Date of Award

2024

Document Type

Thesis (Master's)

Department or Program

Engineering Sciences

First Advisor

Kimberley Samkoe

Second Advisor

Eric Henderson

Abstract

Fluorescence guided surgery (FGS) is an evolving field that aims to improve patient outcomes by using fluorophores to identify important tissues during surgery, such as tumors and nerves. In this thesis work, we explored different methods of identifying nerve and tumor tissues for FGS and a novel fluorescence-based method to determine the depths of these structures.

Researchers have explored using fluorescence guided surgery for surgical resection of cancerous tissues, including recent work by our group focusing on identifying soft tissue sarcomas with ABY-029, an epidermal growth factor receptor targeting probe. However, our preclinical and clinical work shows no single reporter characterizes all areas of the tumor, which compromises our ability to reliably detect residual cancer in the tumor bed. We developed an innovative strategy to enhance tumor contrast by using multiple near-infrared fluorophore reporters with similar emission wavelengths that target different regions of the tumor milieu. In this work, fluorescence from single fluorophores (ABY-029, bevacizumab-IRDye800, indocyanine green (ICG), and 6QC-ICG) were compared in a murine STS model.

Fluorescence guided surgery can not only be used to identify structures for removal, such as tumors, but also to distinguish structures that surgeons aim to avoid, such as nerves. Presently, intraoperative guidance for nerve and other normal structure identification is limited. In this work, we aimed to test the ability of a novel nerve targeting agent, LGW16-03, to label human nerve tissue in two ex vivo preclinical models using innovative methods that utilize freshly resected human specimens. We demonstrated that signal-to-background ratios could be achieved that are similar to preclinical studies of similar fluorophores. Therefore, ex vivo human tissue models appear to provide physiologically relevant preclinical evaluation of fluorophores with no known risks to patients and may aid in improved selection of lead agents prior to first-in-human trials.

We then aimed to quantitatively evaluate depth of structures of interest using a newly developed multi-excitation wavelength emission ratio (MEWER) methodology tested in validated tissue simulating gelatin phantoms. Results suggest that MEWER has the potential to discern depths less than 6 mm. However, improved identification methods for optical properties of tissue are necessary to determine unknown depths.

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