Intracranial Hemorrhage Detection by Open MIT Sensor Array

Abstract

Magnetic induction tomography (MIT) is a promising technology in medical imaging due to its nonradioactive, noninvasive, and noncontact properties. To realize the local detection of intracranial hemorrhage with small volume, an open planar MIT sensor array with gradiometers is proposed. With the 3-D head model, the phase response of the hemorrhages in different volumes under this sensor structure was investigated and compared with the sensor structure with Bx sensors. The evaluation indexes: intensity of hemorrhage signals <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$A_{\mathrm {H}}$ </tex-math></inline-formula> and useful signal to background signal ratio(UBR) were introduced for quantitatively compare the performance of the two sensor arrays in hemorrhage detection. For the 2 mL hemorrhage, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$A_{\mathrm {H}}$ </tex-math></inline-formula> and UBR under the planar array with Bx sensors are only 15.33% and 16.67% of those under the planar array with gradiometers, respectively. The results indicate that the planar array with gradiometers can effectively enhance the hemorrhage signals and reduce the effect of normal head tissues, which will facilitate the accurate reconstruction of hemorrhage. Then, the capability of the open planar sensor array with gradiometers in hemorrhage reconstruction was investigated by the time difference MIT, frequency difference MIT, and multifrequency difference MIT method. In the simulation and experimental results, the spatial resolution of the intracranial hemorrhage imaging could, respectively, reach 2 and 6.4 mL under the designed MIT sensor array. This study provides a portable solution for local detection of intracranial hemorrhage with small volume, which will promote the practical application of MIT.