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Magnetic induction phase shift is a promising technology for the detection of cerebral hemorrhage, owing to its nonradioactive, noninvasive, and real-time detection properties. To enhance the detection sensitivity and linearity, a zero-flow sensor was proposed. The uniform primary magnetic field and its counteraction were achieved. Phase-change responses to solutions of varying conductivities and rabbits with cerebral hemorrhage were investigated and compared with traditional sensors. The sensitivities in detecting solutions with different conductivities were 1.84, 1.39, and 1.22 times higher than those for a low-pass birdcage coil, planar gradiometer, and Bx-sensor, respectively. The results for rabbits with cerebral hemorrhage showed that the sensitivities increased by 1.17, 1.67, and 6.3 times compared with a low-pass birdcage coil, symmetric cancelation-type sensor, and single co-axial coil, respectively. This sensor could accurately detect three stages in the pathological process. Blood loss of 1 mL meant that the compensatory mechanism of cerebrospinal fluid began to fail, and 1.4 mL of blood loss meant that the compensatory mechanism failed completely. The adjusted R-squared value of the first-order linear fit was above 0.98 in both physical and animal experiments, indicating that high detection linearity was achieved. The proposed sensor provides a more accurate method for cerebral hemorrhage detection and facilitates the practical application of magnetic induction phase shift in pre-hospital and bedside real-time detection.
Liu et al. (Mon,) studied this question.