6,804 research outputs found
Technical quality
No full textClose attention to technical quality or image optimization in transthoracic\ud
echocardiography (TTE) is important for the acquisition of\ud
high-quality diagnostic images and to ensure that measurements are\ud
accurately performed. For this purpose, the echocardiographer\ud
must be familiar with all the controls on the ultrasound machine\ud
that can be manipulated to optimize the two-dimensional (2D)\ud
images, color Doppler images, and spectral Doppler traces..
Objective selection of short-axis slices for automated quantification of left ventricular size and function by cardiovascular magnetic resonance
No full textBackground: Quantification of left ventricular (LV) volume from cardiovascular magnetic resonance images relies on subjective and often challenging selection of short-axis (SAX) slices. We hypothesized that this could be solved by defining mitral annular (MA) plane and apex in long-axis (LAX) views, which could be combined with automated LV volume analysis that does not rely on manual tracing of the endocardial border. Methods: SAX images from 50 subjects were analyzed using custom software. LV apex and insertion points of the mitral leaflets were marked on LAX views and used to approximate MA plane. End-systolic and end-diastolic LV volumes (ESV, EDV) were measured while including only slices or their parts located between MA plane and LV apex. Endocardial borders were automatically detected using our previously validated algorithm and also manually traced to obtain reference values. Results: Selection of anatomic landmarks in LAX views allowed automated measurement of LV volumes without the need for subjective slice selection. Intertechnique comparisons resulted in high correlations (EDV: r. = 0.95; ESV: r. = 0.96) and small biases (1 and 9 ml). Combined three-dimensional displays of LAX and SAX views with the MA plane showed that in 7/10 worst cases, intertechnique discordance was due to incorrect manual tracing at LV base that erroneously included part of atrial cavity in LV volume or excluded part of LV cavity, i.e., incorrect reference values. Conclusion: Defining the MA plane and apex in the LAX views obviates the need for subjective slice selection and eliminates errors in LV volume measurements
Newer Methods to Assess Diastolic Function
No full textEchocardiographic assessment of LV diastolic function and LV filling pressures currently requires a multi-variable approach and current ASE/EACVI guideline document has recommended use of decision trees for aggregating the cluster of echocardiographic variables that are associated with a given severity of diastolic dysfunction1,2. Such algorithmic approach may not always be reproducible or accurate3, and therefore search for newer variables has continued. This chapter reviews the newer variables in myocardial muscle mechanics and fluid mechanics that may have potential role in the assessment of diastolic dysfunction
Measuring and analyzing German and Spanish customer satisfaction of using the iPhone 4S Mobile Cloud service
No full textThis paper presents the customer satisfaction analysis for measuring popularity in the Mobile Cloud, which is an emerging area in the Cloud and Big Data Computing. Organizational Sustainability Modeling (OSM) is the proposed method used in this research. The twelve-month of German and Spanish consumer data are used for the analysis to investigate the return and risk status associated with the ratings of customer satisfaction in the iPhone 4S Mobile Cloud services. Results show that there is a decline in the satisfaction ratings in Germany and Spain due to economic downturn and competitions in the market, which support our hypothesis. Key outputs have been explained and they confirm that all analysis and interpretations fulfill the criteria for OSM. The use of statistical and visualization method proposed by OSM can expose unexploited data and allows the stakeholders to understand the status of return and risk of their Cloud strategies easier than the use of other data analysis
Morphologic Analysis of the Normal Right Ventricle Using Three-Dimensional Echocardiography-Derived Curvature Indices
No full textBACKGROUND: Right ventricular (RV) remodeling involves changes in size, wall thickness, function, and shape. Previous studies have suggested that regional curvature indices (rCI) may be useful for RV shape analysis. The aim of this study was to establish normal three-dimensional echocardiographic values of rCI in a large group of healthy subjects to facilitate future three-dimensional echocardiographic study of adverse RV remodeling.
METHODS: RV endocardial surfaces were reconstructed at end-diastole and end-systole in 245 healthy subjects (mean age, 42 ± 12 years) and analyzed using custom software to calculate mean curvature in six regions: RV inflow tract (RVIT) and RV outflow tract, apex, and body (both divided into free wall and septal regions). Associations with age and gender were studied.
RESULTS: The apical free wall was convex, while the septum (apex and body) was more concave than the body free wall. Septal curvature did not change significantly from end-diastole to end-systole. The RV outflow tract and RVIT became flatter from end-diastole to end-systole. In keeping with the "bellows-like" action of RV contraction, the body free wall became flatter, while the apex free wall changed to a more convex surface. There were no intergender differences in rCI. In older subjects (≥55 years of age), the RV free wall and RV outflow tract were flatter, and from end-diastole to end-systole, the RVIT became less flattened and the apex less pointed. These changes suggest that the right ventricle is stiffer in older subjects, with less dynamic contraction of the RVIT and less bellows-like movement.
CONCLUSIONS: This study established normal three-dimensional echocardiographic values for RV rCI, which are needed to further study RV diastolic dysfunction and remodeling with disease
DYNAMIC RIGHT VENTRICULAR SHAPE ANALYSIS IN THE NORMAL HEART USING 3D ECHOCARDIOGRAPHY-DERIVED CURVATURE INDICES
No full textFeasibility of automated frame-by-frame myocardial segmentation as a basis for quantification of first-pass perfusion images
No full textA Semi-Automated Approach for the quantification of the left ventricle chamber volumes from Cine Magnetic Resonance Images
No full textCardiac magnetic resonance imaging is the golden standard for the quantification of left ventricular function. However manual segmentation of the endocardium and epicardium boundaries has proven to be a time-consuming task, and the tools used in in clinical practice depend on the cardiologist's experience to assess the mitral valve plane, identifying papillary muscles and trabeculations. The goal of this work was to develop a new algorithm for the segmentation of the endocardium and epicardium of the left ventricle. To this end both a probabilistic and a Malladi-Sethian level-set models were used, followed by morphological operators and curvature flow to regularize the surfaces and exclude unconnected regions. The proposed algorithm and the ensuing workflow were applied to cine magnetic resonance data in 12 patients. Linear regression and Bland-Altman analysis for end-diastolic, end-systolic volumes and ejection fraction were performed, and clinical indexes derived from the surfaces were in good agreement with the ones obtained by manual tracings. This work provides the basis for faster and still accurate quantification of the cardiac function from cardiac magnetic resonance, and the basis for further processing aimed at the assessment of heart remodeling and diseases
Studio e sviluppo di tecniche automatiche per la valutazione di massa e volumi del ventricolo sinistro in risonanza magnetica cardiaca
No full textLa risonanza magnetica cardiaca è una tecnica di imaging non invasiva, in quanto non necessita l’uso di radiazioni ionizzanti, caratterizzata da un’elevata risoluzione spaziale e che permette acquisizioni in 4-D senza vincoli di orientazione. Grazie a queste peculiarità, la metodica della risonanza magnetica ha mostrato la sua superiorità nei confronti delle altre tecniche diagnostiche ed è riconosciuta come il gold standard per lo studio della fisiologia e fisiopatologia della pompa cardiaca. Nonostante la potenza di questi vantaggi, esistono ancora varie problematiche che, se superate, potrebbero probabilmente migliorare ulteriormente la qualità delle indagini diagnostiche. I software attualmente utilizzati nella pratica clinica per le misure del volume e della massa ventricolare richiedono un tracciamento manuale dei contorni dell’endocardio e dell’epicardio per ciascuna fetta, per ogni frame temporale del ciclo cardiaco. Analogamente avviene per il tracciamento dei contorni del tessuto non vitale. In questo modo l’analisi è spesso qualitativa. Di fatti, la necessità dell’intervento attivo dell’operatore rende questa procedura soggettiva e dipendente dall’esperienza, provocando un’elevata variabilità e difficile ripetibilità delle misure intra e inter operatore, oltre ad essere estremamente dispendiosa in termini di tempo, a causa dell’elevato numero di immagini da analizzare. La disponibilità di una tecnica affidabile per il tracciamento automatico dei contorni dell’endocardio e dell’epicardio consente di superare queste limitazioni ed aumentare l’accuratezza e la ripetibilità delle misure di interesse clinico, quali dimensione, massa e curve di volume ventricolari.
Lo scopo di questa tesi è di sviluppare e validare una tecnica di segmentazione automatica che consenta l’identificazione e la quantificazione di cicatrici nel miocardio, a seguito di infarto cardiaco. Il lavoro è composto da due tappe principali. Inizialmente, è presentato un metodo innovativo che permette, in via totalmente automatica, di tracciare in modo accurato e rapido i contorni dell’endocardio e dell’epicardio nel corso dell’intero ciclo cardiaco. Successivamente, l’informazione sulla morfologia cardiaca ricavata nella prima fase è utilizzata per circoscrivere il miocardio e quantificare la transmuralità dell’infarto presente in pazienti ischemici
- …
