Multifrequency Weighted Difference Magnetic Induction Tomography for Intracranial Hemorrhage Detection

Magnetic induction tomography (MIT) is an attractive technology for timely diagnosis and continuous monitoring of the intracranial hemorrhage due to its nonradioactive, portable, and contactless features. In the frequency difference MIT (fdMIT), the normal head tissues would cause serious artifacts in hemorrhage imaging and reduce the detection accuracy. To solve this problem, a multifrequency weighted difference MIT (mfwdMIT) method is proposed, which utilizes the proportional relationship between the phase shift and frequency in the biomedical MIT and eliminates the influence of the normal head tissues by the weighted difference between the phase shift measurements at multiple frequencies. To verify the performance of mfwdMIT in hemorrhage imaging, 3-D multilayer head models with three different volumes of hemorrhage were numerically simulated. Imaging results show that the artifacts from the normal head tissues in fdMIT method could be effectively suppressed by the mfwdMIT method. For the 2 mL hemorrhage, the shape error in mfwdMIT is reduced by 98.66% than that in fdMIT. Experimental verification results indicate that by mfwdMIT, the artifacts in hemorrhage imaging are reduced and a 6.4 mL hemorrhage could be reconstructed accurately. The proposed method could improve the spatial resolution in the intracranial hemorrhage detection, which promotes the development of MIT in the biomedical applications.