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bioRxiv · 10.1101/2021.07.29.454121

Optimizing large organ scale micro computed tomography imaging in pig and human hearts using a novel air-drying technique

Pallares-Lupon, N.·Ramlugun, G. S.·Ozenne, V.·Duchateau, J.·Delgove, A.·Bayer, J. D.·Moreno, A.·Constantin, M.·Gerneke, D.·Sands, G. B.·Trew, M. L.·Hocini, M.·Haissaguerre, M.·Vigmond, E. J.·Quesson, B.·Bernus, O.·Walton, R. D.
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Abstract

Underlying electrical propagation in the heart and potentially fatal arrhythmia is the cardiac microstructure. Despite the critical role of muscle architecture, a non-destructive approach to examine not only myocyte orientation, but cellular arrangement in to laminar organization is lacking in hearts from translational animal models and humans. X-ray micro computed tomography using contrast enhancing agents achieves three-dimensional images at near-histological resolutions. However, imaging large mammalian hearts presents challenges including X-ray over-attenuation and loss of image contrast. The goal of this study was to rethink tissue pre-treatment to optimize, and benefit from micro computed tomography imaging resolution in large tissues. Whole pig and human hearts were dehydrated and perfused with a tissue reinforcing agent, hexamethyldisilazane, and slowly air-dried. Heart morphology was conserved and temporally stable. This enabled direct air-mounting for micro computed tomography imaging. Moreover, the desiccated tissue density was significantly reduced compared to the initial hydrated state (P=0.04). Three-dimensional image reconstructions of air-dried hearts segmented using a single intensity threshold revealed detailed microstructural architecture of myolaminae. Conversely, one-step segmentation of hearts loaded with contrast agents poorly estimated the gross anatomical morphology of the heart and lacked identification of tissue microarchitecture. Air-drying large mammalian hearts optimizes X-ray imaging of cardiac microstructure.

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Pallares-Lupon, N., Ramlugun, G. S., Ozenne, V., Duchateau, J., Delgove, A., Bayer, J. D., Moreno, A., Constantin, M., Gerneke, D., Sands, G. B., Trew, M. L., Hocini, M., Haissaguerre, M., Vigmond, E. J., Quesson, B., Bernus, O., Walton, R. D.. 2021-07-29. Optimizing large organ scale micro computed tomography imaging in pig and human hearts using a novel air-drying technique. https://doi.org/10.1101/2021.07.29.454121

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