Phase-Retrieved Tomography enables Mesoscopic imaging of Opaque Tumor Spheroids

Abstract

We present a new Phase-Retrieved Tomography (PRT) method to radically improve mesoscopic imaging at regimes beyond one transport mean-free-path and achieve high resolution, uniformly throughout the volume of opaque samples. The method exploits multi-view acquisition in a hybrid Selective Plane Illumination Microscope (SPIM) and Optical Projection Tomography (OPT) setup and a three-dimensional Gerchberg-Saxton phase-retrieval algorithm applied in 3D through the autocorrelation sinogram. We have successfully applied this innovative protocol to image optically dense 3D cell cultures in the form of tumor spheroids, highly versatile models to study cancer behavior and response to chemotherapy. We have thus achieved a significant improvement of resolution in depths not yet accessible with the currently used methods in SPIM/OPT, while overcoming all registration and alignment problems inherent to these techniques.This work was supported by the grants "Skin-DOCTor" (1778) implemented under the "ARISTEIA" Action of the "Operational Programme Education and Lifelong Learning" co-funded by the European Social Fund (ESF) and National Resources, the EU Marie Curie ITN "OILTEBIA" PITN-GA-2012-317526 and the H2020 Laserlab Europe (EC-GA 654148). J.R. acknowledges support from the EC-FP7-CIG grant HIGH-THROUGHPUT TOMO and MINECO grant FIS2016-77892-R. The Authors also acknowledge support from the Institute of Molecular Biology and Biotechnology of the Foundation for Research and Technology - Hellas for the use of the cell culture facilities