In vivo colonoscopic optical coherence tomography for transmural inflammation in inflammatory bowel disease

Advances in Pediatric Diagnostic Endoscopy: A State-of-the-Art Review

Pediatric endoscopy has revolutionized the way we diagnose and treat gastrointestinal disorders in children. Technological advances in computer processing and imaging continue to affect endoscopic equipment and advance diagnostic tools for pediatric endoscopy. Although commonly used by adult gastroenterologists, modalities, such as endomicroscopy, image-enhanced endoscopy, and impedance planimetry, are not routinely used in pediatric gastroenterology. This state-of-the-art review describes advances in diagnostic modalities, including image-enhanced endoscopy, confocal laser endomicroscopy, optical coherence tomography, endo functional luminal imaging probes, wireless motility/pH capsule, wireless colon capsule endoscopy, endoscopic ultrasound, and discusses the basic principles of each technology, including adult indications and pediatric applications, safety cost, and training data.

Research progress on the application of optical coherence tomography in the field of oncology

Optical coherence tomography (OCT) is a non-invasive imaging technique which has become the “gold standard” for diagnosis in the field of ophthalmology. However, in contrast to the eye, nontransparent tissues exhibit a high degree of optical scattering and absorption, resulting in a limited OCT imaging depth. And the progress made in the past decade in OCT technology have made it possible to image nontransparent tissues with high spatial resolution at large (up to 2mm) imaging depth. On the one hand, OCT can be used in a rapid, noninvasive way to detect diseased tissues, organs, blood vessels or glands. On the other hand, it can also identify the optical characteristics of suspicious parts in the early stage of the disease, which is of great significance for the early diagnosis of tumor diseases. Furthermore, OCT imaging has been explored for imaging tumor cells and their dynamics, and for the monitoring of tumor responses to treatments. This review summarizes the recent advances in the OCT area, which application in oncological diagnosis and treatment in different types: (1) superficial tumors:OCT could detect microscopic information on the skin’s surface at high resolution and has been demonstrated to help diagnose common skin cancers; (2) gastrointestinal tumors: OCT can be integrated into small probes and catheters to image the structure of the stomach wall, enabling the diagnosis and differentiation of gastrointestinal tumors and inflammation; (3) deep tumors: with the rapid development of OCT imaging technology, it has shown great potential in the diagnosis of deep tumors such in brain tumors, breast cancer, bladder cancer, and lung cancer.

In vivo assessment of inflammatory bowel disease in rats with ultrahigh-resolution colonoscopic OCT

A technology capable of high-resolution, label-free imaging of subtle pathology in vivo during colonoscopy is imperative for the early detection of disease and the performance of accurate biopsies. While colonoscopic OCT has been developed to visualize colonic microstructures beyond the mucosal surface, its clinical potential remains limited by sub-optimal resolution (∼6.5 µm in tissue), inadequate imaging contrast, and a lack of high-resolution OCT criteria for lesion detection. In this study, we developed an ultrahigh-resolution (UHR) colonoscopic OCT and evaluated its ability to volumetrically visualize and identify the pathological features of inflammatory bowel disease (IBD) in a rat model. Owing to its improved resolution (∼1.7 µm in tissue) and enhanced contrast, UHR colonoscopic OCT can accurately delineate fine colonic microstructures and identify the pathophysiological characteristics of IBD in vivo. By using a quantitative optical attenuation map, UHR colonoscopic OCT is able to differentiate diseased tissue (such as crypt distortion and microabscess) from normal colonic mucosa over a large field of view in vivo. Our results suggest the clinical potential of UHR colonoscopic OCT for in vivo assessment of IBD pathology.

Optical coherence tomography

Optical coherence tomography (OCT) is a non-contact method for imaging the topological and internal microstructure of samples in three dimensions. OCT can be configured as a conventional microscope, as an ophthalmic scanner, or using endoscopes and small diameter catheters for accessing internal biological organs. In this Primer, we describe the principles underpinning the different instrument configurations that are tailored to distinct imaging applications and explain the origin of signal, based on light scattering and propagation. Although OCT has been used for imaging inanimate objects, we focus our discussion on biological and medical imaging. We examine the signal processing methods and algorithms that make OCT exquisitely sensitive to reflections as weak as just a few photons and that reveal functional information in addition to structure. Image processing, display and interpretation, which are all critical for effective biomedical imaging, are discussed in the context of specific applications. Finally, we consider image artifacts and limitations that commonly arise and reflect on future advances and opportunities.

Smart pills for gastrointestinal diagnostics and therapy

Ingestible smart pills have the potential to be a powerful clinical tool in the diagnosis and treatment of gastrointestinal disease. Though examples of this technology, such as capsule endoscopy, have been successfully translated from the lab into clinically used products, there are still numerous challenges that need to be overcome. This review gives an overview of the research being done in the area of ingestible smart pills and reports on the technical challenges in this field.

Optical coherence tomography of small intestine allograft biopsies using a handheld surgical probe

SIGNIFICANCE

The current gold standard for monitoring small intestinal transplant (IT) rejection is endoscopic visual assessment and biopsy of suspicious lesions; however, these lesions are only superficially visualized by endoscopy. Invasive biopsies provide a coarse sampling of tissue health without depicting the true presence and extent of any pathology. Optical coherence tomography (OCT) presents a potential alternative approach with significant advantages over traditional white-light endoscopy.

AIM

The aim of our investigation was to evaluate OCT performance in distinguishing clinically relevant morphological features associated with IT graft failure.

APPROACH

OCT was applied to evaluate the small bowel tissues of two rhesus macaques that had undergone IT of the ileum. The traditional assessment from routine histological observation was compared with OCT captured using a handheld surgical probe during the days post-transplant and subsequently was compared with histophaology.

RESULTS

The reported OCT system was capable of identifying major biological landmarks in healthy intestinal tissue. Following IT, one nonhuman primate (NHP) model suffered a severe graft ischemia, and the second NHP graft failed due to acute cellular rejection. OCT images show visual evidence of correspondence with histological signs of IT rejection.

CONCLUSIONS

Results suggest that OCT imaging has significant potential to reveal morphological changes associated with IT rejection and to improve patient outcomes overall.

In vivo optical molecular imaging of inflammation and immunity

Inflammation is the phenotypic form of various diseases. Recent development in molecular imaging provides new insights into the diagnostic and therapeutic evaluation of different inflammatory diseases as well as diseases involving inflammation such as cancer. While conventional imaging techniques used in the clinical setting provide only indirect measures of inflammation such as increased perfusion and altered endothelial permeability, optical imaging is able to report molecular information on diseased tissue and cells. Optical imaging is a quick, noninvasive, nonionizing, and easy-to-use diagnostic technology which has been successfully applied for preclinical research. Further development of optical imaging technology such as optoacoustic imaging overcomes the limitations of mere fluorescence imaging, thereby enabling pilot clinical applications in humans. By means of endogenous and exogenous contrast agents, sites of inflammation can be accurately visualized in vivo. This allows for early disease detection and specific disease characterization, enabling more rapid and targeted therapeutic interventions. In this review, we summarize currently available optical imaging techniques used to detect inflammation, including optical coherence tomography (OCT), bioluminescence, fluorescence, optoacoustics, and Raman spectroscopy. We discuss advantages and disadvantages of the different in vivo imaging applications with a special focus on targeting inflammation including immune cell tracking.

Endoscopic imaging in inflammatory bowel disease: current developments and emerging strategies

INTRODUCTION

Developments in enhanced and magnified endoscopy have signified major advances in endoscopic imaging of ileocolonic pathology in inflammatory bowel disease (IBD). Artificial intelligence is increasingly being used to augment the benefits of these advanced techniques. Nevertheless, treatment of IBD patients is frustrated by high rates of non-response to therapy, while delayed detection and failures to detect neoplastic lesions impede successful surveillance. A possible solution is offered by molecular imaging, which adds functional imaging data to mucosal morphology assessment through visualizing biological parameters. Other label-free modalities enable visualization beyond the mucosal surface without the need of tracers.

AREAS COVERED

A literature search up to May 2020 was conducted in PubMed/MEDLINE in order to find relevant articles that involve the (pre-)clinical application of high-definition white light endoscopy, chromoendoscopy, artificial intelligence, confocal laser endomicroscopy, endocytoscopy, molecular imaging, optical coherence tomography, and Raman spectroscopy in IBD.

EXPERT OPINION

Enhanced and magnified endoscopy have enabled an improved assessment of the ileocolonic mucosa. Implementing molecular imaging in endoscopy could overcome the remaining clinical challenges by giving practitioners a real-time in vivo view of targeted biomarkers. Label-free modalities could help optimize the endoscopic assessment of mucosal healing and dysplasia detection in IBD patients.

Imaging Inflammation - From Whole Body Imaging to Cellular Resolution

Imaging techniques have evolved impressively lately, allowing whole new concepts like multimodal imaging, personal medicine, theranostic therapies, and molecular imaging to increase general awareness of possiblities of imaging to medicine field. Here, we have collected the selected (3D) imaging modalities and evaluated the recent findings on preclinical and clinical inflammation imaging. The focus has been on the feasibility of imaging to aid in inflammation precision medicine, and the key challenges and opportunities of the imaging modalities are presented. Some examples of the current usage in clinics/close to clinics have been brought out as an example. This review evaluates the future prospects of the imaging technologies for clinical applications in precision medicine from the pre-clinical development point of view.

Real-time colorectal cancer diagnosis using PR-OCT with deep learning

Prior reports have shown optical coherence tomography (OCT) can differentiate normal colonic mucosa from neoplasia, potentially offering an alternative technique to endoscopic biopsy - the current gold-standard colorectal cancer screening and surveillance modality. To help clinical translation limited by processing the large volume of generated data, we designed a deep learning-based pattern recognition (PR) OCT system that automates image processing and provides accurate diagnosis potentially in real-time. Method: OCT is an emerging imaging technique to obtain 3-dimensional (3D) "optical biopsies" of biological samples with high resolution. We designed a convolutional neural network to capture the structure patterns in human colon OCT images. The network is trained and tested using around 26,000 OCT images acquired from 20 tumor areas, 16 benign areas, and 6 other abnormal areas. Results: The trained network successfully detected patterns that identify normal and neoplastic colorectal tissue. Experimental diagnoses predicted by the PR-OCT system were compared to the known histologic findings and quantitatively evaluated. A sensitivity of 100% and specificity of 99.7% can be reached. Further, the area under the receiver operating characteristic (ROC) curves (AUC) of 0.998 is achieved. Conclusions: Our results demonstrate that PR-OCT can be used to give an accurate real-time computer-aided diagnosis of colonic neoplastic mucosa. Future development of this system as an "optical biopsy" tool to assist doctors in real-time for early mucosal neoplasms screening and treatment evaluation following initial oncologic therapy is planned.

[Overview of modern methods for the diagnosis of exudative otitis media]

Modern methods for diagnosis of exudative otitis media (EOM) have great potential, however, the problem of diagnosis of EOM is still relevant. The article describes the methods of modern diagnostics that are widely used in the daily practice of an otolaryngologist. The basic principles, advantages and disadvantages of generally accepted diagnostic methods for EOM are presented. The method of optical coherence tomography (OCT) is described as a method of studying biological tissues, which is used in many fields of medicine. Information is provided on the possibilities of OCT in the diagnosis of diseases of the ENT organs and, in particular, of the middle ear. The results of studies of the tympanic cavity structures in various inflammatory conditions, the possibilities of intrasurgery use of OCT, as well as the possibilities and perspectives of introducing OCT into the practice of an otorhinolaryngologist in the diagnosis of exudative otitis media are described.

Gastrointestinal diagnosis using non-white light imaging capsule endoscopy

Capsule endoscopy (CE) has proved to be a powerful tool in the diagnosis and management of small bowel disorders since its introduction in 2001. However, white light imaging (WLI) is the principal technology used in clinical CE at present, and therefore, CE is limited to mucosal inspection, with diagnosis remaining reliant on visible manifestations of disease. The introduction of WLI CE has motivated a wide range of research to improve its diagnostic capabilities through integration with other sensing modalities. These developments have the potential to overcome the limitations of WLI through enhanced detection of subtle mucosal microlesions and submucosal and/or transmural pathology, providing novel diagnostic avenues. Other research aims to utilize a range of sensors to measure physiological parameters or to discover new biomarkers to improve the sensitivity, specificity and thus the clinical utility of CE. This multidisciplinary Review summarizes research into non-WLI CE devices by organizing them into a taxonomic structure on the basis of their sensing modality. The potential of these capsules to realize clinically useful virtual biopsy and computer-aided diagnosis (CADx) is also reported.

Advanced endoscopic methods in gastrointestinal diseases: a systematic review

Endoscopic imaging is the main method for detecting gastrointestinal diseases, which adversely affect human health. White light endoscopy (WLE) was the first method used for endoscopic examination and is still the preliminary step in the detection of gastrointestinal diseases during clinical examination. However, it cannot accurately diagnose gastrointestinal diseases owing to its poor correlation with histopathological diagnosis. In recent years, many advanced endoscopic methods have emerged to improve the detection accuracy by endoscopy. Chromoendoscopy (CE) enhances the contrast between normal and diseased tissues using biocompatible dye agents. Narrow band imaging (NBI) can improve the contrast between capillaries and submucosal vessels by changing the light source acting on the tissue using special filters to realize the visualization of the vascular structure. Flexible spectral imaging color enhancement (FICE) technique uses the reflectance spectrum estimation technique to obtain individual spectral images and reconstructs an enhanced image of the mucosal surface using three selected spectral images. The i-Scan technology takes advantage of the different reflective properties of normal and diseased tissues to obtain images, and enhances image contrast through post-processing algorithms. These abovementioned methods can be used to detect gastrointestinal diseases by observing the macroscopic structure of the digestive tract mucosa, but the ability of early cancer detection is limited with low resolution. However, based on the principle of confocal imaging, probe-based confocal laser endomicroscopy (pCLE) can enable cellular visualization with high-performance probes, which can present cellular morphology that is highly consistent with that shown by biopsy to provide the possibility of early detection of cancer. Other endoscopic imaging techniques including endoscopic optical coherence tomography (EOCT) and photoacoustic endoscopy (PAE), are also promising for diagnosing gastrointestinal diseases. This review focuses on these technologies and aims to provide an overview of different technologies and their clinical applicability.

The Angular Spectrum of the Scattering Coefficient Map Reveals Subsurface Colorectal Cancer

Colorectal cancer diagnosis currently relies on histological detection of endoluminal neoplasia in biopsy specimens. However, clinical visual endoscopy provides no quantitative subsurface cancer information. In this ex vivo study of nine fresh human colon specimens, we report the first use of quantified subsurface scattering coefficient maps acquired by swept-source optical coherence tomography to reveal subsurface abnormities. We generate subsurface scattering coefficient maps with a novel wavelet-based-curve-fitting method that provides significantly improved accuracy. The angular spectra of scattering coefficient maps of normal tissues exhibit a spatial feature distinct from those of abnormal tissues. An angular spectrum index to quantify the differences between the normal and abnormal tissues is derived, and its strength in revealing subsurface cancer in ex vivo samples is statistically analyzed. The study demonstrates that the angular spectrum of the scattering coefficient map can effectively reveal subsurface colorectal cancer and potentially provide a fast and more accurate diagnosis.

Preliminary human application of optical coherence tomography for quantification and localization of primordial follicles aimed at effective ovarian tissue transplantation

Purpose

The purpose of this study was to evaluate the possible clinical application of optical coherence tomography for assessing ovarian reserve in individual specimens of human ovarian tissue for fertility preservation.

Methods

Ovarian tissue examination by optical coherence tomography was performed before ovarian tissue cryopreservation. Three of the four subjects had hematological disease or cancer, and they faced a threat to their fertility due to impending chemotherapy. One patient underwent ovarian tissue extraction for in vitro activation of dormant follicles as fertility treatment.

Results

The current full-field optical coherence tomography technique can detect primordial follicles in non-fixed and non-embedded human ovarian tissue. These images are well correlated with histological evaluation and the ovarian reserve test, including follicle counts.

Conclusion

It was demonstrated that optical coherence tomography could assess localization of primordial follicles and ovarian reserve in specimens of non-fixed human ovarian cortex, although optimization for examination of human ovarian tissue is needed for clinical application. Additionally, this technique holds the possibility of assessing the ovarian reserve of patients with unevaluable ovarian reserve.

Trial registration number

UMIN000023141

Interventional IBD: The Role of Endoscopist in the Multidisciplinary Team Management of IBD

Inflammatory bowel disease (IBD) has been traditionally managed by IBD medical doctors or IBDologists and colorectal surgeons. Complications related to IBD and IBD surgery, such as stricture, fistula, and abscess, are common. For the past decade, endoscopic therapy has emerged as a valid treatment option for those complications. Endoscopic therapy provides more effective therapy for those structural complications than medical treatment, while being a less invasive approach than surgery. Endoscopic therapy plays a growing role in bridging medical and surgical therapies and is becoming an important component in the multidisciplinary approach to complex IBD. In fact, endoscopic therapy has become the treatment of choice for anastomotic stricture and anastomotic sinus. The role of endoscopic resection of colitis-associated neoplasia is currently being explored. Interventional IBD is intellectually and technically challenging. We are calling for proper teaching and training of our next generation of IBD interventionists.

Optical coherence tomography in gastroenterology: a review and future outlook

Optical coherence tomography (OCT) is an imaging technique optically analogous to ultrasound that can generate depth-resolved images with micrometer-scale resolution. Advances in fiber optics and miniaturized actuation technologies allow OCT imaging of the human body and further expand OCT utilization in applications including but not limited to cardiology and gastroenterology. This review article provides an overview of current OCT development and its clinical utility in the gastrointestinal tract, including disease detection/differentiation and endoscopic therapy guidance, as well as a discussion of its future applications.

Imaging of Mucosal Inflammation: Current Technological Developments, Clinical Implications, and Future Perspectives

In recent years, various technological developments markedly improved imaging of mucosal inflammation in patients with inflammatory bowel diseases. Although technological developments such as high-definition-, chromo-, and autofluorescence-endoscopy led to a more precise and detailed assessment of mucosal inflammation during wide-field endoscopy, probe-based and stationary confocal laser microscopy enabled in vivo real-time microscopic imaging of mucosal surfaces within the gastrointestinal tract. Through the use of fluorochromes with specificity against a defined molecular target combined with endoscopic techniques that allow ultrastructural resolution, molecular imaging enables in vivo visualization of single molecules or receptors during endoscopy. Molecular imaging has therefore greatly expanded the clinical utility and applications of modern innovative endoscopy, which include the diagnosis, surveillance, and treatment of disease as well as the prediction of the therapeutic response of individual patients. Furthermore, non-invasive imaging techniques such as computed tomography, magnetic resonance imaging, scintigraphy, and ultrasound provide helpful information as supplement to invasive endoscopic procedures. In this review, we provide an overview on the current status of advanced imaging technologies for the clinical non-invasive and endoscopic evaluation of mucosal inflammation. Furthermore, the value of novel methods such as multiphoton microscopy, optoacoustics, and optical coherence tomography and their possible future implementation into clinical diagnosis and evaluation of mucosal inflammation will be discussed.

Endoscopic optical coherence tomography: technologies and clinical applications [Invited]

In this paper, we review the current state of technology development and clinical applications of endoscopic optical coherence tomography (OCT). Key design and engineering considerations are discussed for most OCT endoscopes, including side-viewing and forward-viewing probes, along with different scanning mechanisms (proximal-scanning versus distal-scanning). Multi-modal endoscopes that integrate OCT with other imaging modalities are also discussed. The review of clinical applications of endoscopic OCT focuses heavily on diagnosis of diseases and guidance of interventions. Representative applications in several organ systems are presented, such as in the cardiovascular, digestive, respiratory, and reproductive systems. A brief outlook of the field of endoscopic OCT is also discussed.

Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

Except for histological study, there are currently no suitable techniques available for the detection and identification of primordial follicles in ovary of primary ovarian insufficiency patients who have undetectable AMH levels. Also, the ability to locate and quantify follicles on ovarian cortex strips, without fixation, is valuable for patients who could undergo subsequent successful ovarian tissue transplantation. Although optical coherence tomography (OCT) is a well-established high resolution imaging technique without fixation commonly applied in biomedicine, few reports are available on ovarian tissue imaging. In present study, we established standard OCT follicle images at each developmental stage, including the primordial follicle, and demonstrated the efficacy of OCT to estimate IVF outcome in transplanted mice ovary like ovarian reserve tests. Unfortunately, the current commercial OCT could not be used to accurate follicle count the number of follicles for whole ovary, because the maximum depth of examination was 100 μm. And we demonstrated the safety of OCT examination, it did not affect IVF outcome and birth defect rate, and reproductive ability. Although there is room for improvement, these findings will be first step to bring OCT examination a step closer to clinical application for measuring true ovarian reserve and localizing follicles.

Clinical characterization of in vivo inflammatory bowel disease with Raman spectroscopy

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), affects over 1 million Americans and 2 million Europeans, and the incidence is increasing worldwide. While these diseases require unique medical care, the differentiation between UC and CD lacks a gold standard, and therefore relies on long term follow up, success or failure of existing treatment, and recurrence of the disease. Here, we present colonoscopy-coupled fiber optic probe-based Raman spectroscopy as a minimally-invasive diagnostic tool for IBD of the colon (UC and Crohn's colitis). This pilot in vivo study of subjects with existing IBD diagnoses of UC (n = 8), CD (n = 15), and normal control (n = 8) aimed to characterize spectral signatures of UC and CD. Samples were correlated with tissue pathology markers and endoscopic evaluation. The collected spectra were processed and analyzed using multivariate statistical techniques to identify spectral markers and discriminate IBD and disease classes. Confounding factors including the presence of active inflammation and the particular colon segment measured were investigated and integrated into the devised prediction algorithm, reaching 90% sensitivity and 75% specificity to CD from this in vivo data set. These results represent significant progress towards improved real-time classification for accurate and automated in vivo detection and discrimination of IBD during colonoscopy procedures.

Advances in endoscopic imaging in ulcerative colitis

Modern strategies for the treatment of ulcerative colitis require more accurate tools for gastrointestinal imaging to better assess mucosal disease activity and long-term prognostic clinical outcomes. Recent advances in gastrointestinal luminal endoscopy are radically changing the role of endoscopy in every-day clinical practice and research trials. Advanced endoscopic imaging techniques including high-definition endoscopes, optical magnification endoscopy, and various chromoendoscopy techniques have remarkably improved endoscopic assessment of ulcerative colitis. More recently, optical biopsy techniques with either endocytoscopy or confocal laser endomicroscopy have shown great potential in predicting several histological changes in real time during ongoing endoscopy. Here, we review current applications of advanced endoscopic imaging techniques in ulcerative colitis and present the most promising upcoming headways in this field.

Characterizing intestinal inflammation and fibrosis in Crohn's disease by photoacoustic imaging: feasibility study

The pathology of Crohn's disease (CD) is characterized by obstructing intestinal strictures because of inflammation (with high levels of hemoglobin), fibrosis (high levels of collagen), or a combination of both. The accurate characterization of the strictures is critical for the management of CD. This study examines the feasibility of characterizing intestinal strictures by Photoacoustic imaging (PAI) without extrapolation from superficial biopsies. Ex vivo normal rat colon tissue, inflammatory and fibrotic intestinal strictures in rat trinitrobenzene sulfonic acid (TNBS) model were first differentiated by a PA-US parallel imaging system. Surgically removed human intestinal stricture specimens were afterwards imaged by a multiwavelength acoustic resolution PA microscope (ARPAM). The experiment results suggest that PAI is a potential tool for the diagnosis of the diseased conditions in intestinal strictures.

In-vivo microscopy in the diagnosis of intestinal neoplasia and inflammatory conditions

Confocal laser endomicroscopy (CLE) is a rapidly emerging tool in endoscopic imaging allowing in-vivo microscopy of examined gastrointestinal mucosa. This review will discuss the most recent advances of confocal laser endomicroscopy in the diagnosis of intestinal neoplasia and inflammatory conditions.

An overview of optical coherence tomography for ovarian tissue imaging and characterization

Ovarian cancer has the lowest survival rate among all the gynecologic cancers because it is predominantly diagnosed at late stages due to the lack of reliable symptoms and efficacious screening techniques. Optical coherence tomography (OCT) is an emerging technique that provides high-resolution images of biological tissue in real time, and demonstrates great potential for imaging of ovarian tissue. In this article, we review OCT studies for visualization and diagnosis of human ovaries as well as quantitative extraction of ovarian tissue optical properties for classifying normal and malignant ovaries. OCT combined with other imaging modalities to further improve ovarian tissue diagnosis is also reviewed.

Ultrahigh speed endoscopic optical coherence tomography for gastroenterology

We describe an ultrahigh speed endoscopic swept source optical coherence tomography (OCT) system for clinical gastroenterology using a vertical-cavity surface-emitting laser (VCSEL) and micromotor imaging catheter. The system had a 600 kHz axial scan rate and 8 µm axial resolution in tissue. Imaging was performed with a 3.2 mm diameter imaging catheter at 400 frames per second with a 12 µm spot size. Three-dimensional OCT (3D-OCT) imaging was performed in patients with a cross section of pathologies undergoing upper and lower endoscopy. The use of distally actuated imaging catheters enabled OCT imaging with more flexibility, such as volumetric imaging in the small intestine and the assessment of hiatal hernia using retroflex imaging. The high rotational scanning stability of the micromotor enabled 3D volumetric imaging with micron scale volumetric accuracy for both en face OCT and cross-sectional imaging, as well as OCT angiography (OCTA) for 3D visualization of subsurface microvasculature. The ability to perform both structural and functional 3D OCT imaging in the GI tract with microscopic accuracy should enable a wide range of studies and enhance the sensitivity and specificity of OCT for detecting pathology.

Endoscopic Optical Coherence Tomography for Clinical Gastroenterology

Optical coherence tomography (OCT) is a real-time optical imaging technique that is similar in principle to ultrasonography, but employs light instead of sound waves and allows depth-resolved images with near-microscopic resolution. Endoscopic OCT allows the evaluation of broad-field and subsurface areas and can be used ancillary to standard endoscopy, narrow band imaging, chromoendoscopy, magnification endoscopy, and confocal endomicroscopy. This review article will provide an overview of the clinical utility of endoscopic OCT in the gastrointestinal tract and of recent achievements using state-of-the-art endoscopic 3D-OCT imaging systems.

Clinical applications of optical coherence tomography in urology

Since optical coherence tomography (OCT) was first demonstrated in 1991, it has advanced significantly in technical aspects such as imaging speed and resolution, and has been clinically demonstrated in a diverse set of medical and surgical applications, including ophthalmology, cardiology, gastroenterology, dermatology, oncology, among others. This work reviews current clinical applications in urology, particularly in bladder, urether, and kidney. Clinical applications in bladder and urether mainly focus on cancer detection and staging based on tissue morphology, image contrast, and OCT backscattering. The application in kidney includes kidney cancer detection based on OCT backscattering attenuation and non-destructive evaluation of transplant kidney viability or acute tubular necrosis based on both tissue morphology from OCT images and function from Doppler OCT (DOCT) images. OCT holds the promise to positively impact the future clinical practices in urology.

Endoscopic Optical Coherence Tomography (OCT): Advances in Gastrointestinal Imaging

In the rapidly evolving field of endoscopic gastrointestinal imaging, Optical Coherence Tomography (OCT) has found many diverse applications. We present the current status of OCT and its practical applications in imaging normal and abnormal mucosa in the esophagus, stomach, small and large intestines, and biliary and pancreatic ducts. We highlight technical aspects and principles of imaging, assess published data, and suggest future directions for OCT-guided evaluation and therapy.

Advanced endoscopic imaging for surveillance for dysplasia and colorectal cancer in inflammatory bowel disease: could the pathologist be further helped?

Patients with inflammatory bowel disease (IBD) have an increased risk of developing intestinal cancer. The magnitude of that increased risk as well as how best to mitigate it remain a topic of ongoing investigation in the field. It is important to quantify the risk of colorectal cancer in association with IBD. The reported risk varies widely between studies. This is partly due to the different methodologies used in the studies. Because of the limitations of surveillance strategies based on the detection of dysplasia, advanced endoscopic imaging and techniques involving the detection of alterations in mucosal antigens and genetic abnormalities are being investigated. Development of new biomarkers, predicting future occurrence of colonic neoplasia may lead to more biomarker-based surveillance. There are promising results that may lead to more efficient surveillance in IBD patients and more general acceptance of its use. A multidisciplinary approach, involving in particular endoscopists and pathologists, together with a centralized patient management, could help to optimize treatments and follow-up measures, both of which could help to reduce the IBD-associated cancer risk.

Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging

An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced JMT achieves a sufficiently long depth measurement range for clinical cases of posterior eye disease. Furthermore, a fine spectral shift compensation method based on the cross-correlation of calibration signals was devised for stabilizing the phase of OCT, which enables a high sensitivity Doppler OCT measurement. In addition, a new theory of JMT which integrates the Jones matrix measurement, Doppler measurement, and scattering measurement is presented. This theory enables a sensitivity-enhanced scattering OCT and high-sensitivity Doppler OCT. These new features enable the application of this system to clinical cases. A healthy subject and a geographic atrophy patient were measured in vivo, and simultaneous imaging of choroidal vasculature and birefringence structures are demonstrated.

Full-field optical coherence microscopy is a novel technique for imaging enteric ganglia in the gastrointestinal tract

BACKGROUND

Noninvasive methods are needed to improve the diagnosis of enteric neuropathies. Full-field optical coherence microscopy (FFOCM) is a novel optical microscopy modality that can acquire 1 μm resolution images of tissue. The objective of this research was to demonstrate FFOCM imaging for the characterization of the enteric nervous system (ENS).

METHODS

Normal mice and EdnrB(-/-) mice, a model of Hirschsprung's disease (HD), were imaged in three-dimensions ex vivo using FFOCM through the entire thickness and length of the gut. Quantitative analysis of myenteric ganglia was performed on FFOCM images obtained from whole-mount tissues and compared with immunohistochemistry imaged by confocal microscopy.

KEY RESULTS

Full-field optical coherence microscopy enabled visualization of the full thickness gut wall from serosa to mucosa. Images of the myenteric plexus were successfully acquired from the stomach, duodenum, colon, and rectum. Quantification of ganglionic neuronal counts on FFOCM images revealed strong interobserver agreement and identical values to those obtained by immunofluorescence microscopy. In EdnrB(-/-) mice, FFOCM analysis revealed a significant decrease in ganglia density along the colorectum and a significantly lower density of ganglia in all colorectal segments compared with normal mice.

CONCLUSIONS & INFERENCES

Full-field optical coherence microscopy enables optical microscopic imaging of the ENS within the bowel wall along the entire intestine. FFOCM is able to differentiate ganglionic from aganglionic colon in a mouse model of HD, and can provide quantitative assessment of ganglionic density. With further refinements that enable bowel wall imaging in vivo, this technology has the potential to revolutionize the characterization of the ENS and the diagnosis of enteric neuropathies.

Multiphoton tomographic imaging: a potential optical biopsy tool for detecting gastrointestinal inflammation and neoplasia

Endoscopy is widely used to detect and remove premalignant lesions with the goal of preventing gastrointestinal (GI) cancers. Because current endoscopes do not provide cellular resolution, all suspicious lesions are biopsied and subjected to histologic evaluation. Technologies that facilitate directed biopsies should decrease both procedure-related morbidity and cost. Here we explore the use of multiphoton microscopy (MPM), an optical biopsy tool that relies on intrinsic tissue emissions, to evaluate pathology in both experimental and human GI specimens, using hematoxylin and eosin (H&E)-stained sections from these tissues for comparison. After evaluating the entire normal mouse GI tract, MPM was used to investigate disease progression in mouse models of colitis and colorectal carcinogenesis. MPM provided sufficient histologic detail to identify all relevant substructures in ex vivo normal GI tissue, visualize both acute and resolving stages of colitis, and show the progression of colorectal carcinogenesis. Next, ex vivo specimens from human subjects with celiac sprue, inflammatory bowel disease, and colorectal neoplasia were imaged by MPM. Finally, colonic mucosa in live anesthetized rats was imaged in vivo using a flexible endoscope prototype. In both animal models and human specimens, MPM images showed a striking similarity to the results of H&E staining, as shown by the 100% concordance achieved by the study pathologists' diagnoses. In summary, MPM is a promising technique that accurately visualizes histology in fresh, unstained tissues. Our findings support the continued development of MPM as a technology to enhance the early detection of GI pathologies including premalignant lesions.

Review of advanced imaging techniques

Pathology informatics encompasses digital imaging and related applications. Several specialized microscopy techniques have emerged which permit the acquisition of digital images (“optical biopsies”) at high resolution. Coupled with fiber-optic and micro-optic components, some of these imaging techniques (e.g., optical coherence tomography) are now integrated with a wide range of imaging devices such as endoscopes, laparoscopes, catheters, and needles that enable imaging inside the body. These advanced imaging modalities have exciting diagnostic potential and introduce new opportunities in pathology. Therefore, it is important that pathology informaticists understand these advanced imaging techniques and the impact they have on pathology. This paper reviews several recently developed microscopic techniques, including diffraction-limited methods (e.g., confocal microscopy, 2-photon microscopy, 4Pi microscopy, and spatially modulated illumination microscopy) and subdiffraction techniques (e.g., photoactivated localization microscopy, stochastic optical reconstruction microscopy, and stimulated emission depletion microscopy). This article serves as a primer for pathology informaticists, highlighting the fundamentals and applications of advanced optical imaging techniques.

Colorectal cancer surveillance in patients with inflammatory bowel disease: What is new?

Several studies assessing the incidence of colorectal cancer (CRC) in inflammatory bowel disease (IBD) patients have found an increased risk globally estimated to be 2 to 5 times higher than for the general population of the same age group. The real magnitude of this risk, however, is still open to debate. Research is currently being carried out on several risk and protective factors for CRC that have recently been identified in IBD patients. A deeper understanding of these factors could help stratify patient risk and aid specialists in choosing which surveillance program is most efficient. There are several guidelines for choosing the correct surveillance program for IBD patients; many present common characteristics with various distinctions. Current recommendations are far from perfect and have important limitations such as the fact that their efficiency has not been demonstrated through randomized controlled trials, the limited number of biopsies performed in daily endoscopic practice, and the difficulty in establishing the correct time to begin a given surveillance program and maintain a schedule of surveillance. That being said, new endoscopic technologies should help by replacing random biopsy protocols with targeted biopsies in IBD patients, thereby improving the efficiency of surveillance programs. However, further studies are needed to evaluate the cost-effectiveness of introducing these techniques into daily endoscopic practice.

Transmural inflammation is not pathognomonic for Crohn's disease of the pouch

BACKGROUND

Transmural inflammation shown by imaging and histology has been considered a hallmark of Crohn's disease (CD). However, the diagnostic and prognostic value of this feature in CD of the pouch has not been evaluated. This study aimed to evaluate the clinical utility of transmural inflammation in patients with ileal pouch-anal anastomosis (IPAA) using in vivo optical coherence tomography (OCT) and histopathology.

METHODS

All the patients were recruited from the subspecialty Pouchitis Clinic. The study consisted of two parts: (1) a prospective study with in vivo through-the-scope OCT for the evaluation of transmural disease in patients with normal or diseased pouches and (2) a retrospective pathology re-review for transmural inflammation in excised pouch specimens of CD and chronic pouchitis.

RESULTS

This prospective OCT study enrolled 53 patients: 11 (20.8%) with normal pouches or irritable pouch syndrome, 10 (18.9%) with acute pouchitis, 11 (20.8%) with chronic antibiotic-refractory pouchitis (CARP), and 21 (39.6%) with CD of the pouch. Transmural inflammation, characterized by the loss of layered structure on OCT, was detected in 16 patients (30.2%): 4 with chronic pouchitis and 12 with CD of the pouch. None of the patients with normal pouches, irritable pouch syndrome, or acute pouchitis had transmural disease shown on OCT. Of the 26 patients with pouch failure who had pouch excision, the surgical specimens showed transmural disease in 30% of the CARP patients (3/10) and 12.5% (2/16) of those with CD of the pouch.

CONCLUSIONS

Transmural disease in the setting of IPAA is not pathognomonic of CD. Transmural inflammation shown by imaging or histopathology was seen in both CD and CARP. Transmural inflammation of the pouch appeared to be associated with poor pouch outcome.

Crohn's disease of the pouch: diagnosis and management

Approximately 30% of patients with ulcerative colitis will eventually require surgery. Ileal pouch-anal anastomosis has become the surgical treatment of choice in ulcerative colitis patients with refractory disease or dysplasia who require proctocolectomy. A subset of patients with ileal pouches may develop Crohn's disease or a Crohn's disease-like condition of the pouch after the surgery. Diagnosis and management can be challenging. A combined assessment of endoscopy, histology, radiographic imaging and examination under anesthesia is often necessary for an accurate diagnosis, disease classification, management and prognosis. A multidisciplinary approach by a medical and surgical team, together with experienced pathologists and radiologists, is advocated.

Three-dimensional endomicroscopy of the human colon using optical coherence tomography

Three-dimensional (3D) endomicroscopy imaging of the human gastrointestinal tract is demonstrated in vivo using a swept source optical coherence tomography (OCT) system. 3D datasets of normal and pathologic regions of the colon, rectum, and anal verge were obtained from seven volunteers undergoing diagnostic or therapeutic colonoscopy. 3D-OCT enables high resolution endomicroscopy examination through visualization of tissue architectural morphology using virtual cross-sectional images with arbitrary orientations as well as en face projection images. Axial image resolutions of 6 mum in tissue are obtained over a approximately 180 mm2 field with an imaging range of 1.6 mm. A Fourier domain mode locked (FDML) laser providing a tuning range of 180 nm at a sweep rate of 62 kHz is used as the system light source. This clinical pilot study demonstrates the potential of 3D-OCT for distinguishing normal from pathologic colorectal tissue, assessing endoscopic therapies and healing progression.

Optical coherence tomography in detection of dysplasia and cancer of the gastrointestinal tract and bilio-pancreatic ductal system

Optical coherence tomography (OCT) is an optical imaging modality that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure of tissues. The physical principle of OCT is similar to that of B-mode ultrasound imaging, except that it uses infrared light waves rather than acoustic waves. The in vivo resolution is 10-25 times better (about 10 μm) than with high-frequency ultrasound imaging, but the depth of penetration is limited to 1-3 mm, depending upon tissue structure, depth of focus of the probe used, and pressure applied to the tissue surface. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal (GI) tract and pancreatic-biliary ductal system. OCT imaging from the GI tract can be done in humans by using narrow-diameter, catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope, for investigating the epithelial structure of the GI tract, or a side-view endoscope, inside a standard transparent ERCP catheter, for investigating the pancreatico-biliary ductal system. Esophagus and the esophago-gastric junction has been the most widely investigated organ so far; more recently, also duodenum, colon and pancreatico-biliary ductal system have been extensively investigated. OCT imaging of the gastro-intestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa, lamina propria, muscularis mucosae, and part of the submucosa. The technique may be, therefore, used to identify pre-neoplastic conditions of the GI tract, such as Barrett's epithelium and dysplasia, and evaluate the depth of penetration of early-stage neoplastic lesions. OCT imaging of the pancreatic and biliary ductal system could improve the diagnostic accuracy for ductal epithelial changes and the differential diagnosis between neoplastic and non-neoplastic lesions.

Future expectations in digestive endoscopy: competition with other novel imaging techniques

Digestive endoscopy has been evolving from primary diagnostic to extensive therapeutic modalities in the management of gastrointestinal diseases. The present endoscopic imaging includes (A) standard endoscopy alone and /or with adjunct technologies such as point enhancement, e.g. confocal endomicroscopy and field enhancement technologies such as chromoendoscopy, NBI and FICE and (B) endoscopic ultrasound. Other novel imaging technologies including virtual colonoscopy or CT/MR colonography, CT or MRI enterography and capsule endoscopy have also been developed. This article reviews the diagnostic and therapeutic role of digestive endoscopy and future directions of digestive endoscopy are discussed. Digestive endoscopy is also compared with emerging novel imaging techniques in gastrointestinal diseases such as capsule endoscopy and CT colonography. The fact that digestive endoscopy has become a multidisciplinary specialty combining advances in all fields (radiology, bioengineering, surgery and gastroenterology) is highlighted.

Optical coherence tomography in inflammatory bowel disease: prospective evaluation of 35 patients

PURPOSE

Optical coherence tomography is a technique using infrared light in tissues of the gastrointestinal tract and human colon affected by inflammatory diseases. We evaluated whether there are specific patterns of optical coherence tomography for inflammatory bowel disease and compared the technique performance to the histology.

METHODS

Optical coherence tomography was performed in 35 patients (18 men; 31 ulcerative colitis, 4 Crohn's disease). The images were obtained from affected and normal colon at endoscopy. Two biopsies of the sites visualized were taken. Two endoscopists scored the images, and two pathologists, blind to the endoscopy and optical coherence tomography, performed the histologic evaluation.

RESULTS

Three optical coherence tomography patterns were identified: 1) mucosal backscattering alteration, 2) delimited dark areas, and 3) layered colonic wall. Compared with the histology, mucosal backscattering alteration was the most effective in recognizing the disease in patients (P = 0.007 in colon segments affected, and P < 0.001 in normal segments). The sensitivity and specificity have been 100 and 78 percent, respectively.

CONCLUSIONS

The in vivo optical coherence tomography correctly detected inflammatory bowel disease features in affected and apparently normal colon, and allowed to discriminate patterns for active ulcerative colitis and Crohn's disease.

Application of optical coherence tomography for monitoring changes in cervicovaginal epithelial morphology in macaques: potential for assessment of microbicide safety

OBJECTIVES

Safety is a primary concern in the development of topical microbicides. Optical coherence tomography (OCT), a high-resolution, in-depth cross-sectional imaging modality, was utilized in conjunction with colposcopy to assess induced cervicovaginal epithelial changes that may predict product safety.

STUDY DESIGN

OCT and colposcopic images of macaque vaginal and cervical tissues were obtained in excised tissue and in vivo under various conditions, including mechanical injury and nonoxynol-9 treatment.

RESULTS

A scoring system was developed to categorize and quantify the OCT images based on morphologic features that indicate the presence or absence of an intact epithelial layer and inflammation. Using 3 categories (normal, mild to moderately abnormal, and severely abnormal), differences between healthy and injured tissue were apparent on OCT images. Normal images (category 1) had a bilayered structure representative of the epithelium and submucosa. Mild to moderately abnormal images (category 2) had areas of normal and abnormal epithelium. Severely abnormal images (category 3) had complete loss of the epithelium and/or inflammation, with loss of the bilayered structure on OCT.

CONCLUSIONS

OCT is a noninvasive imaging modality complementary to colposcopy. It distinguished between normal and abnormal (or injured) tissue and thus holds promise for safety evaluations of candidate microbicides and other vaginal products.

Antiglycan antibodies as serological markers in the differential diagnosis of inflammatory bowel disease

BACKGROUND

The objective of the study was to evaluate the diagnostic accuracy of recently developed antiglycan serological tests in clinical practice for the diagnosis of Crohn's disease.

METHODS

This study was a cohort analysis of both clinical and biochemical parameters of patients with diagnosed inflammatory bowel disease compared with those in a control population. Antiglycan antibodies were determined using commercially available enzyme immunoassays. The setting was the outpatient unit of the gastroenterology department of a large, tertiary-care referral academic hospital. Participants were 214 consecutive patients, enrolled over a 5-month period, including 116 with Crohn's disease and 53 with ulcerative colitis, as well as 45 with other gastrointestinal diseases and 51 healthy controls.

RESULTS

Anti-Saccharomyces cerevisiae antibodies showed the best performance (54% sensitivity and 88%-95% specificity for Crohn's disease). Among patients with negative anti-Saccharomyces antibodies, 19 (34%) had high titers of at least another tested antiglycan antibody. Anti-Saccharomyces and anti-laminaribioside antibodies were associated with disease involving the small bowel and with penetrating or stricturing phenotype. Anti-laminaribioside was significantly higher in patients with a familial history of inflammatory bowel disease.

CONCLUSIONS

The new proposed serological markers are significantly associated with Crohn's disease, with low sensitivity but good specificity. About one third of anti-Saccharomyces-negative patients may be positive for at least 1 of those markers. Antiglycan antibodies appear to be associated with characteristic localization and phenotype of the disease.