[Progress of fMRI-based deqi research in recent 10 years]

The research regarding the central mechanism of acupuncture deqi (arrival of qi) based on functional magnetic resonance imaging (fMRI) in recent 10 years was analyzed to summarize existing research achievements and experience.

The literature regarding fMRI-based deqi research published from January of 2007 through December of 2016 in CNKI and PubMed databases was collected. The research content and methods, including research design, inclusion criteria, acupoint selection and deqi evaluation, were analyzed.

Totally 18 articles regarding the central mechanism of acupuncture deqi based on fMRI was included. According to research content, the literature was divided into two categories: deqi research and deqi sensation research. In deqi research, the differences of deqi and not deqi on brain functional activity were compared to summarize the central response pattern of deqi; in deqi sensation research, the differences of different sensations and intensities of deqi on central response were compared to explore the effects of different sensations and intensities of deqi on brain functional activity. In recent 10 years, the number of research gradually increased, and the type of design was various, mainly RCT and paired design. The majority of participants was healthy people, and single acupoint was the focus of researches, including Zusanli (ST 36), Waiguan (TE 5), Hegu (LI 4), etc. The evaluation of deqi was based on visual analogue scale (VAS). The research contents were mainly the effects of deqi and not deqi and different deqi sensations on brain function activities. The present studies confirmed that deqi and not deqi as well as different deqi sensations had different impacts on brain functional effects, and different acupoints had specific activated brain areas. There was a positive correlation between the degree of deqi and the intensity of the activation of brain regions. Furthermore, tingling sensation was not included to deqi sensations.

The number and quality of fMRI-based deqi research need to be improved; the research content is simple, and research method is in exploratory stage. The results obtained in the literature are the phenomena of deqi in the central level, and it is imperative to summarize the essential link between deqi and the central effect through these phenomena to reveal the mechanism of deqi. The specific impact of deqi for brain function needs more clinical exploration.