Study on Data Acquisition and Image Characteristics of Brain Multifrequency EIT in Healthy People and Patients With Brain Diseases

For subjects who received clinical trials, 16 electrodes were placed equidistantly in their head, and brain EIT data were measured at 9 frequencies in the range of 21 kHz to 100 kHz by applying a current RMS of 176 microamps. The healthy group included 16 individuals (male, age 40.25±11.18). No history of brain disease and no abnormalities were seen on plain CT scans of their brains. Cerebral EIT data collection from healthy volunteers was performed in a dedicated laboratory with temperature controlled at 24±1 °C and 52%±1% humidity in 2022. The subjects were lying in a horizontal position. The patient group included 8 patients with brain diseases (7 males, age 59±10.46). Obvious lesions were visible on the patients' CT or MRI images, including 6 patients with intracranial hemorrhage, 1 patient with cerebral ischemia, and 1 patient with cerebral edema. Data from patients with brain diseases were collected at the neurosurgical intensive care unit at the Army Medical Center of PLA in 2022. The cerebral EIT data of the patients were collected in the same position as the healthy individuals. The MFEIT image sequence is obtained according to a certain imaging algorithm, and the ROI area ratio (AR\_ROI) on the left and right sides of the image and the average value of the reconstructed ROI resistivity change (MVRRC\_ROI) are extracted. Based on the extracted indicators, the geometric asymmetry index (GAI) and intensity asymmetry index (IAI) was further proposed to characterize the symmetry of MFEIT images, and the differences between the two groups of subjects on MFEIT images were statistically compared and analyzed.