Stian Langeland

Learn More
BACKGROUND Strain and strain rate have been proposed as tools to quantify regional myocardial function. One of the major pitfalls of the current methodology is its angle dependency. To overcome this problem, we have developed a new method for the estimation of strain, independent of angle. The aim of this study was to validate this new methodology in an(More)
Speckle tracking in 2-D ultrasound images has become an established tool for assessment of left ventricular function. The recent development of ultrasound systems with capability to acquire real-time full volume data of the left ventricle makes it possible to perform speckle tracking in three dimensions, and thereby track the real motion of the myocardium.(More)
One-dimensional strain imaging has been shown to be angle dependent. To address this problem, a new methodology, 2D-strain, has become available. The aim of this study was to validate this methodology in an in vivo set-up against sonomicrometry. In five open chest sheep, ultrasound gray-scale images were acquired of the inferolateral wall from two different(More)
Techniques have been described in the literature to enable multidimensional strain rate estimation. They are based on multidimensional velocity estimation. One of the problems in obtaining robust lateral strain rate estimates is the fact that lateral velocity estimates are intrinsically noisier than axial ones. The aim of this study was to find the optimal(More)
Strain and strain rate imaging have been shown to be useful techniques for the assessment of cardiac function. However, one of the major problems of these techniques is their angle dependency. In order to overcome this problem, a new method for estimating the strain (rate) tensor had previously been proposed by our lab. The aim of this study was to validate(More)
In this paper, we extend a computationally efficient framework for tracking of deformable subdivision surfaces in 3D echocardiography with speckle-tracking measurements to track material points. Tracking is performed in a sequential stateestimation fashion, using an extended Kalman filter to update a subdivision surface in a two-step process: Edge-detection(More)
Most available ultrasound imaging simulation methods are based on the spatial impulse response approach. The execution speed of such a simulation is of the order of days for one heart-sized frame using desktop computers. For some applications, the accuracy of such rigorous simulation approaches is not necessary. This work outlines a much faster 3-D(More)
In this paper, we extend a computationally efficient framework for real-time tracking of deformable subdivision surfaces in 3D echocardiography with speckle-tracking measurements to track material points. Tracking is performed in a sequential state-estimation fashion, using an extended Kalman filter to update the subdivision surface based on displacement(More)
Myocardial strain quantification in the mouse based on 2-D speckle tracking using real-time ultrasound datasets is feasible but remains challenging. The major difficulty lies in the fact that the frame rate-to-heart rate ratio is relatively low, causing significant decorrelation between subsequent frames. In this setting, regularization is therefore(More)
UNLABELLED Active stress (sigmaA) developed by cardiac muscle has been measured in isolated muscle preparations, under physiological loading conditions, by subtracting the passive stress (sigmaP) from the total stress (sigmaT). We previously developed a mechanical model based on M-mode ultrasound imaging to calculate these stresses in beating hearts.(More)