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The original publication is available at www.springerlink.com
Breast cancer is one of the most prevalent forms of cancer in the world today. The search for effective treatment and screening methods is a highly active area of research. The Digital Image-based Elasto-Tomography (DIET) project is a new breast cancer screening system under development, where surface motion from the mechanically actuated breast is measured in 3D, and used as input to an inverse problem solving for breast elasticity. Cancerous lesions appear as high contrast features, being an order of magnitude stiffer than healthy tissue. The 3D motion capture is measured by an array of digital cameras using computer vision techniques. This paper presents a computer vision imaging system for the capture of 3D breast surface motion for the DIET system, including the image acquisition system, camera calibration, and 3D surface and moti...
A minimal model of the cardio-vascular system (CVS) with ventricular interaction and inertial effects that accurately captures the physiological trends of a variety of disease states has been developed. However, the physiologically accurate open on pressure, close on flow valve law is computationally heavy to implement, reducing the model's potential clinical benefit. A significantly simpler representation of the valve law using Heaviside functions is derived and the ventricular interaction equations are reformulated to obtain a unique closed form analytical solution. The new formulation is tested and compared with the previous formulation for a healthy human and four clinically significant disease states: mitral and aortic stenosis, pulmonary embolism and septic shock. The new model formulation matches the previous model definition, d...
This communication discusses the possibility of identifying the shear and structure relaxation functions in inorganic glass by means of a single, simple, and non-intrusive experiment. The latter consists of measuring the thickness variation over time of a glass plate cooled symmetrically from both sides from a temperature above the glass transition temperature down to room temperature. Results with "artificially" created experimental observations suggest that in spite of its simplicity, the thickness variation curve contains sufficient information to identify uniquely the relaxation function parameters using the Levenberg-Marquardt method.
This paper describes an algorithm for 3D reconstruction of a smooth surface with a relatively dense set of self-similar point features from two calibrated views. We bypass the usual correspondence problem by triangulating a point in space from all pairs of features satisfying the epipolar constraint. The surface is then extracted from the resulting point cloud by taking advantage of the statistical and geometric properties of the point distribution on the surface. Results are presented for computer simulations and for a laboratory experiment on a silicon gel phantom used in a breast cancer screening project.
Acute Respiratory Distress Syndrome (ARDS) results in collapse of alveolar units and loss of lung volume at end of expiration. Mechanical ventilation (MV) is used on patients with ARDS or Acute Lung Injury (ALI), with the end objective being to increase the end expiratory volume (EEV) and hence increasing overall functional residual capacity (FRC). Simple methods to estimate EEV at a given positive end expiratory pressure (PEEP) level in patients with ARDS/ ALI currently do not exist. Current viable methods are time consuming, relatively invasive and not model based. Previous studies have found a constant linear relationship between the global stress and strain in the lung independent of lung condition. This study utilizes the constant stress strain ratio and an individual patient’s volume responsiveness to PEEP to estimate EEV. The es...
A majority of patients admitted to the Intensive Care Unit (ICU) require some form of respiratory support. In the case of Acute Respiratory Distress Syndrome (ARDS), the patient often requires full intervention from a mechanical ventilator. ARDS is also associated with mortality rates as high as 70%. Despite many recent studies on ventilator treatment of the disease, there are no well established methods to determine the optimal Positive End expiratory Pressure (PEEP) ventilator setting for individual patients [1]. A model of fundamental lung mechanics is developed based on capturing the recruitment status of lung units. The model produces good correlation with clinical data, and is clinically applicable due to the minimal number of patient specific parameters to identify. The ability to use this identified patient specific model to op...
Digital Image Elasto Tomography (DIET) is a non-invasive breast cancer screening technology that images the surface motion of a breast under harmonic mechanical actuation. A new approach capturing the dynamics and characteristics of tumor behavior is presented. A simple mechanical model of the breast is used to identify a transfer function relating the input harmonic actuation to the output surface displacements using imaging data of a silicone phantom. Areas of higher stiffness cause significant changes of damping and resonant frequencies as seen in the resulting Bode plots. A case study on a healthy and tumor silicone breast phantom shows the potential for this model-based method to clearly distinguish cancerous and healthy tissue as well as correctly predicting the tumor position.
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