Combination laser and imaging approach improves blood flow mapping

Mapping blood flow is an important part of monitoring many vascular-related diseases, and the most common method employed is laser speckle contrast imaging (LSCI). This fast, label-free method can image wide-field blood flow at high resolution. However, LSCI is hard to use in clinical settings, as many factors — tissue absorption, scattering, and structural variations — can change the speckle signal, making quantitative blood flow assessment difficult.

Hoping to improve the quantitative reliability of LSCI, Feng et al. developed an imaging method called Flow dynamic and Optical property Coupled Laser Speckle Imaging (FOCUS), which integrates LSCI with spatial frequency domain imaging (SFDI).

Normally, LSCI is used to measure blood-flow-related speckle fluctuations, while spatial frequency domain imaging (SFDI) is used to image tissue optical properties. Since the two methods have different light coherence requirements, the researchers designed a system with a single laser source, a laser speckle reducer, and a digital micromirror device. This combination has the additional advantage of improving sampling depth consistency and measurement sensitivity.

The data from FOCUS are analyzed using two correlation-diffusion-based effective motion models: a Brownian-motion model and a directed-flow model, which are used to describe different blood flow regimes.

“We are most excited that FOCUS can reduce the ambiguity caused by tissue optical properties in laser speckle blood-flow measurements,” said author Jinling Lu. “We hope this work can help make laser speckle imaging more quantitative and reliable for longitudinal studies, cross-subject comparisons, and disease models where tissue optical properties may change over time.”

In addition to the direct biomedical applications, such as studies of stroke or burn assessment, the authors hope the integrated strategy they employed could be extended to other multimodal optical imaging applications.

Source: “FOCUS: Flow dynamic and optical property coupled laser speckle imaging for quantitative blood flow mapping,” by Shijie Feng, Tingyu Sun, Jiachi Hong, Junshuai Yan, Zimeng Xu, Alexander V. Priezzhev, Pengcheng Li, and Jinling Lu, APL Photonics (2026). The article can be accessed at https://doi.org/10.1063/5.0313526 .