Photoacoustics. 2026 May 2;49:100836. doi: 10.1016/j.pacs.2026.100836. eCollection 2026 Jun.
ABSTRACT
Microcirculatory dysfunction is central to the pathophysiology of diseases such as sepsis, diabetes, and cardiovascular disorders. While clinical tools like near-infrared spectroscopy (NIRS) and transcutaneous oxygen monitoring (TcPO₂) offer global oxygenation insights, they lack the spatial resolution for localized microvascular assessment. Photoacoustic computed tomography provides sub-millimeter oxygenation imaging, yet resolving ultra-fine structures for morphology-based functional analysis remains challenging. To address this, we developed the Nine-Grid Segmentation Strategy (NGSS), a significance-analysis framework integrated with a non-invasive vascular occlusion test (VOT). Using the microcirculation-rich thenar muscle as the imaging site, NGSS characterizes each pixel across two physiological dimensions: occlusion response and reperfusion efficiency. The NGSS framework categorizes pixels based on their oxygenation trajectories during occlusion and reperfusion, assigning each to one of three functional states: significant increase, non-significant change, or significant decrease. This two-dimensional classification generates a nine-type map capturing the spatial heterogeneity of tissue microregions. Our results demonstrate that even without discerning specific microvascular morphologies, NGSS evaluates tissue oxygenation on a hundred-micron scale. The analysis reveals distinct oxygenation patterns and perfusion efficiencies across phenotypes, providing quantitative volumetric distributions. NGSS offers a novel, high-resolution, non-invasive approach for microcirculatory assessment, showing significant promise for both clinical monitoring and fundamental vascular research.
PMID:42125644 | PMC:PMC13158772 | DOI:10.1016/j.pacs.2026.100836