Breast cancer is known to have metastasis via lymph vessels and lymph nodes. Sentinel lymph node(SLN) biopsy is effective to determine whether breast cancer has metastasized or not. SLN is the lymphwhich cancer cells first reaches. In order to perform the biopsy, it is necessary to identify the location ofSLN. Conventionally, a method using radioisotope and blue dye has been mainstream, however in recentyears, a method using magnetic field has attracted attention. After magnetic nanoparticles are injected nearthe breast cancer, they flow into SLN using the lymph flow. The position of SLN is identified by detectingmagnetic nanoparticles from outside the body. Previous studies have reported using permanent magnets and AC magnetic field but the accuracy is not enough for patients with high BMI. Because a pulsedmagnetic field generates larger magnetic fields compared to them, highly accurate tests are expected forpatients with high BMI. Resovist® (Fuji Film Co.) including superparamagnetic particles was used in thisstudy. Two search coils used as sensors to detect magnetic nanoparticles were connected with oppositepolarities. The voltage ratio of EMFs generated from the two coils was changed by a potentiometer, andthereby EMFs of them were canceled. Fig. 1 shows canceled EMFs of two 50-turn search coils in the caseof a blank that there is nothing inside two coils and in the case where Resovist® was inserted into eachcoil. Generated pulsed magnetic field reaches a peak at 2 ms. Measured EMFs were integrated by Eq. (1)as shown in Fig. 2 and the signal amplitude ΔB∗ of Resovist® at 2 ms was evaluated.
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