Photoacoustic imaging of acupoint specificity and meridian transmission at Shousanli (LI10): a blood oxygen metabolism study.

OBJECTIVE: To examine how acupuncture at Shousanli (LI10) influences blood oxygen metabolism in tissues beneath acupoints along the Hand-Yangming Large Intestine Meridian, as well as at non-meridian sites, with the aim of validating acupoint specificity and meridian transmission. METHODS: 60 healthy volunteers were randomized to acupoint (n=30, LI10) or non-meridian (n=30, 2 cm medial to LI10) groups. Photoacoustic imaging assessed oxygen saturation (SO2) at LI10, LI11, LI8, LI4, and corresponding non-meridian sites at baseline, post-deqi, post-withdrawal, and 15/30 min post-withdrawal. RESULTS: Following acupuncture at LI10, local SO2 at LI10 increased significantly (P<0.01), with transmission along the meridian to LI11 and LI8. No significant changes were observed at non-meridian non-acupoint sites. CONCLUSION: Acupuncture at Shousanli can specifically regulate blood oxygen metabolism at acupoint regions and demonstrates meridian-oriented transmission characteristics, providing visualized evidence for acupoint specificity.