Diagnosing Cancer in Vivo

Pixel-level multimodal fusion deep networks for predicting subcellular organelle localization from label-free live-cell imaging

Complex intracellular organizations are commonly represented by dividing the metabolic process of cells into different organelles. Therefore, identifying sub-cellular organelle architecture is significant for understanding intracellular structural properties, specific functions, and biological processes in cells. However, the discrimination of these structures in the natural organizational environment and their functional consequences are not clear. In this article, we propose a new pixel-level multimodal fusion (PLMF) deep network which can be used to predict the location of cellular organelle using label-free cell optical microscopy images followed by deep-learning-based automated image denoising. It provides valuable insights that can be of tremendous help in improving the specificity of label-free cell optical microscopy by using the Transformer-Unet network to predict the ground truth imaging which corresponds to different sub-cellular organelle architectures. The new prediction method proposed in this article combines the advantages of a transformer's global prediction and CNN's local detail analytic ability of background features for label-free cell optical microscopy images, so as to improve the prediction accuracy. Our experimental results showed that the PLMF network can achieve over 0.91 Pearson's correlation coefficient (PCC) correlation between estimated and true fractions on lung cancer cell-imaging datasets. In addition, we applied the PLMF network method on the cell images for label-free prediction of several different subcellular components simultaneously, rather than using several fluorescent labels. These results open up a new way for the time-resolved study of subcellular components in different cells, especially for cancer cells.

Multiple Parallel Fusion Network for Predicting Protein Subcellular Localization from Stimulated Raman Scattering (SRS) Microscopy Images in Living Cells

Stimulated Raman Scattering Microscopy (SRS) is a powerful tool for label-free detailed recognition and investigation of the cellular and subcellular structures of living cells. Determining subcellular protein localization from the cell level of SRS images is one of the basic goals of cell biology, which can not only provide useful clues for their functions and biological processes but also help to determine the priority and select the appropriate target for drug development. However, the bottleneck in predicting subcellular protein locations of SRS cell imaging lies in modeling complicated relationships concealed beneath the original cell imaging data owing to the spectral overlap information from different protein molecules. In this work, a multiple parallel fusion network, MPFnetwork, is proposed to study the subcellular locations from SRS images. This model used a multiple parallel fusion model to construct feature representations and combined multiple nonlinear decomposing algorithms as the automated subcellular detection method. Our experimental results showed that the MPFnetwork could achieve over 0.93 dice correlation between estimated and true fractions on SRS lung cancer cell datasets. In addition, we applied the MPFnetwork method to cell images for label-free prediction of several different subcellular components simultaneously, rather than using several fluorescent labels. These results open up a new method for the time-resolved study of subcellular components in different cells, especially cancer cells.

A Flexi-PEGDA Upconversion Implant for Wireless Brain Photodynamic Therapy

Near-infrared (NIR) activatable upconversion nanoparticles (UCNPs) enable wireless-based phototherapies by converting deep-tissue-penetrating NIR to visible light. UCNPs are therefore ideal as wireless transducers for photodynamic therapy (PDT) of deep-sited tumors. However, the retention of unsequestered UCNPs in tissue with minimal options for removal limits their clinical translation. To address this shortcoming, biocompatible UCNPs implants are developed to deliver upconversion photonic properties in a flexible, optical guide design. To enhance its translatability, the UCNPs implant is constructed with an FDA-approved poly(ethylene glycol) diacrylate (PEGDA) core clad with fluorinated ethylene propylene (FEP). The emission spectrum of the UCNPs implant can be tuned to overlap with the absorption spectra of the clinically relevant photosensitizer, 5-aminolevulinic acid (5-ALA). The UCNPs implant can wirelessly transmit upconverted visible light till 8 cm in length and in a bendable manner even when implanted underneath the skin or scalp. With this system, it is demonstrated that NIR-based chronic PDT is achievable in an untethered and noninvasive manner in a mouse xenograft glioblastoma multiforme (GBM) model. It is postulated that such encapsulated UCNPs implants represent a translational shift for wireless deep-tissue phototherapy by enabling sequestration of UCNPs without compromising wireless deep-tissue light delivery.

Toward a miniature endomicroscope: pixelation-free and diffraction-limited imaging through a fiber bundle

A fiber bundle is widely used for endoscopic imaging due to its direct image delivery capability. However, there exists an inevitable pixelation artifact, which limits spatial resolution to the diameter of individual fibers. In this Letter, we present a method that can eliminate this artifact and achieve diffraction-limited spatial resolution. We exploited the binary control of a digital micromirror device to measure a transmission matrix of a fiber bundle and to subsequently control mode mixing among individual fibers. In doing so, we achieved a 22 kHz scanning rate of a diffraction-limited focused spot and obtained fluorescence endoscope imaging (58 μm × 58 μm) with near video-rate (10.3 Hz) acquisition. Our study lays a foundation for developing an ultrathin and high-resolution microendoscope.

Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber

A single multimode fiber is considered an ideal optical element for endoscopic imaging due to the possibility of direct image transmission via multiple spatial modes. However, the wave distortion induced by the mode dispersion has been a fundamental limitation. In this Letter, we propose a method for eliminating the effect of mode dispersion and therefore realize wide-field endoscopic imaging by using only a single multimode fiber with no scanner attached to the fiber. Our method will potentially revolutionize endoscopy in various fields encompassing medicine and industry.

Dye-enhanced multimodal confocal imaging as a novel approach to intraoperative diagnosis of brain tumors

Intraoperative diagnosis plays an important role in accurate sampling of brain tumors, limiting the number of biopsies required and improving the distinction between brain and tumor. The goal of this study was to evaluate dye-enhanced multimodal confocal imaging for discriminating gliomas from nonglial brain tumors and from normal brain tissue for diagnostic use. We investigated a total of 37 samples including glioma (13), meningioma (7), metastatic tumors (9) and normal brain removed for nontumoral indications (8). Tissue was stained in 0.05 mg/mL aqueous solution of methylene blue (MB) for 2-5 minutes and multimodal confocal images were acquired using a custom-built microscope. After imaging, tissue was formalin fixed and paraffin embedded for standard neuropathologic evaluation. Thirteen pathologists provided diagnoses based on the multimodal confocal images. The investigated tumor types exhibited distinctive and complimentary characteristics in both the reflectance and fluorescence responses. Images showed distinct morphological features similar to standard histology. Pathologists were able to distinguish gliomas from normal brain tissue and nonglial brain tumors, and to render diagnoses from the images in a manner comparable to haematoxylin and eosin (H&E) slides. These results confirm the feasibility of multimodal confocal imaging for intravital intraoperative diagnosis.

Intraoperative confocal microscopy for brain tumors: a feasibility analysis in humans

BACKGROUND

The ability to diagnose brain tumors intraoperatively and identify tumor margins during resection could maximize resection and minimize morbidity. Advances in optical imaging enabled production of a handheld intraoperative confocal microscope.

OBJECTIVE

To present a feasibility analysis of the intraoperative confocal microscope for brain tumor resection.

METHODS

Thirty-three patients with brain tumor treated at Barrow Neurological Institute were examined. All patients received an intravenous bolus of sodium fluorescein before confocal imaging with the Optiscan FIVE 1 system probe. Optical biopsies were obtained within each tumor and along the tumor-brain interfaces. Corresponding pathologic specimens were then excised and processed. These data was compared by a neuropathologist to identify the concordance for tumor histology, grade, and margins.

RESULTS

Thirty-one of 33 lesions were tumors (93.9%) and 2 cases were identified as radiation necrosis (6.1%). Of the former, 25 (80.6%) were intra-axial and 6 (19.4%) were extra-axial. Intra-axial tumors were most commonly gliomas and metastases, while all extra-axial tumors were meningiomas. Among high-grade gliomas, vascular neoproliferation, as well as tumor margins, were identifiable using confocal imaging. Meningothelial and fibrous meningiomas were distinct on confocal microscopy--the latter featured spindle-shaped cells distinguishable from adjacent parenchyma. Other tumor histologies correlated well with standard neuropathology tissue preparations.

CONCLUSION

Intraoperative confocal microscopy is a practicable technology for the resection of human brain tumors. Preliminary analysis demonstrates reliability for a variety of lesions in identifying tumor cells and the tumor-brain interface. Further refinement of this technology depends upon the approval of tumor-specific fluorescent contrast agents for human use.

APPLICATIONS OF GOLD NANOPARTICLES IN THE EARLY DETECTION OF CANCER

Worldwide, oral cancer is the sixth most common cancer for both sexes. In Singapore, the 5-year survival rate of oral cancer is about 50%. The high mortality rate has been attributed to the difficulties in detecting the disease in an early treatable stage. Here, we present two application examples of gold nanoparticles in the early detection of oral cancer. In the first, gold nanoparticles were used as a reflective contrast agent for performing molecular imaging under confocal reflectance microscopy for the early diagnosis of epithelial carcinoma. While in the second, closely-packed gold nanoparticle, films were used as a bio-sensing surface for the chemical analysis of saliva via Surface Enhanced Raman Scattering. Preliminary results will be discussed.

Early detection in head and neck cancer - current state and future perspectives

Survival and quality of life in head and neck cancer are directly linked to the size of the primary tumor at first detection. In order to achieve substantial gain at these issues, both, primary prevention and secondary prevention, which is early detection of malignant lesions at a small size, have to be improved. So far, there is not only a lack in the necessary infrastructure not only in Germany, but rather worldwide, but additionally the techniques developed so far for early detection have a significance and specificity too low as to warrant safe implementation for screening programs. However, the advancements recently achieved in endoscopy and in quantitative analysis of hypocellular specimens open new perspectives for secondary prevention. Chromoendoscopy and narrow band imaging (NBI) pinpoint suspicious lesions more easily, confocal endomicroscopy and optical coherence tomography obtain optical sections through those lesions, and hyperspectral imaging classifies lesions according to characteristic spectral signatures. These techniques therefore obtain optical biopsies. Once a "bloody" biopsy has been taken, the plethora of parameters that can be quantified objectively has been increased and could be the basis for an objective and quantitative classification of epithelial lesions (multiparametric cytometry, quantitative histology). Finally, cytomics and proteomics approaches, and lab-on-the-chip technology might help to identify patients at high-risk. Sensitivity and specificity of these approaches have to be validated, yet, and some techniques have to be adapted for the specific conditions for early detection of head and neck cancer. On this background it has to be stated that it is still a long way to go until a population based screening for head and neck cancer is available. The recent results of screening for cancer of the prostate and breast highlight the difficulties implemented in such a task.

Registration of in vivo fluorescence endomicroscopy images based on feature detection

The confocal fluorescence endomicroscopy is an emerging technology for imaging the living subjects inside the animals and human bodies. However, the acquired images vary, due to two degrees of freedom-tissue movement and tissue expansion/contraction. This makes the 3D reconstruction of them difficult and thus limits the clinic applications. In this chapter, we propose a feature-based registration algorithm to correct the distortions between these fluorescence images. The good alignment enables us to reconstruct and visualize the 3D structure of the living cells and tissues in real time, which provides the opportunity for the clinicians to diagnose various diseases, including the early-stage cancers. Experimental results on a collection of more than 300 confocal fluorescence images of the gerbil brain microvasculature clearly demonstrate the effectiveness and accuracy of our method.

Miniaturized handheld confocal microscopy for neurosurgery: results in an experimental glioblastoma model

INTRODUCTION

Recent developments in optical science and image processing have miniaturized the components required for confocal microscopy. Clinical confocal imaging applications have emerged, including assessment of colonic mucosal dysplasia during colonoscopy. We present our initial experience with handheld, miniaturized confocal imaging in a murine brain tumor model.

METHODS

Twelve C57/BL6 mice were implanted intracranially with 10(5) GL261 glioblastoma cells. The brains of 6 anesthetized mice each at 14 and 21 days after implantation were exposed surgically, and the brain surface was imaged using a handheld confocal probe affixed to a stereotactic frame. The probe was moved systematically over regions of normal and tumor-containing tissue. Intravenous fluorescein and topical acriflavine contrast agents were used. Biopsies were obtained at each imaging site beneath the probe and assessed histologically. Mice were killed after imaging.

RESULTS

Handheld confocal imaging produced exquisite images, well-correlated with corresponding histologic sections, of cellular shape and tissue architecture in murine brain infiltrated by glial neoplasm. Reproducible patterns of cortical vasculature, as well as normal gray and white matter, were identified. Imaging effectively distinguished between tumor and nontumor tissue, including infiltrative tumor margins. Margins were easily identified by observers without prior neuropathology training after minimum experience with the technology.

CONCLUSION

Miniaturized handheld confocal imaging may assist neurosurgeons in detecting infiltrative brain tumor margins during surgery. It may help to avoid sampling error during biopsy of heterogeneous glial neoplasms, with the potential to supplement conventional intraoperative frozen section pathology. Clinical trials are warranted on the basis of these promising initial results.

Virtual histology

Confocal laser endomicroscopy enables in vivo microscopy of the mucosal layer of the GI-tract with subcellular resolution during ongoing endoscopy. Endomicroscopy opens a new door for immediate tissue and vessel analysis. Different types of diseases can be diagnosed with optical surface and subsurface analysis. Analysis of the in vivo microarchitecture can be used for targeting biopsies to relevant areas. Furthermore, subsurface imaging can unmask microscopic diseases - (microscopic colitis) or bacterial infection (Helicobacter pylori), for example. Molecular imaging is becoming feasible, and this will shortly open the door to new indications in gastrointestinal endoscopy. This chapter reviews the currently rapidly expanding clinical data about endomicroscopy and gives a look into future research.

Endoscopic image analysis of photosensitizer fluorescence as a promising noninvasive approach for pathological grading of bladder cancer in situ

Our aim is to apply image analysis on photosensitizer fluorescence and compare the relationship between histopathology and endoscopic fluorescence imaging. The correlation between hypericin fluorescence and histopathology of diseased tissue was explored in a clinical study involving 58 fluorescence cystoscopic images from 23 patients. Based on quantification of fluorescence colorimetric parameters extracted from the image analysis, diagnostic functions were developed to pathologically classify the bladder cancer. Our preliminary results show that the differences in fluorescence intensity ratios among the three different grades of bladder cancer are statistically significant. The results also show a decrease in macroscopic fluorescence intensity that correlated with higher cancer grades. By combining both the red-to-green and red-to-blue fluorescence intensity ratios into a 2-D scatter plot and defining diagnostic linear discrimination functions on the data points, this technique is able to yield an average sensitivity and specificity of around 68.6% and 86.1%, respectively, for pathological cancer grading of the three different grades of bladder cancer in our study. We conclude that our proposed approach in applying colorimetric intensity ratio analysis on hypericin fluorescence shows potential to optically grade bladder cancer in situ.

Enhancement of ultraweak photon emission with 3 MHz ultrasonic irradiation on transplanted tumor tissues of mice

We investigated photon emissions of various bio-samples which were induced by ultrasonic stimulation. It has been reported that ultrasonic stimulations induced the thermal excitation of the bio-tissues. After ultrasonic stimulation, any measurement of photon radiation in the visible spectral range has not been carried out yet. The instruments consisted of electronic devices for an ultrasonic generator of the frequency 3 MHz and a photomultiplier tube (PMT) system counting photons from bio-tissues. The transplanted tumor tissues of mice were prepared for the experiments and their liver and spleen tissues were also used for the controls. It was found that the continuous ultrasonic stimulations with the electrical power 2300 mW induced ultraweak photon emissions from the tumor tissues. The number of induced photon was dependent of the type of the tissues and the stimulation time intervals. The level of photon emission was increased from the mouse tumor exposed to the ultrasonic stimulations, and the changes were discriminated from those of the spleens and livers.

Confocal laser endomicroscopy for gastrointestinal diseases

Confocal laser endomicroscopy enables in vivo microscopy of the mucosal layer of the gastrointestinal tract with subcellular resolution during ongoing endoscopy. Endomicroscopy opens the door to immediate tissue and vessel analysis. Different types of diseases can be diagnosed with optical surface and subsurface analysis. Analysis of the in vivo microarchitecture can be used for targeting biopsies to relevant areas, and subsurface imaging can unmask microscopic diseases or bacterial infection. Molecular imaging is becoming feasible, which will enable new indications in gastrointestinal endoscopy. This article reviews the current and rapidly expanding clinical data on endomicroscopy and gives a look into future research.

[Cytomics and predictive medicine for oncology]

One hundred and fifty years after Virchow introduced his fundamental concept of cellular pathology, we now have tools that allow us to unravel the mechanisms of single living cells on a previously unprecedented level of detail. By exploring the molecular cellular phenotype, multiparametric cytometry not only detects specific cellular functions in general but also offers insights into the interaction of single subunits of proteins (e.g., growth factor receptors). Several quantitative and objective techniques allow analysis of single-cell preparations as well as tissue sections to obtain data on different cellular parameters. This opens the way to quantitative and objective histology, which in the future may be possible even without blood or the need to make an incision. To use this huge amount of data for treatment decisions in an individual patient, novel bioinformatic concepts are needed in order to predict the individual course of a disease. The concept of cytomics centers on the cell as the integral unit of all life and explores diseases starting from the cell and going to subcellular units (top-down analysis).

Molecular contrast of EGFR expression using gold nanoparticles as a reflectance-based imaging probe

Advanced reflectance-based optical techniques for in vivo imaging often suffer from low contrast between neoplastic and normal tissue and are unable to image early biomolecular changes associated with carcinogenesis, thus limiting their clinical value. In this study, we exploit the resonance light scattering property of gold nanoparticles at their surface plasmon resonance to develop them as potential molecular contrast probes for imaging biomolecular changes during carcinogenesis under reflectance-mode imaging techniques. Gold nanoparticles were synthesized and conjugated to anti-epidermal growth factor receptor (EGFR). Their localization on the EGFR of nasopharyngeal carcinoma CNE2 cells and normal human lung fibroblast (NHLF) cells were imaged and compared under confocal microscopy in vitro. We have shown that the localization of gold bioconjugates on EGFR increases the reflectance properties of CNE2 cells and the regions of increased reflectance correspond to regions of high EGFR expression in the cells. The optical properties of normal fibroblast cells are not greatly affected. These gold bioconjugates are thus able to map the expression of relevant biomarkers and elicit an optical contrast for cancer cells over normal cells under confocal reflectance microscopy. Our study demonstrates the potential of gold nanoparticles to target and probe cancer cells and illuminates them for cancer detection under reflectance-based imaging systems based on biomolecular changes.

Histology-based simulations for the ultrasonic detection of microscopic cancer in vivo

Ultrasonic spectroscopy may offer an alternative to imaging methods for the in vivo detection of microscopic cancer. To investigate this potential, a numerical model that incorporates multiple scattering, wave-mode conversion, and hierarchical microstructures was developed to simulate ultrasonic interactions in biological tissue at the microscopic level. Simulated high-frequency (20-75 MHz) spectra of up to 2137 cells displayed significant correlations to nucleus diameter and malignant cell infiltration, and indicated as few as 300 malignant cells may be detectable in normal tissue. The results suggest that ultrasonic spectroscopy combined with simulation-based interpretive models may provide real-time histopathology during surgeries, biopsies, and endoscopies.

Silencing of human ferrochelatase causes abundant protoporphyrin-IX accumulation in colon cancer

Hemes and heme proteins are vital components of essentially every cell of virtually every eukaryote organism. Previously, we demonstrated accumulation of the heme precursor protoporphyrin-IX (PpIX) in gastrointestinal tumor tissues. To elucidate the mechanisms of PpIX accumulation by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we studied expression of the relevant enzymes of the heme synthetic pathway. Here, we describe a significant down-regulation of ferrochelatase (FECH) mRNA expression in gastric, colonic, and rectal carcinomas. Accordingly, in an in vitro model of several carcinoma cell lines, ferrochelatase down-regulation and loss of enzymatic activity corresponded with an enhanced PpIX-dependent fluorescence. Direct detection of PpIX in minute amounts was achieved by a specifically developed pulsed solid-state laser dual delay fluorimetry setup. Silencing of FECH using small interfering RNA (siRNA) technology led to a maximum 50-fold increased PpIX accumulation, imageable by a specifically adapted two-photon microscopy unit. Our results show that in malignant tissue a transcriptional down-regulation of FECH occurs, which causes endogenous PpIX accumulation. Furthermore, accumulation of intracellular PpIX because of FECH siRNA silencing provides a small-molecule-based approach to molecular imaging and molecular therapy.

Visualization of basal cell carcinoma by fluorescence diagnosis and independent component analysis

Photodynamic detection (PDD) of skin tumours is based on the visualization of a fluorophores, with the ability to accumulate in tumour tissue, by the use of fluorescence imaging. Of particular importance is the application of δ-5-aminolaevulinic acid (ALA) that, through the process of biosynthesis causes formation of the protoporphyrin IX (PpIX). The PpIX has the ability of selective fluorescence after basal cell carcinoma (BCC) has been treated with ALA. Higher concentration of PpIX in tumour tissue compared to surrounding normal skin is the basis for PDD. Our contribution in this preliminary study is application of the independent component analysis (ICA) to extract the BCC spatial map, by processing fluorescent RGB image acquired under excitation with 405nm light. Comparative performance analysis with other two widely used image processing methods: ratio imaging and optimal threshold based imaging, reveals that ICA produces BCC spatial map that is most consistent in term of diagnostic quality by both visual assessment and calculation of the BCC demarcation line. We believe this represents a solid basis for the design of a compact and low-cost multi-spectral fluorescence imaging system, capable for real time calculation of the skin tumour demarcation.

A fluorescence confocal endomicroscope for in vivo microscopy of the upper- and the lower-GI tract

BACKGROUND

This report describes the development and the clinical evaluation of a novel confocal endomicroscope for obtaining fluorescence images of cellular morphology of the mucosae of the upper- and the lower-GI tract in vivo. The work assessed the feasibility of performing in vivo microscopy at endoscopic examination and evaluated fluorescence imaging protocols.

METHODS

Images were collected in real time by using two prototype endoscope configurations, featuring slightly different miniaturized fiber-optic confocal microscopes, fitted integrally into the tips of conventional endoscopes. Confocal scanning was performed at 488 nm illumination for excitation of exogenously applied fluorophores (topical acriflavine and intravenous fluorescein). The images were compared with conventional histology of biopsy specimens and the findings of white-light endoscopy.

RESULTS

Confocal endomicroscopy enabled imaging of cellular and subcellular structures (i.e., nuclei) of the GI tract. The crypts of the colonic mucosa, the villi of the terminal ileum and duodenum, the gastric pits of the stomach, and the squamous epithelium of the distal esophagus could be clearly visualized. Acriflavine strongly contrasted the cell nuclei of the surface epithelium, including the absorptive epithelial cells and the mucous secreting goblet cells. Fluorescein stained the extracellular matrix of the surface epithelium and also the subepithelial layers of the lamina propria. Images at increasing depth beneath the epithelium showed the mucosal capillary network. The findings correlated with the histology of biopsy specimens.

CONCLUSIONS

The development of a fluorescence confocal endomicroscope makes it practical to examine the upper- and the lower-GI mucosa in cellular detail during otherwise routine endoscopic examination. The results represent a major technical advance in the development of this new optical imaging modality for the in vivo examination of GI tissue.

Confocal laser endomicroscopy

A miniaturized confocal microscope was developed that could be integrated in the distal tip of a conventional colonoscope. With this technique, denoted confocal endomicroscopy, subsurface analysis of the gut mucosa and in-vivo histology during ongoing endoscopy are possible in full resolution by point scanning laser analysis. The diagnostic spectrum of confocal endomicroscopy is expanding from screening and surveillance for colorectal cancer to Barrett's esophagus, Helicobacter pylori-associated gastritis, and gastric cancer. The new detailed images seen with confocal laser endomicroscopy allow a unique look on cellular structures at and below the surface of the gut. This review describes the optical and diagnostic possibilities of confocal laser endomicroscopy.

Advances in colonic imaging: new endoscopic imaging methods

There is a need for better endoscopic visualization in specific circumstances like detection of flat colorectal lesions and dysplasia-screening in ulcerative colitis. Chromoendoscopy is a technique with proven success, but many more, novel endoscopic techniques are currently under investigation. In this article different point measurement and still imaging methods are discussed: Raman spectroscopy, elastic (light) scattering spectroscopy, fluorescence spectroscopy, optical coherence tomography and confocal laser microscopy. Furthermore, real-time endoscopic imaging methods are discussed. These include narrow band imaging, fluorescence imaging and endocytoscopy. The results of fluoroscence imaging might be improved by application of photosensitizers or coupling of fluorescent dyes to tumour-related antigens (immunoscopy). Most of these techniques still have to be developed further and are not yet available for routine use. In our opinion, a combination of a red-flag technique and a microscopic technique carries an enormous potential.

Endoscopic confocal imaging

In vivo fluorescence endomicroscopy is a newly developed diagnostic tool enabling virtual in vivo histology of the mucosal layer during ongoing endoscopy. This review summarizes currently available data about the technique and clinical use of confocal endomicroscopy. Indications discussed include colorectal cancer evaluation, ulcerative colitis and surveillance, Barrett's esophagus, and detection of Helicobacter pylori infection in vivo.

Confocal laser endoscopy for diagnosing intraepithelial neoplasias and colorectal cancer in vivo

BACKGROUND & AIMS

A confocal laser endoscopy system has recently been developed that may allow subsurface imaging of living cells in colonic tissue in vivo. The aim of the present study was to assess its potential for prediction of histology during screening colonoscopy for colorectal cancer.

METHODS

Twenty-seven patients underwent colonoscopy with the confocal endoscope using acriflavine hydrochloride or fluorescein sodium with blue laser illumination. Furthermore, 42 patients underwent colonoscopy with this system using fluorescein sodium. Standardized locations and circumscript lesions were examined by confocal imaging before taking biopsy specimens. Confocal images were graded according to cellular and vascular changes and correlated with conventional histology in a prospective and blinded fashion.

RESULTS

Acriflavine hydrochloride and fluorescein sodium both yielded high-quality images. Whereas acriflavine hydrochloride strongly labeled the superficial epithelial cells, fluorescein sodium offered deeper imaging into the lamina propria. Fluorescein sodium was thus used for the prospective component of the study in which 13,020 confocal images from 390 different locations were compared with histologic data from 1038 biopsy specimens. Subsurface analysis during confocal laser endoscopy allowed detailed analysis of cellular structures. The presence of neoplastic changes could be predicted with high accuracy (sensitivity, 97.4%; specificity, 99.4%; accuracy, 99.2%).

CONCLUSIONS

Confocal laser endoscopy is a novel diagnostic tool to analyze living cells during colonoscopy, thereby enabling virtual histology of neoplastic changes with high accuracy. These newly discovered diagnostic possibilities may be of crucial importance in clinical practice and lead to an optimized rapid diagnosis of neoplastic changes during ongoing colonoscopy.

In vivo pathology: microendoscopy as a new endoscopic imaging modality

Confocal microendoscopy permits direct observation of pathologic change at the microscopic level rather than traditional inference based on indirect changes at the macroscopic (cell) level. The main benefit includes earlier detection of precancerous and cancer conditions through improved biopsy selection and examination and more cost-effective solutions to screening and surveillance. Numerous outstanding research and commercial groups with varying approaches to confocal microendoscopy are allocating significant efforts to making the technology commercially available. The initial instruments will likely be geared toward screening for and surveillance of esophageal and colon-related conditions. Future developments related to greater functionality, improved ease of use, and automated analysis are likely to facilitate adoption and use of the technology. Clinical gastroenterologists should look forward to the potential of confocal microendoscopy as a logical and needed modality to advance the field of gastroenterology.

Confocal laser scanning microscopy of urinary bladder after intravesical instillation of a fluorescent dye

OBJECTIVES

To assess the potential of confocal laser scanning microscopy for imaging of the urinary bladder after intravesical instillation of a fluorescent dye.

METHODS

The study was performed on the bladder of male Copenhagen rats. For confocal fluorescence microscopy (CFM), a standard confocal laser scanning microscope (Zeiss LSM 410) was used. Before measuring, the fluorescent marker SYTO 17 was instilled intravesically. After 2 hours of incubation, the rat was killed, the bladder excised and opened, and CFM was performed starting from the surface going through the urothelium and superficial layers of the lamina propria. Except for the opening incision, the bladder was left intact and no biopsies were taken. After imaging, the bladder was sent for conventional histologic studies.

RESULTS

CFM allows imaging of cellular details of the entire urothelium (superficial umbrella cells, intermediate, and basal urothelial cells) and superficial layers of the lamina propria. CFM images are close to those obtained by standard microscopy after conventional hematoxylin-eosin staining. Cell structure (eg, shape, size, chromatin texture, nucleoli, mitotic figures, nuclear/cytoplasmic ratio), as well as the structure of the connective tissue (eg, collagen fibers, blood vessels, erythrocytes), can be studied, allowing a standard histologic evaluation. Furthermore, in contrast to conventional histologic evaluation, CFM provides three-dimensional information and allows the study of intact tissue representing the true in vivo situation.

CONCLUSIONS

CFM enables the study of the microscopic anatomy of bladder mucosa in its in vivo state. In combination with optical fiber bundles, endoscopic microscopy of the bladder may be possible in the future.

Future developments in endoscopic imaging

Flexible gastrointestinal endoscopy was introduced more than 30 years ago; this chapter will try to look into its future. Developments are expected in five different categories. We will see better with the use of high-resolution magnification endoscopy as well as by using other light-tissue interactions (such as spectroscopy). We will also be able to look just below the surface with laser-scanning microscopy and optical coherence tomography with a resolution of 1 microm (in vivo histology). Computers will assist with the interpretation of what we see, and the availability of broadband networks all around the world will allow real-time consultation globally. Invisible areas of the gastrointestinal tract will be seen with the help of improved endoscopy capsules and virtual endoscopy. Finally, we will treat endoscopically, with the help of new instruments and accessories, more of the lesions that we see.

Interventional endoscopy in the diagnosis and staging of upper gastrointestinal malignancy

Increased population longevity as well as an emphasis on earlier diagnosis and more effective treatment of cancer have created an environment for new technologies and techniques to flourish. Some of the endoscopic entities discussed in this article have not been fully validated in clinical practice. Innovative spectroscopic modalities hold a great deal of promise, but are years away from general applicability. In contrast, many interventional endoscopic techniques are currently available and confer heightened levels of diagnostic and staging accuracy for gastric and esophageal malignancies. Earlier diagnosis can identify patients who may be eligible for less-invasive treatment options such as EMR. Minimally invasive treatment options and maximum staging accuracy are more important for patients who are marginal surgical candidates and for accurate comparison of clinical trials studying treatment options. Our challenge for the future is to properly integrate these technologic advances with the science of good medical practice.