Coherent raman tissue spectroscopy for in vivo disease diagnosis

如果及早诊断并及时进行治疗，癌症患者的生存率会更高。因此，在过去的10-15年里，人们在开发用于不同临床应用的光学诊断方面做出了巨大的努力，包括基于组织吸收光、弹性散射、荧光（内源性和外源性给药荧光团）的技术。每种技术都有其自身的优势和局限性，这取决于信号的强度、速度、分辨率（空间、时间和/或光谱）以及对改变的组织特性（结构、生化、分子）的敏感性和特异性等因素。近红外拉曼光谱（NIRS）具有对组织生物化学变化敏感的特殊优势，无需额外的造影剂或药物。它基于分子对光的非弹性散射现象，探测生物分子的振动状态。近红外光谱（NIRS）在近10年来已被广泛研究，用于非或微创组织临床诊断（“光学活检”），并对癌症诊断和手术指导有很大帮助，但主要因其信号强度低而遇到了广泛临床应用的重要障碍。相干拉曼效应（CARS）可用于产生比近红外光谱强得多的拉曼信号，而不会产生与内源荧光相关的问题。本提案的基本假设是，这种新型光学技术将为自发拉曼提供必要的改进，以允许其在临床用于非侵入性癌症诊断的粗成像和/或精细成像（更高采样或生化图）。为了证明这一假设，我们将构建一个宽带CARS光谱系统，并将其与近红外光谱在组织样本和癌症动物模型中的性能进行比较。一旦证明了CARS光谱相对于自发拉曼光谱的优势，我们将在具有有限成像能力的原型机的临床前试验中确认CARS光谱在体内的技术可行性。

The survival rate of cancer patients is better when a diagnosis is made early and treatment is carried out promptly. Hence, there has been a large effort in the development of optical diagnostics for different clinical applications over the last 10-15 years, including techniques based on light absorption by tissues, elastic scattering, fluorescence (endogenous and with exogenous administered fluorophores). Each of these techniques has its own strengths and limitations, depending on factors such as the strength of the signals, speed, resolution (spatial, temporal and/or spectral) and sensitivity and specificity to altered tissue properties (structural, biochemical, molecular). Near Infrared Raman Spectroscopy (NIRS) has the specific advantage that it is sensitive to changes in the tissue biochemistry, without additional contrast agents or drugs. It is based on the phenomenon of inelastic scattering of light by molecules and probes the vibrational states of (bio)molecules. NIRS has been investigated intensely especially in the past 10 years, for non- or minimally-invasive tissue clinical diagnostics ("optical biopsies"), and has been very helpful cancer diagnosis and surgery guidance, but has encountered important roadblocks for widespread clinical applications mainly related to its low signal strength. The coherent Raman effect (CARS) can be used to generate a Raman signal much stronger than in NIRS without problems related to endogenous fluorescence. The basic assumption in this proposal is that this novel optical technique will provide the necessary improvements over spontaneous Raman to permit its use for coarse and/or fine imaging (higher sampling or biochemical maps) in the clinic for non invasive cancer diagnosis. To prove this hypothesis, we will construct a broadband CARS spectroscopy system and compare its performance to NIRS in tissue samples and animal models of cancer. Once the superiority of CARS spectroscopy over spontaneous Raman has been demonstrated, we will confirm the technical feasibility of CARS spectroscopy in vivo in a pre-clinical trial with a prototype having limited imaging capabilities.