Readout-dependent time-of-flight weighting of absorption and flow in interferometric diffuse optics
- 1Institute of Physical Chemistry PAS
Abstract
Joint optical measurement of hemoglobin and blood-flow dynamics could provide a compact route to richer functional monitoring of tissue physiology. However, hybrid diffuse-optical systems commonly optimize photon time-of-flight (TOF) for individual readouts, even when absorption and flow are recovered from the same acquisition. Here, we asked whether a single TOF window can optimally preserve both signals. Dual-wavelength TOF-iSCOS recovered absorption, hemoglobin and relative blood-flow index (BFI) from the same interferometrically sensed optical field, while Early, Middle and Late photon windows provided progressively greater weighting of longer and deeper photon paths. During forearm cuff occlusion in 11 adults, absorption and flow showed markedly different TOF dependence: Late-gate BFI responses were retained, whereas absorption decreased to a median Late/Early ratio of 0.18. The resulting readout-by-TOF interaction was positive in all 11 participants (median 2.61 octaves, 95% bootstrap CI 2.44-3.22; exact sign-test P = 9.8 x 10-4). Readout-specific gate selection increased held-out response retention by 24.8% (95% CI 8.8-42.5%) relative to a single common gate. We then tested the approach during prefrontal working-memory activation in seven participants using a higher-load 2-back task relative to a low-load 0-back control. Late-gate BFI increased in all seven participants (+5.07%, 95% CI 1.46-8.68%; P = 0.014) and remained positive after adjustment using an Early-TOF signal, whereas hemoglobin responses were less consistent. Layered Monte Carlo modeling showed that the same detected photon histories acquire different absorption and dynamic-scattering sensitivity across TOF, linking the experimental effects to anatomy- and geometry-conditioned tissue weighting. Within the present geometry and photon budget, the central result is therefore not that one readout is intrinsically superior, but that absorption and flow recovered from the same optical field retain physiological information differently across photon time-of-flight.
Related
- Spoken language comprehension relies on context-dependent neural weighting of syntax and prosody
- A transformer-based model reveals sparse, stimulus-dependent orientation readout from macaque V1 population activity
- In situ pulse dispersion estimation via third-harmonic generation interferometric autocorrelation for multiphoton microscopy
- A unified framework reveals how evolutionary scale and abundance weighting shape phylogenetic community structure
- Dynamic interactions between sensory and decision-making circuits shape temporal evidence weighting
BibTeX
@misc{marzejon2026readoutdependent,
title = {{Readout-dependent time-of-flight weighting of absorption and flow in interferometric diffuse optics}},
author = {M. Marzejon and N. Mogharari and K. Nowacka-Pieszak and D. Borycki},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.02.748230},
url = {https://www.biorxiv.org/content/10.64898/2026.09.02.748230v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Readout-dependent time-of-flight weighting of absorption and flow in interferometric diffuse optics
AU - M. Marzejon
AU - N. Mogharari
AU - K. Nowacka-Pieszak
AU - D. Borycki
PY - 2026
DA - 2026/09/02
PB - bioRxiv
DO - 10.64898/2026.09.02.748230
UR - https://www.biorxiv.org/content/10.64898/2026.09.02.748230v1
AB - Joint optical measurement of hemoglobin and blood-flow dynamics could provide a compact route to richer functional monitoring of tissue physiology. However, hybrid diffuse-optical systems commonly optimize photon time-of-flight (TOF) for individual readouts, even when absorption and flow are recovered from the same acquisition. Here, we asked whether a single TOF window can optimally preserve both signals. Dual-wavelength TOF-iSCOS recovered absorption, hemoglobin and relative blood-flow index (BFI) from the same interferometrically sensed optical field, while Early, Middle and Late photon windows provided progressively greater weighting of longer and deeper photon paths. During forearm cuff occlusion in 11 adults, absorption and flow showed markedly different TOF dependence: Late-gate BFI responses were retained, whereas absorption decreased to a median Late/Early ratio of 0.18. The resulting readout-by-TOF interaction was positive in all 11 participants (median 2.61 octaves, 95% bootstrap CI 2.44-3.22; exact sign-test P = 9.8 x 10-4). Readout-specific gate selection increased held-out response retention by 24.8% (95% CI 8.8-42.5%) relative to a single common gate. We then tested the approach during prefrontal working-memory activation in seven participants using a higher-load 2-back task relative to a low-load 0-back control. Late-gate BFI increased in all seven participants (+5.07%, 95% CI 1.46-8.68%; P = 0.014) and remained positive after adjustment using an Early-TOF signal, whereas hemoglobin responses were less consistent. Layered Monte Carlo modeling showed that the same detected photon histories acquire different absorption and dynamic-scattering sensitivity across TOF, linking the experimental effects to anatomy- and geometry-conditioned tissue weighting. Within the present geometry and photon budget, the central result is therefore not that one readout is intrinsically superior, but that absorption and flow recovered from the same optical field retain physiological information differently across photon time-of-flight.
ER -