Multicenter study on ultrasound characteristics of acupoints in the Hand Yangming Meridian and related factors.

OBJECTIVE

To investigate sonographic characteristics and influencing factors of Hegu (LI 4), Xialian (LI 8) and Shousanli (LI 10) on the Hand-Yangming Large Intestine Meridian via multimodal ultrasonography.

METHODS

In total of 110 healthy volunteers were recruited across multiple centers, with standardized localization of Hegu(HG, LI 4), Xialian(XL, LI 8) andshousanli(SSL, LI 10) performed. Grayscale ultrasonography, color Doppler flow imaging and shear wave elastography were used for ultrasonic data acquisition. Needle tip depth, acupoint-bone adjacent distance, tissue composition, blood perfusion and biomechanical properties at acupoints were quantitatively detected.

RESULTS

Baseline information and observational indices were consistent among research centers (P > 0.05). No correlations were identified between acupoint ultrasonic parameters and volunteers' baseline characteristics (P > 0.05). The median skin depth and mid-radius distance were 1.72 cm (1.38, 1.96 cm) and 0.93 cm (0.63, 1.24 cm) for LI 4; 1.64 cm (1.36, 1.95 cm) and 0.43 cm (0.29, 0.60 cm) for LI 8 1.75 cm (1.51, 2.14 cm) and 0.66 cm (0.45, 0.84 cm) for LI 10. Anatomically, LI 4 was mainly located in adductor pollicis muscle (62.7%), LI 8 in supinator muscle (41.8%), and LI 10 in the fascia between extensor carpi radialis longus and supinator muscles (39.1%). All three acupoints were closely associated with fascia structures (χ² = 11.864, P = 0.003)., and presented higher elastic modulus than surrounding reference tissues (P < 0.05).

CONCLUSIONS

Acupoints of the Hand-Yangming Large Intestine Meridian have specific ultrasonic manifestations, including definite anatomical location, tight fascial attachment, increasing fascial correlation along the meridian, and superior local tissue biomechanics. This study provides quantitative ultrasonic evidence for the meridian-connective tissue hypothesis, and offers a practical method for exploring acupuncture mechanisms.