Prostate cancer diagnosis by optical coherence tomography: First results from a needle based optical platform for tissue sampling

Optical-coherence-tomography-based deep-learning scatterer-density estimator using physically accurate noise model

We demonstrate a deep-learning-based scatterer density estimator (SDE) that processes local speckle patterns of optical coherence tomography (OCT) images and estimates the scatterer density behind each speckle pattern. The SDE is trained using large quantities of numerically simulated OCT images and their associated scatterer densities. The numerical simulation uses a noise model that incorporates the spatial properties of three types of noise, i.e., shot noise, relative-intensity noise, and non-optical noise. The SDE's performance was evaluated numerically and experimentally using two types of scattering phantom and in vitro tumor spheroids. The results confirmed that the SDE estimates scatterer densities accurately. The estimation accuracy improved significantly when compared with our previous deep-learning-based SDE, which was trained using numerical speckle patterns generated from a noise model that did not account for the spatial properties of noise.

Advancements in Intraoperative Near-Infrared Fluorescence Imaging for Accurate Tumor Resection: A Promising Technique for Improved Surgical Outcomes and Patient Survival

Clear surgical margins for solid tumor resection are essential for preventing cancer recurrence and improving overall patient survival. Complete resection of tumors is often limited by a surgeon's ability to accurately locate malignant tissues and differentiate them from healthy tissue. Therefore, techniques or imaging modalities are required that would ease the identification and resection of tumors by real-time intraoperative visualization of tumors. Although conventional imaging techniques such as positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), or radiography play an essential role in preoperative diagnostics, these cannot be utilized in intraoperative tumor detection due to their large size, high cost, long imaging time, and lack of cancer specificity. The inception of several imaging techniques has paved the way to intraoperative tumor margin detection with a high degree of sensitivity and specificity. Particularly, molecular imaging using near-infrared fluorescence (NIRF) based nanoprobes provides superior imaging quality due to high signal-to-noise ratio, deep penetration to tissues, and low autofluorescence, enabling accurate tumor resection and improved survival rates. In this review, we discuss the recent developments in imaging technologies, specifically focusing on NIRF nanoprobes that aid in highly specific intraoperative surgeries with real-time recognition of tumor margins.

Motionless volumetric structured light sheet microscopy

To meet the increasing need for low-cost, compact imaging technology with cellular resolution, we have developed a microLED-based structured light sheet microscope for three-dimensional ex vivo and in vivo imaging of biological tissue in multiple modalities. All the illumination structure is generated directly at the microLED panel-which serves as the source-so light sheet scanning and modulation is completely digital, yielding a system that is simpler and less prone to error than previously reported methods. Volumetric images with optical sectioning are thus achieved in an inexpensive, compact form factor without any moving parts. We demonstrate the unique properties and general applicability of our technique by ex vivo imaging of porcine and murine tissue from the gastrointestinal tract, kidney, and brain.

Optical coherence tomography holds promise to transform the diagnostic anatomic pathology gross evaluation process

SIGNIFICANCE

Real-time histology can close a variety of gaps in tissue diagnostics. Currently, gross pathology analysis of excised tissue is dependent upon visual inspection and palpation to identify regions of interest for histopathological processing. Such analysis is limited by the variable correlation between macroscopic and microscopic findings. The current standard of care is costly, burdensome, and inefficient.

AIM

We are the first to address this gap by introducing optical coherence tomography (OCT) to be integrated in real-time during the pathology grossing process.

APPROACH

This is achieved by our high-resolution, ultrahigh-speed, large field-of-view OCT device designed for this clinical application.

RESULTS

We demonstrate the feasibility of imaging tissue sections from multiple human organs (breast, prostate, lung, and pancreas) in a clinical gross pathology setting without interrupting standard workflows.

CONCLUSIONS

OCT-based real-time histology evaluation holds promise for addressing a gap that has been present for >100 years.

En-face optical coherence tomography for the detection of cancer in prostatectomy specimens: Quantitative analysis in 20 patients

The increase histopathological evaluation of prostatectomy specimens rises the workload on pathologists. Automated histopathology systems, preferably directly on unstained specimens, would accelerate the pathology workflow. In this study, we investigate the potential of quantitative analysis of optical coherence tomography (OCT) to separate benign from malignant prostate tissue automatically. Twenty fixated prostates were cut, from which 54 slices were scanned by OCT. Quantitative OCT metrics (attenuation coefficient, residue, goodness-of-fit) were compared for different tissue types, annotated on the histology slides. To avoid misclassification, the poor-quality slides, and edges of annotations were excluded. Accurate registration of OCT data with histology was achieved in 31 slices. After removing outliers, 56% of the OCT data was compared with histopathology. The quantitative data could not separate malignant from benign tissue. Logistic regression resulted in malignant detection with a sensitivity of 0.80 and a specificity of 0.34. Quantitative OCT analysis should be improved before clinical use.

Towards an Optical Biopsy during Visceral Surgical Interventions

Background

Cancer will replace cardiovascular diseases as the most frequent cause of death. Therefore, the goals of cancer treatment are prevention strategies and early detection by cancer screening and ideal stage therapy. From an oncological point of view, complete tumor resection is a significant prognostic factor. Optical coherence tomography (OCT) and confocal laser microscopy (CLM) are two techniques that have the potential to complement intraoperative frozen section analysis as in vivo and real-time optical biopsies.

Summary

In this review we present both procedures and review the progress of evaluation for intraoperative application in visceral surgery. For visceral surgery, there are promising studies evaluating OCT and CLM; however, application during routine visceral surgical interventions is still lacking.

Key Message

OCT and CLM are not competing but complementary approaches of tissue analysis to intraoperative frozen section analysis. Although intraoperative application of OCT and CLM is at an early stage, they are two promising techniques of intraoperative in vivo and real-time tissue examination. Additionally, deep learning strategies provide a significant supplement for automated tissue detection.

"Real-time" Assessment of Surgical Margins During Radical Prostatectomy: State-of-the-Art

Histopathologic examination of the pathologic specimens using hematoxylin & eosin stains represents the backbone of the modern pathology. It is time-consuming; thus, "real-time" assessment of prostatic and periprostatic tissue has gained special interest in the diagnosis and management of prostate cancer. The current study focuses on the review of the different available techniques for "real-time" evaluation of surgical margins during radical prostatectomy (RP). We performed a comprehensive search of the Medline database to identify all the articles discussing "real-time" or intraoperative assessment of surgical margins during RP. Several filters were applied to the search to include only English articles performed on human subjects and published between January 2000 and March 2019. The search revealed several options for pathologic assessment of surgical margins including intraoperative frozen sections, confocal laser endomicroscopy, optical spectroscopy, photodynamic diagnosis, optical coherence tomography, multiphoton microscopy, structured illumination microscopy, 3D augmented reality, and ex vivo fluorescence confocal microscope. Frozen section represents the gold standard technique for real-time pathologic examinations of surgical margins during RP; however, several other options showed promising results in the initial clinical trials, and considering the rapid development in the field of molecular and cellular imaging, some of these options may serve as an alternative to frozen section.

One-to-one registration of en-face optical coherence tomography attenuation coefficients with histology of a prostatectomy specimen

Optical coherence tomography (OCT), enables high-resolution 3D imaging of the morphology of light scattering tissues. From the OCT signal, parameters can be extracted and related to tissue structures. One of the quantitative parameters is the attenuation coefficient; the rate at which the intensity of detected light decays in depth. To couple the quantitative parameters with the histology one-to-one registration is needed. The primary aim of this study is to validate a registration method of quantitative OCT parameters to histological tissue outcome through one-to-one registration of OCT with histology. We matched OCT images of unstained fixated prostate tissue slices with corresponding histology slides, wherein different histologic types were demarcated. Attenuation coefficients were determined by a supervised automated exponential fit (corrected for point spread function and sensitivity roll-off related signal losses) over a depth of 0.32 mm starting from 0.10 mm below the automatically detected tissue edge. Finally, the attenuation coefficients corresponding to the different tissue types of the prostate were compared. From the attenuation coefficients, we produced the squared relative residue and goodness-of-fit metric R² . This article explains the method to perform supervised automated quantitative analysis of OCT data, and the one-to-one registration of OCT extracted quantitative data with histopathological outcomes.

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.

Confocal Laser Endomicroscopy and Optical Coherence Tomography for the Diagnosis of Prostate Cancer: A Needle-Based, In Vivo Feasibility Study Protocol (IDEAL Phase 2A)

BACKGROUND

Focal therapy for prostate cancer has been proposed as an alternative treatment to whole-gland therapies in selected men to diminish side effects in localized prostate cancer. As nowadays imaging cannot offer complete prostate cancer disease characterization, multicore systematic biopsies are recommended (transrectal or transperineal). Optical imaging techniques such as confocal laser endomicroscopy and optical coherence tomography allow in vivo, high-resolution imaging. Moreover, they can provide real-time visualization and analysis of tissue and have the potential to offer additive diagnostic information.

OBJECTIVE

This study has 2 separate primary objectives. The first is to assess the technical feasibility and safety of in vivo focal imaging with confocal laser endomicroscopy and optical coherence tomography. The second is to identify and define characteristics of prostate cancer and normal prostate tissue in confocal laser endomicroscopy and optical coherence tomography imaging by comparing these images with the corresponding histopathology.

METHODS

In this prospective, in vivo feasibility study, needle-based confocal laser endomicroscopy and optical coherence tomography imaging will be performed before transperineal template mapping biopsy or radical prostatectomy. First, confocal laser endomicroscopy and optical coherence tomography will be performed in 4 patients (2 for each imaging modality) undergoing transperineal template mapping biopsy to assess the feasibility and safety of confocal laser endomicroscopy and optical coherence tomography. If proven to be safe and feasible, confocal laser endomicroscopy and optical coherence tomography will be performed in 10 patients (5 for each imaging modality) undergoing radical prostatectomy. Confocal laser endomicroscopy and optical coherence tomography images will be analyzed by independent, blinded observers. Confocal laser endomicroscopy- and optical coherence tomography-based qualitative and quantitative characteristics and histopathology will be compared. The study complies with the IDEAL (Idea, Development, Exploration, Assessment, Long-term study) stage 2a recommendations.

RESULTS

At present, the study is enrolling patients and results and outcomes are expected in 2019.

CONCLUSIONS

Confocal laser endomicroscopy and optical coherence tomography are promising optical imaging techniques that can visualize and analyze tissue structure, possible tumor grade, and architecture in real time. They can potentially provide real-time, high-resolution microscopic imaging and tissue characteristics of prostate cancer in conjunction with magnetic resonance imaging or transrectal ultrasound fusion-guided biopsy procedures. This study will provide insight into the feasibility and tissue-specific characteristics of confocal laser endomicroscopy and optical coherence tomography for real-time optical analysis of prostate cancer.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03253458; https://clinicaltrials.gov/ct2/show/NCT03253458 (Archived by WebCite at http://www.webcitation.org/6z9owM66B).

REGISTERED REPORT IDENTIFIER

RR1-10.2196/9813.

Histopathology: ditch the slides, because digital and 3D are on show

Due to the growing field of digital pathology, more and more digital histology slides are becoming available. This improves the accessibility, allows teleconsultations from specialized pathologists, improves education, and might give urologist the possibility to review the slides in patient management systems. Moreover, by stacking multiple two-dimensional (2D) digital slides, three-dimensional volumes can be created, allowing improved insight in the growth pattern of a tumor. With the addition of computer-aided diagnosis systems, pathologist can be guided to regions of interest, potentially reducing the workload and interobserver variation. Digital (3D) pathology has the potential to improve dialog between the pathologist and urologist, and, therefore, results in a better treatment selection for urologic patients.

A new method using Raman spectroscopy for in vivo targeted brain cancer tissue biopsy

Modern cancer diagnosis requires histological, molecular, and genomic tumor analyses. Tumor sampling is often achieved using a targeted needle biopsy approach. Targeting errors and cancer heterogeneity causing inaccurate sampling are important limitations of this blind technique leading to non-diagnostic or poor quality samples, and the need for repeated biopsies pose elevated patient risk. An optical technology that can analyze the molecular nature of the tissue prior to harvesting could improve cancer targeting and mitigate patient risk. Here we report on the design, development, and validation of an in situ intraoperative, label-free, cancer detection system based on high wavenumber Raman spectroscopy. This optical detection device was engineered into a commercially available biopsy system allowing tumor analysis prior to tissue harvesting without disrupting workflow. Using a dual validation approach we show that high wavenumber Raman spectroscopy can detect human dense cancer with >60% cancer cells in situ during surgery with a sensitivity and specificity of 80% and 90%, respectively. We also demonstrate for the first time the use of this system in a swine brain biopsy model. These studies set the stage for the clinical translation of this optical molecular imaging method for high yield and safe targeted biopsy.

An In-vivo Prospective Study of the Diagnostic Yield and Accuracy of Optical Biopsy Compared with Conventional Renal Mass Biopsy for the Diagnosis of Renal Cell Carcinoma: The Interim Analysis

BACKGROUND

Lack of accuracy in preoperative imaging leads to overtreatment of benign renal masses (RMs) or indolent renal cell carcinomas (RCCs). Optical coherence tomography (OCT) is real time and high resolution, enabling quantitative analysis through attenuation coefficient (μ_OCT, mm^-1).

OBJECTIVE

To determine the accuracy and diagnostic yield of OCT and renal mass biopsy (RMB) for the differentiation of benign RMs versus RCC and oncocytoma versus RCC.

DESIGN, SETTING, AND PARTICIPANTS

From October 2013 to June 2016, 95 patients with solid enhancing RMs on cross-sectional imaging were prospectively included. All patients underwent subsequent excision or ablation.

INTERVENTION

Percutaneous, image-guided, needle-based OCT followed by RMB in an outpatient setting under local anaesthesia.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Accuracy and diagnostic yield, μ_OCT correlated to resection pathology or second biopsy during ablation. Tables (2×2) for RMB, receiver operating characteristic curve for OCT. Mann-Whitney test to differentiate μ_OCT of RMs.

RESULTS AND LIMITATIONS

RMB diagnostic yield was 79% with sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 100%, 89%, 99%, and 100%, respectively. Diagnostic yield and added value of OCT to differentiate RCC from benign was 99% and 15%, respectively. Significant difference was observed in median μ_OCT between benign RMs (3.2mm^-1, interquartile range [IQR]: 2.65-4.35) and RCCs (4.3mm^-1, IQR: 3.70-5.00), p=0.0171, and oncocytomas (3.38mm^-1, IQR: 2.68-3.95) and RCCs (4.3mm^-1, IQR: 3.70-5.00), p=0.0031. OCT showed sensitivity, specificity, positive predictive value. and NPV of 91%, 56%, 91%, and 56%, respectively, to differentiate benign RMs from RCCs and 92%, 67%, 95%, and 55%, respectively, to differentiate oncocytoma from RCC. Limitations include two reference standards and heterogeneity benign RMs.

CONCLUSIONS

Compared with RMB, OCT has a higher diagnostic yield. OCT accurately distinguishes benign RMs from RCCs, and oncocytoma from RCCs, although specificity and NPV are lower.

PATIENT SUMMARY

Optical coherence tomography, a new optical scan, exhibits similar sensitivity and positive predictive value than renal mass biopsy, although lower specificity and negative predictive value. Optical coherence tomography has a higher diagnostic yield for diagnosing renal cell carcinoma.

Automatic Gleason grading of prostate cancer using quantitative phase imaging and machine learning

We present an approach for automatic diagnosis of tissue biopsies. Our methodology consists of a quantitative phase imaging tissue scanner and machine learning algorithms to process these data. We illustrate the performance by automatic Gleason grading of prostate specimens. The imaging system operates on the principle of interferometry and, as a result, reports on the nanoscale architecture of the unlabeled specimen. We use these data to train a random forest classifier to learn textural behaviors of prostate samples and classify each pixel in the image into different classes. Automatic diagnosis results were computed from the segmented regions. By combining morphological features with quantitative information from the glands and stroma, logistic regression was used to discriminate regions with Gleason grade 3 versus grade 4 cancer in prostatectomy tissue. The overall accuracy of this classification derived from a receiver operating curve was 82%, which is in the range of human error when interobserver variability is considered. We anticipate that our approach will provide a clinically objective and quantitative metric for Gleason grading, allowing us to corroborate results across instruments and laboratories and feed the computer algorithms for improved accuracy.

Live volumetric (4D) visualization and guidance of in vivo human ophthalmic surgery with intraoperative optical coherence tomography

Minimally-invasive microsurgery has resulted in improved outcomes for patients. However, operating through a microscope limits depth perception and fixes the visual perspective, which result in a steep learning curve to achieve microsurgical proficiency. We introduce a surgical imaging system employing four-dimensional (live volumetric imaging through time) microscope-integrated optical coherence tomography (4D MIOCT) capable of imaging at up to 10 volumes per second to visualize human microsurgery. A custom stereoscopic heads-up display provides real-time interactive volumetric feedback to the surgeon. We report that 4D MIOCT enhanced suturing accuracy and control of instrument positioning in mock surgical trials involving 17 ophthalmic surgeons. Additionally, 4D MIOCT imaging was performed in 48 human eye surgeries and was demonstrated to successfully visualize the pathology of interest in concordance with preoperative diagnosis in 93% of retinal surgeries and the surgical site of interest in 100% of anterior segment surgeries. In vivo 4D MIOCT imaging revealed sub-surface pathologic structures and instrument-induced lesions that were invisible through the operating microscope during standard surgical maneuvers. In select cases, 4D MIOCT guidance was necessary to resolve such lesions and prevent post-operative complications. Our novel surgical visualization platform achieves surgeon-interactive 4D visualization of live surgery which could expand the surgeon’s capabilities.