The Role of Probe-Based Confocal Laser Endomicroscopy (pCLE) in the Diagnosis of Sustained Clinical Complete Response Under Watch-and-Wait Strategy After Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Adenocarcinoma: a Score Validation

BACKGROUND

Watch-and-wait strategy has been increasingly accepted for patients with clinical complete response (cCR) after multimodal treatment for locally advanced rectal adenocarcinoma. Close follow-up is essential to the early detection of local regrowth. It was previously demonstrated that probe-based confocal laser endomicroscopy (pCLE) scoring using the combination of epithelial and vascular features might improve the diagnostic accuracy of cCR.

AIM

To validate the pCLE scoring system in the assessment of patients with cCR after neoadjuvant chemoradiotherapy (nCRxt) for advanced rectal adenocarcinoma.

METHODS

Digital rectal examination, pelvic magnetic resonance imaging (MRI), and pCLE were performed in 43 patients with cCR, who presented either a scar (N = 33; 76.7%) or a small ulcer with no signs of tumor, and/or biopsy negative for malignancy (N = 10; 23.3%).

RESULTS

Twenty-five (58.1%) patients were men, and the mean age was 58.4 years. During the follow-up, 12/43 (27.9%) patients presented local regrowth and underwent salvage surgery. There was an association between pCLE diagnostic scoring and final histological report (for patients who underwent surgical resection) or final diagnosis at the latest follow-up (p = 0.0001), while this association was not observed with MRI (p = 0.49). pCLE sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 66.7%, 93.5%, 80%, 88.9%, and 86%, respectively. MRI sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 66.7%, 48.4%, 66.7%, 78.9%, and 53.5%, respectively.

CONCLUSIONS

pCLE scoring system based on epithelial and vascular features improved the diagnosis of sustained cCR and might be recommended during follow-up. pCLE might add some valuable contribution for identifying local regrowth. Trial Registration This protocol was registered at the Clinical Trials (ClinicalTrials.gov identifier NCT02284802).

Accuracy and agreement of a large panel of endosonographers for endomicroscopy-guided virtual biopsy of pancreatic cystic lesions

BACKGROUND

Although emerging data evidences that EUS-guided needle-based confocal laser endomicroscopy (nCLE) accurately diagnoses pancreatic cystic lesions (PCLs), there are a lack of interobserver agreement (IOA) studies utilizing reference histopathological diagnosis and for specific PCL subtypes. Hence, we sought to assess the IOA, intra-observer reliability (IOR), and diagnostic performance of EUS-nCLE using a large cohort of patients with histopathological diagnosis amongst a broad panel of international observers.

METHODS

EUS-nCLE videos (n = 76) of subjects with PCLs [intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm (MCN), serous cystadenoma (SCA), pseudocyst, and cystic-neuroendocrine tumors/solid pseudopapillary neoplasm (cystic-NET/SPN)], simulating clinical prevalence rates were obtained from 3 prospective studies. An international panel of 13 endosonographers with nCLE experience, blinded to all PCL data, evaluated the video library twice with a two-week washout for PCL differentiation (mucinous vs. non-mucinous) and subtype diagnosis.

RESULTS

The IOA (κ = 0.82, 95% CI 0.77-0.87) and IOR (κ = 0.82, 95% CI 0.78-0.85) were "almost perfect" to differentiate mucinous vs. non-mucinous PCLs. For PCL subtype, IOA was highest for SCA (almost perfect; κ = 0.85), followed by IPMN (substantial, κ = 0.72), and cystic-NET/SPN (substantial, κ = 0.73). The IOA was moderate for MCN (κ = 0.47), and pseudocyst (κ = 0.57). Compared to histopathology, observers differentiated mucinous vs. non-mucinous PCLs with high accuracy (94.8%, 95% CI 93.3-96.1). For detecting specific PCLs subtypes, EUS-nCLE was highly accurate in diagnosing non-mucinous cysts (SCA: 98%; cystic-NET/SPN: 96%; pseudocyst: 96%) and slightly less accurate for mucinous lesions (IPMN: 86%; MCN: 84%).

CONCLUSION

Diagnosis of PCLs by EUS-nCLE guided virtual biopsy is very accurate and reliable for the most prevalent pancreatic cysts in clinical practice.

pCLE detects mucosal neoplastic vascular pattern in gastric linitis plastica

Linitis plastica (LP) is a very aggressive and rare carcinoma with a scirrhous stroma that affects the submucosal and muscular layers of the stomach even without mucosal alterations. Lack of timely diagnosis is a crucial problem related to its prognosis and treatment. In this study, we investigated the LP-associated vascular pattern as a possible means to improve the diagnosis of these patients. During standard endoscopy, mucosal architecture, tortuosity and enlargement of vessels, as well as the presence of vascular leakage and efficiency of the blood flow were assessed in six LP patients using probe-based Confocal Laser Endomicroscopy (pCLE). In all LP patients, we detected abnormal changes in vasculature. The aberrant features of the vascular network were common to all LP patients examined and consisted of vessel enlargement, tortuosity, and leakage associated with the affected submucosal layer. This is the first study to highlight the presence of marked vascularization associated with LP, characterized by the presence of abnormal and non-functional vessels, similar to what is observed in neoplastic tissues. Therefore, the analysis of LP by pCLE may provide a new endoscopic approach and strategy to better define these patients.

Confocal endomicroscopy and robot-assisted bronchoplasty integration to treat an endobronchial tumour

We present a case of a young man with an endobronchial carcinoid in the left main bronchus, which was treated integrating probe-based confocal laser endomicroscopy and fluorescence imaging during a robot-assisted bronchoplasty. This technique allowed precise detection of the neoplastic area, avoiding associated lung resection. The incorporation of new technologies to our current practice may lead to a better approach to airway tumours.

Laparoscopic surgical device with modular end tools for real-time endomicroscopy and therapy

In recent years, laparoscopic surgery attracts considerable attention for its distinct advantages owing to minimized invasiveness. However, traditional surgical instruments have a single function and lack the ability to provide high-resolution images for real-time tissue assessment. Thus, it remains a challenge to perform complex procedures with the traditional surgical instruments. In this paper, a novel laparoscopic surgical device for real-time endomicroscopy and therapy is proposed. The device is integrated with a visualization unit to provide endoscopic images in a constrained cavity for real-time observation. Moreover, modular end tools can be assembled and switched with the multi-DOF manipulator. The experimental results demonstrate that the surface-scanning tool can perform smooth scanning and obtain a large area mosaic of 6.99 mm² in 40.2 s for tissue assessment. The spring-loaded forceps can generate an output force of 1.47 N to manipulate tissue. These experimental results demonstrate the potential value of the device for intraoperative endomicroscopy-guided surgery and robot-assisted surgery.

Diagnosis of Clinical Complete Response by Probe-Based Confocal Laser Endomicroscopy (pCLE) After Chemoradiation for Advanced Rectal Cancer

BACKGROUND

Neoadjuvant chemoradiotherapy (nCRxt) followed by radical surgery is the optimal treatment for advanced rectal adenocarcinoma. Patients with clinical complete response (cCR) may be followed closely without immediate surgery. Probe-based confocal laser endomicroscopy (pCLE) is a real-time in vivo method that allows acquisition of optical biopsies with 1000 times magnification, evaluating both epithelial and vascular patterns.

AIM

To evaluate the role of pCLE in the diagnosis of cCR after nCRxt for advanced rectal adenocarcinoma.

METHODS

pCLE was performed in 47 patients with locally advanced rectal adenocarcinoma (T3/T4, or N+) who underwent nCRxt (5-fluorouracil, 5040 cGy).

RESULTS

Twenty-seven (57.5%) patients were men, and the mean age was 62.8 years. Thirty-seven had partial response confirmed by pCLE. Ten (21.3%) patients had good endoscopic response and presented small ulcer (n = 5) or residual scar (n = 5). After nCRxt, the essential features to differentiate malignancy from post-radiation alterations at pCLE were the presence of irregular crypts, budding, back-to-back glands, cribriform pattern, increased vessel/crypt ratio, and fluorescein leakage. A scoring system was created considering these epithelial and vascular features, with high accuracy for differentiating patients with complete response from those with residual neoplasia (p < 0.00001). pCLE sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 100%, 71.4%, 95.2%, 100%, and 95.7%, respectively.

CONCLUSIONS

(1) pCLE evaluation of epithelial and vascular features may improve the diagnosis of cCR and may alter patient management; (2) pCLE might be valuable for identifying patients with advanced rectal cancer who will benefit from watch and wait strategy, avoiding immediate surgical treatment.

Confocal endomicroscopy for the diagnosis of pancreatic lesions

Confocal endomicroscopy (EMC) is a thriving technology that allows real-time and non-invasive imaging in vivo. EMC demonstrated its effectiveness to differentiate neoplastic from normal tissue and to search dysplasia. In addition to the significant developments of this technique in Barrett oesophagus, celiac disease, characterization of colonic polyps, or monitoring of chronic inflammatory bowel disease, EMC is currently developing in bilio-pancreatic pathology. Indeed, it is currently used to characterize biliary stenosis as well as pancreatic lesions (especially cystic). The aim of our study was to evaluate through a review of the literature the value of this technique in the characterization of pancreatic lesions.

Endosonographic diagnosis of advanced neoplasia in intraductal papillary mucinous neoplasms

Pancreatic cancer has a high mortality rate with minimal proven interventions. Intraductal Papillary Mucinous Neoplasms (IPMNs) are known precursor lesions for pancreatic cancer. Identification of pancreatic cysts has improved from advances in abdominal imaging. Despite multiple revisions of the international consensus recommendations and various guidelines by other major societies, successful risk stratification of the malignant potential of mucinous pancreatic cysts remains challenging. Specifically, detection and accurate classification of advanced neoplasia (high-grade dysplasia and/or adenocarcinoma) in IPMNs is suboptimal with current diagnostic strategies. Development of interventional techniques utilizing endoscopic ultrasound include - through-the-needle microforceps biopsy, next-generation or whole genome molecular analysis of cyst fluid, and needle-based confocal laser endomicroscopy. These techniques suffer from a series of limitations in technical success, diagnostic yield, and clinical feasibility, but a combination approach may offer a solution that optimizes their cyst evaluation and risk stratification. Assessment and comparison of these techniques is restricted by lack of adequate surgical specimens for testing of diagnostic accuracy, resulting in a possible sample bias. Additional large-scale multicenter studies are needed to accumulate evidence for the utility and feasibility of their translation into clinical practice. Great strides have been made in pancreatic cyst evaluation, but further research is required to improve diagnostic accuracy and clinical management of IPMNs.

Confocal Laser Endomicroscopy for Intraoperative Tumor Assessment: Development of a Conceptual Model for an Evaluation Study

Brain tumor surgery is a complex medical procedure. The extent of tumor resection is essential for postoperative recovery and survival. The neurosurgeon needs to regularly check the borderline between healthy and cancerous tissue. Currently, tissue samples are extracted via instantaneous sections and sent to a neuropathologist for examination. This process takes time and requires extensive human resources. Confocal laser endomicroscopy (CLE) allows visualization of cellular structures in vivo without the need for sample extraction. This paper presents a conceptual model which serves as the hypothetical basis for a planned intervention study to evaluate CLE with the case example of brain tumor surgery. Using current literature and expert interviews, the model has been tested. The expected improvement of the medical outcome could be confirmed. Regarding the socioeconomic impact of CLE, the literature is scarce. Expert interviews confirmed the hypotheses that costs and the workload for clinical staff might increase.

Advanced diagnostics for pancreatic cysts: Confocal endomicroscopy and molecular analysis

Technological advances and the widespread use of medical imaging have led to an increase in the identification of pancreatic cysts in patients who undergo cross-sectional imaging. Current methods for the diagnosis and risk-stratification of pancreatic cysts are suboptimal, resulting in both unnecessary surgical resection and overlooked cases of neoplasia. Accurate diagnosis is crucial for guiding how a pancreatic cyst is managed, whether with surveillance for low-risk lesions or surgical resection for high-risk lesions. This review aims to summarize the current literature on confocal endomicroscopy and cyst fluid molecular analysis for the evaluation of pancreatic cysts. These recent technologies are promising adjuncts to existing approaches with the potential to improve diagnostic accuracy and ultimately patient outcomes.

Modular laser-based endoluminal ablation of the gastrointestinal tract: in vivo dose-effect evaluation and predictive numerical model

BACKGROUND

Endoscopic submucosal dissection allows for "en bloc" removal of early gastrointestinal neoplasms. However, it is technically demanding and time-consuming. Alternatives could rely on energy-based techniques. We aimed to evaluate a predictive numerical model of thermal damage to preoperatively define optimal laser settings allowing for a controlled ablation down to the submucosa, and the ability of confocal endomicroscopy to provide damage information.

MATERIALS AND METHODS

A Nd:YAG laser was applied onto the gastric mucosa of 21 Wistar rats on 10 spots (total 210). Power settings ranging from 0.5 to 2.5W were applied during 1-12 s, with a consequent energy delivery varying from 0.5 to 30 J. Out of the 210 samples, a total of 1050 hematoxilin-eosin stained slides were obtained. To evaluate thermal injury, the ratio between the damage depth (DD) over the mucosa and the submucosa thickness (T) was calculated. Effective and safe ablation was considered for a DD/T ratio ≤ 1 (only mucosal and submucosal damage). Confocal endomicroscopy was performed before and after ablation. A numerical model, using human physical properties, was developed to predict thermal damage.

RESULTS

No full-thickness perforations were detected. On histology, the DD/T ratio at 0.5 J was 0.57 ± 0.21, significantly lower when compared to energies ranging from 15 J (a DD/T ratio = 1.2 ± 0.3; p < 0.001) until 30 J (a DD/T ratio = 1.33 ± 0.31; p < 0.001). Safe mucosal and submucosal ablations were achieved applying energy between 4 and 12 J, never impairing the muscularis propria. Confocal endomicroscopy showed a distorted gland architecture. The predicted damage depth demonstrated a significant positive linear correlation with the experimental data (Pearson's r 0.85; 95% CI 0.66-0.94).

CONCLUSIONS

Low-power settings achieved effective and safe mucosal and submucosal ablation. The numerical model allowed for an accurate prediction of the ablated layers. Confocal endomicroscopy provided real-time thermal damage visualization. Further studies on larger animal models are required.

New horizons in the endoscopic ultrasonography-based diagnosis of pancreatic cystic lesions

Pancreatic cystic lesions (PCLs) are increasingly being identified because of the widespread use of high-resolution abdominal imaging. These cysts encompass a spectrum from malignant disease to benign lesions, and therefore, accurate diagnosis is crucial to determine the best management strategy, either surgical resection or surveillance. However, the current standard of diagnosis is not accurate enough due to limitations of imaging and tissue sampling techniques, which entail the risk of unnecessary burdensome surgery for benign lesions or missed opportunities of prophylactic surgery for potentially malignant PCLs. In the last decade, endoscopic innovations based on endoscopic ultrasonography (EUS) imaging have emerged, aiming to overcome the present limitations. These new EUS-based technologies are contrast harmonic EUS, needle-based confocal endomicroscopy, through-the-needle cystoscopy and through-the needle intracystic biopsy. Here, we present a comprehensive and critical review of these emerging endoscopic tools for the diagnosis of PCLs, with a special emphasis on feasibility, safety and diagnostic performance.

Diagnostic Accuracy of a Confocal Laser Endomicroscope for In Vivo Differentiation Between Normal Injured And Tumor Tissue During Fluorescein-Guided Glioma Resection: Laboratory Investigation

OBJECTIVE

Glioma resection with fluorescein sodium (FNa) guidance has a potential drawback of nonspecific leakage of FNa from nontumor areas with a compromised blood-brain barrier. We investigated the diagnostic accuracy of in vivo confocal laser endomicroscopy (CLE) after FNa administration to differentiate normal brain, injured normal brain, and tumor tissue in an animal glioma model.

METHODS

GL261-Luc2 gliomas in C57BL/6 mice were used as a brain tumor model. CLE images of normal, injured normal, and tumor brain tissues were collected after intravenous FNa administration. Correlative sections stained with hematoxylin and eosin were taken at the same sites. A set of 40 CLE images was given to 1 neuropathologist and 3 neurosurgeons to assess diagnostic accuracy and rate image quality (1-10 scale). Additionally, we developed a deep convolution neural network (DCNN) model for automatic image classification.

RESULTS

The mean observer accuracy for correct diagnosis of glioma compared with either injured or uninjured brain using CLE images was 85%, and the DCNN model accuracy was 80%. For differentiation of tumor from nontumor tissue, the experts' mean accuracy, specificity, and sensitivity were 90%, 86%, and 96%, respectively, with high interobserver agreement overall (Cohen κ = 0.74). The percentage of correctly identified images was significantly higher for images with a quality rating >5 (104/116, 90%) than for images with a quality rating ≤5 (32/44, 73%) (P = 0.007).

CONCLUSIONS

With sufficient FNa present in tissues, CLE was an effective tool for intraoperative differentiation among normal, injured normal, and tumor brain tissue. Clinical studies are warranted to confirm these findings.

Robotic Scanning Device for Intraoperative Thyroid Gland Endomicroscopy

Probe-based confocal laser endomicroscopy has a high potential to be a promising tool that can provide intraoperative high-resolution in vivo morphological imaging at cellular and subcellular levels for thyroidectomy, and allow real-time assessment of tumor margins. However, the typical images acquired with this technique cover a very small area limited by the field of view of the probe, accompanied by tissue deformation and inconsistent probe-tissue contact when operated manually. In this paper, a novel compact robotic device for large area scanning has been developed. The device can scan a large surface in a spiral trajectory by rotating the tip frame along the spiral groove of the base frame. The fiber Bragg grating sensor with a passive linear structure is used to detect and maintain a stable probe-tissue contact force during scanning. An active linear actuation is also integrated for adjusting the probe-tissue contact level prior to each scan. Results demonstrate that the scanning device ensures a suitable probe-tissue contact force and compensates for simulated hand tremor. Mosaicing results of lens tissue paper and porcine belly tissue with both bench and hand-held experiments show the effectiveness and usability of the device, demonstrating the potential clinical value of the system.

Confocal endomicroscopy and cyst fluid molecular analysis: Comprehensive evaluation of pancreatic cysts

Increases in the quality as well as utilization of cross-sectional imaging have led to rising diagnoses of pancreatic cystic lesions (PCL). Accurate presurgical diagnosis enables appropriate triage of PCLs. Unfortunately, current diagnostic approaches have suboptimal accuracy and may lead to unnecessary surgical resections or missed diagnoses of advanced neoplasia. Additionally, early detection represents an opportunity for intervention to prevent the progression to pancreatic adenocarcinoma. Our aim for this review is to systematically review the current literature on confocal endomicroscopy and molecular biomarkers in the evaluation of PCLs. Confocal laser endomicroscopy is a novel technology that allows for real-time in vivo microscopic imaging with multiple clinical trials identifying characteristic endomicroscopy findings of various pancreatic cystic lesions. DNA-based molecular markers have also emerged as another diagnostic modality as the pattern of genetic alternations present in cyst fluid can provide both diagnostic and prognostic data. We propose that both techniques can be utilized to improve patient outcomes.

Evaluation of immunological markers of ovine vaginal irritation: Implications for preclinical assessment of non-vaccine HIV preventive agents

The presence of genital inflammatory responses and a compromised vaginal epithelial barrier have been linked to an increased risk of HIV acquisition. It is important to assure that application of candidate microbicides designed to limit HIV transmission will not cause these adverse events. We previously developed high resolution in vivo imaging methodologies in sheep to assess epithelial integrity following vaginal application of a model microbicide, however characterization of genital inflammation in sheep has not been previously possible. In this study, we significantly advanced the sheep model by developing approaches to detect and quantify inflammatory responses resulting from application of a nonoxynol-9-containing gel known to elicit vaginal irritation. Vaginal application of this model microbicide resulted in foci of disrupted epithelium detectable by confocal endomicroscopy. Leukocytes also infiltrated the treated mucosa and the number and composition of leukocytes obtained by cervicovaginal lavage (CVL) were determined by differential staining and flow cytometry. By 18h post-treatment, a population comprised predominantly of granulocytes and monocytes infiltrated the vagina and persisted through 44h post-treatment. The concentration of proinflammatory cytokines and chemokines in CVL was determined by quantitative ELISA. Concentrations of IL-8 and IL-1β were consistently significantly increased after microbicide application suggesting these cytokines are useful biomarkers for epithelial injury in the sheep model. Together, the results of these immunological assessments mirror those obtained in previous animal models and human trials with the same compound and greatly extend the utility of the sheep vaginal model in assessing the vaginal barrier and immune microenvironment.

Future Directions for Endoscopic Ultrasound: Where Are We Heading?

Endoscopic ultrasound (EUS) plays an important role as a diagnostic and therapeutic modality in gastroenterology. New developments have emerged, especially in the last decade, and are being introduced to endoscopists. The ability to readily visualize and access organs in the gastrointestinal tract has allowed endoscopists to perform new interventional procedures. EUS procedures have taken the place of conventional approaches for the treatment of various gastrointestinal diseases, including pancreatic cystic lesions. This article focuses on the advances and future of diagnostic and therapeutic EUS.

Review: Surveillance of patients with Barrett oesophagus

There has been a rapid increase in the incidence of oesophageal adenocarcinoma in most Western countries over the past thirty years. Barrett's oesophagus (BE) is a common premalignant lesion of oesophageal adenocarcinoma, although the risk of developing cancer in BE remains low. Therefore, screening is not recommended in the general population. Surveillance of BE is recommended to detect high grade dysplasia or carcinoma in an early stage, although there is no clear evidence that surveillance leads to a reduced mortality. This review discusses the several screening and surveillance techniques, including chromoendoscopy, narrow band imaging, autofluorescence imaging and confocal laser endomicroscopy, pointing out the areas that are well established as well as the new techniques that require more research.

Endomicroscopy and Molecular Tools to Evaluate Inflammatory Bowel Disease

Endoscopy is an essential tool for effective care of patients with inflammatory bowel disease (IBD), including Crohn disease and ulcerative colitis. The newest endoscopic small-field imaging technologies with confocal endomicroscopy have allowed real-time imaging of gastrointestinal mucosal during ongoing endoscopic evaluation and in vivo histology. Thus, endomicroscopy has a potential to further enhance the endoscopic evaluation of IBD. Advances in molecular in vivo imaging in IBD may be used not only to better understand the pathophysiology of IBD but also to guide optimized therapy and thus to allow a personalized, new approach to the IBD management.

Raman Spectroscopy for the Endoscopic Diagnosis of Esophageal, Gastric, and Colonic Diseases

Globally white-light endoscopy with biopsy sampling is the gold standard diagnostic modality for esophageal, gastric, and colonic pathologies. However, there is overwhelming evidence to highlight the deficiencies of an approach based predominantly on eyeball visualization. Biopsy sampling is also problematic due in part to excessive sampling and hence attendant cost. Various innovations are currently taking place in the endoscopic domain to aid operators in diagnosis forming. These include narrow band imaging which aims to enhance the surface anatomy and vasculature, and confocal laser endomicroscopy which provides real time histological information. However, both of these tools are limited by the skill of the operator and the extensive learning curve associated with their use. There is a gap therefore for a new form of technology that relies solely on an objective measure of disease and reduces the need for biopsy sampling. Raman spectroscopy (RS) is a potential platform that aims to satisfy these criteria. It enables a fingerprint capture of tissue in relation to the protein, DNA, and lipid content. This focused review highlights the strong potential for the use of RS during endoscopic gastroenterological examination.

A Review of Probe-Based Confocal Laser Endomicroscopy for Pancreaticobiliary Disease

Confocal laser endomicroscopy (CLE) is a novel in vivo imaging technique that can provide real-time optical biopsies in the evaluation of pancreaticobiliary strictures and pancreatic cystic lesions (PCLs), both of which are plagued by low sensitivities of routine evaluation techniques. Compared to pathology alone, CLE is associated with a higher sensitivity and accuracy for the evaluation of indeterminate pancreaticobiliary strictures. CLE has the ability to determine the malignant potential of PCLs. As such, CLE can increase the diagnostic yield of endoscopic retrograde cholangiopancreatography and endoscopic ultrasound, reducing the need for repeat procedures. It has been shown to be safe, with an adverse event rate of ≤1%. Published literature regarding its cost-effectiveness is needed.

Light and sound - emerging imaging techniques for inflammatory bowel disease

Patients with inflammatory bowel disease are known to have a high demand of recurrent evaluation for therapy and disease activity. Further, the risk of developing cancer during the disease progression is increasing from year to year. New, mostly non-radiant, quick to perform and quantitative methods are challenging, conventional endoscopy with biopsy as gold standard. Especially, new physical imaging approaches utilizing light and sound waves have facilitated the development of advanced functional and molecular modalities. Besides these advantages they hold the promise to predict personalized therapeutic responses and to spare frequent invasive procedures. Within this article we highlight their potential for initial diagnosis, assessment of disease activity and surveillance of cancer development in established techniques and recent advances such as wide-view full-spectrum endoscopy, chromoendoscopy, autofluorescence endoscopy, endocytoscopy, confocal laser endoscopy, multiphoton endoscopy, molecular imaging endoscopy, B-mode and Doppler ultrasound, contrast-enhanced ultrasound, ultrasound molecular imaging, and elastography.

The quest for precision in transanal total mesorectal excision. Tech Coloproctol. 2016;20:11-18. [PMID: 26611358 DOI: 10.1007/s10151-015-1405-3]

Transanal total mesorectal excision (TME) is an emerging minimally invasive approach to rectal cancer, with encouraging preliminary results. However, the new surgical anatomy of the bottom-up approach complicates surgical understanding and increases the risks of inadvertent injuries to crucial anatomical structures, including nerves. Key elements to improve the safety and stimulate interest in such a complex technique might be robotics and image guidance, to enhance the level of precision. In this editorial, some of the technologies that could be used for precision TME are outlined, in light of the experience of our Institute for Image-Guided Surgery.

Detection of superficial esophageal squamous cell neoplasia by chromoendoscopy-guided confocal laser endomicroscopy

AIM: To evaluate the diagnostic potential of Lugol’s chromoendoscopy-guided confocal laser endomicroscopy (CLE) in detecting superficial esophageal squamous cell neoplasia (ESCN).

METHODS: Between December 2008 and September 2010, a total of 52 patients were enrolled at the Chinese PLA General Hospital in Beijing, China. First, Lugol’s chromoendoscopy-guided CLE was performed in these patients and the CLE in vivo histological diagnosis was recorded. Then, chromoendoscopy-guided biopsy was performed in the same patients by another endoscopist who was blinded to the CLE findings. Based on the biopsy and CLE diagnosis, en bloc endoscopic resection was performed. The CLE in vivo diagnosis and the histological diagnosis of biopsy of ESCN were compared, using a histological examination of the endoscopic resection specimens as the standard reference.

RESULTS: A total of 152 chromoendoscopy-guided biopsies were obtained from 56 lesions. In the 56 lesions of 52 patients, a total of 679 CLE images were obtained vs 152 corresponding biopsies. The sensitivity, specificity, negative predictive value and positive predictive value of chromoendoscopy-guided CLE compared with biopsy were 95.7% vs 82% (P < 0.05), 90% vs 70% (P < 0.05), 81.8% vs 46.7% (P < 0.05), and 97.8% vs 92.7% (P > 0.05), respectively. There was a significant improvement in sensitivity, specificity, negative predictive value, and accuracy when comparing chromoendoscopy-guided CLE with biopsy.

CONCLUSION: Lugol’s chromoendoscopy-guided CLE is a real-time, non-invasive endoscopic diagnostic technology; the accuracy of the detection of superficial ESCN is equivalent to or may be superior to biopsy histology.

Probe-based confocal laser endomicroscopy in the pancreatic duct provides direct visualization of ductal structures and aids in clinical management

BACKGROUND

Confocal endomicroscopy provides real-time evaluation of various sites and has been used to provide detailed endomicroscopic imaging of the biliary tree. We aimed to evaluate the feasibility and utility of probe-based confocal laser endomicroscopy of the pancreatic duct as compared to cytologic and histologic results in patients with indeterminate pancreatic duct strictures.

METHODS

Retrospective data on patients with indeterminate pancreatic strictures undergoing endoscopic retrograde cholangiopancreatography (ERCP) and confocal endomicroscopy were collected from two tertiary care centres. Real-time confocal endomicroscopy images were obtained during ERCP and immediate interpretation according to the Miami Classification was performed.

RESULTS

18 patients underwent confocal endomicroscopy for evaluation of pancreatic strictures from July 2011 to December 2012. Mean pancreatic duct size was 4.2mm (range 2.2-8mm). Eight cases were interpreted as benign, 4 as malignant, 4 suggestive of intraductal papillary mucinous neoplasms, and 2 appeared normal. Cytology/histopathology for 15/16 cases showed similar results to confocal endomicroscopy interpretation. Kappa coefficient of agreement between cyto/histopathology and confocal endomicroscopy was 0.8 (p=0.0001). Pancreatic confocal endomicroscopy changed management in four patients, changing the type of surgery from total pancreatectomy to whipple.

CONCLUSIONS

Confocal endomicroscopy is effective in assisting with diagnosis of indeterminate pancreatic duct strictures as well as mapping of abnormal pancreatic ducts prior to surgery.

Next step in minimally invasive surgery: hybrid image-guided surgery

Surgery, interventional radiology, and advanced endoscopy have all developed minimally invasive techniques to effectively treat a variety of diseases with positive impact on patients' postoperative outcomes. However, those techniques are challenging and require extensive training. Robotics and computer sciences can help facilitate minimally invasive approaches. Furthermore, surgery, advanced endoscopy, and interventional radiology could converge towards a new hybrid specialty, hybrid image-guided minimally invasive therapies, in which the three fundamental disciplines could complement one another to maximize the positive effects and reduce the iatrogenic footprint on patients. The present manuscript describes the fundamental steps of this new paradigm shift in surgical therapies that, in our opinion, will be the next revolutionary step in minimally invasive approaches.

Poor agreement between endoscopists and gastrointestinal pathologists for the interpretation of probe-based confocal laser endomicroscopy findings

AIM: To compare the interpretation of probe-based confocal laser endomicroscopy (pCLE) findings between endoscopists and gastrointestinal (GI)-pathologists.

METHODS: All pCLE procedures were undertaken and the endoscopist rendered assessment. The same pCLE videos were then viewed offline by an expert GI pathologist. Histopathology was considered the gold standard for definitive diagnosis. The sensitivity, specificity and accuracy for diagnosis of dysplastic/ neoplastic GI lesions and interobserver agreement between endoscopists and experienced gastrointestinal pathologist for pCLE findings were analyzed.

RESULTS: Of the 66 included patients, 40 (60.6%) had lesions in the esophagus, 7 (10.6%) in the stomach, 15 (22.7%) in the biliary tract, 3 (4.5%) in the ampulla and 1 (1.5%) in the colon. The overall sensitivity, specificity and accuracy for diagnosing dysplastic/neoplastic lesions using pCLE were higher for endoscopists than pathologist at 87.0% vs 69.6%, 80.0% vs 40.0% and 84.8% vs 60.6% (P = 0.0003), respectively. Area under the ROC curve (AUC) was greater for endoscopists than the pathologist (0.83 vs 0.55, P = 0.0001). Overall agreement between endoscopists and pathologist was moderate for all GI lesions (K = 0.43; 95%CI: 0.26-0.61), luminal lesions (K = 0.40; 95%CI: 0.20-0.60) and those of dysplastic/neoplastic pathology (K = 0.55; 95%CI: 0.37-0.72), the agreement was poor for benign (K = 0.13; 95%CI: -0.097-0.36) and pancreaticobiliary lesions (K = 0.19; 95%CI: -0.26-0.63).

CONCLUSION: There is a wide discrepancy in the interpretation of pCLE findings between endoscopists and pathologist, particularly for benign and malignant pancreaticobiliary lesions. Further studies are needed to identify the cause of this poor agreement.

Beyond standard image-enhanced endoscopy confocal endomicroscopy

Endomicroscopy is a new imaging tool for gastrointestinal endoscopy. In vivo histology becomes possible at subcellular resolution during ongoing colonoscopy. Panchromoendoscopy with targeted biopsies has become the method of choice for surveillance of patients with inflammatory bowel disease. Endomicroscopy can be added after chromoendoscopy to clarify whether standard biopsies are needed. This smart biopsy concept can increase the diagnostic yield of intraepithelial neoplasia and substantially reduce the need for biopsies. Clinical acceptance is increasing because of a multitude of positive studies about the diagnostic value of endomicroscopy. Smart biopsies, functional imaging, and molecular imaging may represent the future for endomicroscopy.

Beyond white light endoscopy: The role of optical biopsy in inflammatory bowel disease

In this review, we will discuss the use of two optical biopsy modalities in inflammatory bowel disease (IBD). The two techniques reviewed here are confocal laser endomicroscopy and endocytoscopy. We will describe the technical performance of the procedure, discuss the clinical indications for optical biopsy in IBD, and highlight active research areas with respect to the pathogenesis of IBD. Clinical indications for optical biopsies in IBD include assessment of mucosal inflammation, dysplasia detection and evaluation of cell shedding for disease relapse. Research application in the area of barrier dysfunction will also be discussed.

Ultra high magnification endoscopy: Is seeing really believing?

Endoscopy is an indispensible diagnostic and therapeutic instrument for gastrointestinal diseases. Endocytoscopy and confocal endomicroscopy are two types of ultra high magnification endoscopy techniques. Standard endoscopy allows for 50 × magnification, whereas endocytoscopy can magnify up to 1400 × and confocal endomicroscopy can magnify up to 1000 ×. These methods open the realm of real time microscopic evaluation of the GI tract, including cellular and subcellular structures. Confocal endomicroscopy has the additional advantage of being able to visualize subsurface structures. The use of high magnification endoscopy in conjunction with standard endoscopy allows for a real-time microscopic assessment of areas with macroscopic abnormalities, providing “virtual biopsies” with valuable information about cellular and subcellular changes. This can minimize the number of biopsies taken at the time of endoscopy. The use of this technology may assist in detecting pre-malignant or malignant changes at an earlier state, allowing for earlier intervention and treatment. High magnification endoscopy has shown promising results in clinical trials for Barrett’s esophagus, esophageal adenocarcinoma, esophageal squamous cell cancer, gastric cancer, celiac disease, colorectal cancer, and inflammatory bowel disease. As the use of high magnification endoscopy techniques increases, the clinical applications will increase as well. Of the two systems, only confocal endomicroscopy is currently commercially available. Like all new technologies there will be an initial learning curve before operators become proficient in obtaining high quality images and discerning abnormal from normal pathology. Validated criteria for the diagnosis of the various gastrointestinal diseases will need to be developed for each method. In this review, the basic principles of both modalities are discussed, along with their clinical applicability and limitations.

Recent advances in targeted endoscopic imaging: Early detection of gastrointestinal neoplasms

Molecular imaging has emerged as a new discipline in gastrointestinal endoscopy. This technology encompasses modalities that can visualize disease-specific morphological or functional tissue changes based on the molecular signature of individual cells. Molecular imaging has several advantages including minimal damage to tissues, repetitive visualization, and utility for conducting quantitative analyses. Advancements in basic science coupled with endoscopy have made early detection of gastrointestinal cancer possible. Molecular imaging during gastrointestinal endoscopy requires the development of safe biomarkers and exogenous probes to detect molecular changes in cells with high specificity anda high signal-to-background ratio. Additionally, a high-resolution endoscope with an accurate wide-field viewing capability must be developed. Targeted endoscopic imaging is expected to improve early diagnosis and individual therapy of gastrointestinal cancer.

Endoscopic Imaging in Barrett's Oesophagus: Applications in Routine Clinical Practice and Future Outlook

The practice for endoscopic surveillance of Barrett's oesophagus has evolved from "blind" or random 4 quadrant biopsies (Seattle protocol) to a more "intelligent" targeted biopsy approach. This evolution has been possible due to the rapid advances in endoscopic imaging technology and expertise in the last decade. Previous endoscopes had relatively poor image resolution that often did not allow the subtle mucosal changes associated with dysplastic Barrett's mucosa to be identified. Newer endoscopic imaging techniques available today may allow endoscopists to identify areas of dysplasia or malignancy and target biopsies accordingly. These modalities which include narrow band imaging, chromoendoscopy, autofluorescence imaging, and confocal endomicroscopy as well as a few novel imaging modalities on the horizon will be discussed further.

Current research status of confocal endomicroscopy

Confocal endomicroscope integrates a miniaturized confocal microscope in the distal tip of a conventional endoscope, and enables subsurface analysis of gastrointestinal mucosa and in vivo histology during ongoing endoscopy. The diagnostic spectrum of confocal endomicroscopy is currently expanding from screening and surveillance for colorectal cancer towards ulcerative colitis, Barrett's esophagus, Helicobacter pylori, early gastric cancer, oral carcinoma and so on. It's tempting to speculate that confocal endomicroscopy will play an important diagnostic role in gastrointestinal diseases in the future.