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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session D

Poster G5 - Raman Topographic Imaging: A New Tool to Guide Tumor Resection

Friday, October 25, 2024
3:30 PM - 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  In this study, we emphasize the importance of achieving complete tumor resection during initial surgical intervention to enhance patient outcomes and minimize repeat surgeries. However, intraoperative confirmation of complete tumor removal, particularly in breast cancer lumpectomies, poses significant challenges. Current techniques, such as touch preparation cytology, have proven inconsistent in detecting residual malignant cells, and the fatty nature of breast tissue complicates rapid histological processing. To address this, we propose a novel workflow that involves immunostaining and topographically imaging the surface of freshly excised lumpectomy specimens. This method utilizes highly sensitive and spectrally separable surface-enhanced Raman scattering nanoparticles (SERS NPs) as targeted contrast agents. SERS NPs are ideal for this application due to their sensitivity and their narrow spectral bands, which allows for rapid detection and enables extensive intra-pixel multiplexing. By synchronizing an advanced Raman microscope with a new rotational accessory device, we achieve topographic mapping of entire specimen surfaces and accurate detection of our SERS NPs. This work details the development and validation of our Raman topography imaging method, demonstrating its potential to significantly improve surgical outcomes by providing a comprehensive and accurate assessment of tumor margins.

Materials and

Methods:  Our study utilized a Renishaw RA816 Biological Analyser Raman microscope, equipped with a Leica N PLAN L 50 × 0.50 NA objective lens, Renishaw MS 20 encoded stage, and a 785 nm diode laser operating at 10mW, all controlled by Renishaw’s WiRE software for setting pixel step size, laser power, exposure time, and postprocessing tasks like spectral baseline correction and quantitative spectral unmixing. To validate topographic imaging, molded polymer phantoms with identifiable test patterns were used, demonstrating accurate replication of the phantom’s size, shape, and texture through the Raman microscope’s autofocusing system. 3D renderings of topographic images were created using a spiral acquisition protocol and point cloud surface mesh reconstruction, providing detailed, manipulatable views of the specimen’s surface. SERS NPs were synthesized by encapsulating different reporter molecules and functionalizing them with antibodies targeting specific cancer biomarkers. These SERS NPs were mixed into cocktails, enabling quantitative spectral unmixing to determine the distribution and concentration of biomarker-specific SERS NPs on the stained surface.

Results, Conclusions, and Discussions: Our study confirmed the efficacy of topographic Raman imaging in accurately capturing the visual characteristics of various samples, including size, shape, and surface texture. Applied to porcine abdominal tissue, which closely resembles human breast tissue, our method effectively identified and localized SERS NPs present on the tissue surface. We successfully mapped and recognized 26 distinct types of SERS NPs and effectively deconvolved and localized randomly mixed NP samples. We also quantitatively assessed the impact of increasing NP concentrations, finding a linear relationship with the Raman signal. These results further support the high specificity and multiplexing capabilities of our nanoparticles and our overall imaging technique.

Acknowledgements (Optional):