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Biomedical Imaging and Instrumentation

Biomedical Imaging and Instrumentation - Poster Session C & D

V9 - Non-contact optical spectroscopy for functional characterizations of orthotopic tongue tumor models in vivo

Friday, October 10, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

Md Zahid Hasan

Phd Candidate
Department of Biomedical Engineering, University of Kentucky
Lexington, Kentucky, United States

Co-Author(s)

JY

Jing Yan

Phd Candidate
University of Kentucky
Lexington, Kentucky, United States
SS

Sumit Sarkar, n/a

Graduate Student
University of Kentucky
Lexington, Kentucky, United States
PS

Pranto Soumik Saha

PhD Student
University of Kentucky, United States
Caigang Zhu

Associate Professor
University of Kentucky, Kentucky, United States

Primary Investigator(s)

Caigang Zhu

Associate Professor
University of Kentucky, Kentucky, United States

Introduction: : Precise optical spectroscopy measurements on mouse tongue tumors in vivo by a fiber probe is critically difficult as the inconsistent probe-tissue contact may introduce significant measurement errors [1, 2]. To address this challenge, we report a non-contact optical spectroscopy platform to enable accurate quantification of several key vascular (oxygenation, total hemoglobin concentration) and metabolic (glucose uptake and mitochondrial membrane potential) endpoints of mouse tongue tumors in vivo to advance oral cancer discovery.

Materials and

Methods: : We combined dark field [3] based diffuse reflectance and lens-based fluorescence spectroscopy into one portable platform [4] to enable multi-parametric functional characterizations of orthotopic tongue cancer models in vivo. We also implemented simple spectroscopic algorithms [5] with the system for rapid quantification of the key metabolic (glucose uptake using 2-NBDG, and mitochondrial membrane potential using TMRE) and vascular parameters (oxygenation (StO2), and total hemoglobin concentration ([THB])) on biological tissue models with high accuracy. We then validated our non-contact optical spectroscopy and spectroscopic algorithms using tissue-mimicking hemoglobin phantoms and tissue-mimicking fluorescence phantoms [5]. We further demonstrated our technique via preclinical animal studies using an orthotopic mice tongue tumor model to study the metabolic and vascular changes of tongue tumors with different radiation sensitivities. All animal work was approved by the University of Kentucky Institutional Animal Care and Use Committee (IACUC). The animal study involved 17 female athymic nude mice (nu/nu), aged 8–10 weeks. Mice were divided into three groups: normal group (n = 5), SCC-61 tumor group (n = 6, radiosensitive), and rSCC-61 tumor group (n = 6, radioresistant). The optical spectra collected from in vivo animals were processed using the spectroscopic algorithms to report the metabolic and vascular parameters of normal tongue tissues or tongue tumors.

Results, Conclusions, and Discussions::

Results: Figure 2 showed the validation of our non-contact spectroscopy and spectroscopic method for accurate measurements of the key metabolic and vascular parameters from diffuse reflectance and fluorescence measurements. Figure 2 (A)-(B) showed the raw diffuse reflectance spectra measured on hemoglobin phantom. Figure 2 (C)-(D) showed the corresponding analytical model extracted StO2 and [THB] indicator. The hemoglobin phantom studies demonstrated that our non-contact spectroscopy can indicate [THB] with high accuracy (R² = 0.964; Fig. 2C) and quantify StO2 values with comparable accuracy compared to a fiber-probe based spectroscopy[5] (Fig. 2D). Figure 2 (E)-(F) showed that our non-contact spectroscopy implemented with formerly reported ratio-metric method [6] can quantify intrinsic fluorescence of TMRE and 2-NBDG with a high accuracy. Figure 3 showed the in vivo animal study results. Figure 3 (A) showed that tongue tumors had significantly lower StO2 in both SCC-61 and rSCC-61 tumors compared to normal tongue tissues (p = 0.008, and p = 0.02; Fig. 3A). Figure 3 (B) showed that [THB] indicator was also lower in tumors, with a significant reduction in rSCC-61 compared to normal (p = 0.005, Fig. 3B). Figure 3 (C) and (D) showed that tongue tumors had significantly different metabolic profiles compared to normal tongue tissues [7]. Moreover, rSCC-61 tumors had higher 2-NBDG uptake and comparable TMRE uptake compared to SCC-61 tumors.

Discussion: Our in vivo study revealed significantly lower StO2 and [THB] in SCC-61 and rSCC-61 tumors compared to normal tissue indicating tumor hypoxia and impaired vasculature [8]. Additionally, elevated 2-NBDG uptake and TMRE uptake in tongue tumors, reporting altered energy demands and metabolic reprogramming that support tumor survival and growth. These distinct metabolic signatures, particularly in rSCC-61 compared to SCC-61 and normal tissue, suggest altered pathways that may contribute to the development of radiation resistance.

Conclusions: We reported a novel non-contact optical spectroscopy system enables accurate functional characterization of tissue metabolism and vasculature in vivo. Its portability, ease of use, and ability to quantify multiple metabolic and vascular endpoints make it a promising tool for preclinical oral cancer research and potential future clinical translation.

Acknowledgements and/or References (Optional): :

References:
[1] G. M. Palmer et al., "Assessing effects of pressure on tumor and normal tissue physiology using an automated self-calibrated, pressure-sensing probe for diffuse reflectance spectroscopy," Journal of biomedical optics, vol. 23, no. 5, pp. 057004-057004, 2018.
[2] A. Nath et al., "Effect of probe pressure on cervical fluorescence spectroscopy measurements," Journal of biomedical optics, vol. 9, no. 3, pp. 523-533, 2004.
[3] X. Liu, Y. Huang, and J. U. Kang, "Dark-field illuminated reflectance fiber bundle endoscopic microscope," Journal of biomedical optics, vol. 16, no. 4, pp. 046003-046003-7, 2011.
[4] M. Z. Hasan, P. S. Saha, M. O. Korfhage, and C. Zhu, "Non-contact optical spectroscopy for tumor-sensitive diffuse reflectance and fluorescence measurements on murine subcutaneous tissue models: Monte Carlo modeling and experimental validations," Biomedical Optics Express, vol. 14, no. 10, pp. 5418-5439, 2023.
[5] M. Z. Hasan, J. Yan, and C. Zhu, "Point-of-care optical spectroscopy platform and ratio-metric algorithms for rapid and systematic functional characterization of biological models in vivo," Journal of Biomedical Optics, vol. 29, no. 12, pp. 125002-125002, 2024.
[6] T. Sun and C. Zhu, "Empirical method for rapid quantification of intrinsic fluorescence signals of key metabolic probes from optical spectra measured on tissue-mimicking turbid medium," Journal of Biomedical Optics, vol. 26, no. 4, pp. 045001-045001, 2021.
[7] P. Soumik Saha, J. Yan, and C. Zhu, "Portable multi-parametric microscopy for noninvasive metabolic and vascular imaging of orthotopic tongue cancer models in vivo," Journal of Biomedical Optics, vol. 30, no. S2, pp. S23905-S23905, 2025.
[8] P. S. Saha, J. Yan, and C. Zhu, "Diffuse reflectance spectroscopy for optical characterizations of orthotopic head and neck cancer models in vivo," Biomedical Optics Express, vol. 15, no. 7, pp. 4176-4189, 2024.