Probe-based confocal laser endomicroscopy of the urinary tract: the technique

Optical imaging technology realizes early tumor diagnosis by detecting angiogenesis

The occurrence and development of blood vessels play a key role in different stages of tumor growth, while current imaging techniques are difficult to detect early tumor angiogenesis because of their low sensitivity. Therefore, this article introduces high-sensitivity optical imaging technology to achieve early tumor diagnosis by detecting tumor angiogenesis. Liver and pancreatic tumor models in nude mice were respectively established to represent tumors with a rich or poor blood supply. The two optical imaging methods, in vivo confocal fluorescence imaging and photoacoustic imaging, were used to detect tumor angiogenesis at different stages. Finally, the changes in blood vessels were verified by immunostaining. Both autoluminescence imaging and pathological staining confirmed that these two tumor models were successfully established. In vivo confocal fluorescence imaging found that the early tumor blood vessel structure had obvious characteristics: disorder, tortuous deformation, thin diameter, which were significantly different from the normal tissues. Photoacoustic imaging could effectively identify blood vessels inside early tumors, which were small and disordered and might be used as one of the predictors of early tumor development. CD31 immunostaining was used to evaluate the vascular status of tumors at different stages and under different blood supply conditions. The vascular structures observed under the microscope in the two tumor models were consistent with the results observed by optical imaging methods. The optical imaging methods could monitor the characteristics of angiogenesis in the rich or poor blood supply tumors, especially the early diagnosis of tumors.

Diagnostic Accuracy of Confocal Laser Endomicroscopy for the Diagnosis of Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

Background: Advances in treatment approaches for patients with oral squamous cell carcinoma (OSCC) have been unsuccessful in preventing frequent recurrences and distant metastases, leading to a poor prognosis. Early detection and prevention enable an improved 5-year survival and better prognosis. Confocal Laser Endomicroscopy (CLE) is a non-invasive imaging instrument that could enable an earlier diagnosis and possibly help in reducing unnecessary invasive surgical procedures. Objective: To present an up to date systematic review and meta-analysis assessing the diagnostic accuracy of CLE in diagnosing OSCC. Materials and Methods. PubMed, Scopus, and Web of Science databases were explored up to 30 June 2021, to collect articles concerning the diagnosis of OSCC through CLE. Screening: data extraction and appraisal was done by two reviewers. The quality of the methodology followed by the studies included in this review was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. A random effects model was used for the meta-analysis. Results: Six studies were included, leading to a total number of 361 lesions in 213 patients. The pooled sensitivity and specificity were 95% (95% CI, 92–97%; I² = 77.5%) and 93% (95% CI, 90–95%; I² = 68.6%); the pooled positive likelihood ratios and negative likelihood ratios were 10.85 (95% CI, 5.4–21.7; I² = 55.9%) and 0.08 (95% CI, 0.03–0.2; I² = 83.5%); and the pooled diagnostic odds ratio was 174.45 (95% CI, 34.51–881.69; I² = 73.6%). Although risk of bias and heterogeneity is observed, this study validates that CLE may have a noteworthy clinical influence on the diagnosis of OSCC, through its high sensitivity and specificity. Conclusions: This review indicates an exceptionally high sensitivity and specificity of CLE for diagnosing OSCC. Whilst it is a promising diagnostic instrument, the limited number of existing studies and potential risk of bias of included studies does not allow us to draw firm conclusions. A conclusive inference can be drawn when more studies, possibly with homogeneous methodological approach, are performed.

Ab Externo Imaging of Human Episcleral Vessels Using Fiberoptic Confocal Laser Endomicroscopy

Purpose

There is a growing interest in targeting minimally invasive surgery devices to the aqueous outflow system to optimize treatment outcomes. However, methods to visualize functioning, large-caliber aqueous and episcleral veins in-vivo are lacking. This pilot study establishes an ex-vivo system to evaluate the use of a confocal laser microendoscope to noninvasively image episcleral vessels and quantify regional flow variation along the limbal circumference.

Methods

A fiber-optic confocal laser endomicroscopy (CLE) system with lateral and axial resolution of 3.5 μm and 15 μm, respectively, was used on three porcine and four human eyes. Diluted fluorescein (0.04%) was injected into eyes kept under constant infusion. The microprobe was applied to the sclera 1 mm behind the limbus to acquire real-time video. Image acquisition was performed at 15-degree intervals along the limbal circumference to quantify regional flow variation in human eyes.

Results

Vascular structures were visualized in whole human eyes without processing. Schlemm's canal was visualized only after a scleral flap was created. Fluorescent signal intensity and vessel diameter variation were observed along the limbal circumference, with the inferior quadrant having a statistically higher fluorescein signal compared to the other quadrants in human eyes (P < 0.05).

Conclusion

This study demonstrates for the first time that the fiber-optic CLE platform can visualize the episcleral vasculature with high resolution ex-vivo with minimal tissue manipulation. Intravascular signal intensities and vessel diameters were acquired in real-time; such information can help select target areas for minimally invasive glaucoma surgery (MIGS) to achieve greater intraocular pressure reduction.

Optical and Cross-Sectional Imaging Technologies for Bladder Cancer

Optical and cross-sectional imaging plays critical roles in bladder cancer diagnostics. White light cystoscopy remains the cornerstone for the management of non-muscle-invasive bladder cancer. In the last decade, significant technological improvements have been introduced for optical imaging to address the known shortcomings of white light cystoscopy. Enhanced cystoscopy modalities such as blue light cystoscopy and narrowband imaging survey a large area of the urothelium and provide contrast enhancement to detect additional lesions and decrease cancer recurrence. However, higher false-positive rates accompany the gain of sensitivity. Optical biopsy technologies, including confocal laser endomicroscopy and optical coherence tomography, provide cellular resolutions combined with subsurface imaging, thereby enabling optical-based cancer characterization, and may lead to real-time cancer grading and staging. Coupling of fluorescently labeled binding agents with optical imaging devices may translate into high molecular specificity, thus enabling visualization and characterization of biological processes at the molecular level. For cross-sectional imaging, upper urinary tract evaluation and assessment potential extravesical tumor extension and metastases are currently the primary roles, particularly for management of muscle-invasive bladder cancer. Multi-parametric MRI, including dynamic gadolinium-enhanced and diffusion-weighted sequences, has been investigated for primary bladder tumor detection. Ultrasmall superparamagnetic particles of iron oxide (USPIO) are a new class of contrast agents that increased the accuracy of lymph node imaging. Combination of multi-parametric MRI with positron emission tomography is on the horizon to improve accuracy rates for primary tumor diagnostics as well as lymph node evaluation. As these high-resolution optical and cross-sectional technologies emerge and develop, judicious assessment and validation await for their clinical integration toward improving the overall management of bladder cancer.

Optical biopsy of bladder cancer using confocal laser endomicroscopy

OBJECTIVE

Confocal laser endomicroscopy (CLE) is an emerging endoscopic technique that can provide in vivo histopathologic information. It may improve the diagnostic criteria for benign and neoplastic lesions of the bladder. In this study, we reported our experience with utilizing CLE imaging when treating bladder neoplasms, and investigated its diagnostic value with respect to histologic diagnosis.

MATERIALS AND METHODS

Twenty-one patients scheduled for diagnostic cystoscopy or transurethral resection of the bladder tumor were enrolled prospectively. CLE was performed after intravesical fluorescein administration and confocal video sequences were reviewed and analyzed retrospectively. Histopathology served as reference standard for comparison.

RESULTS

Confocal laser endomicroscopy-based classification combined with white light cystoscopy (WLC) images was consistent with histopathology in 17 cases (81.0%). Consensus with histopathological results was found in six cases (85.7%) for low-grade urothelial carcinoma and eight cases (80.0%) for high-grade urothelial carcinoma.

CONCLUSION

Confocal laser endomicroscopy was proved to be a useful technique that could complement white light cystoscopy by providing real-time histopathological information of bladder lesions.

Identification of Bronchoalveolar Lavage Components Applying Confocal Laser Endomicroscopy

BACKGROUND In many studies, confocal laser endomicroscopy (CLE) has proven to be a useful tool in pulmonology; nevertheless, the application in this field is still experimental. By contrast, CLE is almost a standard technique in gastroenterology. The aim of the present study was to demonstrate the identification of bronchoalveolar lavage (BAL) components applying CLE, using a dye. MATERIAL AND METHODS In 21 patients with various underlying diseases a bronchoscopy with BAL was performed. As in routine clinical practice common, BAL fluid (BALF) was analyzed in terms of cytologic, virologic, and microbiologic aspects. To one fraction of BALF, we added acriflavine. After centrifugation CLE was applied and the video sequences were analyzed by an experienced investigator. RESULTS Using CLE, BALF components (such as alveolar macrophages or leucocytes) could be easily identified. A further subdivision of leucocytes (neutrophilic, eosinophilic granulocytes, and lymphocytes) was not possible. Analogous to conventional cytology, a precise distinction of lymphocyte subpopulation (cd 4/cd 8 ratio) was not feasible. In terms of quantification, this is still the application field of flow cytometry and immunohistochemistry. CONCLUSIONS Using CLE, alveolar macrophages and leucocytes in stained BALF can be differentiated independent of smoking status. Further studies should be initiated in order to subclassify leucocytes in eosinophilic, neutrophilic granulocytes, and lymphocytes, which is important for routine clinical practice.

Image-Guided Transurethral Resection of Bladder Tumors - Current Practice and Future Outlooks

Transurethral resection of bladder tumor (TURBT) under white light cystoscopy (WLC) is the cornerstone for the diagnosis, removal and local staging of non-muscle invasive bladder cancer (NMIBC). Despite technological improvements over the decades, significant shortcomings remain with WLC for tumor detection, thereby impacting the surgical quality and contributing to tumor recurrence and progression. Enhanced cystoscopy modalities such as blue light cystoscopy (BLC) and narrow band imaging (NBI) aid resections by highlighting tumors that might be missed on WLC. Optical biopsy technologies such as confocal laser endomicroscopy (CLE) and optical coherence tomography (OCT) characterize tissue in real-time to ensure a more thorough resection. New resection techniques, particularly en bloc resection, are actively under investigation to improve the overall quality of resections and aid pathologic interpretation. Moreover, new image processing computer algorithms may improve perioperative planning and longitudinal follow-up. Clinical translation of molecular imaging agents is also on the horizon to improve optical diagnosis of bladder cancer. This review focuses on emerging technologies that can impact the quality of TURBT to improve the overall management of NMIBC.

Identification of liver metastases with probe-based confocal laser endomicroscopy at two excitation wavelengths

BACKGROUND

Metastasis of colorectal cancer to the liver is the most common indication for hepatic resection in a western population. Incomplete excision of malignancy due to residual microscopic disease normally results in worse patient outcome. Therefore, a method aiding in the real time discrimination of normal and malignant tissue on a microscopic level would be of benefit.

MATERIAL AND METHODS

The ability of fluorescent probe-based confocal laser endomicroscopy (pCLE) to identify normal and malignant liver tissue was evaluated in an orthotopic murine model of colorectal cancer liver metastasis (CRLM). To maximise information yield, two clinical fluorophores, fluorescein and indocyanine green (ICG) were injected and imaged in a dual wavelength approach (488 and 660 nm, respectively). Visual tissue characteristics on pCLE examination were compared with histological features. Fluorescence intensity in both tissues was statistically analysed to elucidate if this can be used to differentiate between normal and malignant tissue.

RESULTS

Fluorescein (488 nm) enabled good visualisation of normal and CRLM tissue, whereas ICG (660 nm) visualisation was limited to normal liver tissue only. Fluorescence intensity in areas of CRLM was typically 53-100% lower than normal hepatic parenchyma. Using general linear mixed modelling and receiver operating characteristic analysis, high fluorescence intensity was found to be statistically more likely in normal hepatic tissue.

CONCLUSION

Real time discrimination between normal liver parenchyma and metastatic tissue with pCLE examination of fluorescein and ICG is feasible. Employing two (rather than a single) fluorophores allows a combination of qualitative and quantitative characteristics to be used to distinguish between hepatic parenchyma and CRLM. Lasers Surg. Med. 49:280-292, 2017. © 2016 Wiley Periodicals, Inc.

Role of Narrow Band Imaging in Management of Urothelial Carcinoma

Urothelial carcinoma of the bladder and upper tract is primarily diagnosed by white light endoscopy, which has well-known limitations that contribute to the increased risk of tumor recurrence and progression. Narrow band imaging (NBI) is an optical imaging technology that facilitates detection of tumor vasculature and differentiation of benign urothelium from neoplastic tissue. For urothelial carcinoma, NBI may be utilized in a variety of clinical settings, including office cystoscopy for initial identification and surveillance, transurethral resection for pathological diagnosis, and ureteroscopic management of upper tract lesions. Early evidence suggests that NBI increases the detection of urothelial carcinoma in the bladder and upper tract, including flat high-grade lesions such as carcinoma-in-situ that are a diagnostic challenge under white light. NBI also appears to improve the quality of transurethral resection and thereby reduce the frequency of tumor recurrence.

Intraoperative Optical Biopsy during Robotic Assisted Radical Prostatectomy Using Confocal Endomicroscopy

PURPOSE

Intraoperative optical biopsy technologies may aid in the identification of important anatomical landmarks and improve surgical outcomes of robotic assisted radical prostatectomy. We evaluate the feasibility of confocal laser endomicroscopy during robotic assisted radical prostatectomy.

MATERIALS AND METHODS

A total of 21 patients with biopsy proven prostate cancer scheduled for robotic assisted radical prostatectomy were recruited. After intravenous administration of fluorescein 15 patients underwent in vivo intraoperative confocal laser endomicroscopy of prostatic and periprostatic structures using a 2.6 or 0.85 mm imaging probe. Standard robotic instruments were used to grasp and maneuver the confocal laser endomicroscopy probes for image acquisition. Confocal laser endomicroscopy imaging was performed ex vivo on fresh prostate specimens from 20 patients. Confocal video sequences acquired in vivo and ex vivo were reviewed and analyzed, with additional image processing using a mosaicing algorithm. Processed confocal images were compared with standard hematoxylin and eosin analysis of imaged regions.

RESULTS

Confocal laser endomicroscopy was successfully integrated with robotic surgery, including co-registration of confocal video sequences with white light and probe handling with standard robotic instrumentation. Intraoperative confocal laser endomicroscopy imaging of the neurovascular bundle before and after nerve sparing dissection revealed characteristic features including dynamic vascular flow and intact axon fibers. Ex vivo confocal imaging of the prostatic parenchyma demonstrated normal prostate glands, stroma and prostatic carcinoma.

CONCLUSIONS

We report the initial feasibility of optical biopsy of prostatic and periprostatic tissue during robotic assisted radical prostatectomy. Image guidance and tissue interrogation using confocal laser endomicroscopy offer a new intraoperative imaging method that has the potential to improve the functional and oncologic outcomes of prostate cancer surgery.

Confocal laser endomicroscopy of bladder and upper tract urothelial carcinoma: a new era of optical diagnosis?

Urothelial carcinoma of the bladder and upper tract pose significant diagnostic and therapeutic challenges. White light endoscopy plays a central role in the management of urothelial carcinoma but has several well-recognized shortcomings. New optical imaging technologies may improve diagnostic accuracy, enhance local cancer control, and better stratify treatment options. Confocal laser endomicroscopy enables dynamic imaging of the cellular structures below the mucosal surface and holds promise in providing real time optical diagnosis and grading of urothelial carcinoma. A variety of imaging probes are available that are compatible with the full spectrum of cystoscopes and ureteroscopes. We review the underlying principles and technique of confocal laser endomicroscopy in the urinary tract, with emphasis on specific application towards urothelial carcinoma. While the available data are largely related to urothelial carcinoma of the bladder, the lessons learned are directly applicable to the upper tract, where the clinical needs are significant. Ongoing efforts to optimize this technology offer an exciting glimpse into future advances in optical imaging and intraoperative image guidance.

Emerging endoscopic imaging technologies for bladder cancer detection

Modern urologic endoscopy is the result of continuous innovations since the early nineteenth century. White-light cystoscopy is the primary strategy for identification, resection, and local staging of bladder cancer. While highly effective, white light cystoscopy has several well-recognized shortcomings. Recent advances in optical imaging technologies and device miniaturization hold the potential to improve bladder cancer diagnosis and resection. Photodynamic diagnosis and narrow band imaging are the first to enter the clinical arena. Confocal laser endomicroscopy, optical coherence tomography, Raman spectroscopy, UV autofluorescence, and others have shown promising clinical and pre-clinical feasibility. We review their mechanisms of action, highlight their respective advantages, and propose future directions.

Intraoperative optical imaging and tissue interrogation during urologic surgery

PURPOSE OF REVIEW

To review optical imaging technologies in urologic surgery aimed to facilitate intraoperative imaging and tissue interrogation.

RECENT FINDINGS

Emerging new optical imaging technologies can be integrated in the operating room environment during minimally invasive and open surgery. These technologies include macroscopic fluorescence imaging that provides contrast enhancement between normal and diseased tissue and microscopic imaging that provides tissue characterization.

SUMMARY

Optical imaging technologies that have reached the clinical arena in urologic surgery were reviewed, including photodynamic diagnosis, near infrared fluorescence imaging, optical coherence tomography, and confocal laser endomicroscopy.

Newly developed techniques in andrology: endoscopy of the vas deference and a new imaging technique for in situ localization of vital spermatozoa

During the past decade, endourology represents the most advanced technology in urology which has provided minimal invasive diagnostic and therapeutic tool for patients with urology diseases. However, because of the much smaller lumen of genital tract, endoscopic andrology remained a dream for andrologists until the first clinical application of vesiculoscopy in laser lithotripsy of seminal vesicle stones in 2006. Lately, Dr Trottmann at Ludwig-Maximilians University, Germany, for the first time established vasoscopy in the seminal duct using a new prototype of a microendoscope and also applied a new imaging technique for in situ localization of vital spermatozoa. These newly developed techniques will greatly speed up the clinical practice of endoandrology.