Optical coherence tomography for bladder cancer -- ready as a surrogate for optical biopsy? Results of a prospective mono-centre study

Advanced optical imaging techniques for bladder cancer detection and diagnosis: a systematic review

OBJECTIVES

To systematically assess the current available literature concerning advanced optical imaging methods for the detection and diagnosis of bladder cancer (BCa), focusing particularly on the sensitivity and specificity of these techniques.

METHODS

First a scoping search was performed to identify all available optical techniques for BCa detection and diagnosis. The optical imaging techniques used for detecting BCa are: the Storz professional image enhancement system (IMAGE1 S), narrow-band imaging (NBI), photoacoustic imaging (PAI), autofluorescence imaging (AFI), photodynamic diagnosis (PDD), and scanning fibre endoscopy (SFE). The staging and grading techniques for BCa are: optical coherence tomography (OCT), confocal laser endomicroscopy (CLE), Raman spectroscopy, endocytoscopy, and non-linear optical microscopy (NLO). Then a systematic literature search was conducted using MEDLINE, EMBASE and Web of Science from inception to 21 November 2023. Articles were screened and selected by two independent reviewers. Inclusion criteria were: reporting on both the sensitivity and specificity of a particular technique and comparison to histopathology, and in the case of a detection technique comparison to white light cystoscopy (WLC).

RESULTS

Out of 6707 articles, 189 underwent full-text review, resulting in 52 inclusions. No articles met criteria for IMAGE1 S, PAI, SFE, Raman spectroscopy, and endocytoscopy. All detection techniques showed higher sensitivity than WLC, with NBI leading (87.8-100%). Overall, detection technique specificity was comparable to WLC, with PDD being most specific (23.3-100%). CLE and OCT varied in sensitivity and specificity, with OCT showing higher specificity for BCa diagnosis, notably for carcinoma in situ (97-99%) compared to CLE (62.5-81.3%). NLO demonstrated high sensitivity and specificity (90-97% and 77-100%, respectively) based on limited data from two small ex vivo studies.

CONCLUSIONS

Optical techniques with the most potential are PDD for detecting and OCT for staging and grading BCa. Further research is crucial to validate their integration into routine practice and explore the value of other imaging techniques.

Polarimetric imaging-based cancer bladder tissue's detection: A comparative study of bulk and formalin-fixed paraffin-embedded samples

The polarimetry imaging technique as a promising technique for pathological diagnosis provides a handy tool for identifying and discriminating cancerous tissues. In this paper, the optical polarization properties of bulk bladder tissues without any further processing and Formalin-Fixed Paraffin-Embedded (FFPE) blocks of bladder tissues have been measured. The images of the Muller matrix for both normal and cancerous samples have been obtained and for quantitative analysis and to provide a more precise comparison, two methods have been applied; the Mueller matrix polar decomposition (MMPD), and the Mueller matrix transformation (MMT). The results have shown that some of the extracted parameters from these methods can be used to identify the microstructural differentiations between normal and cancerous tissues. The results revealed a good accord between the obtained optical parameters for bulk and FFPE bladder tissues. By measuring the polarimetric properties of the tissue right after resection, and also in the early stages of pathology (FFPE tissues), this method can be applied in vivo to perform an optical biopsy; Furthermore, this method has the potential to significantly shortens the duration of pathological diagnosis. The approach seems remarkable, simple, precise, and economical compared to the existing techniques for the detection of cancerous samples.

Segmentation of the urothelium in optical coherence tomography images with dynamic contrast

SIGNIFICANCE

Speckle variation induced by intracellular motion (IM) in the urothelium was observed in optical coherence tomography (OCT) images. IM can be used as a dynamic contrast to segment the urothelium by comparing two sequential OCT images. This method opens the possibility of specifically tracking the distribution of urothelial cancerous cells for identifying the microinvasion of bladder tumors.

APPROACH

OCT images were acquired ex vivo with fresh porcine bladder tissue. IM was analyzed by tracking speckle variation using autocorrelation function, then quantified with constrained regularization method for inverting data (CONTIN method) to identify the decorrelation time (DT) of the speckle variations. Variance analysis was also conducted to show IM amplitude and distribution in the urothelium. The segmentation of the urothelium was demonstrated with OCT images with a visible urothelial layer and OCT images with an invisible urothelial layer.

RESULTS

Significant speckle variation induced by IM was observed in the urothelium. However, the distribution of the IM is heterogeneous. The DTs are mostly concentrated between 1 and 30 ms. With the IM as a dynamic contrast, the urothelium can be accurately and exclusively segmented, even the urothelial layer is invisible in normal OCT images.

CONCLUSIONS

IM can be used as a dynamic contrast to exclusively track urothelial cell distribution. This contrast may provide a new mechanism for OCT to image the invasion depth and pattern of urothelial cancerous cells for accurately substaging of bladder cancer.

Optical Vaginal Biopsy Using Optical Coherence Tomography

OBJECTIVE

Optical coherence tomography is a noninvasive technology that visualizes tissue microstructure with high spatial resolution. We designed a novel vaginal system that demonstrates a clear distinction between vaginal tissues planes. In this study, we sought to compare vaginal tomographic images of premenopausal, perimenopausal, and postmenopausal women, demonstrate feasibility of tracking vaginal tissue changes after treatment with fractional-pixel CO2 laser therapy, and obtain a histologic correlation of these findings.

METHODS

Enrolled subjects underwent imaging and were divided into 3 groups based on menopausal status. Women with genitourinary syndrome of menopause who received fractional-pixel CO2 laser therapy were assessed before and after treatment. A cadaveric vagina was used to obtain tomographic and histologic images to assess for accuracy. Our primary outcome was mean vaginal epithelial thickness. Statistical analysis was performed using analysis of variance and t tests, respectively.

RESULTS

Among 6 women, the mean vaginal epithelial thickness decreased with menopause (P < 0.01). Although change in epithelial thickness after fractional-pixel CO2 laser treatment varied between the 2 subjects evaluated, it increased significantly for the subject who reported improvement of vaginal symptoms (P < 0.01). Using a cadaveric specimen, optical biopsy was correlated to an hematoxylin and eosin-stained biopsy of the same vaginal site.

CONCLUSIONS

This study establishes feasibility of optical coherence tomography in providing an optical biopsy of the vaginal epithelium and lamina propria. In addition, it demonstrates vaginal changes as women enter menopause. This report is the initial phase of a longitudinal cohort study to evaluate changes in vaginal microstructure after energy-based treatment.

Statistical evaluation of reader variability in assessing the diagnostic performance of optical coherence tomography

SIGNIFICANCE

Optical coherence tomography (OCT) is widely used as a potential diagnostic tool for a variety of diseases including various types of cancer. However, sensitivity and specificity analyses of OCT in different cancers yield results varying from 11% to 100%. Hence, there is a need for more detailed statistical analysis of blinded reader studies.

AIM

Extensive statistical analysis is performed on results from a blinded study involving OCT of breast tumor margins to assess the impact of reader variability on sensitivity and specificity.

APPROACH

Five readers with varying levels of experience reading OCT images assessed 50 OCT images of breast tumor margins collected using an intraoperative OCT system. Statistical modeling and analysis was performed using the R language to analyze reader experience and variability.

RESULTS

Statistical analysis showed that the readers' prior experience with OCT images was directly related to the probability of the readers' assessment agreeing with histology. Additionally, results from readers with prior experience specific to OCT in breast cancer had a higher probability of agreement with histology compared to readers with experience with OCT in other (noncancer) diseases.

CONCLUSIONS

The results from this study demonstrate the potential impact of reader training and experience in the assessment of sensitivity and specificity. They also demonstrate even greater potential improvement in diagnostic performance by combining results from multiple readers. These preliminary findings suggest valuable directions for further study.

[Supplementary optical techniques for the detection of nonmuscle invasive bladder cancer]

White light cystoscopy (WL) is the gold standard for the detection of bladder cancer. It can be performed using a rigid or flexible urethrocystoscope. With the more recent introduction of high definition (HD) techniques, WL cystoscopy has been decisively improved. Supplementary optical techniques are also used to improve the detection of bladder cancer. Among these are photodynamic diagnosis (PDD), narrow-band imaging (NBI), S‑technologies of IMAGE1 S, optical coherence tomography (OCT), confocal laser endomicroscopy (CLE), and Raman spectroscopy. The aim of the present work is to introduce the techniques and to discuss their current role and future potential in the detection of bladder cancer.

[Optical coherence tomography of bladder resection specimen]

INTRODUCTION

The diagnosis of bladder urothelial tumors is based on bladder resection and histological analysis of the specimen. The time to obtain the results of the histological analysis increases the treatment delay. Furthermore, the lack of muscle on the specimen forces the surgeon to practice on other procedure. Full field optical coherence tomography (FFOCT) is a recent imaging technique to analyze tissue. The aim of our study was to evaluate the feasibility and diagnostic accuracy of FFOCT to detect muscle and tumor in bladder resection specimen.

PATIENTS AND METHODS

We analyzed with the FFOCT technique bladder resection specimen of 24 consecutives patients. Three readers did the blind analyze of the images, looking for the presence of muscle and tumor on each specimen. Their results were compared with histological analysis to calculate diagnostic accuracy for each reader.

RESULTS

Mean sensibilities for the detection of muscle and tumor were respectively 75% and 81%. Mean specificities for the detection of muscle and tumor were respectively 78.3% and 55.3%.

CONCLUSIONS

Our results suggest that the FFOCT is feasible to analyze bladder resection specimen. Sensibilities and specificities calculated are encouraging for the detection of muscle and tumor. The accuracy of this detection and early-staging tool should be validated by larger studies.

LEVEL OF EVIDENCE

3.

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.

Diagnostic accuracy of optical coherence tomography for bladder cancer: A systematic review and meta-analysis

BACKGROUND

Bladder cancer is the fourth most common malignancy in men and a considerable disease burden globally. Multiple studies have focused on the accuracy of optical coherence tomography for bladder cancer diagnosis; however, the findings are inconsistent. Here, we assessed the accuracy of optical coherence tomography for bladder cancer diagnosis.

METHODS

Embase, PubMed, Medline, Web of Science, and the Cochrane Library database were searched for relevant studies from the earliest date available through March 11, 2019. Studies evaluating the accuracy of optical coherence tomography bladder cancer diagnosis were included. Pooled sensitivity, specificity, and area under the curve values of weighted symmetric summary receiver operating curves, were calculated at the per-lesion level.

RESULTS

Eleven studies, with a total of 1933 lesions, were included in the final analysis. The pooled results indicated that optical coherence tomography can differentiate bladder cancer from benign lesions: sensitivity, 94.9% (95% confidence interval: 92.7%-96.6%); specificity, 84.6% (95% confidence interval: 82.6%-86.4%); area under the curve, 0.97. Moreover, compared with optical coherence tomography alone, combined optical coherence tomography and fluorescence cystoscopy increased the diagnostic accuracy (sensitivity, 94.3% vs. 87.3%; specificity, 89.2% vs. 73.9%). Cross-polarization optical coherence tomography could also distinguish bladder cancer from normal tissue: sensitivity, 92.0% (95% confidence interval: 87.0%-95.6%); specificity, 84.4% (95% confidence interval: 81.7%-86.9%); area under the curve, 0.95.

CONCLUSIONS

Optical coherence tomography can accurately differentiate malignant from benign bladder lesions, particularly when combined with fluorescence cystoscopy.

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.

The clinical usefulness of optical coherence tomography during cancer interventions

INTRODUCTION

Tumor detection and visualization plays a key role in the clinical workflow of a patient with suspected cancer, both in the diagnosis and treatment. Several optical imaging techniques have been evaluated for guidance during oncological interventions. Optical coherence tomography (OCT) is a technique which has been widely evaluated during the past decades. This review aims to determine the clinical usefulness of OCT during cancer interventions focussing on qualitative features, quantitative features and the diagnostic value of OCT.

METHODS

A systematic literature search was performed for articles published before May 2018 using OCT in the field of surgical oncology. Based on these articles, an overview of the clinical usefulness of OCT was provided per tumor type.

RESULTS

A total of 785 articles were revealed by our search, of which a total of 136 original articles were available for analysis, which formed the basis of this review. OCT is currently utilised for both preoperative diagnosis and intraoperative detection of skin, oral, lung, breast, hepatobiliary, gastrointestinal, urological, and gynaecological malignancies. It showed promising results in tumor detection on a microscopic level, especially using higher resolution imaging techniques, such as high-definition OCT and full-field OCT.

CONCLUSION

In the near future, OCT could be used as an additional tool during bronchoscopic or endoscopic interventions and could also be implemented in margin assessment during (laparoscopic) cancer surgery if a laparoscopic or handheld OCT device will be further developed to make routine clinical use possible.

In Vivo Microscopy in Neurosurgical Oncology

Intraoperative neurosurgical histopathologic diagnoses rely on evaluation of rapid tissue preparations such as frozen sections and smears with conventional light microscopy. Although useful, these techniques are time consuming and therefore cannot provide real-time intraoperative feedback. In vivo molecular imaging techniques are emerging as novel methods for generating real-time diagnostic histopathologic images of tumors and their surrounding tissues. These imaging techniques rely on contrast generated by exogenous fluorescent dyes, autofluorescence of endogenous molecules, fluorescence decay of excited molecules, or light scattering. Large molecular imaging instruments are being miniaturized for clinical in vivo use. This review discusses pertinent imaging systems that have been developed for neurosurgical use and imaging techniques currently under development for neurosurgical molecular imaging.

Molecular mobility and activity in an intravital imaging setting - implications for cancer progression and targeting

Molecular mobility, localisation and spatiotemporal activity are at the core of cell biological processes and deregulation of these dynamic events can underpin disease development and progression. Recent advances in intravital imaging techniques in mice are providing new avenues to study real-time molecular behaviour in intact tissues within a live organism and to gain exciting insights into the intricate regulation of live cell biology at the microscale level. The monitoring of fluorescently labelled proteins and agents can be combined with autofluorescent properties of the microenvironment to provide a comprehensive snapshot of in vivo cell biology. In this Review, we summarise recent intravital microscopy approaches in mice, in processes ranging from normal development and homeostasis to disease progression and treatment in cancer, where we emphasise the utility of intravital imaging to observe dynamic and transient events in vivo We also highlight the recent integration of advanced subcellular imaging techniques into the intravital imaging pipeline, which can provide in-depth biological information beyond the single-cell level. We conclude with an outlook of ongoing developments in intravital microscopy towards imaging in humans, as well as provide an overview of the challenges the intravital imaging community currently faces and outline potential ways for overcoming these hurdles.

Diagnostic accuracy of optical coherence tomography in bladder cancer patients: A systematic review and meta-analysis

A meta-analysis was performed to evaluate the accuracy of optical coherence tomography (OCT) for diagnostic accuracy studies in bladder cancer patients. English language studies reporting the diagnostic accuracy of OCT for bladder cancer were retrieved from the PubMed, EMBASE and Cochrane Library databases in December 2014. Histopathology was a reference standard. Sensitivities, specificities, positive likelihood ratios and negative likelihood ratios were calculated, and summary receiver operating characteristic curves were drawn to determine the diagnostic accuracy of OCT. Finally, 9 eligible studies (468 patients) were included in our meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio and negative likelihood ratio of OCT were 0.96 [95% confidence interval (CI): 0.94-0.98], 0.82 (95% CI: 0.80-0.85), 6.83 (95% CI: 3.24-14.1) and 0.05 (95% CI: 0.02-0.16), respectively. The summary diagnostic odds ratio was 138.88 (95% CI: 29.63-650.89) and the overall area under the curve was 0.9735. These results suggest that OCT has excellent diagnostic performance in patients with bladder cancer and recurrent lesions.

Advancements in optical techniques and imaging in the diagnosis and management of bladder cancer

Accurate detection and staging is critical to the appropriate management of urothelial cancer (UC). The use of advanced optical techniques during cystoscopy is becoming more widespread to prevent recurrent nonmuscle invasive bladder cancer. Standard of care for muscle-invasive UC includes the use of computed tomography and/or magnetic resonance imaging, but staging accuracy of these tests remains imperfect. Novel imaging modalities are being developed to improve current test performance. Positron emission tomography/computed tomography has a role in the initial evaluation of select patients with muscle-invasive bladder cancer and in disease recurrence in some cases. Several novel immuno-positron emission tomography tracers are currently in development to address the inadequacy of current imaging modalities for monitoring of tumor response to newer immune-based treatments. This review summaries the current standards and recent advances in optical techniques and imaging modalities in localized and metastatic UC.

Review of optical coherence tomography in oncology

The application of optical coherence tomography (OCT) in the field of oncology has been prospering over the past decade. OCT imaging has been used to image a broad spectrum of malignancies, including those arising in the breast, brain, bladder, the gastrointestinal, respiratory, and reproductive tracts, the skin, and oral cavity, among others. OCT imaging has initially been applied for guiding biopsies, for intraoperatively evaluating tumor margins and lymph nodes, and for the early detection of small lesions that would often not be visible on gross examination, tasks that align well with the clinical emphasis on early detection and intervention. Recently, OCT imaging has been explored for imaging tumor cells and their dynamics, and for the monitoring of tumor responses to treatments. This paper reviews the evolution of OCT technologies for the clinical application of OCT in surgical and noninvasive interventional oncology procedures and concludes with a discussion of the future directions for OCT technologies, with particular emphasis on their applications in oncology.

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.

Urothelial Tumors and Dual-Band Imaging: A New Concept in Confocal Laser Endomicroscopy

OBJECTIVES

Confocal laser endomicroscopy (CLE) uses a low-energy laser light source to obtain microscopic histology images of bladder tissue exposed to a fluorescent dye. To evaluate the feasibility of using CLE with two fluorophores: fluorescein (FLUO) and hexylaminolevulinate (HAL) to determine histologic and cytologic bladder cancer criteria.

METHODS

Patients eligible for HAL-photodynamic diagnosis-assisted transurethral resection of bladder tumor were included. The procedures were performed with the patient under regional or general anesthesia (60-90 minutes) after bladder instillation of HAL (50 mL, 8 mmol/L; Hexvix^®; Ipsen, France). Resected tissue was examined ex vivo using CLE either with Cellvizio^® system (CVI) single laser (488 nm) or with Cellvizio Dual system (CVII) double laser (488, 660 nm).

RESULTS

Twenty-one patients were included, 12 examined by CVI and 9 by CVII. Sample examination on CVI after HAL-CLE-only histologic analysis was not possible because HAL is mostly cytoplasmic and gives poor details on cellular architecture. On the contrary, FLUO-CLE gives good extracellular architecture and not clear information of nucleocytoplasmic abnormality. Samples on CVII for seven out of nine patients clearly showed cytoplasm of suspect cells and nuclei. In real time, fluorescence observed on bandwidth (673-800 nm) with HAL and FLUO was associated with the presence of cancer, with a sensibility and specificity of 80% and 100%, respectively.

CONCLUSIONS

Real-time cytodetection was feasible using two fluorophores (FLUO and HAL) and the new system of CVII. This technology was useful to observe cytoplasm, nuclei, and nucleocytoplasmic abnormality, but an improved system is necessary (to overcome the overlapping of fluorescence) to increase the specificity.

Intraoperative assessment of laryngeal pathologies with optical coherence tomography integrated into a surgical microscope

OBJECTIVE

Endoscopic examination followed by tissue biopsy is the gold standard in the evaluation of lesions of the upper aerodigestive tract. However, it can be difficult to distinguish between healthy mucosa, dysplasia, and invasive carcinoma. Optical coherence tomography (OCT) is a non-invasive technique which acquires high-resolution, cross-sectional images of tissue in vivo. Integrated into a surgical microscope, it allows the intraoperative evaluation of lesions simultaneously with microscopic visualization.

STUDY DESIGN

In a prospective case series, we evaluated the use of OCT integrated into a surgical microscope during microlaryngoscopy to help differentiating various laryngeal pathologies.

METHODS

33 patients with laryngeal pathologies were examined with an OCT- microscope (OPMedT iOCT-camera, HS Hi-R 1000G-microscope, Haag-Streit Surgical GmbH, Wedel, Germany) during microlaryngoscopy. The suspected intraoperative diagnoses were compared to the histopathological reports of subsequent tissue biopsies.

RESULTS

Hands-free non-contact OCT revealed high-resolution images of the larynx with a varying penetration depth of up to 1.2 mm and an average of 0.6 mm. Picture quality was variable. OCT showed disorders of horizontal tissue layering in dysplasias with a disruption of the basement membrane in carcinomas. When comparing the suspected diagnosis during OCT-supported microlaryngoscopy with histology, 79% of the laryngeal lesions could be correctly identified. Premalignant lesions were difficult to diagnose and falsely classified as carcinoma.

CONCLUSION

OCT integrated into a surgical microscope seems to be a promising adjunct tool to discriminate pathologies of the upper aerodigestive tract intraoperatively. However, picture quality and penetration depth were variable. Although premalignant lesions were difficult to diagnose, the system proved overall helpful for the intraoperative discrimination of benign and malignant tumors. Further studies will be necessary to define its value in the future. Lasers Surg. Med. 49:490-497, 2017. © 2017 Wiley Periodicals, Inc.

Non-muscle-invasive bladder cancer: a vision for the future

The management of non-muscle-invasive bladder cancer (NMIBC) has evolved from the first reports on bladder endoscopy and transurethral resection to the introduction of adjuvant intravesical treatment. However, disease recurrence and progression remain an ongoing risk, placing a heavy burden on healthcare resources and on patients' quality of life. Deeper understanding of the molecular basis of the disease and developments in optics, lasers and computer science are already offering opportunities to revolutionize care and improve long-term prognosis. This article discusses developments likely to cause a paradigm shift towards the delivery of personalized care and reduced burden of disease in NMIBC.

Nonmuscle-invasive bladder cancer: what's changing and what has changed

PURPOSE

Nonmuscle-invasive bladder cancer (NMIBC) is a challenging disease to manage primarily due to its varied clinical course. The management of NMIBC has witnessed a widespread change with respect to its diagnosis and treatment. Although transurethral resection (TUR) and adjuvant bacillus Calmette-Guerin (BCG) stills remain the cornerstone, newer protocols has come into vogue to achieve optimal care. On the basis of a literature review, we aimed to establish 'what changes has already occurred and what is expected in the future' in NMIBC.

METHODS

A Medline search was performed to identify the published literature with respect to diagnosis, treatment and future perspectives on NMIBC. Particular emphasis was directed to determinants such as the quality of TUR and the newer modifications, Re-TUR, current status of newer macroscopic and microscopic imaging, role of urinary biomarkers, clinical, histologic and molecular predictors of high-risk disease, administration of intravesical agents, salvage therapy in BCG recurrence and the current best practice guidelines were analyzed.

RESULTS AND CONCLUSIONS

Optimal TUR, restaging in select group, incorporation of newer endoscopic imaging and judicious administration of intravesical chemo-immunotherapeutic agents can contribute to better patient care. Although there is a plethora of urinary markers, there is insufficient evidence for their use in isolation. The future probably lies in identification of genetic markers to determine disease recurrence, nonresponders to standard treatment and early institution of alternative/targeted therapy.

Natural biology and management of nonmuscle invasive bladder cancer

PURPOSE OF REVIEW

This article reviews the natural biology of noninvasive bladder cancer and its management strategies while summarizing the most recent advances in the field.

RECENT FINDINGS

Nonmuscle invasive bladder cancer (NMIBC) has a tendency to recur and progress. Risk stratification has helped triage patients but improved tools, including biomarkers, are still needed. Enhanced endoscopy with photodynamic imaging, narrow band imaging, optical coherence tomography and confocal laser endomicroscopy show promise for diagnosis, risk stratification and disease monitoring. Attempts at better treatment, especially in refractory high-risk cases, include the addition of intravesical hyperthermia, combination and sequential therapy with existing agents and the use of novel agents such as mycobacterial cell wall extract. New data are emerging regarding the potential role of active surveillance in low-risk patients.

SUMMARY

NMIBC represents a variety of disease states and continues to pose management challenges. As our understanding of tumor biology improves and technology advances, achieving better outcomes through individualized care may be possible.

Review of current optical diagnostic techniques for non-muscle-invasive bladder cancer

Introduction

Urinary bladder urothelial cell carcinoma is one of the most commonly diagnosed cancers in Europe. After prostate, lung and colon cancers, bladder cancer rates as the fourth most common cancer in men in the world.

Urinary bladder cancer detection, treatment, and staging have traditionally been based on an endoscopic examination – cystoscopy.

Material and methods

A Medline, and Web of Science database search was performed on September 2015 without setting time limits, using the terms ‘bladder cancer’ in conjunction with ‘cystoscopy’, ‘diagnosis’, ‘detection’, ‘fluorescence’, ‘blue-light’, ‘PDD’, ‘narrow band imaging’, ‘molecular imaging’, ‘optical coherence tomography’ or ‘confocal laser endomicroscopy’.

Results

The new imaging techniques can be classified according to their scope as macroscopic, microscopic, and molecular. Macroscopic techniques, such as narrow band imaging, are similar to white light cystoscopy; however, they help visualize even very minute lesions in the bladder mucosa by means of contrast enhancement.

Microscopic imaging techniques, such as optical coherence tomography and confocal laser endomicroscopy, provide high-resolution cross-sectional views of vesicular tissues, which resemble images obtained by histopathological examination. Therefore, these are referred as ‘optical biopsy’. Molecular imaging methods offer highly specific real-time visualization of cancer cells and their differentiation from healthy tissue, by combining optical imaging with fluorescent labeling of elements such as antibodies.

Conclusions

In this article we present a review of studies and literature concerning modern optical diagnostic techniques for non-muscle-invasive bladder cancer. We present available technology with its advantages and disadvantages, and studies regarding its effectiveness.

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.

Multimodal 3D cancer-mimicking optical phantom

Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing various aspects of optical systems, including for evaluating new probe designs, characterizing the diagnostic potential of new technologies, and assessing novel image processing algorithms prior to validation in real tissue. We introduce and characterize the use of a new material, Dragon Skin (Smooth-On Inc.), and fabrication technique, air-brushing, for fabrication of a 3D phantom that mimics the appearance of a real organ under multiple imaging modalities. We demonstrate the utility of the material and technique by fabricating the first 3D, hollow bladder phantom with realistic normal and multi-stage pathology features suitable for endoscopic detection using the gold standard imaging technique, white light cystoscopy (WLC), as well as the complementary imaging modalities of optical coherence tomography and blue light cystoscopy, which are aimed at improving the sensitivity and specificity of WLC to bladder cancer detection. The flexibility of the material and technique used for phantom construction allowed for the representation of a wide range of diseased tissue states, ranging from inflammation (benign) to high-grade cancerous lesions. Such phantoms can serve as important tools for trainee education and evaluation of new endoscopic instrumentation.

Optical coherence tomography detects structural abnormalities of the nasal mucosa in patients with cystic fibrosis

BACKGROUND

Chronic inflammation and remodeling of the airways remain a hallmark of cystic fibrosis (CF). However, knowledge of the associated mucosal micro-anatomical changes is limited. We evaluated the potential of optical coherence tomography (OCT) for in vivo imaging of the upper airway mucosa in CF patients.

METHODS

A flexible OCT probe was used for cross-sectional imaging of the nasal mucosa in 25 CF patients and 25 healthy controls.

RESULTS

OCT images showed mucosal details including epithelium, basement membrane, lamina propria with seromucinous glands, and underlying cartilaginous structures. Mean nasal mucosa and epithelial layer thickness were increased in CF compared to controls. In CF patients, antibiotic therapy was associated with reduced nasal mucosa thickening.

CONCLUSIONS

OCT detected mucosal changes associated with upper airway inflammation and response to antibiotic therapy in CF patients. OCT may be a useful tool for quantitative in vivo assessment of structural changes of the airway mucosa.

Advances in imaging technologies in the evaluation of high-grade bladder cancer

Bladder cancer ranges from a low-grade variant to high-grade disease. Assessment for treatment depends on white light cystoscopy, however because of its limitations there is a need for improved visualization of flat, multifocal, high-grade, and muscle-invasive lesions. Photodynamic diagnosis and narrow-band imaging provide additional contrast enhancement of bladder tumors and have been shown to improve detection rates. Confocal laser endomicroscopy and optical coherence tomography enable real-time, high-resolution, subsurface tissue characterization with spatial resolutions similar to histology. Molecular imaging offers the potential for the combination of optical imaging technologies with cancer-specific molecular agents to improve the specificity of disease detection.

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.

Molecular Imaging in Optical Coherence Tomography

Optical coherence tomography (OCT) is a medical imaging technique that provides tomographic images at micron scales in three dimensions and high speeds. The addition of molecular contrast to the available morphological image holds great promise for extending OCT's impact in clinical practice and beyond. Fundamental limitations prevent OCT from directly taking advantage of powerful molecular processes such as fluorescence emission and incoherent Raman scattering. A wide range of approaches is being researched to provide molecular contrast to OCT. Here we review those approaches with particular attention to those that derive their molecular contrast directly from modulation of the OCT signal. We also provide a brief overview of the multimodal approaches to gaining molecular contrast coincident with OCT.

Optical coherence tomography diagnostics for onco-urology. Review of clinical perspectives

Introduction

Optical coherence tomography (OCT) is being investigated widely for use in urologic pathology. The current imaging of urogenital cancers cannot be perfect, thus, routine methods demands new updates or inventions of alternative radiological scope. OCT presents so–called “live” optical biopsy. The authors aim to review this modality for uro–oncological purposes.

Matherial and methods

A series of 37 publications between 1989 and 2012 was selected and cited from GoogleScholar and PubMED/MEDLINE. The urogenital tract (bladder, ureter, scrotum organs and prostate) was imaged by OCT.

Results

The overall OCT sensitivity, specificity, accuracy, negative and positive predictive values ranged a lot on example of the urinary bladder's tumors screening. The data were 75–100%, 65–97.9%, 92%, 75%, 100%, respectively. Notwithstanding, a diagnostic importance of OCT may be comparable with urine cytology, cystoscopy, computerized tomography and magnetic resonance imaging.

Conclusions

OCT demonstrated its imaging potential, while till the present OCT plays role of an additional imaging. Future progress of OCT involvement in experimental and clinical once–urological diagnostics is needed under high evidence control.

New imaging techniques for non-muscle invasive bladder cancer: ready for primetime

Treatment of non-muscle invasive bladder cancer (NMBIC) requires direct visual appreciation of the tumor. Transurethral resection that is dependent solely on white light cystoscopy (WLC) often fails to accurately stage or completely resect NMIBC. These deficiencies of WLC are significant contributors to the high rates of recurrence and eventual progression to muscle invasive disease. This article looks at technologies that are being used in adjunct to WLC to augment the urologist's ability to identify, stage, and treat NMIBC.

Detection of bladder urothelial carcinoma using in vivo noncontact, ultraviolet excited autofluorescence measurements converted into simple color coded images: a feasibility study

PURPOSE

A difficulty in nonmuscle invasive bladder cancers is the diagnosis of flat and small lesions during white light cystoscopy. We assessed a prototype that measures ultraviolet laser induced autofluorescence for endoscopic detection of nonmuscle invasive bladder cancer.

MATERIALS AND METHODS

We compared spectroscopic results with histological findings in 3 groups, including normal urothelium, papillary tumors and flat lesions. The developed method is based on exciting the fluorescence of molecules naturally present in tissue using ultraviolet laser pulses. The diagnostic signal was converted into the intensity ratio of the emitted light at approximately 360 and 450 nm. This ratio depends on the histopathological state of the tissue. The signal was converted into a simple color coded image, in which green indicates normal tissue and red indicates neoplasm.

RESULTS

A total of 14 patients were included in analysis. At 360 and 450 nm excitation wavelengths the overall fluorescence intensity of bladder tumors was clearly decreased compared to that of normal urothelium regardless of tumor stage or grade. At the 308 nm excitation wavelength the shape of the tumor spectra, including carcinoma in situ, was markedly different from that of normal or nonspecific inflammatory mucosa. The correlation between red images and tumor in the specimen was 100%. No absolute intensity determinations were required since a definite diagnosis was established based on the fluorescence intensity ratio at 360 and 450 nm.

CONCLUSIONS

This feasibility study confirms the functionality of our clinical prototype for the noncontact imaging detection of nonmuscle invasive bladder cancer via an endoscope using ultraviolet excited autofluorescence measurements.

Optical coherence tomography in conjunction with bronchoscopy

OBJECTIVE

To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways.

METHODS

This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rabbit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion.

RESULTS

The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall.

CONCLUSIONS

It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high-resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology.

New optical imaging technologies for bladder cancer: considerations and perspectives

PURPOSE

Bladder cancer presents as a spectrum of different diatheses. Accurate assessment for individualized treatment depends on initial diagnostic accuracy. Detection relies on white light cystoscopy accuracy and comprehensiveness. Aside from invasiveness and potential risks, white light cystoscopy shortcomings include difficult flat lesion detection, precise tumor delineation to enable complete resection, inflammation and malignancy differentiation, and grade and stage determination. Each shortcoming depends on surgeon ability and experience with the technology available for visualization and resection. Fluorescence cystoscopy/photodynamic diagnosis, narrow band imaging, confocal laser endomicroscopy and optical coherence tomography address the limitations and have in vivo feasibility. They detect suspicious lesions (photodynamic diagnosis and narrow band imaging) and further characterize lesions (optical coherence tomography and confocal laser endomicroscopy). We analyzed the added value of each technology beyond white light cystoscopy and evaluated their maturity to alter the cancer course.

MATERIALS AND METHODS

Detailed PubMed® searches were done using the terms "fluorescence cystoscopy," "photodynamic diagnosis," "narrow band imaging," "optical coherence tomography" and "confocal laser endomicroscopy" with "optical imaging," "bladder cancer" and "urothelial carcinoma." Diagnostic accuracy reports and all prospective studies were selected for analysis. We explored technological principles, preclinical and clinical evidence supporting nonmuscle invasive bladder cancer detection and characterization, and whether improved sensitivity vs specificity translates into improved correlation of diagnostic accuracy with recurrence and progression. Emerging preclinical technologies with potential application were reviewed.

RESULTS

Photodynamic diagnosis and narrow band imaging improve nonmuscle invasive bladder cancer detection, including carcinoma in situ. Photodynamic diagnosis identifies more papillary lesions than white light cystoscopy, enabling more complete resection and fewer residual tumors. Despite improved treatment current data on photodynamic diagnosis do not support improved high risk diathetic detection and characterization or correlation with disease progression. Prospective recurrence data are lacking on narrow band imaging. Confocal laser endomicroscopy and optical coherence tomography potentially grade and stage lesions but data are lacking on diagnostic accuracy. Several emerging preclinical technologies may enhance the diagnostic capability of endoscopic imaging.

CONCLUSIONS

New optical imaging technologies may improve bladder cancer detection and characterization, and transurethral resection quality. While data on photodynamic diagnosis are strongest, the clinical effectiveness of these technologies is not proven. Prospective studies are needed, particularly of narrow band imaging, confocal laser endomicroscopy and optical coherence tomography. As each technology matures and new ones emerge, cost-effectiveness analysis must be addressed in the context of the various bladder cancer types.

Perioperative management of nonmuscle-invasive bladder cancer

PURPOSE OF REVIEW

The management of nonmuscle-invasive bladder cancer is a challenge. Despite current guidelines, the treatment is suboptimal as illustrated by the high risk of recurrence and progression. Transurethral resection plays a pivotal role in the management of bladder cancer, but the quality varies dramatically. In this review, we discuss the latest developments that aim to improve the outcome of a transurethral resection such as photodynamic diagnosis, a second resection and adjuvant therapy.

RECENT FINDINGS

The treatment of a bladder cancer patient can be improved, for example, with a standard second resection in a subset of the patients or the use of visual enhancement techniques. There is conflicting data on the clinical value of techniques like photodynamic diagnosis, as it does not always seem to translate into a better long-term outcome. Comparison of studies is difficult because of differences in patient selection and endpoints. Better classification in (personalized) risk categories may facilitate the treatment choice and prediction of the long-term outcome.

SUMMARY

The outcome of bladder cancer patients can be improved. A good-quality transurethral resection of the bladder tumor is crucial and novel technological developments may improve the outcome, but they remain the subject of discussion.

Emerging endoscopic and photodynamic techniques for bladder cancer detection and surveillance

This review provides an overview of emerging techniques, namely, photodynamic diagnosis (PDD), narrow band imaging (NBI), Raman spectroscopy, optical coherence tomography, virtual cystoscopy, and endoscopic microscopy for its use in the diagnosis and surveillance of bladder cancer. The technology, clinical evidence and future applications of these approaches are discussed with particular emphasis on PDD and NBI. These approaches show promise to optimise cystoscopy and transurethral resection of bladder tumours.

Optimal timing of radical cystectomy in T1 high-grade bladder cancer

T1 high-grade (formerly T1G3) bladder cancer is a challenging clinical entity representing approximately 10-15% of all new bladder cancer cases. The variable natural history of the disease and possible impairment in quality of life associated with radical treatment makes T1 high-grade one of the most challenging uro-oncological patient groups to manage. In particular, the risk of clinical understaging and not recognizing muscle-invasive disease may have detrimental effects on patient outcome. The cornerstone of contemporary staging is restaging transurethral resection (TUR), which helps in defining further management. In patients with restaging TUR stage less than T1, induction bacillus Calmette-Guérin combined with maintenance offers good results. The option of radical cystectomy should be discussed with patients with restaging TUR stage T1 or higher and it is highly recommended to all patients with recurrent T1 of carcinoma in situ during bacillus Calmette-Guérin maintenance. In addition to restaging TUR stage, several other clinicopathological factors, such T1 substaging, associated carcinoma in situ, tumor size and appearance, lymphovascular invasion, and hydronephrosis, aid in the decision making between radical and conservative treatment. Future prospects include improved staging and molecular markers that may guide toward conservative therapy or allow more cT1 patients to be offered nerve-sparing cystectomies and neobladders and, thus, improving quality of life for patients undergoing radical surgery.

Raman spectroscopy in head and neck cancer

In recent years there has been much interest in the use of optical diagnostics in cancer detection. Early diagnosis of cancer affords early intervention and greatest chance of cure. Raman spectroscopy is based on the interaction of photons with the target material producing a highly detailed biochemical 'fingerprint' of the sample. It can be appreciated that such a sensitive biochemical detection system could confer diagnostic benefit in a clinical setting. Raman has been used successfully in key health areas such as cardiovascular diseases, and dental care but there is a paucity of literature on Raman spectroscopy in Head and Neck cancer. Following the introduction of health care targets for cancer, and with an ever-aging population the need for rapid cancer detection has never been greater. Raman spectroscopy could confer great patient benefit with early, rapid and accurate diagnosis. This technique is almost labour free without the need for sample preparation. It could reduce the need for whole pathological specimen examination, in theatre it could help to determine margin status, and finally peripheral blood diagnosis may be an achievable target.