In vivo testing of a non-invasive prototype device for the continuous monitoring of intracerebral hemorrhage

Background: Intracerebral hemorrhage (ICH) is a stroke subtype with the highest mortality rate. Hematoma expansion and re-bleeding post-ICH are common and exacerbate the initial cerebral insult. There is a need for continuous monitoring of the neurologic status of patients with an ICH injury. New method: A prototype device for non-invasive continuous monitoring of an ICH was developed and tested in vivo using a porcine ICH model. The device consists of receiving and transmitting antennae in the 400-1000. MHz frequency range, placed directly in line with the site of the ICH. The device exploits the differences in the dielectric properties and geometry of tissue media of a healthy brain and a brain with an ICH injury. The power received by the receiving antenna is measured and the percent change in power received immediately after infusion of blood and 30. min after the infusion, allowing for the blood to clot, is calculated. Results: An increase in the received power in the presence of an ICH is observed at 400. MHz, consistent with previous in vitro studies. Frequency sweep experiments show a maximum percent change in received power in the 750-1000. MHz frequency range. Comparison with existing methods: Currently, CT, MRI and catheter angiography (CA) are the main clinical neuroimaging modalities. However, these techniques require specialized equipment and personnel, substantial time, and patient-transportation to a radiology suite to obtain results. Moreover, CA is invasive and uses intra-venous dye or vascular catheters to accomplish the imaging. Conclusions: The device has the potential to significantly improve neurologic care in the critically ill brain-injured patient.