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

Clinical usefulness of hypoxia imaging colonoscopy for the objective measurement of ulcerative colitis disease activity

BACKGROUND AND AIMS

Colonic mucosal hypoxia is associated with mucosal inflammation in ulcerative colitis (UC). We aimed to assess the clinical usefulness of hypoxia imaging colonoscopy for the evaluation of clinical, endoscopic, and histologic disease activities of UC.

METHODS

This retrospective cohort study comprised 100 consecutive patients with UC who underwent hypoxia imaging colonoscopy between September 2022 and September 2023 at the University of Tsukuba Hospital. Colonic tissue oxygen saturation (StO2) was measured at the biopsy sites, and StO2 values between different disease activities were compared. Receiver-operating characteristic (ROC) analysis was used to calculate the area under the ROC curve (AUROC).

RESULTS

A significant correlation was identified between rectal StO2 and the Simple Clinical Colitis Activity Index, with moderate accuracy to predict bowel urgency at a 40.5% cutoff (AUROC, .74; 95% confidence interval [CI], .62-.87). Our analysis of 490 images showed median StO2 values for Mayo endoscopic subscores 0, 1, 2, and 3 as 52% (interquartile range [IQR], 48%-56%), 47% (IQR, 43%-52%), 42% (IQR, 38.8%-47%), and 39.5% (IQR, 37.3%-41.8%), respectively. Differences for all pairs were significant. Median StO2 was 49% (IQR, 44%-54%) for Geboes scores 0 to 2, significantly higher than histologically active disease (Geboes score ≥3). At a colonic StO2 cutoff of 45.5%, AUROCs for endoscopically and histologically active diseases were .79 (95% CI, .74-.84) and .72 (95% CI, .66-.77).

CONCLUSIONS

StO2 obtained by hypoxia imaging colonoscopy is useful for assessing clinical, endoscopic, and histologic activities of UC, suggesting that StO2 may be a novel and objective endoscopic measurement.

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

Hypoxic regions in solid tumors are highly resistant to drugs and thus represents an obstacle in drug discovery. Currently, however, there are technical barriers in sampling human hypoxic tumors and examining drug delivery with high sensitivity and accuracy. Herein, we present a new platform combining functional endoscopy and highly sensitive liquid chromatography-mass spectrometry (LC-MS) to assess drug delivery to hypoxic regions. Because oxygen saturation endoscopic imaging (OXEI), a functional endoscopy, can evaluate lesions and hypoxia in real-time by simultaneously acquiring a pseudocolor map of oxygen saturation and conventional endoscopic images, this platform can be used to evaluate drug delivery with human samples from hypoxic regions. As the first clinical application of this platform, the relationship between hypoxic regions and the concentration of trifluridine (FTD) incorporated into DNA was evaluated in patients with advanced gastric cancer treated with FTD/tipiracil (FTD/TPI; n = 13) by obtaining and analysis of tissue samples by OXEI and LC-MS and vascular maturity index by CD31/α-SMA staining ex vivo. The results showed that the concentration of FTD was significantly higher in the normoxic region than in the hypoxic region (P < 0.05) and there were significantly more immature vessels in hypoxic regions than in normoxic regions (P < 0.05). These results indicate that the platform was sufficiently sensitive to evaluate differences in drug anabolism in different oxygenic regions of human tumor tissue. This new platform allows quantitative drug analysis in hypoxic regions and is expected to initiate a new era of drug discovery and development.

Immunohistochemistry and oxygen saturation endoscopic imaging reveal hypoxia in submucosal invasive esophageal squamous cell carcinoma

BACKGROUND

Hypoxic microenvironment is prominent in advanced esophageal squamous cell carcinoma (ESCC). However, it is unclear whether ESCC becomes hypoxic when it remains in the mucosal layer or as it invades the submucosal layer. We aimed to investigate whether intramucosal (Tis-T1a) or submucosal invasive (T1b) ESCC becomes hypoxic using endoscopic submucosal dissection samples.

METHODS

We evaluated the expression of hypoxia markers including hypoxia inducible factor 1α (HIF-1α), carbonic anhydrase IX (CAIX), and glucose transporter 1 (GLUT1) by H-score and vessel density by microvessel count (MVC) and microvessel density (MVD) for CD31 and α-smooth muscle actin (α-SMA) with immunohistochemical staining (n = 109). Further, we quantified oxygen saturation (StO2 ) with oxygen saturation endoscopic imaging (OXEI) (n = 16) and compared them to non-neoplasia controls, Tis-T1a, and T1b.

RESULTS

In Tis-T1a, cccIX (13.0 vs. 0.290, p < 0.001) and GLUT1 (199 vs. 37.6, p < 0.001) were significantly increased. Similarly, median MVC (22.7/mm2 vs. 14.2/mm2 , p < 0.001) and MVD (0.991% vs. 0.478%, p < 0.001) were markedly augmented. Additionally, in T1b, the mean expression of HIF-1α (16.0 vs. 4.95, p < 0.001), CAIX (15.7 vs. 0.290, p < 0.001), and GLUT1 (177 vs. 37.6, p < 0.001) were significantly heightened, and median MVC (24.8/mm2 vs. 14.2/mm2 , p < 0.001) and MVD (1.51% vs. 0.478%, p < 0.001) were markedly higher. Furthermore, OXEI revealed that median StO2 was significantly lower in T1b than in non-neoplasia (54% vs. 61.5%, p = 0.00131) and tended to be lower in T1b than in Tis-T1a (54% vs. 62%, p = 0.0606).

CONCLUSION

These results suggest that ESCC becomes hypoxic even at an early stage, and is especially prominent in T1b.

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

Bile duct cancer is the second most common primary liver cancer, with most diagnoses occurring in the advanced stages. This leads to a poor survival rate, which means a technique capable of reliably detecting pre-cancer in the bile duct is urgently required. Unfortunately, radiological imaging lacks adequate accuracy for distinguishing dysplastic and benign biliary ducts, while endoscopic techniques, which can directly assess the bile duct lining, often suffer from insufficient sampling. Here, we report an endoscopic optical light scattering technique for clinical evaluation of the malignant potential of the bile duct. This technique employs an ultraminiature spatial gating fiber optic probe compatible with cholangioscopes and endoscopic retrograde cholangiopancreatography (ERCP) catheters. The probe allowed us to investigate the internal cellular composition of the bile duct epithelium with light scattering spectroscopy (LSS) and phenotypic properties of the underlying connective tissue with diffuse reflectance spectroscopy (DRS). In a pilot in vivo double-blind prospective study involving 29 patients undergoing routine ERCP procedures, the technique detected malignant transformation with 97% accuracy, showing that biliary duct pre-cancer can be reliably identified in vivo non-invasively.