Optical imaging with a high-resolution microendoscope to identify cholesteatoma of the middle ear

Intelligent smartphone-based multimode imaging otoscope for the mobile diagnosis of otitis media

Otitis media (OM) is one of the most common ear diseases in children and a common reason for outpatient visits to medical doctors in primary care practices. Adhesive OM (AdOM) is recognized as a sequela of OM with effusion (OME) and often requires surgical intervention. OME and AdOM exhibit similar symptoms, and it is difficult to distinguish between them using a conventional otoscope in a primary care unit. The accuracy of the diagnosis is highly dependent on the experience of the examiner. The development of an advanced otoscope with less variation in diagnostic accuracy by the examiner is crucial for a more accurate diagnosis. Thus, we developed an intelligent smartphone-based multimode imaging otoscope for better diagnosis of OM, even in mobile environments. The system offers spectral and autofluorescence imaging of the tympanic membrane using a smartphone attached to the developed multimode imaging module. Moreover, it is capable of intelligent analysis for distinguishing between normal, OME, and AdOM ears using a machine learning algorithm. Using the developed system, we examined the ears of 69 patients to assess their performance for distinguishing between normal, OME, and AdOM ears. In the classification of ear diseases, the multimode system based on machine learning analysis performed better in terms of accuracy and F1 scores than single RGB image analysis, RGB/fluorescence image analysis, and the analysis of spectral image cubes only, respectively. These results demonstrate that the intelligent multimode diagnostic capability of an otoscope would be beneficial for better diagnosis and management of OM.

Determination of the optical properties of cholesteatoma in the spectral range of 250 to 800 nm

Cholesteatoma of the ear can lead to life-threatening complications and its only treatment is surgery. The smallest remnants of cholesteatoma can lead to recurrence of this disease. Therefore, the optical properties of this tissue are of high importance to identify and remove all cholesteatoma during therapy. In this paper, we determine the absorption coefficient µ a and scattering coefficient µ s ' of cholesteatoma and bone samples in the wavelength range of 250 nm to 800 nm obtained during five surgeries. These values are determined by high precision integrating sphere measurements in combination with an optimized inverse Monte Carlo simulation (iMCS). To conserve the optical behavior of living tissues, the optical spectroscopy measurements are performed immediately after tissue removal and preparation. It is shown that in the near-UV and visible spectrum clear differences exist between cholesteatoma and bone tissue. While µ a is decreasing homogeneously for cholesteatoma, it retains at the high level for bone in the region of 350 nm to 580 nm. Further, the results for the cholesteatoma measurements correspond to published healthy epidermis data. These differences in the optical parameters reveal the future possibility to detect and identify, automatically or semi-automatically, cholesteatoma tissue for active treatment decisions during image-guided surgery leading to a better surgical outcome.

Automated classification platform for the identification of otitis media using optical coherence tomography

The diagnosis and treatment of otitis media (OM), a common childhood infection, is a significant burden on the healthcare system. Diagnosis relies on observer experience via otoscopy, although for non-specialists or inexperienced users, accurate diagnosis can be difficult. In past studies, optical coherence tomography (OCT) has been used to quantitatively characterize disease states of OM, although with the involvement of experts to interpret and correlate image-based indicators of infection with clinical information. In this paper, a flexible and comprehensive framework is presented that automatically extracts features from OCT images, classifies data, and presents clinically relevant results in a user-friendly platform suitable for point-of-care and primary care settings. This framework was used to test the discrimination between OCT images of normal controls, ears with biofilms, and ears with biofilms and middle ear fluid (effusion). Predicted future performance of this classification platform returned promising results (90%+ accuracy) in various initial tests. With integration into patient healthcare workflow, users of all levels of medical experience may be able to collect OCT data and accurately identify the presence of middle ear fluid and/or biofilms.

Optical imaging with a high-resolution microendoscope to identify sinonasal pathology

OBJECTIVES

High-resolution microendoscopy (HRME) is an optical imaging modality that allows real time imaging of epithelial tissue and structural changes within. We hypothesize that HRME, using proflavine, a contrast agent that preferentially stains cell nuclei and allows detection of cellular morphologic changes, can distinguish sinonasal pathology from uninvolved mucosa, potentially enabling real-time surgical margin differentiation.

STUDY DESIGN

Ex vivo imaging of histopathologically confirmed samples of sinonasal pathology and uninvolved, normal sinus epithelium.

SETTING

Single tertiary-level institution.

SUBJECTS AND METHODS

Five inverted papillomas, one oncocytic papilloma, two uninvolved sinus epithelia specimens, and three inflammatory polyps were imaged ex vivo with HRME after surface staining with proflavine. Following imaging, the specimens were submitted for hematoxylin and eosin staining to allow histopathological correlation.

RESULTS

Results show that sinonasal pathology and normal sinus epithelia have distinct HRME imaging characteristics. Schneiderian papilloma specimens show increased nuclear-to-cytoplasmic ratio, nuclear crowding, and small internuclear separation, whereas normal sinus epithelia specimens show small, bright nuclei with dark cytoplasm and relatively large internuclear separation. Inflammatory polyps, however, have varying imaging characteristics, that resemble both Schneiderian papilloma and normal sinus epithelia.

CONCLUSIONS

This study demonstrates the feasibility of HRME imaging to discriminate sinonasal pathology from normal sinus epithelia. While the system performed well in the absence of inflammation, discrimination of inflamed tissue was inconsistent, creating a significant limitation for this application. Novel imaging systems such as HRME with alternative contrast agents may assist with real-time surgical margin differentiation, enabling complete surgical resection of inverted papilloma and reducing recurrence rates.

Direct Analysis of Pathogenic Structures Affixed to the Tympanic Membrane during Chronic Otitis Media

Objective To characterize otitis media-associated structures affixed to the mucosal surface of the tympanic membrane (TM) in vivo and in surgically recovered in vitro samples. Study Design Prospective case series without comparison. Setting Outpatient surgical care center. Subjects and Methods Forty pediatric subjects scheduled for tympanostomy tube placement surgery were imaged intraoperatively under general anesthesia. Postmyringotomy, a portable optical coherence tomography (OCT) imaging system assessed for the presence of any biofilm affixed to the mucosal surface of the TM. Samples of suspected microbial infection-related structures were collected through the myringotomy incision. The sampled site was subsequently reimaged with OCT to confirm collection from the original image site on the TM. In vitro analysis based on confocal laser scanning microscope (CLSM) images of fluorescence in situ hybridization-tagged samples and polymerase chain reaction (PCR) provided microbiological characterization and verification of biofilm activity. Results OCT imaging was achieved for 38 of 40 subjects (95%). Images from 38 of 38 (100%) of subjects observed with OCT showed the presence of additional microbial infection-related structures. Thirty-four samples were collected from these 38 subjects. CLSM images provided evidence of clustered bacteria in 32 of 33 (97%) of samples. PCR detected the presence of active bacterial DNA signatures in 20 of 31 (65%) of samples. Conclusion PCR and CLSM analysis of fluorescence in situ hybridization-stained samples validates the presence of active bacteria that have formed into a middle ear biofilm that extends across the mucosal layer of the TM. OCT can rapidly and noninvasively identify middle ear biofilms in subjects with severe and persistent cases of otitis media.

Review on Otological Robotic Systems: Toward Microrobot-Assisted Cholesteatoma Surgery

Otologic surgical procedures over time have become minimally invasive due to the development of medicine, microtechniques, and robotics. This trend then provides an expected reduction in the patient's recovery time and improvement in the accuracy of diagnosis and treatment. One of the most challenging difficulties that such techniques face are precise control of the instrument and supply of an ergonomic system to the surgeon. The objective of this literature review is to present requirements and guidelines for a surgical robotic system dedicated to middle ear surgery. This review is particularly focused on cholesteatoma surgery (diagnosis and surgical tools), which is one of the most frequent pathologies that urge for an enhanced treatment. This review also presents the current robotic systems that are implemented for otologic applications.

Towards monitoring dysplastic progression in the oral cavity using a hybrid fiber-bundle imaging and spectroscopy probe

Intraepithelial dysplasia of the oral mucosa typically originates in the proliferative cell layer at the basement membrane and extends to the upper epithelial layers as the disease progresses. Detection of malignancies typically occurs upon visual inspection by non-specialists at a late-stage. In this manuscript, we validate a quantitative hybrid imaging and spectroscopy microendoscope to monitor dysplastic progression within the oral cavity microenvironment in a phantom and pre-clinical study. We use an empirical model to quantify optical properties and sampling depth from sub-diffuse reflectance spectra (450–750 nm) at two source-detector separations (374 and 730 μm). Average errors in recovering reduced scattering (5–26 cm⁻¹) and absorption coefficients (0–10 cm⁻¹) in hemoglobin-based phantoms were approximately 2% and 6%, respectively. Next, a 300 μm-thick phantom tumor model was used to validate the probe’s ability to monitor progression of a proliferating optical heterogeneity. Finally, the technique was demonstrated on 13 healthy volunteers and volume-averaged optical coefficients, scattering exponent, hemoglobin concentration, oxygen saturation, and sampling depth are presented alongside a high-resolution microendoscopy image of oral mucosa from one volunteer. This multimodal microendoscopy approach encompasses both structural and spectroscopic reporters of perfusion within the tissue microenvironment and can potentially be used to monitor tumor response to therapy.

Discerning the differential molecular pathology of proliferative middle ear lesions using Raman spectroscopy

Despite its widespread prevalence, middle ear pathology, especially the development of proliferative lesions, remains largely unexplored and poorly understood. Diagnostic evaluation is still predicated upon a high index of clinical suspicion on otoscopic examination of gross morphologic features. We report the first technique that has the potential to non-invasively identify two key lesions, namely cholesteatoma and myringosclerosis, by providing real-time information of differentially expressed molecules. In addition to revealing signatures consistent with the known pathobiology of these lesions, our observations provide the first evidence of the presence of carbonate- and silicate-substitutions in the calcium phosphate plaques found in myringosclerosis. Collectively, these results demonstrate the potential of Raman spectroscopy to not only provide new understanding of the etiology of these conditions by defining objective molecular markers but also aid in margin assessment to improve surgical outcome.

High-resolution microendoscope imaging of inverted papilloma and normal sinonasal mucosa: evaluation of interobserver concordance

BACKGROUND

High-resolution microendoscopy (HRME) enables real-time imaging of epithelial tissue. The utility of this novel imaging modality for inverted papilloma has not been previously described. This study examines the ability of otolaryngologists to differentiate between images of inverted papilloma and normal sinonasal mucosa obtained with a HRME.

METHODS

Inverted papilloma and normal sinonasal mucosa specimens were stained with a contrast agent, proflavine. HRME images were subsequently captured. Histopathological diagnosis was obtained for each sample. Quality-controlled images were used to assemble a training set. After reviewing the training images, 6 otolaryngologists without prior HRME experience reviewed and classified test images.

RESULTS

Five samples of inverted papilloma and 2 normal sinonasal mucosa samples were collected. Four representative images from each specimen were used for the 28-image test set. The mean accuracy among all reviewers was 89.9% (95% confidence interval [CI], 84.3% to 94.0%). The sensitivity to correctly identify inverted papilloma was 86.7% (95% CI, 79.2% to 92.2%), and the specificity was 92.9% (95% CI, 89.0% to 100.0%). The Fleiss kappa interrater reliability score was 0.80 (95% CI, 0.70 to 0.89).

CONCLUSION

Inverted papilloma and normal sinonasal mucosa have distinct HRME imaging characteristics. Otolaryngologists can be successfully trained to distinguish between inverted papilloma and normal sinonasal mucosa. HRME is a feasible tool for identification of inverted papilloma. By conducting future in vivo trials, HRME potentially may enable real-time surgical margin determination during surgical excision of inverted papilloma.

Feasibility of transoral robotic-assisted high-resolution microendoscopic imaging of oropharyngeal squamous cell carcinoma

BACKGROUND

Transoral robotic-assisted oncologic surgery of the head and neck offers promising functional results. Nonetheless, the efficacy of oncologic surgery remains critically dependent on obtaining negative margins. We aimed to integrate a miniaturized high-resolution fiber-optic microendoscope (HRME), which provides real-time histological assessment, with the da Vinci robotic system (Intuitive Surgical, Sunnyvale, CA).

METHODS

Three patients undergoing transoral robotic surgery (TORS) were prospectively enrolled in this study. Optical imaging of the oropharynx was performed intraoperatively with the robotic-assisted HRME.

RESULTS

All patients underwent the procedure successfully with no complications. The HRME was successfully integrated with the da Vinci robotic system. Several sites of the oropharynx and associated malignancy were imaged, which correlated with the standard histopathological analysis.

CONCLUSION

Transoral robotic-assisted HRME imaging of the oropharynx is a safe and technically feasible approach, providing a real-time histological assessment and may serve as a valuable aid in oncologic surgery.

Operative margin control with high-resolution optical microendoscopy for head and neck squamous cell carcinoma

OBJECTIVES/HYPOTHESIS

High-resolution microendoscopy (HRME) provides real-time visualization of the mucosal surface in the upper aerodigestive tract. This technology allows noninvasive discrimination of benign and neoplastic epithelium and has potential applications for intraoperative margin detection.

STUDY DESIGN

Single institution, prospective, feasibility trial (phase I) of in vivo optical imaging.

METHODS

The study was conducted on patients with squamous cell carcinoma of the upper aerodigestive tract. High-resolution microendoscopy images obtained during surgery were correlated with histopathologic diagnosis to determine the ability of HRME to differentiate between benign and malignant mucosa. Blinded reviewers evaluated HRME images and made determinations of the status of the mucosa. Accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and interrater agreement between multiple raters were calculated to determine the accuracy of HRME imaging.

RESULTS

The mean accuracy of reviewers in differentiating neoplastic or benign mucosa was 95.1% (95% confidence interval [CI], 94%-96%). Sensitivity and specificity were 96% (95% CI, 94%-99%) and 95% (95 % CI, 90%-99%), respectively. The NPV was 98% (95% CI, 97%-99%), and PPV was 91% (95% CI, 85%-98%). The Fleiss kappa statistic for interrater reliability was 0.81, with a standard error of 0.014 and a 95% CI (0.78-0.84).

CONCLUSION

High-resolution microendoscopy allows real-time discrimination between benign and neoplastic mucosa. High levels of sensitivity and specificity can be obtained with this technology when interrogating mucosal surfaces. Despite several technical limitations, HRME shows promise as a technique for intraoperative margin control and platform for molecular imaging technologies.

LEVEL OF EVIDENCE

3b.

Multiwavelength fluorescence otoscope for video-rate chemical imaging of middle ear pathology

A common motif in otolaryngology is the lack of certainty regarding diagnosis for middle ear conditions, resulting in many patients being overtreated under the worst-case assumption. Although pneumatic otoscopy and adjunctive tests offer additional information, white light otoscopy has been the main tool for diagnosis of external auditory canal and middle ear pathologies for over a century. In middle ear pathologies, the inability to avail high-resolution structural and/or molecular imaging is particularly glaring, leading to a complicated and erratic decision analysis. Here, we propose a novel multiwavelength fluorescence-based video-rate imaging strategy that combines readily available optical elements and software components to create a novel otoscopic device. This modified otoscope enables low-cost, detailed and objective diagnosis of common middle ear pathological conditions. Using the detection of congenital cholesteatoma as a specific example, we demonstrate the feasibility of fluorescence imaging to differentiate this proliferative lesion from uninvolved middle ear tissue based on the characteristic autofluorescence signals. Availability of real-time, wide-field chemical information should enable more complete removal of cholesteatoma, allowing for better hearing preservation and substantially reducing the well-documented risks, costs and psychological effects of repeated surgical procedures.

Physical and chemical stability of proflavine contrast agent solutions for early detection of oral cancer

BACKGROUND AND PURPOSE

Proflavine hemisulfate solution is a fluorescence contrast agent to visualize cell nuclei using high-resolution optical imaging devices such as the high-resolution microendoscope. These devices provide real-time imaging to distinguish between normal versus neoplastic tissue. These images could be helpful for early screening of oral cancer and its precursors and to determine accurate margins of malignant tissue for ablative surgery. Extemporaneous preparation of proflavine solution for these diagnostic procedures requires preparation in batches and long-term storage to improve compounding efficiency in the pharmacy. However, there is a paucity of long-term stability data for proflavine contrast solutions.

METHODS

The physical and chemical stability of 0.01% (10 mg/100 ml) proflavine hemisulfate solutions prepared in sterile water was determined following storage at refrigeration (4-8℃) and room temperature (23℃). Concentrations of proflavine were measured at predetermined time points up to 12 months using a validated stability-indicating high-performance liquid chromatography method.

RESULTS

Proflavine solutions stored under refrigeration were physically and chemically stable for at least 12 months with concentrations ranging from 95% to 105% compared to initial concentration. However, in solutions stored at room temperature increased turbidity and particulates were observed in some of the tested vials at 9 months and 12 months with peak particle count reaching 17-fold increase compared to baseline. Solutions stored at room temperature were chemically stable up to six months (94-105%).

CONCLUSION

Proflavine solutions at concentration of 0.01% were chemically and physically stable for at least 12 months under refrigeration. The solution was chemically stable for six months when stored at room temperature. We recommend long-term storage of proflavine solutions under refrigeration prior to diagnostic procedure.

High-resolution microendoscope images of middle ear cholesteatoma and surrounding tissue: evaluation of interobserver concordance

OBJECTIVE

Investigate how accurately otolaryngologists could differentiate between images obtained with high-resolution microendoscopy (HRME) of ex vivo cholesteatoma specimens and surrounding middle ear epithelium.

STUDY DESIGN

HRME images of surgically resected cholesteatoma and middle ear epithelium were obtained and otolaryngologists classified these images.

SETTING

Tertiary medical center.

SUBJECTS AND METHODS

Resected cholesteatoma and middle ear epithelium were stained with a contrast agent, proflavine, and HRME images were captured. Specimens were sent for standard histopathology and compared with HRME images. Quality-controlled images were used to assemble a training set. After viewing training images, otolaryngologists without prior cholesteatoma HRME experience reviewed and classified test images.

RESULTS

Ten cholesteatoma and 9 middle ear specimens were collected, of which 17 representative cholesteatoma and 19 middle ear epithelium images were extracted for a testing set. Qualitative analysis for concordance between HRME images and histological images yielded a strong correlation between modalities. The mean accuracy of all reviewers in correctly identifying images was 95% (95% confidence interval [CI], 92%-98%). The sensitivity to correctly detect cholesteatoma images was 98% (95% CI, 93%-100%), and the specificity was 92% (95% CI, 87%-97%). The Fleiss kappa interrater reliability score was 0.83, (95% CI, 0.77-0.89).

CONCLUSIONS

Medical professionals can quickly be trained to accurately distinguish between HRME images of cholesteatoma and normal middle ear epithelium, both of which have distinct imaging characteristics. Real-time HRME optical imaging can potentially improve the results of otologic surgery by allowing for extirpation of cholesteatomas while eliminating residual disease.