Treatment will be performed by a single licensed acupuncturist. Both the patient and the investigator are unaware of the treatment assigned. A specially designed copper needle (0.22x4mm), which can be used safely in MRI suite, will be inserted through a plaster over the respective acupoints, under which a plastic ring will be positioned, connected with electrical stimulation machine (EY-3308 Model, G6805-2 Mayfair) through wires with stimulation frequency of 150Hz, lasting for 30 minutes. For sham acupuncture, the needle will be positioned at 2cm away from the true respective acupoints., the same electric stimulation will be the same as real acupuncture treatment. The treatment will be given by an independent acupuncturist who is not involved in the data acquisition and analysis. Points for acupuncture treatment are chosen to regain the balance of liver qi stagnation and strengthen the spleen: