Abstract WMP102: Pilot Study of a Non-invasive Radiofrequency Method to Monitor Intracranial Hemorrhage: A First-in-Human Study

Abstract

Introduction: Intracerebral hemorrhage (ICH) is a devastating form of stroke. Hemorrhage expansion after ICH occurs in ~40% of patients and leads to worse outcomes. Currently, ICH patients are monitored for hemorrhage expansion by neurologic exam and head CT. CT studies are a source of radiation exposure and can require transporting the patient out of the ICU. There is a clinical need for a non-invasive bedside monitor of ICH. Methods: A radiofrequency based monitor (RFM) was developed as a non-invasive method to monitor ICH at the bedside. The RFM consists of a 9-antenna array mounted around the head, cables, and driving electronics. A 913 MHz signal is transmitted from a given antenna, crosses the brain, and is received by the remaining 8 antennae. A complete measurement consists of one cycle with all antenna serving as the transmitting antenna. As the signal traverses the brain, it is partially scattered and absorbed by the ICH, thus changing the signal at the receiving antennae. The altered signal can be compared to signals at earlier times to detect changes induced by ICH expansion. Based upon pre-clinical work it was hypothesized that ICH expansion of ≥3 ml would be detected by the RFM. The RFM device was approved for human study under an IDE from the FDA. The device was tested on 10 ICH subjects admitted within 24 hours of stroke onset. All subjects received a baseline head CT and a repeat head CT at 12 (+/- 6) hours. ICH volumes were determined by a blinded neuroradiologist. Subjects were scanned with the device every 10 minutes. Results: Data from one subject was lost due to user error. Among the remaining nine, two experienced hemorrhage expansion of ≥ 3ml (3 and 8.2 ml respectively). The RFM readings were 100% concordant with CT scans in identifying presence and absence of hemorrhage expansion. The figure shows monitor readings from a subject with expansion. Conclusion: The RFM may be useful in detection of real-time hemorrhage expansion in ICH patients. A pivotal clinical study is planned.