A study of evaluating specific tissue oxygen saturation values of gastrointestinal tumors by removing adherent substances in oxygen saturation imaging

Abstract

Objectives Oxygen saturation (OS) imaging is a new method of endoscopic imaging that has clinical applications in oncology which can directly measure tissue oxygen saturation (Sto2) of the surface of gastrointestinal tract without any additional drugs or devices. This imaging technology is expected to contribute to research into cancer biology which leads to clinical benefit such as prediction to efficacy of chemotherapy or radiotherapy. However, adherent substances on tumors such as blood and white coating, pose a challenge for accurate measurements of the StO2 values in tumors. The aim of this study was to develop algorithms for discriminating between the tumors and their adherent substances, and to investigate whether it is possible to evaluate the tumor specific StO2 values excluding adherent substances during OS imaging. Methods We plotted areas of tumors and their adherent substances using white-light images of 50 upper digestive tumors: blood (68 plots); reddish tumor (83 plots); white coating (89 plots); and whitish tumor (79 plots). Scatter diagrams and discriminating algorithms using spectrum signal intensity values were constructed and verified using validation datasets. StO2 values were compared between the tumors and tumor adherent substances using OS images of gastrointestinal tumors. Results The discriminating algorithms and their accuracy rates (AR) were as follows: blood vs. reddish tumor: Y> - 4.90X+7.13 (AR: 95.9%) and white coating vs. whitish tumor: Y< -0.52X+0.17 (AR: 96.0%). The StO2 values (median, [range]) were as follows: blood, 79.3% [37.8%–100.0%]; reddish tumor, 74.5% [62.0%–86.9%]; white coating, 73.8% [42.1%–100.0%]; and whitish tumor, 65.7% [53.0%–76.3%]. Conclusions OS imaging is strongly influenced by adherent substances for evaluating the specific StO2 value of tumors; therefore, it is important to eliminate the information of adherent substances for clinical application of OS imaging.

In vivo detection of bile duct pre-cancer with endoscopic light scattering spectroscopy

“…Though the increase in the hemoglobin concentration could be explained by angiogenesis and the decrease in oxygen saturation from ~72% on average for benign and inflammation sites to below 65% on average for high-grade dysplasia and cancer sites is consistent with the changes that has previously been observed in various gastrointestinal organs such as esophagus 52 , stomach 53 , and colon 22 , none of these changes could be used for reliable differentiation of malignancy.…”

Endoscopic light scattering spectroscopy for in vivo detection of pre-cancer in bile duct

“…2A. A similar rationale applies to oxygen saturation that tumor growth leads to rapid oxygen consumption by proliferating cells, creating a hypoxic environment [19]. Thus, the lowest oxygen saturation values are of particular interest.…”

Quantitative Analysis of the Concentration of Trifluridine in Tumor Hypoxic Regions Using a Novel Platform Combining Functional Endoscopy and Mass Spectrometry

“…The information of oxygen saturation measured with this system was validated using the ex vivo phantom model, animal models, and first‐in‐human study in our prior study 13 . Because of the wavelength of 473 nm principal laser, the information of oxygen saturation could interfere with the adherent substances on the tumor surfaces 18 …”

“…13 Because of the wavelength of 473 nm principal laser, the information of oxygen saturation could interfere with the adherent substances on the tumor surfaces. 18 To quantify oxygen saturation in the tissue, a 5-mm-diameter circle centered at the point where the biopsy was taken was drawn on the OXEI image, then information on oxygen saturation inside the circle with ~ 1,845 pixels was extracted, and the median value of tissue oxygen saturation (StO 2 ) was calculated. OXEI scans were analyzed using the OSI sample pick tool (Fujifilm Corporation, Tokyo, Japan).…”