Functional MR Imaging Study Of The Cervical Spinal Cord By Use Of Electrical Acupuncture Stimulation At LI4(Hegu)

PurposeThe purpose of this study was to investigate the neuronal activity in cervical spinalcord assessed with SEEP-fMRI through the comparative study between electricalacupuncture stimulation at LI4 and electrical stimulation on thumb-index web skin. Andmake our primary discussion on the acupuncture response in the cervical spinal cord andassessments of both acu-point and nonacu-point stimulation applications.Methods:1. General information: 22 healthy voluntary college students, age range from 23-27 yearsold, average age 23.8 years old, were included. The volunteers consist of fifteen males andseven females. All were right-handed. Subjects had no history of cervical spine trauma,neurological disease, substance abuse, or dependency.2. MR Protocol: Images were acquired with a 1.5-T MR GE imaging system. Head fixationwas achieved with two foam cushions. The MR imager room was dimly lit, and the subjectswere instructed to close their eyes during the experiment. The functional imaging sessionfor the sagittal images was obtained using single-shot fast spin-echo imaging sequence withthe following parameters: Flow compensation, No phase wrap. TR=1065.0ms, TE=42.4ms; Bank Width: 32 KHz; FOV: 16cm×16cm; Matrix: 128×128; NEX 1; 7slices;section thickness: 2.8mm; spacing: 0.5mm. Slices were oriented transverse to the spinalcord and the thickness was adjusted so that every second slice was aligned with either theinter-vertebral discs or centers of the vertebrae, spanning the entire cervical cord.Adjusting the slice thickness accordingly resulted in a slice thickness range of 7.0-7.5mm,and the parameters were as follows: TR=1065.0ms, TE=42.4ms; Bank Width: 32 KHz;FOV; 12cm×12cm; Matrix: 128×128; NEX 1; 7 slices; section thickness: 7.0mm; spacing:2.0mm. Spatial saturation pulses were applied to eliminate signal from surrounding areasto avoid aliasing and to reduce motion artifacts arising from regions anterior to the spine.3. Experiment design: The volunteers were divided into two groups: electrical acupuncturestimulation at LI 4 and electrical stimulation thumb-index web skin. All 22 subjects were performed with constant current pulses at a frequency of 5 Hz. The stimulation current(35-40mA) was adjusted to induce. 8 volunteers were performed for the sagittal images andthe other 6 volunteers for transverse images by s-fMRI in GroupⅠ. And 8 volunteers inGroupⅡwere divided into 4 volunteers for the sagittal images and 4 volunteers fortransverse images.4. Data analysis: The image data were analyzed within the framework of the general linearmodel in AFNI. The first two volumes in each scan series, collected before equilibriummagnetization was reached, were discarded. Then, all volumes were registered to thevolume collected nearest in time to the high-resolution anatomy. Next, a spatial filter with aroot-mean-square width of 4ram was applied to each echo-planar volume. The response toeach stimulus category compared with the fixation baseline was calculated using multipleregressions. All areas that showed a response to any stimulus type were included in theanalysis.Result1. All volunteers cooperated well and had no any uncomfortable feeling such as pain,nausea, vomiting and the like. The sense of acupuncture was distinct and the functionalimage was obtained successfully for each volunteer.2. In the sagittal view: GroupⅠ: One subject's neck moved significantly, so he was excludedfrom the statistical processing. The other 7 subjects had an fMRI response both in theupper and lower cervical spinal cord. The localizations of the segmental fMRI activationare C6 through T1, and C2～3 level as well. GroupⅡAll 4 subjects had an fMRI responsejust in the lower cervical spinal cord; no upper fMRI activation was detected.3. In the transverse imaging view: Significant fMRI responses could be measured both inGroupⅠand GroupⅡ. The cross-sectional localization of the activity measured in thespinal cord was most in terms of the ipsilateral posterior direction.ConclusionElectrical stimulation at the acu-point LI 4 can lead to the functional changes inspecific spinal-areas. Stimulation at LI4 elicits an integrated response from two main levelsof the cervical spinal cord. Activation in the lower cervical segments(C6 through T1 )was at the level corresponding to the dermatome where the stimulus was applied. We propose thatthe activation of the upper cervical segment, in particular C2～3 level, maybe correspond tothe special transmission channel of acupuncture. The functional MR imaging techniquebase on SEEP effect can be use for detecting with activity in the human cervical spinal cord,and for the further study on the spinal response to the acupuncture action.