SignificanceIn the United States, colorectal cancer is the third leading cause of cancer death. Colonoscopy with polyp removal may suffer from incomplete resection. Collagen is altered in dysplastic tissue and can be studied with second harmonic generation (SHG) imaging. SHG imaging endoscopes require miniaturized scanning components, which greatly adds to endoscope complexity.AimWe investigate whether non-imaging, randomly sampled SHG line or point intensity measurements are sufficient to distinguish normal tissue from tumor and tumor-adjacent tissue.ApproachUnstained tumor, normal, and tumor-adjacent thin sections from 10 colorectal cancer subjects were imaged using a multiphoton microscope with constant power. SHG signal from collagen was isolated by grayscale thresholding, and the grayscale mean of the image was calculated. Supra-threshold pixels and lines of pixels in the image were randomly selected to simulate point sampling and line scanning.ResultsThe mean SHG signal from normal samples was significantly greater than adjacent samples (p<0.05) and tumor samples (p<0.01). For both sampling types, the p-value becomes reliable after randomly sampling only 1000 times.ConclusionsReliable cancer detection information may be obtained through non-imaging SHG intensity measurements. A simple endoscope with this capability could help identify suspicious masses or optimum surgical margins.
SignificanceThe current technology has limited ability to detect lateral thermal spread of injury caused by electrosurgical devices during gynecologic procedures.AimWe aim to assess the feasibility of endoscopic optical coherence tomography (OCT) to detect electrothermal ureteral damage.ApproachElectrothermal energy was externally applied to nine explanted porcine ureters. Three segments of each ureter were treated for 5 s at low (16 W), medium (26 W), and high (36 W) powers (n=27 segments). Volumetric OCT images were acquired using a swept source OCT laser endomicroscopy system. OCT datasets were visually inspected for characterization of normal and electrothermally injured tissue architecture. Ground-truth comparisons were made with histology to validate the presence of lesions and to compare lesion size measurements using Pearson’s correlation coefficient. Three physicians were trained to identify OCT images of normal and injured ureters. Physician lesion detection accuracy was tested with 126 OCT images (63 normal and 63 injured). The effect of treatment power on lesion length as measured with OCT was compared using a one-way analysis of variance.ResultsTransmural electrothermal injury was identified on OCT images for all but one histology-confirmed lesion (22/23, 95.7%). The average sensitivity and specificity for physician lesion detection were 82% and 96%, respectively. The mean lesion size measured on OCT was 3.6±1.9, 4.4±1.3, and 7.0±2.9 mm for low, medium, and high powers, respectively (p=0.024). A comparison of lesion size measured on OCT and histology revealed a moderate positive correlation (r=0.65, p=0.00087).ConclusionsEndoscopic OCT could fulfill the unmet clinical need for the timely detection of electrothermal ureteral injury.
Esophageal cancer’s increasing prevalence coupled with a 5-year average survival rate below 20% due largely to late detection indicates a significant need for improved imaging tools that can detect and localize early, unseen lesions and be incorporated into endoscopy for screening and evaluation of early symptoms. While white light imaging or virtual chromoendoscopy contrast-enhancement techniques like narrow-band imaging have largely seen commercialization, there remain emerging label-free imaging-based techniques that show promise for improving diagnosis and biopsy guidance. Among them we investigate the clinical potential of hyperspectral (HSI) and autofluorescence imaging (AFI) which lend themselves well to implementation in an endoscopic system. We performed ex-vivo imaging on esophageal biopsies suspicious for carcinoma (N=11) and/or Barrett’s esophagus (N=6) and adjacent normal appearing squamous mucosa in the same patient as controls. Our results indicate AFI and HSI are both promising imaging modalities for detecting and localizing morphological and metabolic changes associated with esophageal cancer.
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