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Tomas Gustavsson - IEEE Xplore Author Profile

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A computer aided diagnosis (CADx) system for oral mucosal lesions has been developed using clinical cases from India as training examples. The investigated classifiers were support vector machine (SVM) and Bayes point machine (BPM), and the task was to discriminate potentially precancerous lesions from non-precancerous lesions. The discriminating features consisted of color differences and lesions...Show More
Dynamic programming has previously been used when measuring Lumen Diameter (LD) and Intima-Media Thickness (IMT) in single frame ultrasound carotid artery images [1]. An extension to multiframe detection of that procedure is proposed in this paper. Our new method transforms a three dimensional problem into multiple two dimensional problems that can again be solved by dynamic programming. First, se...Show More
This paper describes a system for in vitro cell migration analysis. Adult neural stem/progenitor cells are studied using time-lapse microscopy and thereafter stained immunohistochemically to find and distinguish between undifferentiated glial progenitor cells and cells having differentiated into type-1 or type-2 astrocytes. The cells are automatically segmented and tracked throughout the time-laps...Show More
We investigate support vector machines (SVM) in the context of oral lesion classification using digital color images as input. Two common lesions of similar visual appearance to the human observer were evaluated: oral leukoplakia, which is a potentially pre-cancerous lesion, and oral lichenoid reactions (with subclasses of atrophic, plaqueformed and reticular reactions), which are usually harmless...Show More
This paper treats the problem of tracking contours of flames captured by PLIF imaging using geodesic paths and level sets. Successive images of the combustion process captured in controlled experiments are smoothed by nonlinear diffusion filtering then active contour models are used to obtain the curves that most accurately describe the frame boundary. These curves are matched using the concept of...
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Material samples of silicone rubber with known differences in their composition, i.e. different filler content and extra silicone oil added, have been aged at the Anneberg field station on the west coast of Sweden. ac or dc voltage supplied to cylindrical samples at stress levels of 50 or 100 V/mm. The work includes laboratory examination of material changes together with on-site, visual observati...Show More
By measuring the currents associated with the streamer discharge along silicone rubber surfaces, parameters of streamer propagation such as the minimum field of streamer crossing, the field of stable streamer propagation, the mean velocity and the streamer charge distribution have been analyzed and compared to the streamer discharge in air alone. Clear differences were observed in the measured cur...Show More
Ultrasonic measurements of human carotid and femoral artery walls are conventionally obtained by manually tracing interfaces between tissue layers. The drawbacks of this method are the interobserver variability and inefficiency. Here, the authors present a new automated method which reduces these problems. By applying a multiscale dynamic programming (DP) algorithm, approximate vessel wall positio...Show More
This paper presents the application of active contour models (Snakes) for the segmentation of oral lesions in medical color images acquired from the visual part of the light spectrum. The aim is to assist the clinical expert in locating potentially cancerous cases for further analysis (e.g. classification of cancerous vs. non-cancerous lesions). In order to apply the conventional Snake formulation...Show More
The authors present a method for constraining the deformations of Snakes (active contour models) when segmenting a known class of objects. The method we propose is similar to both active shape models (ASM) but without the landmark identification and correspondence requirement, and to active contour models (ACM), but armed with a priori information about shape variation. Rather than representing th...Show More
The authors propose a method for segmenting the human left ventricle (LV) in ultrasonic images, which is based on principles from both Active Shape Models (ASM) and Active Contour Models (ACM). Principal Component Analysis (PCA) is applied to a frequency-based shape representation of the LV thus eliminating the need for the difficult determination of corresponding landmarks. The average ventricula...Show More
Contrast-echocardiography in conjunction with real-time video-densiometry can be an effective means of studying right ventricular (RV) structural changes, e.g. in patients diagnosed with arrhythmogenic right ventricular dysplasia (ARVD). In order to characterize RV flow pattern it may be necessary to track the front of the contrast agent as it enters the RV. The active contour model (ACM) is a sta...Show More
Silicone rubber samples of 4 material compositions have been energized with AC and DC voltages in a coastal outdoor environment. During the test, leakage current measurements together with visual inspections were used to monitor their performance. The samples were selected according to a 2/sup 3/ factorial test plan, where electrical stress, content of ATH-filler and content of silicone oil were t...Show More
Isointensity directional smoothing is a novel edge-preserving smoothing method. By fitting a polynomial hypersurface to the local intensity, isointensity bands (isobands) are derived which approximately parallel an edge when the centre pixel is close to the edge. Pixels in the isoband passing through the centre are assigned higher weights, while those in other isobands are assigned lower weights a...Show More
This paper deals with the influence of water immersion on the hydrophobicity loss process of different silicone rubbers. The advancing and receding angles (AA and RA) of thin rubber plates were measured. The presented results show that water immersion had only a small effect on the wettability (AA) of the silicone rubbers, but dramatically increased their surface retention properties (RA). In some...Show More
Available techniques for diagnosis and evaluation of right ventricular (RV) function are limited. In patients with arrhythmogenic right ventricular dysplasia (ARVD) it is of great importance to assess RV wall motion and function for diagnosis, prognosis and treatment. Contrast echocardiography and videodensitometry can be used to illustrate regional and global RV hemodynamics. The authors investig...Show More
In this paper we examine four algorithms for automated ultrasonic boundary detection, and describe the application of these algorithms to the quantification of the intima-media thickness (IMT) in the human carotid artery. The first algorithm uses a dynamic programming approach to identify the boundary that minimizes a certain cost function. The second algorithm is based on finding points of maximu...Show More
Describes a technique for studying global and regional motion patterns of the right ventricle (RV) using contrast echocardiography in conjunction with videodensitometric measurements. Two ml of echo-contrast (Haemaccel, Behring/Hoechst) was injected as a bolus into a brachial vein. An image sequence visualizing the RV echocontrast filling and elimination was analysed in real-time. The mean image i...Show More
Describes an automated procedure for boundary detection and 3D reconstruction in echocardiography. Boundary detection is carried out by a combination of knowledge based and dynamic programming procedures. The knowledge based procedure includes a mechanism which controls and evaluates a set of image analysis procedures. The dynamic programming procedure is based on the minimization of a cost functi...Show More
Describes a computerized technique for automated ultrasonic measurements of the carotid artery based on dynamic programming. Local measurements vessel echo intensity, edge strength, and continuity were extracted by image analysis techniques and included as weighted terms in a cost function. The dynamic programming procedure was used for determining the locations of the vessel interfaces in a way t...Show More