Terahertz Spectroscopy and Imaging of Brain Tumors

Abstract

During the past decades, terahertz (THz) spectroscopy and imaging have attracted considerable attention in biophotonics and, in particular, in label-free diagnosis of malignancies with different nosology and localization, thanks to strong sensitivity of THz waves to the content and state (free or bound) of water in tissues. The water content is usually increased in malignancies due to the abnormal vascularity, edema, and (in some cases) presence of necrotic debris, thus, providing an ability of using THz technology for the detection of tumor margins either before or during surgery. Only few years ago, pilot papers dedicated to intraoperative diagnosis of brain tumors using THz waves have been published, opening this novel exciting application of THz technology. In this chapter, we start with brief introduction to THz technology, peculiarities of THz-wave–tissue interactions, and THz pulsed spectroscopy, as a main tool of THz biophotonics nowadays. Then, we review results of THz spectroscopy and imaging of brain tumors ex vivo and in vivo, considering glioma models from mice and rats, human brain gliomas of different grades, as well as pilot measurement of human brain meningioma. Finally, we consider recent THz measurements of traumatic brain injuries in rats, since they feature similar origin of contrast between normal and pathological tissues in the THz range, as compared to that of a tumor. The material of this chapter highlights a bright future of THz technology in the intraoperative diagnosis of human brain tumors.