Cerebral intraventricular hemorrhage in neonatal human infants is common consequence of pre-term delivery. It is currently assessed using ultrasound, MRI or CT scan. These modalities are not suitable for continuous monitoring of infants and involve large personnel or equipment costs. Because blood has a high electrical resistivity contrast relative to other cranial tissue, it appearance can be detected and monitored using electrical impedance methods. In this proposal, the imaging technique of Electrical Impedance Tomography (EIT) is proposed as a non-invasive, low-cost monitoring alternative to these imaging modalities. EIT has the potential to measure bleeding rate and approximately localize the bleeding site. This proposal involves development of a system for capturing and reconstructing impedance images of the head, and extracting information about bleeding-related impedance changes from background noise. Results gathered from two- and three-dimensional finite element models of the head will be used to test reconstruction methods on a skull model. Noise similar to that expected from in-vivo measurements will be simulated and added to synthetic data to determine the approximate uncertainty in rate estimations. Circuits will be designed and constructed to capture phase-accurate data of resistivity and conductivity inside the head. The circuitry and reconstruction methods will be tested first in a spherical tank model and then on a fetal skull phantom. Sensitivity in the fetal skull phantom to different amounts of added blood will be compared with that found in the spherical tank. Finally, the system will be tested on a neonatal pig model. Piglets will be anesthetized and mechanically ventilated and ECG and ventilation data will be recorded synchronously with EIT data. After monitoring and examining the level of artifact produced by these processes, signals will be collected as blood is transfused into a lateral ventricle. These data will be analyzed to determine the best way of separating artifacts produced by shape changes and other body impedance changes from the bleeding process.
Showing the most recent 10 out of 11 publications
