Conventional Endoscopic Images Research Articles

Esophagogastroscopy for predicting endoscopic ultrasonography T-stage by utilizing deep learning methods in esophageal cancer

Endoscopic ultrasonography (EUS) is commonly utilized in preoperative staging of esophageal cancer, however with additional pain and cost as well as adverse events. Meanwhile, the accuracy of EUS is highly depend on the training and practice of operators and not universally available. Different operators would lead to high inter-observer variability. Therefore, it is desirable to explore an alternative way to determine preoperative T stage in esophageal cancer. Whether conventional endoscopy possess the ability to predict EUS T stage has never been investigated yet. In current study, with the assistance of Artificial intelligence, we have developed a deep learning model to predict EUS T stage based on 9,714 images collected from 3,333 patients. ResNet-152 pre-trained on the ImageNet dataset was trained with the appropriate transfer learning and fine-tuning strategies on the conventional endoscopic images and their corresponding labels (e.g., T1, T2, T3, T4 and Normal). Meanwhile, augmentation strategies including rotation and flipping were performed to increase the number of images to improve the prediction accuracy. Finally, 4,382 T1, 243 T2, 3,985 T3, 1,102 T4, 14,302 controls images were obtained and split into training dataset, validation dataset and independent testing dataset with the ratio of 4:1:1. Our model could achieve a satisfied performance with an area under the receiver-operating curve (AUC) were 0.9767, 0.9637, 0.9597 and 0.9442 for T1, T2, T3 and T4, respectively in independent testing dataset. In conclusion, conventional gastroscopy combined with artificial intelligence have the great potential to predict EUS T stage.

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.

Anti-acid treatment for ulcerated early gastric cancer may be a treatment option avoiding unnecessary gastrectomy: a cohort study.

Twelve patients with ulcerated early gastric cancer who were treated with proton pump inhibitors, including vonoprazan, and underwent ESD were included in the study. Conventional endoscopic and narrow-band images were evaluated by five board-certified endoscopists (two physicians: A, B, and three gastrointestinal surgeons: C, D, and E). They assessed the invasion depth, and the results were compared with the pathologic diagnosis. The accuracy of the invasion depth diagnosis was 38.3%. According to the pretreatment diagnosis of invasion depth, gastrectomy was recommended for 41.7% (5/12) of the cases. However, histological examination revealed that additional gastrectomy was required in only one case (8.3%). Thus, in four out of five patients unnecessary gastrectomy could be avoided. Post-ESD mild melena occurred in only one case, and there was no case of perforation. Antiacid treatment contributed to avoid unnecessary gastrectomy in four out of five patients for whom gastrectomy was indicated based on an inaccurate pretreatment diagnosis of the invasion depth.

Real‐time coloring method of laser surgery video based on generative adversarial network

AbstractLasers have become an important technology for the medical treatment of cancer. However, the high power of visible laser knives makes conventional endoscopic imaging light pollution severe. This phenomenon can cause the physician to be unable to determine the condition of the lesion site. In this article, a colorization method for laser surgery videos is proposed. The method performs real‐time colorization of the laser surgery video under black‐and‐white imaging. The main contribution of this work is to propose a new idea for solving laser contamination in medical surgery videos, along with real‐time generative adversarial networks (RTGANs). The network takes advantage of generative adversarial networks and residual networks for fast colorization of black and white images. To evaluate the method, we conducted experiments using three datasets. The experimental results show that the RTGAN network takes only 0.026 s to colorize a single frame image. Coloring speed up to 67 times faster than advanced methods, and the Peak Signal to Noise Ratio reached a maximum of 35.736.

Factors influencing interruption of colorectal endoscopic submucosal dissection.

Although colorectal endoscopic submucosal dissection (ESD) has become a standardized procedure worldwide, the difficulty of the procedure is well known. However, there have been no studies assessing the causes of treatment interruption. The present study aimed to evaluate the factors involved in the interruption of colorectal ESD. We retrospectively analyzed 1116 consecutive superficial colorectal neoplasms of 1012 patients who were treated with ESD between August 2008 and September 2018. The clinicopathological characteristics and treatment outcomes were analyzed. Interrupted ESD was reported in 14 lesions (1.3%) of the total study population. Univariate analysis of clinical characteristics indicated that age, 0-I macroscopic-type tumor, and tumor location on the left side colon were risk factors for interruption. Multivariate analysis revealed that 0-I macroscopic-type tumor was the sole preoperative independent risk factor for interruption. Univariate analysis revealed that the presence of muscle-retracting sign (MRS), deep submucosal tumor invasion, and intermediate invasive growth pattern represented the etiology of interruption. Multivariate analysis indicated that MRS can be a sole key sign for the interruption. Additionally, the resectability and curability of 0-I type tumors were significantly inferior to those of predominantly lateral spreading tumors. Observations of 0-I macroscopic-type tumors, MRS, and submucosal deep invasion were significantly more frequent in interrupted cases. Conventional endoscopic images without magnification endoscopy were more associated with interruption than irregular surfaces or Vi pit patterns in cases with 0-I type tumors. ESD of 0-I type tumors is highly disruptive, and undiagnosable submucosal infiltration can reduce the curability.

The future of endoscopy: Advances in endoscopic image innovations.

The latest state of the art technological innovations have led to a palpable progression in endoscopic imaging and may facilitate standardisation of practice. One of the most rapidly evolving modalities is artificial intelligence with recent studies providing real-time diagnoses and encouraging results in the first randomised trials to conventional endoscopic imaging. Advances in functional hypoxia imaging offer novel opportunities to be used to detect neoplasia and the assessment of colitis. Three-dimensional volumetric imaging provides spatial information and has shown promise in the increased detection of small polyps. Studies to date of self-propelling colonoscopes demonstrate an increased caecal intubation rate and possibly offer patients a more comfortable procedure. Further development in robotic technology has introduced ex vivo automated locomotor upper gastrointestinal and small bowel capsule devices. Eye-tracking has the potential to revolutionise endoscopic training through the identification of differences in experts and non-expert endoscopist as trainable parameters. In this review, we discuss the latest innovations of all these technologies and provide perspective into the exciting future of diagnostic luminal endoscopy.

Using a deep learning system in endoscopy for screening of early esophageal squamous cell carcinoma (with video)

Few artificial intelligence-based technologies have been developed to improve the efficiency of screening for esophageal squamous cell carcinoma (ESCC). Here, we developed and validated a novel system of computer-aided detection (CAD) using a deep neural network (DNN) to localize and identify early ESCC under conventional endoscopic white-light imaging. We collected 2428 (1332 abnormal, 1096 normal) esophagoscopic images from 746 patients to set up a novel DNN-CAD system in 2 centers and prepared a validation dataset containing 187 images from 52 patients. Sixteen endoscopists (senior, mid-level, and junior) were asked to review the images of the validation set. The diagnostic results, including accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), were compared between the DNN-CAD system and endoscopists. The receiver operating characteristic curve for DNN-CAD showed that the area under the curve was >96%. For the validation dataset, DNN-CAD had a sensitivity, specificity, accuracy, PPV, and NPV of 97.8%, 85.4%, 91.4%, 86.4%, and 97.6%, respectively. The senior group achieved an average diagnostic accuracy of 88.8%, whereas the junior group had a lower value of 77.2%. After referring to the results of DNN-CAD, the average diagnostic ability of the endoscopists improved, especially in terms of sensitivity (74.2% vs 89.2%), accuracy (81.7% vs 91.1%), and NPV (79.3% vs 90.4%). The novel DNN-CAD system used for screening of early ESCC has high accuracy and sensitivity, and can help endoscopists to detect lesions previously ignored under white-light imaging.

Endoscopic analysis of colorectal serrated lesions with cancer.

Serrated lesions, including hyperplastic polyps (HPs), traditional serrated adenomas (TSAs) and sessile serrated adenomas/polyps (SSA/Ps), are important contributors to colorectal carcinogenesis. The aim of the present study was to analyze the potential of conventional endoscopy and advanced endoscopic imaging techniques to delineate the characteristic features of serrated lesions with cancer. The present study was a retrospective analysis of the data of 168 patients who had undergone colonoscopy, and a total of 228 serrated lesions (77 HPs, 58 TSAs, 84 SSA/Ps, 9 SSA/P plus TSAs) have been identified in these patients. A cancer component was identified in 2.6% of HPs, 13.8% of TSAs and 10.7% of SSA/Ps, but none of SSA/P plus TSAs. Compared with the lesions without cancer, the lesions with cancer exhibited a larger size (HP, TSA and SSA/P), a reddish appearance (SSA/P), a two-tier raised appearance (HP and SSA/P), a central depression (HP, TSA and SSA/P), the type V pit pattern (HP, TSA and SSA/P), and/or the type III capillary pattern (TSA and SSA/P). Deep invasion was identified in 50.0% of HPs, 12.5% of TSAs and 55.6% of SSA/Ps with cancer. The Ki-67 proliferative zone was distributed diffusely within the area of the cancer, but partially within the non-cancer area of HPs, TSAs and SSA/Ps. The lesion types were also analyzed on the basis of mucin phenotype. The present study suggested that a detailed endoscopic analysis of serrated lesions with cancer is useful for delineating characteristic features, and the analysis aids treatment selection.

Assessment of Gastric Acidity by Conventional Endoscopy With Serological Gastric Markers.

BackgroundGastric acidity could determine Helicobacter pylori (H. pylori)-associated gastritis patterns. In reverse, H. pylori infection could lead disturbance in gastric acid secretion. We attempted to elucidate gastric acid status by conventional endoscopy with pepsinogen test.MethodsA total of 196 subjects who visited our health promotion center were consecutively enrolled and evaluated by conventional endoscopy, and blood examinations with pepsinogen I, II, and fasting serum gastrin were conducted. As a Japanese study suggested that in H. pylori-positive subjects the cutoff value was PG I/II ratio ≤ 2.7 for hypochlorhydia, PG I/II ratio ≥ 3.3 for hyperchlorhydria. Based on these serological data, we compared conventional endoscopic images with each acid level.ResultsIt showed that for hypoacidity, older age, and most of the H. pylori-associated endoscopic appearances featuring mucosal inflammation and more atrophy of corpus or antrum were in favor of hypoacidity in closed type. Mucosal appearances showing severe corpus atrophy and remnant gastritis with advanced background atrophy determine hypoacidity in open type. For hyperacidity, mucosal appearances featuring intact mucosa and less severe atrophy were associated with hyperacid status. Male gender, antrum camouflage were also involved in hyperacidity.ConclusionsConventional endoscopy with pepsinogen test could be useful in gastric acid assessment.

Clinical Application of Magnifying Endoscopy with Narrow-Band Imaging in the Stomach

Magnifying endoscopy with narrow-band imaging (M-NBI) can visualize superficial microanatomies in the stomach. The normal morphology of the microanatomy visualized by M-NBI differs according to the part of the stomach. The gastric fundic glandular mucosa appears as a regular honeycomb-like subepithelial capillary network (SECN) pattern with a regular collecting venule pattern and regular oval crypt opening with circular marginal crypt epithelium (MCE) pattern. The gastric pyloric glandular mucosa displays a regular coil-shaped SECN pattern and regular polygonal or curved MCE pattern. For a diagnosis of early gastric cancer using M-NBI, the vessel plus surface classification system was developed. This system is clinically useful for the differential diagnosis of focal gastritis and small depressed cancer and for determining the horizontal extent of early gastric cancer for successful endoscopic resection. Advantages of M-NBI over conventional endoscopic imaging techniques with white light include accurate diagnosis and cost effectiveness. This technique is a breakthrough in the endoscopic diagnostic field.

Endocytoscopic narrow-band imaging efficiency for evaluation of inflammatory activity in ulcerative colitis.

To assess the efficacy of endocytoscopic narrow-band imaging (EC-NBI) for evaluating the severity of inflammation in ulcerative colitis (UC). This retrospective study was conducted at a single tertiary care referral center. We included UC patients who underwent colonoscopy with endocytoscopy from July 2010 to December 2013. EC-NBI was performed, and the images were evaluated by assessing visibility, increased vascularization, and the increased calibers of capillaries and were classified as Obscure, Visible or Dilated. Obscure was indicative of inactive disease, while Visible and Dilated were indicative of acute inflammation. This study received Institutional Review Board approval. The primary outcome measures included the diagnostic ability of EC-NBI to distinguish between active and inactive UC on the basis of histological activity. The conventional endoscopic images were classified according to the Mayo endoscopic score. A score of 0 or 1 indicated inactive disease, whereas a score of 2 indicated active disease. Fifty-two patients were enrolled. There was a strong correlation between the EC-NBI findings and the histological assessment (r=0.871, P<0.01). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EC-NBI for diagnosing acute inflammation were 84.0%, 100%, 87.1%, 100%, and 92.3%, respectively, while those for the Mayo endoscopic score were 100%, 40.7%, 100%, 61.0%, and 69.2%, respectively. Compared with conventional endoscopy, EC-NBI was superior in diagnostic specificity, negative predictive value, and accuracy (P<0.001, P=0.001 and P=0.047, respectively). The EC-NBI finding of capillaries in the rectal mucosa was strongly correlated with histological inflammation and aided in the differential diagnosis between active and inactive UC.

Real-Time Subglottic Stenosis Imaging Using Optical Coherence Tomography in the Rabbit

Subglottic stenosis (SGS) is a severe, acquired, potentially life-threatening disease that can be caused by endotracheal tube intubation. Newborns and neonates are particularly susceptible to SGS owing to the small caliber of their airway. To demonstrate optical coherence tomography (OCT) capabilities in detecting injury and scar formation using a rabbit model. Optical coherence tomography may provide a noninvasive, bedside or intensive care unit modality for the identification of early airway trauma with the intention of preventing progression to SGS and can image the upper airway through an existing endotracheal tube coupled with a small fiber-optic probe. Rabbits underwent suspension laryngoscopy with induction of of SGS via epithelial injury. This model was used to test and develop our advanced, high-speed, high-resolution OCT imaging system using a 3-dimensional microelectromechanical systems-based scanning device integrated with a fiber-optic probe to acquire high-resolution anatomic images of the subglottic epithelium and lamina propria. All experiments were performed at the Beckman Laser Institute animal operating room. INTERVENTION OR EXPOSURE: Optical coherence tomography and endoscopy was performed with suspension laryngoscopy at 6 different time intervals and compared with conventional digital endoscopic images and histologic sections. Fifteen rabbits were killed at 3, 7, 14, 21, and 42 days after the induction of SGS. The laryngotracheal complexes were serially sectioned for histologic analysis. Histologic sections, endoscopic images, and OCT images were compared with one another to determine if OCT could accurately delineate the degree of SGS achieved. The rabbit model was able to reliably and reproducibly achieve grade I SGS. The real-time OCT imaging system was able to (1) identify multiple structures in the airway; (2) delineate different tissue planes, such as the epithelium, basement membrane, lamina propria, and cartilage; and (3) detect changes in each tissue plane produced by trauma. Optical coherence tomography was also able demonstrate a clear picture of airway injury that correlated with the endoscopic and histologic images. With subjective review, 3 patients had high correlation between OCT and histologic images, 10 demonstrated some correlation with histologic images, and 2 showed little to no correlation with histologic images. Optical coherence tomography, coupled with a fiber-optic probe, identifies subglottic scarring and can detect tissue changes in the rabbit airway to a depth of 1 mm. This technology brings us 1 step closer to minimally invasive subglottic airway monitoring in the intubated neonate, with the ultimate goal of preventing SGS and better managing the airway.

Fiber‐optic Raman spectroscopy probes gastric carcinogenesis in vivo at endoscopy

Intestinal-type gastric carcinogenesis is a complex multi-step disease, and early precursors (e.g. intestinal metaplasia (IM), dysplasia) can be very challenging to identify using conventional white-light endoscopic imaging. This study aims to assess the capability of Raman spectroscopy for multi-class elucidation of intestinal-type gastric carcinogenesis sequence in vivo for improving precancer detection at endoscopy. We employ a novel image-guided Raman endoscopy technique developed for in vivo gastric tissue Raman measurement within 0.5 s during clinical endoscopic examination. We have acquired a total of 1277 in vivo Raman spectra from 83 gastric patients associated with intestinal-type carcinogenesis. In vivo Raman spectroscopy integrated with semi-quantitative spectral modelling (e.g. DNA, lipids, glycoprotein, proteins and blood) reveals the progressive changes of biochemical constituents in gastric tissue associated with preneoplastic and neoplastic transformation (i.e., IM, dysplasia and adenocarcinoma). Multi-class probabilistic partial least squares-discriminant analysis (PLS-DA) diagnostic algorithms based on in vivo Raman spectra are able to identify normal mucosa with sensitivity of 75.88% and specificity of 87.21%; IM with sensitivity of 46.67% and specificity of 87.55%; dysplasia with sensitivity of 83.33%; specificity of 95.80%, and adenocarcinoma with sensitivity of 84.91% and specificity 95.57%, respectively. This work demonstrates that Raman spectroscopy is a sensitive biomolecular probe for monitoring intestinal-type gastric carcinogenesis to realize early diagnosis and detection of precancer and early gastric cancer in vivo during clinical endoscopic examination.

Diagnosis of extent of early gastric cancer using flexible spectral imaging color enhancement

The demarcation line between the cancerous lesion and the surrounding area could be easily recognized with flexible spectral imaging color enhancement (FICE) system compared with conventional white light images. The characteristic finding of depressed-type early gastric cancer (EGC) in most cases was revealed as reddish lesions distinct from the surrounding yellowish non-cancerous area without magnification. Conventional endoscopic images provide little information regarding depressed lesions located in the tangential line, but FICE produces higher color contrast of such cancers. Histological findings in depressed area with reddish color changes show a high density of glandular structure and an apparently irregular microvessel in intervening parts between crypts, resulting in the higher color contrast of FICE image between cancer and surrounding area. Some depressed cancers are shown as whitish lesion by conventional endoscopy. FICE also can produce higher color contrast between whitish cancerous lesions and surrounding atrophic mucosa. For nearly flat cancer, FICE can produce an irregular structural pattern of cancer distinct from that of the surrounding mucosa, leading to a clear demarcation. Most elevated-type EGCs are detected easily as yellowish lesions with clearly contrasting demarcation. In some cases, a partially reddish change is accompanied on the tumor surface similar to depressed type cancer. In addition, the FICE system is quite useful for the detection of minute gastric cancer, even without magnification. These new contrasting images with the FICE system may have the potential to increase the rate of detection of gastric cancers and screen for them more effectively as well as to determine the extent of EGC.

The endoscopic diagnosis of nonerosive reflux disease using flexible spectral imaging color enhancement image: a feasibility trial

Nonerosive reflux disease (NERD) is classified into grade M (minimal change, endoscopically; erythema without sharp demarcation, whitish turbidity, and/or invisibility of vessels due to these findings) and grade N (normal) in the modified Los Angeles classification system in Japan. However, the classification of grades M and N NERD is not included in the original Los Angeles system because interobserver agreement for the conventional endoscopic diagnosis of grades M or N NERD is poor. Flexible spectral imaging color enhancement (FICE) is a virtual chromoendoscopy technique that enhances mucosal and vascular visibility. The aim of this study is to evaluate whether the endoscopic diagnosis of grades M or N NERD using FICE images is feasible. Between April 2006 and May 2008, 26 NERD patients and 31 controls were enrolled in the present study. First, an experienced endoscopist assessed the color pattern of minimal change in FICE images using conventional endoscopic images and FICE images side-by-side and comparing the proportion of minimal change between the two groups. Second, three blinded endoscopists assessed the presence or absence of minimal change in both groups using conventional endoscopic images and FICE images separately. Intraobserver variability was compared using McNemar's test, and interobserver agreement was described using the kappa value. Minimal changes, such as erythema and whitish turbidity, which were detected using conventional endoscopic images, showed up as navy blue and pink-white, respectively, in color using FICE images in the present FICE mode. The NERD group had a higher proportion of minimal change, compared with the control group (77% and 48%, respectively) (P= 0.033). In all three readers, the detection rates of minimal change using FICE images were greater than those using conventional endoscopic images (P= 0.025, <0.0001, and 0.034 for readers A, B, and C, respectively). The kappa values for all pairs of three readers using FICE images were between 0.683 and 0.812, while those using conventional endoscopic images were between 0.364 and 0.624. Thus, the endoscopic diagnosis of grades M or N NERD using FICE images is feasible and may improve interobserver agreement.

Diagnosis of endoscopic Barrett’s esophagus by transnasal flexible spectral imaging color enhancement

The diagnosis of endoscopic Barrett's esophagus (BE) has been under discussion for the past decade because palisade vessels may be obscured by inflammation or the location of upper end of gastric fold may be diversely changed. The flexible spectral imaging color enhancement (FICE) system can reconstruct improved spectral images decomposed from ordinary endoscopic images with free selection of three wavelengths, and can provide non-magnified images with high light intensity. To evaluate whether the transnasal FICE system enables easier diagnosis of endoscopic BE, 72 patients with endoscopic BE were observed prospectively with a transnasal endoscope using both conventional images and FICE images. The visualization of palisade vessels and the identification of the demarcation between endoscopic BE mucosa and gastric mucosa were compared between FICE images and conventional endoscopic images, and the CIELAB color differences were calculated among palisade vessels, background BE mucosa and gastric folds. Palisade vessels could be more clearly visualized in BE mucosa with transnasal FICE than with conventional endoscopy. Demarcation between whitish BE mucosa and the upper end of the brownish gastric mucosa could be clearly identified using transnasal FICE images. Greater color differences existed with FICE images between palisade vessels and background BE mucosa as well as between BE mucosa and gastric folds than with conventional images, leading to better contrasting images. The transnasal FICE system enables clear visualization of palisade vessels and provides better contrasting images of the demarcation between the BE mucosa and the gastric mucosa, and thus contributes to easier diagnosis of endoscopic BE.

Computer‐based endoscopic image‐processing technology for endourology and laparoscopic surgery

Endourology and laparoscopic surgery are evolving in accordance with developments in instrumentation and progress in surgical technique. Recent advances in computer and image-processing technology have enabled novel images to be created from conventional endoscopic and laparoscopic video images. Such technology harbors the potential to advance endourology and laparoscopic surgery by adding new value and function to the endoscope. The panoramic and three-dimensional images created by computer processing are two outstanding features that can address the shortcomings of conventional endoscopy and laparoscopy, such as narrow field of view, lack of depth cue, and discontinuous information. The wide panoramic images show an anatomical 'map' of the abdominal cavity and hollow organs with high brightness and resolution, as the images are collected from video images taken in a close-up manner. To assist in laparoscopic surgery, especially in suturing, a three-dimensional movie can be obtained by enhancing movement parallax using a conventional monocular laparoscope. In tubular organs such as the prostatic urethra, reconstruction of three-dimensional structure can be achieved, implying the possibility of a liquid dynamic model for assessing local urethral resistance in urination. Computer-based processing of endoscopic images will establish new tools for endourology and laparoscopic surgery in the near future.

VIRTUAL ENDOSCOPY OF DOGS USING MULTI‐DETECTOR ROW CT

Virtual endoscopy uses CT data to display hollow viscera such as the stomach, duodenum and colon as if by real endoscopic observation. The results are independent of the operator skill because virtual endoscopy does not require direct manipulation of endoscopic equipment. The purpose of this study was to evaluate the utility of virtual endoscopy in small animals. Ten beagles were examined by conventional endoscopy and virtual endoscopy using multidetector CT. Virtual images were image-processed at a workstation designed for depicting virtual endoscopy using CT data. Virtual images were visually comparable with conventional endoscopic images, especially in the area of the angular incisure and pylorus. The advantages of virtual endoscopy are observation from any viewing angle, a reduced learning curve for diagnostic interpretation, quantification of lesion size in three dimensions and a potential for reducing anesthesia time. The disadvantages of virtual endoscopy are a lack of color recognition information, an inability to retrieve biopsy samples, limited visualization of the duodenum, artifacts from respiration/peristalsis motion and an inability to observe function. Based on our results, we suggest that conventional endoscopy is still superior to virtual endoscopy in dogs. However, as technology improves, virtual endoscopy may emerge as a suitable alternative or adjunctive diagnostic tool for certain digestive disorders in small animals.

Three-dimensional measurement endoscope system with virtual rulers

Conventional endoscopic images do not provide quantitative 3-D information. We present an endoscope system that can measure the size and position of an object in real time. Our endoscope contains four laser beam sources and a camera. The procedural steps for 3-D measurements are as follows. First, to obtain the function that maps 2-D coordinates of an image point to its 3-D coordinates in 3-D space, we observe a standard chart with the endoscope lens and determine the correspondence between the image and object height. In addition to the mapping, this function can correct barrel-shaped distortion of endoscopic images. The system detects laser spots on an object surface automatically using a template matching method, and maps the 2-D coordinates of the laser spots to the 3-D coordinates by the triangulation method. Then the system calculates the magnification ratio on the object plane, which is perpendicular to the optical axis and passes the laser spot, so that the system can superimpose a ruler whose scale fits the 3-D coordinates of the object. Thus, physicians can measure the size and position of objects in real time on undistorted images similar to placing rulers on the surface of an organ.

In Vivo Optical Coherence Tomography of the Human Larynx: Normative and Benign Pathology in 82 Patients

Optical coherence tomography (OCT) is an emerging imaging modality that combines low-coherence light with interferometry to produce cross-sectional images of tissue with resolution about 10 mum. Patients undergoing surgical head and neck endoscopy were examined using a fiberoptic OCT imaging probe to study and characterize microstructural anatomy and features of the larynx and benign laryngeal pathology in vivo. Prospective clinical trial. OCT imaging of the larynx was performed in 82 of 115 patients who underwent surgical endoscopy for various head and neck pathologies. The OCT device employs a 1.3 microm broadband light source (FWHM, 80 nm). The frame rate is 1 Hz. Imaging was performed using a handheld probe placed in near contact with the target site. The maximum axial and lateral dimensions for the region of interest imaged were 2.5 mm x 6 mm, with resolutions of 10 microm. Simultaneously, conventional endoscopic images were obtained to provide anatomic correlation with OCT images and histology. Optical micrometry was performed to measure the epithelium thickness. Systematic OCT imaging of laryngeal structures and subsites provided information on the thickness of the epithelium, integrity of the basement membrane, and structure of the lamina propria. Microstructural features identified included glands, ducts, blood vessels, fluid collection/edema, and the transitions between pseudostratified columnar and stratified squamous epithelium. The mean epithelial thickness of laryngeal subsites was calculated: true vocal cord (129 microm), false vocal cords (124 microm), aryepiglottic fold (177 microm), subglottis (98 microm), and epiglottis (185 microm). True vocal cord pathology imaged included Reinke's edema, papillomatosis, polyps, mucous cysts, and granulation tissue. Subglottic imaging identified boundaries between epithelium, lamina propria, and cartilage. The OCT images compared favorably with conventional histopathology. OCT has the unique ability to image laryngeal tissue microstructure and can detail microanatomic changes in benign, premalignant, and malignant laryngeal pathologies. OCT holds the potential to guide surgical biopsies, direct therapy, and monitor disease, particularly when office-based systems are developed. This is a promising imaging modality to study the larynx.