Being able to acquire, visualize, and analyze 3D time seriesud(4D data) from living embryos makes it possible to understand complexuddynamic movements at early stages of embryonic development.udDespite recent technological breakthroughs in 2D dynamic imaging,udconfocal microscopes remain quite slow at capturing optical sectionsudat successive depths. However, when the studied motion is periodic—udsuch as for a beating heart—a way to circumvent this problem is toudacquire, successively, sets of 2D+time slice sequences at increasinguddepths over at least one time period and later rearrange them to recoveruda 3D+time sequence. In other imaging modalities at macroscopicudscales, external gating signals, e.g., an electro-cardiogram,udhave been used to achieve proper synchronization. Since gating signalsudare either unavailable or cumbersome to acquire in microscopicudorganisms, we have developed a procedure to reconstruct volumesudbased solely on the information contained in the image sequences.udThe central part of the algorithm is a least-squares minimization of anudobjective criterion that depends on the similarity between the dataudfrom neighboring depths. Owing to a wavelet-based multiresolutionudapproach, our method is robust to common confocal microscopy artifacts.udWe validate the procedure on both simulated data and in vivoudmeasurements from living zebrafish embryos.
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