Imaging the effect of acupuncture needling on human connective tissue in vivo

The therapeutic effects of acupuncture have been known fro thousands of years. However, only recently have there been significant attempts to understand the underlying mechanism and provide a scientific basis behind these effects. In this paper, ultra-sound based motion estimation techniques are used in order to understand the effect of acupuncture. It is expected that the understanding of the mechanism of acupuncture will establish the latter in the western world as a valid alternative for treatment of certain pathologies. In vivo ultrasonic imaging using a System FiVe (Vingmed) at 7.5 MHz was performed on the thigh muscle of four human subjects at different stages of needle motion, which included rotation or no rotation (depending on the case), and downward and upward movement using a computer-controlled acupuncture needling instrument based on Langevin et al. (2002) and Langevin et al. (2001). Zero, four, eight and 16 full (360°) needle rotations using a disposable stainless steel needle (0.25 mm in diameter) were applied and compared to the cases without rotation. Displacements were estimated using the ultrasonic radio-frequency data, and crosscorrelation techniques were utilized as previously described in elastography by H.M. Langevin and J.A. Yandow (2002) with a 2mm window and a window overlap of 60%. Seventy RF scans were acquired continuously during each experiment at the rate of 13.2 frames/s. Cine-loop displacement images were generated off-line during and between the different needle movement. We found that tissue displacement could be estimated using only the stimulus caused by the needle movement. Tissue displacement amplitude increased by up to five-fold during needle rotation. Rotation also had a significant effect on tissue displacement during downward (P<0.001) and upward (P<0.05). This technique therefore provided successful mapping and quantitative analysis of the spatial and temporal tissue behavior during acupuncture needle manipulation, and may become a valuable tool for future studies of acupuncture´s mechanism of action.