Imaging Dynamics Beneath Turbid Media via Parallelized Single‐Photon Detection

Abstract

Noninvasive optical imaging through dynamic scattering media has numerous important biomedical applications but still remains a challenging task. While standard diffuse imaging methods measure optical absorption or fluorescent emission, it is also well-established that the temporal correlation of scattered coherent light diffuses through tissue much like optical intensity. Few works to date, however, have aimed to experimentally measure and process such temporal correlation data to demonstrate deep-tissue video reconstruction of decorrelation dynamics. In this work, a single-photon avalanche diode array camera is utilized to simultaneously monitor the temporal dynamics of speckle fluctuations at the single-photon level from 12 different phantom tissue surface locations delivered via a customized fiber bundle array. Then a deep neural network is applied to convert the acquired single-photon measurements into video of scattering dynamics beneath rapidly decorrelating tissue phantoms. The ability to reconstruct images of transient (0.1-0.4 s) dynamic events occurring up to 8 mm beneath a decorrelating tissue phantom with millimeter-scale resolution is demonstrated, and it is highlighted how the model can flexibly extend to monitor flow speed within buried phantom vessels.

Optical imaging and spectroscopy for the study of the human brain: status report

“… 65 Apart from directly averaging the DCS signal across all SPAD pixels within an array, the signal from individual SPAD pixels may also be digitally combined and processed in alternative configurations, for example, to form images and video of deep-tissue dynamics. 68 …”

“…65 Apart from directly averaging the DCS signal across all SPAD pixels within an array, the signal from individual SPAD pixels may also be digitally combined and processed in alternative configurations, for example, to form images and video of deep-tissue dynamics. 68 Currently, one main limitation of SPAD array-based DCS detection is its relatively low per-SPAD temporal sampling rate. While a single SPAD can sample at over 100 MHz, 69 SPAD arrays currently operate at approximately 1 MHz frame rates.…”

scatterBrains: an open database of human head models and companion optode locations for realistic Monte Carlo photon simulations

“…2.1 and 2.2) available as part of the toolbox, so users can import their own MRI scans and subsequently use them as model inputs to MMC. For optode placement, we also aim to incorporate more complex optode placement schemes in the automated pipeline, as recent work has exploited non-linear setups in source–detector placement 56 . With regard to DCS post-processing, we also plan to include MC fitting methods 30 for DCS data, as well as other potential fitting schemes that have demonstrated improvement over the semi-infinite diffuse correlation equation.…”

Advances in Dynamic Light Scattering Imaging of Blood Flow

“…Recently, to facilitate the fulfillment of ergodicity conditions in blood flow measurements, the parallelized diffuse [155] Copyright 2022, The Authors, published by Wiley-VCH GmbH. correlationimaging (PDCI) approach was introduced.…”

“…g 2 (𝜏) changes are caused by the varying deep-tissue dynamic scattering potentials labeled at the bottom left. Reproduced with permission under terms of the CC BY 4.0 license [155]. Copyright 2022, The Authors, published by Wiley-VCH GmbH.…”