Emerging optical techniques in advanced cystoscopy for bladder cancer diagnosis: A review of the current literature

Fluorescent molecular probe for in vivo and in vitro targeting and imaging of an intracellular bacterial infection

Intracellular bacterial infections are difficult to diagnose and treat because the host cells shelter the bacteria from molecular recognition by imaging agents, antibiotics, and the immune system. This problem arises when bladder epithelial cells are infected by uropathogenic Escherichia coli (UPEC)-one of the causative agents of urinary tract infection (UTI). UTIs are among the most common bacterial infections and a worldwide health concern. It is challenging to design molecular probes for intracellular UPEC imaging or targeted antibiotic treatment because the probe must possess multiple capabilities-it must permeate the host cell plasma membrane and selectively associate with the intracellular UPEC. Here, we report a "first-in-class" fluorescent probe called BactVue that is comprised of two structural components: a modified zinc(ii)-2,2'-dipicolylamine complex (Zn-Oxy-DPA) as the bacteria targeting unit and an appended near-infrared cyanine fluorophore that is hydrophilic but with a near-neutral electrostatic charge. The unique capacity of BactVue to penetrate infected bladder cells and stain intracellular UPEC was demonstrated by a series of in vitro and in vivo fluorescence imaging studies, including a mouse model of UTI. The results support the feasibility of incorporating BactVue into diagnostic near-infrared fluorescence imaging methods that visualize the location of infected bladder cells during active UTI.

Transurethral Resection of Bladder Tumor: Novel Techniques in a New Era

Transurethral resection of bladder tumor (TURBT) serves both diagnostic and therapeutic purposes in the management of bladder cancer. Attaining a high-quality TURBT is not always guaranteed due to various factors. En-bloc resection of bladder tumors (ERBT) holds promise to be a primary technique for removing bladder tumors in most non-muscle invasive bladder cancers. However, so far, no conclusive evidence indicates the superiority of any specific energy source used for ERBT. While laser energy can prevent the activation of obturator nerve reflex during ERBT, it poses challenges such as thermal injury and imprecise controllability. Needle-shaped electrodes offer high-level precision and controllability, without causing tissue deterioration or vaporization. The primary limitation of ERBT at present is the extraction/harvesting of large en-bloc specimens. Effective tools have been developed to overcome this limitation. Enhanced cystoscopy improves the detection of flat and small bladder tumors, allowing for better removal of cancerous tissues and significantly reducing recurrence rates. Advances in medical technology have brought forth a multitude of strategies to address the shortcomings of traditional TURBT. Appliances with large operating channel provide a platform for conducting laparoscopic procedures within the context of pneumocystoscopy, facilitating the execution of super TURBT and conferring comparable advantages to en-bloc resection. Moreover, the utilization of pneumocystoscopy enables the safe and effective performance of transurethral partial cystectomy for localized muscle-invasive bladder cancer. Novel techniques significantly improve the precision of the transurethral surgery and lower the risk of complications.

In vivo Raman spectroscopy for bladder cancer detection using a superficial Raman probe compared to a nonsuperficial Raman probe

Raman spectroscopy is promising as a noninvasive tool for cancer diagnosis. A superficial Raman probe might improve the classification of bladder cancer, because information is gained solely from the diseased tissue and irrelevant information from deeper layers is omitted. We compared Raman measurements of a superficial to a nonsuperficial probe, in bladder cancer diagnosis. Two-hundred sixteen Raman measurements and biopsies were taken in vivo from at least one suspicious and one unsuspicious bladder location in 104 patients. A Raman classification model was constructed based on histopathology, using a principal-component fed linear-discriminant-analysis and leave-one-person-out cross-validation. The diagnostic ability measured in area under the receiver operating characteristics curve was 0.95 and 0.80, the sensitivity was 90% and 85% and the specificity was 87% and 88% for the superficial and the nonsuperficial probe, respectively. We found inflammation to be a confounder and additionally we found a gradual transition from benign to low-grade to high-grade urothelial carcinoma. Raman spectroscopy provides additional information to histopathology and the diagnostic value using a superficial probe.

Epigenomic and Metabolomic Integration Reveals Dynamic Metabolic Regulation in Bladder Cancer

Bladder cancer (BC) represents a clinical, social, and economic challenge due to tumor-intrinsic characteristics, limitations of diagnostic techniques and a lack of personalized treatments. In the last decade, the use of liquid biopsy has grown as a non-invasive approach to characterize tumors. Moreover, the emergence of omics has increased our knowledge of cancer biology and identified critical BC biomarkers. The rewiring between epigenetics and metabolism has been closely linked to tumor phenotype. Chromatin remodelers interact with each other to control gene silencing in BC, but also with stress-inducible factors or oncogenic signaling cascades to regulate metabolic reprogramming towards glycolysis, the pentose phosphate pathway, and lipogenesis. Concurrently, one-carbon metabolism supplies methyl groups to histone and DNA methyltransferases, leading to the hypermethylation and silencing of suppressor genes in BC. Conversely, α-KG and acetyl-CoA enhance the activity of histone demethylases and acetyl transferases, increasing gene expression, while succinate and fumarate have an inhibitory role. This review is the first to analyze the interplay between epigenome, metabolome and cell signaling pathways in BC, and shows how their regulation contributes to tumor development and progression. Moreover, it summarizes non-invasive biomarkers that could be applied in clinical practice to improve diagnosis, monitoring, prognosis and the therapeutic options in BC.

Bladder tissue characterization using probe-based Raman spectroscopy: Evaluation of tissue heterogeneity and influence on the model prediction

Existing approaches for early-stage bladder tumor diagnosis largely depend on invasive and time-consuming procedures, resulting in hospitalization, bleeding, bladder perforation, infection and other health risks for the patient. The reduction of current risk factors, while maintaining or even improving the diagnostic precision, is an underlying factor in clinical instrumentation research. For example, for clinic surveillance of patients with a history of noninvasive bladder tumors real-time tumor diagnosis can enable immediate laser-based removal of tumors using flexible cystoscopes in the outpatient clinic. Therefore, novel diagnostic modalities are required that can provide real-time in vivo tumor diagnosis. Raman spectroscopy provides biochemical information of tissue samples ex vivo and in vivo and without the need for complicated sample preparation and staining procedures. For the past decade there has been a rise in applications to diagnose and characterize early cancer in different organs, such as in head and neck, colon and stomach, but also different pathologies, for example, inflammation and atherosclerotic plaques. Bladder pathology has also been studied but only with little attention to aspects that can influence the diagnosis, such as tissue heterogeneity, data preprocessing and model development. The present study presents a clinical investigative study on bladder biopsies to characterize the tumor grading ex vivo, using a compact fiber probe-based imaging Raman system, as a crucial step towards in vivo Raman endoscopy. Furthermore, this study presents an evaluation of the tissue heterogeneity of highly fluorescent bladder tissues, and the multivariate statistical analysis for discrimination between nontumor tissue, and low- and high-grade tumor.

Methods for bladder cancer diagnosis - The role of autofluorescence and photodynamic diagnosis

Bladder cancer is one of the most common Genito-urinary malignant tumors in humans. Improved diagnostic and therapeutic methods that aim to reduce rates of recurrence and progression of bladder cancer are needed. In current publications, one can find information on such methods as Raman spectroscopy, ultraviolet autofluorescence microscopy, confocal laser endoscopy, photoacoustic imaging, molecular imaging, multi-photon microscopy and many other new diagnostic techniques. These methods do not show significant adverse effects and are procedures well tolerated by patients as they use mostly physical phenomena that are neutral towards the human body. This review highlights the techniques of autofluorescence (AF) or laser induced fluorescence (LIF) and photodynamic diagnostics (PDD) which have been widely clinically studied for many years as a complement to cystoscopy. These methods can be performed during standard cystoscopy and they can be used in routine practice. This review shows that Autofluorescent and Photodynamic diagnostics are effective and have great potential in enhancing the diagnosis of bladder cancer. However, more research should be performed to help realize their full potential.

Novel real-time optical imaging modalities for the detection of neoplastic lesions in urology: a systematic review

BACKGROUND

Current optical diagnostic techniques for malignancies are limited in their diagnostic accuracy and lack the ability to further characterise disease, leading to the rapidly increasing development of novel imaging methods within urology. This systematic review critically appraises the literature for novel imagining modalities, in the detection and staging of urological cancer and assesses their effectiveness via their utility and accuracy.

METHODS

A systematic literature search utilising MEDLINE, EMBASE and Cochrane Library Database was conducted from 1970 to September 2018 by two independent reviewers. Studies were included if they assessed real-time imaging modalities not already approved in guidelines, in vivo and in humans. Outcome measures included diagnostic accuracy and utility parameters, including feasibility and cost.

RESULTS

Of 5475 articles identified from screening, a final 46 were included. Imaging modalities for bladder cancer included optical coherence tomography (OCT), confocal laser endomicroscopy, autofluorescence and spectroscopic techniques. OCT was the most widely investigated, with 12 studies demonstrating improvements in overall diagnostic accuracy (sensitivity 74.5-100% and specificity 60-98.5%). Upper urinary tract malignancy diagnosis was assessed using photodynamic diagnosis (PDD), narrow band imaging, optical coherence tomography and confocal laser endomicroscopy. Only PDD demonstrated consistent improvements in overall diagnostic accuracy in five trials (sensitivity 94-96% and specificity 96.6-100%). Limited evidence for optical coherence tomography in percutaneous renal biopsy was identified, with anecdotal evidence for any modality in penile cancer.

CONCLUSIONS

Evidence supporting the efficacy for identified novel imaging modalities remains limited at present. However, OCT for bladder cancer and PDD in upper tract malignancy demonstrate the best potential for improvement in overall diagnostic accuracy. OCT may additionally aid intraoperative decision making via real-time staging of disease. Both modalities require ongoing investigation through larger, well-conducted clinical trials to assess their diagnostic accuracy, use as an intraoperative staging aid and how to best utilise them within clinical practice.

Anticancer effect of miR-96 inhibitor in bladder cancer cell lines

The present study aimed to investigate the role of microRNA-96 (miR-96) in the proliferation, invasion and apoptosis of bladder cancer cell lines, and the associated mechanisms. The expression of miR-96 and human ether-à-go-go-related (HERG1) potassium channel in the normal uroepithelium SV-HUC-1 cell line, and bladder cancer T24 and 5637 cell lines were examined using reverse transcription-polymerase chain reaction or/and western blotting. Transfection with miR-96 inhibitor or scrambled control (SC) was used to study the biological activities of miR-96 in bladder cancer cell lines. MTT, flow cytometric and Transwell assays were applied to detect cell viability, apoptosis and invasion, respectively. A dual-luciferase reporter assay was applied to determine the association between miR-96 and HERG1 expression. As demonstrated, miR-96 was highly expressed in the two bladder cancer cell lines, particularly in T24 cells. Following transfection with miR-96 inhibitor, miR-96 expression was significantly reduced in the T24 cell line, compared with SC. The miR-96 inhibitor suppressed cell proliferation and invasion, promoted apoptosis and arrested the cell cycle at the G₁ phase. Consistently, HERG1 was also highly expressed in the two bladder cancer cell lines at the mRNA and protein level, but not in the normal uroepithelium cell line. The miR-96 inhibitor also significantly decreased HERG1 expression compared with SC. The results of the dual-luciferase reporter assay indicated that miR-96 directly targeted wild-type HERG1. In conclusion, miR-96 inhibitor exhibited anticancer effects on bladder cancer cells by inhibiting proliferation and invasion of cells, and promoting their apoptosis. HERG1 was an important target of miR-96. These results provided experimental evidence supporting miR-96 as a therapeutic target for patients with bladder cancer.

Flexible polarimetric probe for 3 × 3 Mueller matrix measurements of biological tissue

Polarimetry is a noninvasive method that uses polarised light to assess biophysical characteristics of tissues. A series of incident polarisation states illuminates a biological sample, and analysis of sample-altered polarisation states enables polarimetric tissue assessment. The resultant information can, for example, help quantitatively differentiate healthy from pathologic tissue. However, most bio-polarimetric assessments are performed using free-space optics with bulky optical components. Extension to flexible fibre-based systems is clinically desirable, but is challenging due to polarisation-altering properties of optical fibres. Here, we propose a flexible fibre-based polarimetric solution, and describe its design, fabrication, calibration, and initial feasibility demonstration in ex vivo tissue. The design is based on a flexible fibre bundle of six multimode optical fibres, each terminated with a distal polariser that ensures pre-determined output polarisation states. The resultant probe enables linear 3 × 3 Mueller matrix characterization of distal tissue. Potential in vivo Mueller matrix polarimetric tissue examinations in various directly-inaccessible body cavities are envisioned.

BcCluster: A Bladder Cancer Database at the Molecular Level

BACKGROUND

Bladder Cancer (BC) has two clearly distinct phenotypes. Non-muscle invasive BC has good prognosis and is treated with tumor resection and intravesical therapy whereas muscle invasive BC has poor prognosis and requires usually systemic cisplatin based chemotherapy either prior to or after radical cystectomy. Neoadjuvant chemotherapy is not often used for patients undergoing cystectomy. High-throughput analytical omics techniques are now available that allow the identification of individual molecular signatures to characterize the invasive phenotype. However, a large amount of data produced by omics experiments is not easily accessible since it is often scattered over many publications or stored in supplementary files.

OBJECTIVE

To develop a novel open-source database, BcCluster (http://www.bccluster.org/), dedicated to the comprehensive molecular characterization of muscle invasive bladder carcinoma.

MATERIALS

A database was created containing all reported molecular features significant in invasive BC. The query interface was developed in Ruby programming language (version 1.9.3) using the web-framework Rails (version 4.1.5) (http://rubyonrails.org/).

RESULTS

BcCluster contains the data from 112 published references, providing 1,559 statistically significant features relative to BC invasion. The database also holds 435 protein-protein interaction data and 92 molecular pathways significant in BC invasion. The database can be used to retrieve binding partners and pathways for any protein of interest. We illustrate this possibility using survivin, a known BC biomarker.

CONCLUSIONS

BcCluster is an online database for retrieving molecular signatures relative to BC invasion. This application offers a comprehensive view of BC invasiveness at the molecular level and allows formulation of research hypotheses relevant to this phenotype.

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.

Protein interactome of muscle invasive bladder cancer

Muscle invasive bladder carcinoma is a complex, multifactorial disease caused by disruptions and alterations of several molecular pathways that result in heterogeneous phenotypes and variable disease outcome. Combining this disparate knowledge may offer insights for deciphering relevant molecular processes regarding targeted therapeutic approaches guided by molecular signatures allowing improved phenotype profiling. The aim of the study is to characterize muscle invasive bladder carcinoma on a molecular level by incorporating scientific literature screening and signatures from omics profiling. Public domain omics signatures together with molecular features associated with muscle invasive bladder cancer were derived from literature mining to provide 286 unique protein-coding genes. These were integrated in a protein-interaction network to obtain a molecular functional map of the phenotype. This feature map educated on three novel disease-associated pathways with plausible involvement in bladder cancer, namely Regulation of actin cytoskeleton, Neurotrophin signalling pathway and Endocytosis. Systematic integration approaches allow to study the molecular context of individual features reported as associated with a clinical phenotype and could potentially help to improve the molecular mechanistic description of the disorder.

Novel endoscopic diagnosis for bladder cancer

Advances in endoscopic imaging technology may improve sensitivity for the detection of bladder cancer and provide a more complete understanding of the urothelial landscape, and it also may lead to improved short-term and long-term cancer control. Fluorescence cystoscopy requires intravesical administration of a photosensitizing agent (5-aminolevulinic acid or hexaminolevulinate), and imaging with a blue-light endoscopy system demonstrably improves the detection of papillary and flat bladder lesions compared with conventional white-light cystoscopy. Prospective phase 3 clinical trials have demonstrated improved diagnostic ability, enhanced tumor resection, and a small but significant reduction in recurrence-free survival. Optical coherence tomography delineates subsurface microarchitecture information about bladder lesions in real time and has the ability to discriminate between noninvasive and invasive cancers. Narrow-band imaging may augment white-light cystoscopy by providing increased contrast between normal and abnormal tissue on the basis of neovascularity. Confocal laser endoscopy has been applied to the urinary tract using thinner probes adapted from use in gastrointestinal malignancies and provides exquisite images at microscopic resolution. More technology is on the horizon that may further enhance our ability to detect and accurately stage bladder tumors and distinguish benign from malignant or dysplastic lesions.

Clinical applications of optical coherence tomography in urology

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

Recent advances in diagnosis and treatment of transitional cell carcinoma of the bladder

The management of transitional cell carcinoma of the bladder (TCCB) presents a challenge to urological surgeons due to the diversity of patient factors, stage at presentation and propensity for disease recurrence and progression. Advances in the last decade have seen an evolution in techniques for diagnosis, treatment and ongoing surveillance. A good understanding of our patients, the disease and the available diagnostic and therapeutic options is essential for the management of this condition. We review the current literature focusing on the merits of recent advances in this field. Given the breadth of the subject, we have deliberately selected only the most relevant and recent advances already in clinical use.

Real-time bladder lesion registration and navigation: a phantom study

Background

Bladder cancer is the fourth most common malignancy in men, with a recurrence rate of 33–64%. Tumor documentation during cystoscopy of the bladder is suboptimal and might play a role in these high recurrence rates.

Objective

In this project, a bladder registration and navigation system was developed to improve bladder tumor documentation and consequently increase reproducibility of the cystoscopy.

Materials/Methods

The bladder registration and navigation system consists of a stereo-tracker that tracks the location of a newly developed target, which is attached to the endoscope during cystoscopy. With this information the urology registration and navigation software is able to register the 3D position of a lesion of interest. Simultaneously, the endoscopic image is captured in order to combine it with this 3D position. To enable navigation, navigational cues are displayed on the monitor, which subsequently direct the cystoscopist to the previously registered lesion. To test the system, a rigid and a flexible bladder phantom was developed. The system's robustness was tested by measuring the accuracy of registering and navigating the lesions. Different calibration procedures were compared. It was also tested whether system accuracy is limited by using a previously saved calibration, to avoid surgical delay due to calibration. Urological application was tested by comparing a rotational camera (fixed to the rotating endoscope) to a non-rotational camera (dangling by gravity) used in standard urologic practice. Finally, the influence of volume differences on registering and navigating was tested.

Results/Conclusion

The bladder registration and navigation system has an acceptable accuracy for bladder lesion registration and navigation. Limitations for patient determinants included changes in bladder volume and bladder deformation. In vivo studies are required to measure the effect of these limitations and functionality in urological practice as a tool to increase reproducibility of the cystoscopy.