An approach to the synthesis of biological tissue

Mathematical phantoms developed to synthesize realistic complex backgrounds such as those obtained when imaging biological tissue, play a key role in the quantitative assessment of image quality for medical and biomedical imaging. We present a modeling framework for the synthesis of realistic tissue samples. The technique is demonstrated using radiological breast tissue. The model employs a two-component image decomposition consisting of a slowly, spatially varying mean-background and a residual texture image. Each component is synthesized independently. The approach and results presented here constitute an important step towards developing methods for the quantitative assessment of image quality in medical and biomedical imaging, and more generally image science

Exploring the relationship between the Engineering and Physical Sciences and the Health and Life Sciences by advanced bibliometric methods

We investigate the extent to which advances in the health and life sciences (HLS) are dependent on research in the engineering and physical sciences (EPS), particularly physics, chemistry, mathematics, and engineering. The analysis combines two different bibliometric approaches. The first approach to analyze the 'EPS-HLS interface' is based on term map visualizations of HLS research fields. We consider 16 clinical fields and five life science fields. On the basis of expert judgment, EPS research in these fields is studied by identifying EPS-related terms in the term maps. In the second approach, a large-scale citation-based network analysis is applied to publications from all fields of science. We work with about 22,000 clusters of publications, each representing a topic in the scientific literature. Citation relations are used to identify topics at the EPS-HLS interface. The two approaches complement each other. The advantages of working with textual data compensate for the limitations of working with citation relations and the other way around. An important advantage of working with textual data is in the in-depth qualitative insights it provides. Working with citation relations, on the other hand, yields many relevant quantitative statistics. We find that EPS research contributes to HLS developments mainly in the following five ways: new materials and their properties; chemical methods for analysis and molecular synthesis; imaging of parts of the body as well as of biomaterial surfaces; medical engineering mainly related to imaging, radiation therapy, signal processing technology, and other medical instrumentation; mathematical and statistical methods for data analysis. In our analysis, about 10% of all EPS and HLS publications are classified as being at the EPS-HLS interface. This percentage has remained more or less constant during the past decade

On the Adjoint Operator in Photoacoustic Tomography

Photoacoustic Tomography (PAT) is an emerging biomedical "imaging from coupled physics" technique, in which the image contrast is due to optical absorption, but the information is carried to the surface of the tissue as ultrasound pulses. Many algorithms and formulae for PAT image reconstruction have been proposed for the case when a complete data set is available. In many practical imaging scenarios, however, it is not possible to obtain the full data, or the data may be sub-sampled for faster data acquisition. In such cases, image reconstruction algorithms that can incorporate prior knowledge to ameliorate the loss of data are required. Hence, recently there has been an increased interest in using variational image reconstruction. A crucial ingredient for the application of these techniques is the adjoint of the PAT forward operator, which is described in this article from physical, theoretical and numerical perspectives. First, a simple mathematical derivation of the adjoint of the PAT forward operator in the continuous framework is presented. Then, an efficient numerical implementation of the adjoint using a k-space time domain wave propagation model is described and illustrated in the context of variational PAT image reconstruction, on both 2D and 3D examples including inhomogeneous sound speed. The principal advantage of this analytical adjoint over an algebraic adjoint (obtained by taking the direct adjoint of the particular numerical forward scheme used) is that it can be implemented using currently available fast wave propagation solvers.Comment: submitted to "Inverse Problems

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Department of Biomedical EngineeringThe optical imaging has a critical role in biomedical research to analyze functional and morphological variation of an organ, tissue and even a single cell of animal models. Since the optical imaging modality has features of indirect access, volumetric analysis and high resolution, it has been used for biomedical analysis. Especially, as a low coherence interferometric imaging technique, optical coherence tomography (OCT) has been applied in scientific and medical fields from few decades ago. Since OCT can provide endogenous contrast of biological tissue using the infrared light source, it has high potential to be applied in practical medical diagnosis. However, it is hard to acquire uneven or thick sample due to the limited imaging window and penetration depth. To overcome those limitations, lots of optical, mathematical and chemical solutions comes within a decade such as adaptive optics, full-range method and tissue clearing. Despite the existence of suggested solutions, practical application of OCT is limitation due to the cost of time and effort. Here, we present practical methods to enhance acquirable endogenous information of sample through versatile scanning optical coherence tomography(VS-OCT). Conventional OCT utilizes dual-axis based flat focal plane scanning method providing limited depth information of curved samples. Thus, we developed advanced OCT, called VS-OCT, which can fully optimize imaging window by changing focal plane to dual plane and cylindrical plane. The VS-OCT is demonstrated for 1) quantification of engineered skin, 2) monitoring of tadpole development, 3) screening phenotype of zebrafish and 4) quantification of spinal cord injury (SCI) of mouse.ope