Wide-Field Multiphoton Imaging

A UK-wide research team, led by the Uni­versity of St Andrews, has developed an inno­vative new way to optically image through tissue, which could allow for a more detailed under­standing and diagnosis of the early stages of various diseases, including cancer. The study, in colla­boration with the Univer­sity of Southamp­ton and the Cancer Research UK Edinburgh Centre at the Univer­sity of Edinburgh, paves the way to move from super­ficial to functional imaging, trans­forming studies in neuro­science.

Laser light patterns are sequentially focused in time onto a region of interest inside biological tissue. Fluorescence emitted by the sample under each illumination pattern is collected with a single-pixel detector after passing back through the tissue. By adding up the projected patterns weighted by the intensities recorded, an image of the sample can be reconstructed. (Source: St. Andrews U.)

Light does not penetrate through our skin or a piece of tape very well. It scatters and is scrambled. This in turn makes it very hard to create images from deep within a sample. The inno­vative new method focused short pulses of patterned light in time through the tissue. By temporal focusing, the patterns retain their form despite the scat­tering from the tissue. However, this is not imaging. To image, the team collected just a fraction of the return fluores­cence from the sample onto a single-point detector. By simply appro­priately summing the patterns projected on the sample weighted by the inten­sities recorded for the return light, the team were able to form a faithful image. Crucially this image was created without ever having any specific know­ledge of the tissue itself.

The ability to see deeper into tissue with light is currently one of the hottest topics in imaging. The potential appli­cations of the research findings could have wide-ranging impli­cations to aid bio­medical analysis and early detection of diseases, including furthering our under­standing of neuro­science and dege­nerative brain diseases.

Researcher Adrià Escobet-Montalbán, Marie Curie Fellow from the Univer­sity of St Andrews School of Physics and Astro­nomy, said: “Our approach shows an inno­vative way to tackle a long­standing problem in imaging. It is exciting to see the response we have got from the inter­national community as many people thought what we have done is impossible with light.” Kishan Dholakia from the Univer­sity of St Andrews School of Physics and Astronomy added: “This is a timely break­through and I hope it leads to new ways of thinking about imaging at depth.” (Source: St. Andrews U.)

Reference: A. Escobet-Montalbán et al.: Wide-field multiphoton imaging through scattering media without correction, Sci. Adv. 4, eaau1338 (2018); DOI: 10.1126/sciadv.aau1338

Link: SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, UK

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