Label-Free Molecular Vibrational Imaging for Cancer Diagnosis

This chapter describes a novel strategy combining label-free molecular vibrational imaging and automated image quantitation for intraoperative characterization of cancer lesions using the coherent anti-Stokes Raman scattering imaging (CARS) technique. A cell morphology based analytical platform is introduced to characterize CARS images and provide diagnostic information by detecting disease-related pathology features. This strategy is validated for several different applications, including surgical margin detection for radical prostatectomy and differential diagnosis of lung cancer. The developed analytical strategy shows high accuracy and specificity for detection of a number of diseases and thus introduces the CARS imaging technique into the field of human cancer diagnosis with substantial potential for clinical translation.The second half of this chapter focuses on miniaturizing the CARS imaging device into a microendoscope setup using a fiber-delivery strategy. Simultaneous delivery of the two CARS-generating excitation laser beams causes a four-wave mixing (FWM) background signal. As such, a polarization-based strategy is introduced and tested for suppression of this FWM noise. The approach shows effective suppression of the FWM signal, both on microscopic and prototype endoscopic setups, indicating the potential of developing a novel microendoscope with a compatible size for clinical use. These positive results show promise for the development of an all-fiber-based, label-free, chemically selective, and quantitative imaging modality for minimally invasive detection and diagnosis of cancer and cancer subtypes within a heterogeneous population during surgery or surgical-biopsy that will improve surgical outcomes and reduce patient suffering.