Robust hybrid feature-driven on-the-fly mapping enables freehand 3D panoramic photoacoustic angiography

The vascular network defines the perfusion boundaries that are fundamental to surgical resection and functional preservation. Photoacoustic angiography (PAA) offers stereoscopic visualization and quantification of microvascular anatomy and hemodynamics in vivo, but existing implementations remain constrained in field of view and imaging speed, limiting the intraoperative utility. Here, we introduce a real-time PAA tracking and mapping strategy that estimates the six degree-of-freedom motion of a handheld probe and reconstructs panoramic three-dimensional vascular maps for surgical guidance. By associating geometric and intensity-based hybrid vascular features to prevent degeneracy, the method achieves robust online mapping with 99.67% accuracy, even under dynamic freehand operation. In rat radical gastrectomy, the approach expanded the imaging boundary by 42.3-fold to 50.84 mm³ within 16.7 s, enabling panoramic microvascular visualization beyond the surgical field for preoperative planning, postoperative evaluation, and distal hemodynamic surveillance. This on-the-fly, freehand, and field-of-view-unconstrained PAA establishes a practical framework for vascular-focused surgical interventions, supporting precise and timely decision-making.