliable imaging method with potential complementary use to fetal echocardiography. Additionally, valid fetal cardiovascular flow-measurements under the face of fetal motion can be reliably identified at the point of their acquisition, already.Die frühe Diagnose angeborener Herzfehler hat eine prognostische Bedeutung. Eine pränatale Echokardiographie ist in vielen Ländern unverzichtbarer Standard pränataler Screening Untersuchungen. Dennoch müssen oft Abstriche bei der Bildqualität gemacht werden. Während postnatal ergänzende Bildgebungstechniken zur Verfügung stehen, fehlen diese Alternativen pränatal. Die vorliegende Arbeit soll die Möglichkeiten der fetalen kardiovaskulären Magnetresonanztomographie (MRT) als ergänzende Diagnostik zur fetalen Echokardiographie untersuchen. Die vorliegende Arbeit ist untergliedert in die anatomische Darstellung angeborener Herzfehler mittels der MRT und die Untersuchung des Einflusses fetaler Bewegung auf kardiovaskuläre Flussmessungen. 101 schwangere Teilnehmerinnen mit Feten mit dem V.a. einen angeborenen Herzfehler in der fetalen Echokardiographie wurden prospektiv für eine fetale Kardio-MRT rekrutiert. 2D und 3D Bilddatenrekonstruktionen von 85 Feten der Teilnehmerinnen konnten mit den echokardiographischen, sowie postnatalen Daten verglichen werden. Weiterhin wurden 10 erwachsene Proband*innen, sowie 10 schwangere Teilnehmerinnen aus der ersten Substudie rekrutiert. Einflüsse simulierter fetaler Bewegung in den erwachsenen Proband*innen wurden untersucht. Beobachtete Artefakte in den gewonnen Flussmessungen wurden mittels eines Bewertungssystems mit denen der fetalen Messungen verglichen. Vaskuläre Strukturen in MRT-Datensätzen zeigten eine gute Übereinstimmung mit Messungen in echokardiographischen 2D-Datensätzen, wobei 3D-MRT Datensätze hinsichtlich Qualität und diagnostischer Genauigkeit den 2D-MRT Daten überlegen waren. In 10 Fällen gelang die Darstellung zusätzlicher anatomischer Gegebenheiten in der MRT, welche postnatal bestätigt werden konnten. Flussmessungen, welche durch simulierte fetale Bewegung im mittleren Drittel einer Aufnahme verzerrt wurden, wiesen signifikante Fehler auf. Dies konnte bei Messungen unter dem Einfluss fetalen Bewegungen im ersten oder letzten Drittel der Aufnahme nicht beobachtet werden. Die Geschwindigkeit der Bewegungen spielte eine untergeordnete Rolle. Das Ausmaß fetaler Bewegung während einer Aufnahme, sowie ihr Einfluss auf die Flussmessungen kann mittels eines Drei-Punkte-Bewertungssystems zuverlässig identifiziert werden. Fetale Kardio-MRT bietet eine zuverlässige Möglichkeit mittels 3D-Darstellung der fetalen Gefäße die pränatale Echokardiographie als bildgebende Methode zu ergänzen. Zudem können valide Flussmessungen trotz Einfluss fetaler Bewegung zuverlässig zum Zeitpunkt der Aufnahme identifiziert werden

    Comparison of cardiac function between single left ventricle and tricuspid atresia: assessment using echocardiography combined with computational fluid dynamics

    Get PDF
    Patients with single left ventricle (SLV) and tricuspid atresia (TA) have impaired systolic and diastolic function. However, there are few comparative studies among patients with SLV, TA and children without heart disease. The current study includes 15 children in each group. The parameters measured by two-dimensional echocardiography, three-dimensional speckle tracking echocardiography (3DSTE), and vortexes calculated by computational fluid dynamics were compared among these three groups. Twist is best correlated with ejection fraction measured by 3DSTE. Twist, torsion, apical rotation, average radial strain, peak velocity of systolic wave in left lateral wall by tissue Doppler imaging (sL), and myocardial performance index are better in the TA group than those in the SLV group. sL by tissue Doppler imaging in the TA group are even higher than those in the Control group. In patients with SLV, blood flow spreads out in a fan-shaped manner and forms two small vortices. In the TA group, the main vortex is similar to the one in a normal LV chamber, but smaller. The vortex rings during diastolic phase are incomplete in the SLV and TA groups. In summary, patients with SLV or TA have impaired systolic and diastolic function. Patients with SLV had poorer cardiac function than those with TA due to less compensation and more disordered streamline. Twist may be good indicator for LV function
    corecore