Direct EIT Reconstructions of Complex Admittivities on a Chest-Shaped Domain in 2-D

Electrical impedance tomography (EIT) is a medical imaging technique in which current is applied on electrodes on the surface of the body, the resulting voltage is measured, and an inverse problem is solved to recover the conductivity and/or permittivity in the interior. Images are then formed from the reconstructed conductivity and permittivity distributions. In the 2-D geometry, EIT is clinically useful for chest imaging. In this work, an implementation of a D-bar method for complex admittivities on a general 2-D domain is presented. In particular, reconstructions are computed on a chest-shaped domain for several realistic phantoms including a simulated pneumothorax, hyperinflation, and pleural effusion. The method demonstrates robustness in the presence of noise. Reconstructions from trigonometric and pairwise current injection patterns are included

Incorporating a Spatial Prior into Nonlinear D-Bar EIT imaging for Complex Admittivities

Electrical Impedance Tomography (EIT) aims to recover the internal conductivity and permittivity distributions of a body from electrical measurements taken on electrodes on the surface of the body. The reconstruction task is a severely ill-posed nonlinear inverse problem that is highly sensitive to measurement noise and modeling errors. Regularized D-bar methods have shown great promise in producing noise-robust algorithms by employing a low-pass filtering of nonlinear (nonphysical) Fourier transform data specific to the EIT problem. Including prior data with the approximate locations of major organ boundaries in the scattering transform provides a means of extending the radius of the low-pass filter to include higher frequency components in the reconstruction, in particular, features that are known with high confidence. This information is additionally included in the system of D-bar equations with an independent regularization parameter from that of the extended scattering transform. In this paper, this approach is used in the 2-D D-bar method for admittivity (conductivity as well as permittivity) EIT imaging. Noise-robust reconstructions are presented for simulated EIT data on chest-shaped phantoms with a simulated pneumothorax and pleural effusion. No assumption of the pathology is used in the construction of the prior, yet the method still produces significant enhancements of the underlying pathology (pneumothorax or pleural effusion) even in the presence of strong noise.Comment: 18 pages, 10 figure

The Influence of Menarche on Fathers\u27 Perceptions of Father-Daughter Relationships

Adolescence is a time of transformation for a young girl and her relationships with her parents. One way to conceptualize the evolving dynamics between father and adolescent daughter is to use the Circumplex Model of Marital and Family Systems. The purpose of this study is to examine the differences in relationships between fathers and their premenarchal daughters, girls who have not had their first menstrual period, compared to fathers and postmenarchal daughters, girls who have experienced their first menstrual period. The participants completed three questionnaires. The Demographic questionnaire included general demographic questions in order to learn more about the participants. The Family Adaptability and Cohesion Evaluation Scales II-Modified assessed family cohesion and family adaptability. The Parent-Adolescent Communication Scale-Modified assessed the degree of open family communication and extent of problems in father-daughter communication. The overall hypothesis was that there would be a fundamental difference in fathers’ relationships with their daughters as the girls experience menarche. Specifically, it was believed that fathers and premenarchal daughters would have more balanced relationships compared to fathers and postmenarchal daughters. In addition, the effect of amount of time that fathers spend with their daughters was examined. It is important to study this father-daughter relationship because this knowledge may help reduce the conflict that can occur during adolescence and may help a father feel more connected to and open with his daughter. Menarchal status only accounted for a significant difference on the Cohesion subscaie between fathers of premenarchal and postmenarcha) daughters. Monarchal status did not account for any significant differences in levels of communication between fathers of premenarchal or postmenarchal daughters. The results also showed the amount of time that fathers spend with their daughters significantly effects balanced relationships, levels of Cohesion and Adaptability, and Open Family Communication. The results suggest that the amount of time that father spend with their daughters may have a stronger effect on the father-daughter relationship than the daughters’ menarchal status. Continued research should focus on an intensive, longitudinal study that incorporates the daughter’s perspective and examines the influence of other biopsychosocial variables of pubertal development on the father- daughter relationship

A direct reconstruction algorithm for the anisotropic inverse conductivity problem based on Calderon's method in the plane

A direct reconstruction algorithm based on Calderon's linearization method for the reconstruction of isotropic conductivities is proposed for anisotropic conductivities in two-dimensions. To overcome the non-uniqueness of the anisotropic inverse conductivity problem, the entries of the unperturbed anisotropic tensors are assumed known a priori, and it remains to reconstruct the multiplicative scalar field. The quasi-conformal map in the plane facilitates the Calderon-based approach for anisotropic conductivities. The method is demonstrated on discontinuous radially symmetric conductivities of high and low contrast.Peer reviewe

Fast D-bar reconstructions of ventilation and perfusion on a pairwise current injection system

A fast implementation of the D-bar method for reconstructing conductivity changes on a 2-D chest-shaped domain is described. Cross-sectional difference images of ventilation and perfusion in a healthy human subject are presented. The images constitute the first D-bar images from EIT data on a human subject collected on a pairwise current injection system