Microwave sensing of increased intracranial water content

A new technique to monitor brain edema is described that uses microwave energy to detect increased intracranial water content. By recording the phase of a transmitted microwave signal, increases in intracranial water content on the order of 1% are detected in vivo. These findings suggest that the progression of brain edema on a long-term basis can be assessed by progression of brain edema on a long-term basis can be assessed by our technique. Furthermore, phase changes related to small intracranial pressure variations are observed, indicating that the detection of pathologic pressure variations such as Traube-Hering-Mayer waves and plateau waves is possible by a noninvasive microwave technique.