Isotropic high-resolution three-dimensional confocal micro-rotation imaging for non-adherent living cells

Recently, micro-rotation confocal microscopy has enabled the acquisition of a sequence of micro-rotated images of nonadherent living cells obtained during a partially controlled rotation movement of the cell through the focal plane. Although we are now able to estimate the three-dimensional position of every optical section with respect to the cell frame, the reconstruction of the cell from the positioned micro-rotated images remains a last task that this paper addresses. This is not strictly an interpolation problem since a micro-rotated image is a convoluted two-dimensional map of a three-dimensional reality. It is rather a 'reconstruction from projection' problem where the term projection is associated to the PSF of the deconvolution process. Micro-rotation microscopy has a specific difficulty. It does not yield a complete coverage of the volume. In this paper, experiments illustrate the ability of the classical EM algorithm to deconvolve efficiently cell volume despite of the incomplete coverage. This cell reconstruction method is compared to a kernel-based method of interpolation, which does not take account explicitly the point-spread-function (PSF). It is also compared to the standard volume obtained from a conventional z-stack. Our results suggest that deconvolution of micro-rotation image series opens some exciting new avenues for further analysis, ultimately laying the way towards establishing an enhanced resolution 3D light microscopy.