Spectral tissue sensing for guidance and monitoring in oncological procedures

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The emergence of minimally invasive diagnostic and interventional procedures has increased the demand for real time guidance for a variety of oncological applications that rely on accurate instrument positioning and procedural feedback. In this thesis we described the results of various preclinical and clinical studies that were performed to evaluate the potential of diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) – so called spectral tissue sensing - for several applications. We also explored the benefits of incorporation of these technologies into existing medical devices and corresponding clinical workflow. In the first part we describe the challenges faced by translational researchers in their attempt to bridge the gap between technological advances and clinical practice. In the second part we investigated the feasibility of spectral tissue sensing during routine fluoroscopy-guided diagnostic lung biopsy procedures. A key finding was that extending the measured DRS wavelength range up to 1600 nm allowed reliable estimation of two diagnostically useful parameters (i.e. water content and scattering amplitude), regardless of the amount of blood that was encountered. Tissue diagnosis based on identified DRS contrast was diagnostically discriminant in 19 out of 21 clinical cases. In the third part changes in DRS spectral characteristics during radiofrequency ablation correlated with progressive degrees of thermal damage in hepatic and tumor tissue. The method allowed evaluation of the degree of thermal damage during RF ablation with more than 95% accuracy. Spectral ablation monitoring as investigated in the current work could be modified to provide real time feedback during open or percutaneous RF ablation. In the fourth part dual-modality DRS-FS measurements were performed on resected tissue specimens from 21 patients with colorectal cancer. Colon tumors could be distinguished from the surrounding healthy tissue based on various spectral parameters. Furthermore, we demonstrated the capability of dual-modality DRS-FS to monitor the effects of systemic treatment in a mouse model for hereditary breast cancer in an early stage. Although further clinical validation is required to determine the clinical viability of spectral tissue sensing technology, it is expected that it will become an integral part of future medical practice.