使用單發雷射之雙模態光聲/超音波顯微系統

Abstract

本研究致力於開發一套光聲/超音波雙模態顯微系統，以建立腫瘤血管新生三維模型之影像為目標。本研究開發之系統具有微米等級解析度與高影像深度，且不同於傳統光聲影像系統與超音波影像系統，僅使用單一雷射二極體即能產生出共模態影像。系統概念採用雷射誘發式超音波(Laser induced ultrasound)，以PDMS混和物之多層膜結構取代傳統超音波探頭作為超音波激發源，能夠產生高頻、窄頻超音波訊號，藉由頻譜分離法將兩種模態影像分離與分別成像，多層膜所產生之超音波訊號頻譜可創造於12 MHz以下與光聲訊號10 dB影像對比。線與腫囊複合仿體的影像建立，驗證系統具備血管及腫瘤三維影像之潛力，透過標定金奈米粒子於觀測細胞上，近紅外光雷射二極體能夠激發光聲訊號，觀測血管內皮細胞，以利進一步建立新生血管影像。

A dual-modality photoacoustic-ultrasound system was developed for mapping three-dimensional models of tumor angiogenesis. The system features micron scale spatial resolution in photoacoustic imaging, high resolution in ultrasound imaging and high imaging depth. With a single pulsed laser diode, the system is able to make dual-modality images by laser induced ultrasound without an additional ultrasonic pulser. A multilayer film made by PDMS and graphite powder was used to generate high frequency and narrow band ultrasound. Accordingly, photoacoustic and ultrasound signals can be separated with simple filtering and the photoacoustic image and the ultrasound image can be generated concurrently. The scheme creates 10 dB signal contrast and was tested with a fiber and cyst phantom. Gold nanorods with the absorption peak in near infrared range were used to generate the photoacoustic signal. By targeting gold nanorods on the vessels, the system has the potential to investigate neovascularization and establish 3D tumor angiogenesis models.