Terahertz attenuated total reflection imaging of fresh brain glioma based on a solid immersion lens

The diagnosis and treatment of gliomas depend greatly on the precise delineation of tumor boundaries and the rapid extraction of molecular pathological features. The development of high-resolution and high-sensitivity terahertz (THz) attenuated total reflection (ATR) imaging technology can greatly expand its application in the clinical medical field. In this study, we demonstrated a THz ATR imaging system based on a solid immersion lens (SIL). The resolution improvement mechanism by a solid immersion lens in the THz ATR imaging system has been studied theoretically and experimentally. According to the theoretical analysis results, the optimal parameters of the system have been selected. The spatial resolution of the THz imaging system was up to 120μm × 140μm. On this basis, the THz reflectivity of fresh normal brain tissue and glioma tissue in a mouse model was studied. Compared with the visible, MR, and H&E-stained images, the accurate identification of the glioma region boundary and microscopic structures in brain tissues was realized. The glioma regions in H&E-stained and THz ATR images were segmented automatically based on the Chan-Vese active contour model, where the performance evaluation rates were all above 95%. These promising results suggest that THz ATR imaging based on SIL could be used as a tool for label-free, high-sensitivity, and real-time imaging of brain gliomas.