Magnetic Resonance Imaging and Acupuncture: A Feasibility Study on the Migration of Tracers after Injection at Acupoints of Small Animals

Objectives: Acupuncture meridians in traditional Oriental medicine are known to be channels connecting specific points in the surface of the body to corresponding internal organs. We investigated the permeation and the transport of magnetic resonance imaging (MRI) contrast agent and tracer after injection at acupoints of small animals, such as rats and mice. Methods: A geometric and systematic arrangement of acupuncture points on human skin surfaces has been depicted in traditional Oriental medicine, and the positions of the acupoints of small animals were determined by the application of a proportion on the animals corresponding to the morphological structures in humans. After injecting the materials at various acupoints, the agent migration behaviors inside the body were monitored by MRI. The distributions of the injected materials were reconstructed in 3-dimensional images for a more intuitive presentation. Results: The widely-used gadolinium-compound contrast agent was not useful. Rather, a recently developed fluorine compound was effective for imaging the migration of the agent after injection into the acupoints BL18, 20, and 23. Conclusions: The final distributions of the agent from each injection point corresponded to the respective organs of the acupoints. The results suggested different migration paths and destinations for pharmacopuncture drugs.