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Dynamic Imaging of Cyclically Moving Embryonic Structures: Combining Fast Confocal Microscopes and Wavelet-Based Reconstruction Techniques

M. Liebling

Invited Talk
Bernoulli Center, Wavelets and Applications Semester, Research Seminar Series
EPFL, Lausanne, Switzerland, March 16, 2006.

Abstract Assessing the influence on embryonic development of fast biomechanical processes, such as those induced by blood flow in the embryonic heart, requires the ability to acquire dynamic three-dimensional data with high temporal resolution. Despite the availability of confocal laser scanning microscopes that can acquire hundreds of two-dimensional optical sections per second, direct three-dimensional imaging, which is 2-3 orders of magnitude slower, does not yield satisfactory results. However, for objects whose motion is cyclic, we were able to build dynamic three-dimensional reconstructions by sequentially acquiring nongated slice sequences at high speed and at increasing depths then retrospectively synchronizing them. In this talk, I will present the acquisition and synchronization procedures that we developed for that purpose. The reconstruction is based on (non)uniform temporal registration algorithms, which, in turn, rely on the minimization of the intensity difference between adjacent slice-sequence pairs. The challenges are the considerable amount of data and typical fluorescence imaging caveats (e.g. low photon count and photo-bleaching) combined with requirements for a fast and reproducible approach. We have naturally selected wavelets as the tool of choice because of their ability to yield sparse, hierarchical data representations via fast and flexible time-frequency analysis transforms. Through in vivo imaging of zebrafish embryos we were able to extract both qualitative and quantitative information that should contribute to reach a better understanding of the mechanisms that drive heart development. This is joint work with A. S. Forouhar, J. Vermot, M. Gharib, S. E. Fraser, and M. E. Dickinson.