Probe-based confocal laser endomicroscopy for evaluating the submucosal invasion of colorectal neoplasms

Real-time in vivo distal margin selection using confocal laser endomicroscopy in transanal total mesorectal excision for rectal cancer

BACKGROUND

Transanal total mesorectal excision (TaTME) allows patients with ultralow rectal cancer to be treated with sphincter-saving surgery. However, accurate delineation of the distal resection margin (DRM), which is essential to achieve R0 resection for low rectal cancer in TaTME, is technically demanding.

AIM

To assess the feasibility of optical biopsy using probe-based confocal laser endomicroscopy (pCLE) to select the DRM during TaTME for low rectal cancer.

METHODS

A total of 43 consecutive patients who were diagnosed with low rectal cancer and scheduled for TaTME were prospectively enrolled from January 2019 to January 2021. pCLE was used to determine the distal edge of the tumor as well as the DRM during surgery. The final pathological report was used as the gold standard. The diagnostic accuracy of pCLE examination was calculated.

RESULTS

A total of 86 pCLE videos of 43 patients were included in the analyses. The sensitivity, specificity and accuracy of real-time pCLE examination were 90.00% [95% confidence interval (CI): 76.34%-97.21%], 86.96% (95%CI: 73.74%-95.06%) and 88.37% (95%CI: 79.65%-94.28%), respectively. The accuracy of blinded pCLE reinterpretation was 86.05% (95%CI: 76.89%-92.58%). Furthermore, our results show satisfactory interobserver agreement (κ = 0.767, standard error = 0.069) for the detection of cancer tissue by pCLE. There were no positive DRMs (≤ 1 mm) in this study. The median DRM was 7 mm [interquartile range (IQR) = 5-10 mm]. The median Wexner score was 5 (IQR = 3-6) at 6 mo after stoma closure.

CONCLUSION

Real-time in vivo pCLE examination is feasible and safe for selecting the DRM during TaTME for low rectal cancer (clinical trial registration number: NCT04016948).

Diagnostic accuracy of probe-based confocal laser endomicroscopy and tissue sampling by endoscopic retrograde cholangiopancreatography in indeterminate biliary strictures: a meta‑analysis

Probe-based confocal laser endomicroscopy (pCLE), also known as optical biopsy, is a new endoscopic technique that provides real-time magnification of 1000 × microscopic tissue information to diagnose indeterminate biliary strictures. Tissue sampling by endoscopic retrograde cholangiopancreatography (ERCP) is routinely performed to evaluate indeterminate biliary strictures. To evaluate the accuracy of pCLE and tissue sampling by ERCP in the diagnosis of indeterminate biliary strictures, 18 articles were included from 2008 to 2021 through Embase, PubMed, Web of Science, and Cochrane library databases. The summary estimates for the pCLE diagnosis of indeterminate biliary strictures were: sensitivity 0.88 (95% confidence interval (CI), 0.84-0.91); specificity 0.79 (95% CI 0.74-0.83); and Diagnostic Odds Ratio (DOR) 24.63 (95% CI 15.76-38.48). The summary estimates for tissue sampling by ERCP diagnosis for indeterminate biliary strictures were: sensitivity 0.54 (95% CI 0.49-0.59); specificity 0.96 (95% CI 0.94-0.98); and DOR 11.31 (95% CI 3.90-32.82). The area under the sROC curve of pCLE diagnosis of indeterminate biliary strictures is 0.90 higher than 0.65 of tissue sampling by ERCP. The pCLE is a better approach than tissue sampling by ERCP for the diagnosis of indeterminate biliary strictures by providing real-time microscopic images of the bile ducts.

Is barium enema examination negligible for the management of colorectal cancer? Comparison with conventional colonoscopy and magnifying colonoscopy

PURPOSE

The aim of this investigation was to evaluate the clinical value of barium enema (BE) examination for the management of colorectal epithelial neoplasms.

METHODS

We reviewed the colonoscopy records at our institution from 2014 to 2019 and identified cases of endoscopically or surgically resected colorectal epithelial neoplasms evaluated by BE, conventional colonoscopy, magnifying narrow-band imaging colonoscopy (M-NBI), and magnifying chromoendoscopy (MCE). The yield of each modality for the diagnosis of massively submucosal invasive (mSM) colorectal cancer was evaluated by a receiver-operating characteristic analysis including the area under the curve (AUC).

RESULTS

We analyzed the records of 105 patients (17 adenomas, 53 high-grade dysplasias (HGDs), and 35 cancers). Smooth surface, irregularity in depression, and eccentric deformity on the profile view with BE were observed more frequently in mSM cancers than adenomas/HGDs/slightly submucosal invasive cancers (p < 0.01). The AUC of BE was 0.8355, the value of which was not different from the other three modalities (conventional colonoscopy 0.7678; M-NBI 0.7835; MCE 0.8376). Although the specificity, PPV, and accuracy of BE were lower than those of M-NBI and MCE, the sensitivity and NPV of BE were the highest among the four types of examinations.

CONCLUSION

BE is still available and may serve as a supplementary modality for the diagnosis of mSM cancers.

Reduced Intravenous Fluorescein Dose for Upper and Lower Gastrointestinal Tract Probe-Based Confocal Laser Endomicroscopy

BACKGROUND/AIMS

Probe-based confocal laser endomicroscopy (pCLE) requires the administration of intravenous (IV) fluorescein. This study aimed to determine the optimal dose of IV fluorescein for both upper and lower gastrointestinal (GI) tract pCLE.

METHODS

Patients 20 to 79 years old with gastric high-grade dysplasia (HGD) or colorectal neoplasms (CRNs) were enrolled in the study. The dose de-escalation method was employed with five levels. The primary endpoint of the study was the determination of the optimal dose of IV fluorescein for pCLE of the GI tract. The reduced dose was determined based on off-line reviews by three endoscopists. An insufficient dose of fluorescein was defined as the dose of fluorescein with which the pCLE images were not deemed to be visible. If all three endoscopists determined that the tissue structure was visible, the doses were de-escalated.

RESULTS

A total of 12 patients with gastric HGD and 12 patients with CRNs were enrolled in the study. Doses were de-escalated to 0.5 mg/kg of fluorescein for both non-neoplastic duodenal and colorectal mucosa. All gastric HGD or CRNs were visible with pCLE with IV fluorescein at 0.5 mg/kg.

CONCLUSION

In the present study, pCLE with IV fluorescein 0.5 mg/kg was adequate to visualize the magnified structure of both the upper and lower GI tract.

Medical needs related to the endoscopic technology and colonoscopy for colorectal cancer diagnosis

Background

The high incidence and mortality rate of colorectal cancer require new technologies to improve its early diagnosis. This study aims at extracting the medical needs related to the endoscopic technology and the colonoscopy procedure currently used for colorectal cancer diagnosis, essential for designing these demanded technologies.

Methods

Semi-structured interviews and an online survey were used.

Results

Six endoscopists were interviewed and 103 were surveyed, obtaining the demanded needs that can be divided into: a) clinical needs, for better polyp detection and classification (especially flat polyps), location, size, margins and penetration depth; b) computer-aided diagnosis (CAD) system needs, for additional visual information supporting polyp characterization and diagnosis; and c) operational/physical needs, related to limitations of image quality, colon lighting, flexibility of the endoscope tip, and even poor bowel preparation.

Conclusions

This study shows some undertaken initiatives to meet the detected medical needs and challenges to be solved. The great potential of advanced optical technologies suggests their use for a better polyp detection and classification since they provide additional functional and structural information than the currently used image enhancement technologies. The inspection of remaining tissue of diminutive polyps (< 5 mm) should be addressed to reduce recurrence rates. Few progresses have been made in estimating the infiltration depth. Detection and classification methods should be combined into one CAD system, providing visual aids over polyps for detection and displaying a Kudo-based diagnosis suggestion to assist the endoscopist on real-time decision making. Estimated size and location of polyps should also be provided. Endoscopes with 360° vision are still a challenge not met by the mechanical and optical systems developed to improve the colon inspection. Patients and healthcare providers should be trained to improve the patient’s bowel preparation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08190-z.

Colon mucosal neoplasia referred for endoscopic mucosal resection: Recurrence of adenomas and prediction of submucosal invasion

BACKGROUND

Endoscopic mucosal resection (EMR) is an effective and minimally invasive alternative to surgery for large polyps and laterally spreading lesions. Gross morphology and surface characteristics may help predict submucosal invasion of the lesion (SMIL) during endoscopic evaluation. This is one of the largest single-center studies reporting endoscopic mucosal resection for larger (≥ 20 mm) colorectal lesions in the United States.

AIM

To determine the recurrence rate of adenomas and endoscopic features that may predict submucosal invasion of colonic mucosal neoplasia.

METHODS

This is a retrospective cohort study of all the patients referred for endoscopic mucosal resection for lesions ≥ 20 mm, spanning a period from January 2013 to February 2017. The main outcome measure was identifying features that may predict submucosal invasion of mucosal lesions and predict recurrence of adenomas on follow-up surveillance colonoscopy performed at 4-6 mo.

RESULTS

A total of 480 patients with 500 lesions were included in the study. The median age was 68 (Inter quantile range: 14) with 52% males. The most common lesion location was ascending colon (161; 32%). Paris classification 0-IIa (Flat elevation of mucosa - 316; 63.2%); Kudo Pit Pattern IIIs (192; 38%) and Granular surface morphology (260; 52%) were most prevalent. Submucosal invasion was present in 23 (4.6%) out of 500 lesions. The independent risk factors for SMIL were Kudo Pit Pattern IIIL + IV and V (Odds ratio: 4.5; P value < 0.004) and Paris classification 0-IIc (Odds ratio: 18.2; P value < 0.01). Out of 500, 354 post-endoscopic mucosal resection scars were examined at surveillance colonoscopy. Recurrence was noted in 21.8% (77 cases).

CONCLUSION

There was overall low prevalence of SMIL in our study. Kudo pit pattern (IIIL + IV and V) and Paris classification 0-IIc were the only factors identified as an independent risk factor for submucosal invasion. The independent risk factor for recurrence was adenoma size (> 40 mm). Almost all recurrences (98.8%) were treated endoscopically.

A preliminary study of dual-band confocal laser endomicroscopy combined with image mosaic in the diagnosis of liver cancer

Accurate identification of tumor tissues and their margins are still challenging for conventional clinical imaging methods during liver cancer surgery. In this study, dual-band confocal laser endomicroscopy (CLE) combined with image mosaic was used to guide liver cancer surgery. In the experiments with mice bearing orthotropic liver tumor, CLE can accurately detect the tumors and identify their margins with two excitation wavelengths of 488 nm and 660 nm by clinically available dyes fluorescein sodium (FS) or indocyanine green (ICG). The mosaic CLE images enlarged the imaging field and detected the liver tumor margins more accurately. Normal liver tissues fluorescence intensity of CLE images was significantly higher than that of tumor tissues in the same tumor-bearing mice (P < 0.0001). Overall, dual-band CLE imaging demonstrates to be a promising method to identify liver tumor tissues and margins, which has the prospect of clinical application and helps to achieve intraoperative radical resection.

The Status of Advanced Imaging Techniques for Optical Biopsy of Colonic Polyps

The progressive miniaturization of photonic components presents the opportunity to obtain unprecedented microscopic images of colonic polyps in real time during endoscopy. This information has the potential to act as "optical biopsy" to aid clinical decision-making, including the possibility of adopting new paradigms such as a "resect and discard" approach for low-risk lesions. The technologies discussed in this review include confocal laser endomicroscopy, optical coherence tomography, multiphoton microscopy, Raman spectroscopy, and hyperspectral imaging. These are in different stages of development and clinical readiness, but all show the potential to produce reliable in vivo discrimination of different tissue types. A structured literature search of the imaging techniques for colorectal polyps has been conducted. The significant developments in endoscopic imaging were identified for each modality, and the status of current development was discussed. Of the advanced imaging techniques discussed, confocal laser endomicroscopy is in clinical use and, under optimal conditions with an experienced operator, can provide accurate histological assessment of tissue. The remaining techniques show potential for incorporation into endoscopic equipment and practice, although further component development is needed, followed by robust prospective validation of accuracy. Optical coherence tomography illustrates tissue "texture" well and gives good assessment of mucosal thickness and layers. Multiphoton microscopy produces high-resolution images at a subcellular resolution. Raman spectroscopy and hyperspectral imaging are less developed endoscopically but provide a tissue "fingerprint" which can distinguish between tissue types. Molecular imaging may become a powerful adjunct to other techniques, with its ability to precisely label specific molecules within tissue and thereby enhance imaging.

Real-time imaging of head and neck squamous cell carcinomas using confocal micro-endoscopy and applicable dye: A preliminary study

OBJECTIVES

Confocal laser endomicroscopy (CLE) is a technology that enables microscopic visualization of lesions in real-time (optical biopsy) and has been successfully applied for clinical use in gastroenterology. Recently, it was also introduced for head and neck squamous cell carcinoma (HNSCC) diagnostics. We previously designed a self-made CLE, which can provide bichrome images, with topical contrast agents that are safe for use in patients. Herein, we report findings of a pilot study using our self-made CLE to image pairs of normal and cancerous tissues. This study aimed to characterize the features of HNSCC compared with normal mucosa and to establish a methodology of in vivo real-time optical biopsy of HNSCCs.

METHODS

HNSCC tissues were acquired from 10 patients who underwent surgical resection. Dissected specimens were first evaluated for their auto-fluorescence spectral profiles with 473 nm laser excitation and further optical observation. While obtaining the image, auto-fluorescence spectrum and intensity of the reflectance fluorescent signals were measured in real-time by a spectrometer. Subsequently, acriflavine was applied to the specimen to fluorescently label the nuclei and observe the difference between normal and cancerous tissues with 473 nm laser excitation. Finally, double staining with acriflavine and edible Food Red No.106 was performed to observe both nuclei and the cytoplasm of normal and cancerous tissues at 473 nm and 561 nm laser excitation.

RESULTS

Lower signals were detected from auto-fluorescence images of cancer tissues than normal tissues with 473 nm laser excitation. After acriflavine application, there was a clear difference between cancer and normal mucosa in the uniformity of nuclear size and shape. In normal mucosa, cells were arranged in an orderly manner, with each cell resembling a frog's egg. By contrast, in cancer tissues, the cell density was higher, and the cellular arrangement was less orderly. Using both acriflavine and Food Red No.106, images became more vivid, but more complicated because red dye staining of the cytoplasm emerged as fluorescence at different wavelengths.

CONCLUSIONS

Real-time in vivo imaging using the newly developed CLE and conditions may be used to distinguish cancer tissue from normal mucosa without invasive biopsy.

Advanced Endoscopic Imaging in Colonic Neoplasia

BACKGROUND

Endoscopic imaging is a rapidly evolving field with a constant influx of new concepts and technologies. Since the introduction of video endoscopy and subsequently high-definition imaging as the first revolutions in gastrointestinal endoscopy, several technologies of virtual chromoendoscopy have been developed and brought to the market in the past decade, which have shaped and revolutionized for a second time our approach to endoscopic imaging. In parallel to these developments, microscopic imaging technologies, such as endomicroscopy and endocytoscopy, allow us to examine single cells within the mucosa in real time, thereby enabling histological diagnoses during ongoing endoscopy.

SUMMARY

In this review, we provide an overview on the technical background of different technologies of advanced endoscopic imaging, and then review and discuss their role and applications for the diagnosis and management of colorectal neoplasms as well as limitations and challenges that exist despite all technological improvements.

KEY MESSAGES

Technologies of advanced endoscopic imaging have profound impact not only on our imaging capabilities, they are also about to fundamentally change our approach to managing lesions in the gastrointestinal tract: not every lesion found during colonoscopy has to be excised or sent for histopathologic evaluation. However, before this becomes widespread reality, major obstacles such as patient acceptance, adoption by less trained endoscopists, and also legal aspects need to carefully addressed. The development of computer-aided diagnosis and artificial intelligence algorithms hold the potential to overcome the obstacles associated with the concept of optical biopsy and will most likely fundamentally facilitate, shape, and change decision making in the management of colorectal lesions.

Label-free multiphoton microscopic imaging as a novel real-time approach for discriminating colorectal lesions: A preliminary study

BACKGROUND AND AIM

Although various endoscopic technologies have been developed to increase the visual diagnostic accuracy of colorectal precancerosis and early carcinoma, the biopsy-dependent pathology still remains the golden standard. During routine endoscopy, real-time optical histological diagnosis is desired. Without fluorescent label, multiphoton microscopy (MPM) imaging directly reveals live cellular morphology and tissue microenvironment based on intrinsic two-photon excited fluorescence and second harmonic generation signals. Its high-imaging resolution and performance are comparable with the histopathology. We thus aimed to initially investigate the original features of colorectal diseases under MPM and evaluate its potential for real-time diagnosis.

METHODS

Experimental and diagnostic cohorts were designed. Multiphoton images of 40 ex vivo fresh tissues confirmed pathologically of colorectal normal tissues, hyperplastic polyps, adenomas, and adenocarcinomas were collected. Features were recorded to establish diagnostic standards with MPM. For the second cohort with 92 fresh tissues, we distinguished the various colorectal diseases with conclusive MPM features.

RESULTS

Through the investigation, the colorectal diseases were presented differences in the crypt opening, gland structure, epithelial cells, and collagen fibers. With the typical features, we preliminarily tested the diagnostic efficiency and found that its sensitivity for distinguishing normal, hyperplastic polyps, adenoma and adenocarcinoma was 88.89%, 76.47%, 83.33%, and 97.92%, while the specificity was 99.32%, 94.00%, 94.92%, and 94.12%, respectively.

CONCLUSION

The real-time multiphoton microscopic imaging can be effective to identify the colorectal lesions with high resolution. Via integrating with the endoscopes in the future, it could promote precise optical diagnosis in clinics.

Shedding light on fibered confocal fluorescence microscopy: Applications in biomedical imaging and therapies

Discoveries of major importance in life sciences and preclinical research are linked to the invention of microscopes that enable imaging of cells and their microstructures. Imaging technologies involving in vivo procedures using fluorescent dyes that permit labelling of cells have been developed over the last two decades. Fibered confocal fluorescence microscopy (FCFM) is an imaging technology equipped with fiber-optic probes to deliver light to organs and tissues of live animals. This enables not only in vivo detection of fluorescent signals and visualization of cells, but also the study of dynamic processes, such cell proliferation, apoptosis and angiogenesis, under physiological and pathological conditions. This will allow the diagnosis of diseased organs and tissues and the evaluation of the efficacy of new therapies in animal models of human diseases. The aim of this report is to shed light on FCFM and its potential medical applications and discusses some factors that compromise the reliability and reproducibility of monitoring biological processes by FCFM. This report also highlights the issues concerning animal experimentation and welfare, and the contributions of FCFM to the 3Rs principals, replacement, reduction and refinement.

Pilot study on probe-based confocal laser endomicroscopy for colorectal neoplasms: an initial experience in Japan

BACKGROUND

The aim of this pilot study is to investigate the diagnostic yield of probe-based confocal laser endomicroscopy (pCLE) in the evaluation of depth of invasion in colorectal lesions.

METHODS

Patients with colorectal lesions eligible for either endoscopic treatment or surgery were enrolled in the study. Tumor's depth of invasion was classified as mucosal or slight submucosal (M-SM1) and deep submucosal invasion or deeper (SM2 or deeper). White light endoscopy (WLE), magnifying narrow band imaging (M-NBI), and magnifying chromoendoscopy (M-CE) were used to assess colorectal lesions, and pCLE was used to identify tumor's features related to SM2 or deeper. The diagnostic classification of depth of invasion was obtained by correlating pCLE findings with histology results (on-site diagnosis). All colorectal lesions were stratified by a second endoscopist who was blinded to any clinical and histological information with the use of WLE, M-NBI, M-CE, and pCLE (off-line review).

RESULTS

A total of 22 colorectal lesions were analyzed: seven were adenoma, ten intramucosal cancer, and five SM2 or deeper cancer. With respect to pCLE findings, loss of crypt structure was seen in all SM2 or deeper cancers and only in one M-SM1 lesion. Sensitivity, specificity, and accuracy of WLE, M-NBI, and M-CE in off-line review were 60/94/86, 60/94/86, and 80/94/91%, respectively. Sensitivity/specificity/accuracy of pCLE in off-line review were 80/94/91%, respectively. The inter-observer agreement of pCLE between on-site diagnosis and off-line review was 0.64 (95%CI 0.27-1.0).

CONCLUSIONS

pCLE may represent a useful tool to evaluate the depth of invasion in colorectal lesions.