Three-dimensional and dynamic assessment of digital lymphatic vessels using photoacoustic imaging

Digital lymphatic anatomy has been defined largely by cadaveric studies. We evaluated whether photoacoustic lymphangiography (PAL) could depict three-dimensional anatomy and motion-related deformation in vivo. Two healthy volunteers and one patient with secondary upper-extremity lymphedema underwent fingertip indocyanine green injection, near-infrared fluorescence imaging, and static and dynamic PAL. In healthy fingers, lymphatic vessels coursed mainly along the lateral aspects toward the dorsal hand and lay between superficial veins and digital arteries. Flexion produced spiral-like deformation or abrupt angulation, whereas vessels were relatively straight during extension; segmental lymphatic signals moved proximally during motion. In the patient, PAL visualized vessels beneath dermal backflow that appeared more irregular and showed frequent short-segment tortuosity, and guided lymphaticovenular anastomosis. These findings support the feasibility of finger-specific, in vivo three-dimensional and motion-resolved assessment of digital lymphatic morphology using PAL.