The micro-structure of Shangjuxu acupoint (ST37) by X-ray phase-contrast CT imaging based on synchrotron radiation

In this paper, the micro-structure of the Shangjuxu acupuncture point or tissue where there were no acupoints in the fractional rabbit hind limb were studied by in-line phase contrast CT imaging (IL-XPCI-CT) methods based on synchrotron radiation. Then the imaging results are reconstructed in three-dimensional limit, and the 3D images for different tissues are compared. The experiments were performed at X-ray imaging and biomedical application beam-line (BL13W1) of Shanghai Synchrotron Radiation Facility (SSRF). The organization of microvascular alignment can be visualized easily in the projection. The microvascular become rich and have a tendency to be concentrated on the point area. In the slices, there is the phenomenon of more micro reuniting. Using three-dimensional reconstruction, the distribution of microvascular can be seen throughout acupuncture area, there are both the trend along strike meridians and the intermittent aggregation. The density of micro-vessels was calculated for tissues with acupoints or without acupoints. Our results showed that there was one significantly higher density of the micro-vessels, where Shangjuxu acupoint was located. In the acupoint, there was a large number of involutedly microvascular structures, which was segmental. The width of each segment is not equivalent, there is a tendency that the intermediate segment is relatively wide, both sides of the acupuncture are relatively narrow which width is a Gaussian distribution. The FWHM values of Gaussian distribution curve can be determined from the scope of the Shangjuxu acupoints, which are basically consistent with the acupuncture point size in the traditional Chinese medicine theory. Nevertheless, in non-acupoint area, the microvascular structure was relatively simple and flat.