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

A Prospective Double-Blinded Comparison of Reflectance Confocal Microscopy with Conventional Histopathology for In Vivo Assessment in Oral Cancer

PURPOSE

We investigated reflectance confocal microscopy (RCM) as a possible noninvasive approach for the diagnosis of cancer and real-time assessment of surgical margins.

EXPERIMENTAL DESIGN

In a phase I study on 20 patients, we established the RCM imaging morphologic features that distinguish oral squamous cell carcinoma (OSCC) from normal tissue with a newly developed intraoral RCM probe. Our subsequent phase II prospective double-blinded study in 60 patients tested the diagnostic accuracy of RCM against histopathology. Five RCM videos from the tumor and five from normal surrounding mucosa were collected on each patient, followed by a 3-mm punch biopsy of the imaged area. An experienced RCM reader, who was blinded to biopsy location and histologic diagnosis, examined the videos from both regions and classified each as "tumor" or "not tumor" based on RCM features established in phase I. Hematoxylin and eosin slides from the biopsies were read by a pathologist who was blinded to RCM results. Using histology as the gold standard, we calculated the sensitivity and specificity of RCM.

RESULTS

We report a high agreement between the blinded readers (95% for normal tissue and 81.7% for tumors), high specificity (98.3%) and negative predictive values (96.6%) for normal tissue identification, and high sensitivity (90%) and positive predictive values (88.2%) for tumor detection.

CONCLUSIONS

RCM imaging is a promising technology for noninvasive in vivo diagnosis of OSCC and for real-time intraoperative evaluation of mucosal surgical margins. Its inherent constraint, however, stems from the diminished capability to evaluate structures located at more substantial depths within the tissue.

Eugene Nicholas Myers' Lecture on Head and Neck Cancer, 2020: The Surgeon as a Prognostic Factor in Head and Neck Cancer Patients Undergoing Surgery

This paper is a transcript of the 29 th Eugene N. Myers, MD International Lecture on Head and Neck Cancer presented at the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) in 2020. By the end of the 19 th century, the survival rate in treated patients was 10%. With the improvements in surgical techniques, currently, about two thirds of patients survive for > 5 years. Teamwork and progress in surgical reconstruction have led to advancements in ablative surgery; the associated adjuvant treatments have further improved the prognosis in the last 30 years. However, prospective trials are lacking; most of the accumulated knowledge is based on retrospective series and some real-world data analyses. Current knowledge on prognostic factors plays a central role in an efficient treatment decision-making process. Although the influence of most tumor- and patient-related prognostic factors in head and neck cancer cannot be changed by medical interventions, some environmental factors-including treatment, decision-making, and quality-can be modified. Ideally, treatment strategy decisions should be taken in dedicated multidisciplinary team meetings. However, evidence suggests that surgeons and hospital volume and specialization play major roles in patient survival after initial or salvage head and neck cancer treatment. The metrics of surgical quality assurance (surgical margins and nodal yield) in neck dissection have a significant impact on survival in head and neck cancer patients and can be influenced by the surgeon's expertise. Strategies proposed to improve surgical quality include continuous performance measurement, feedback, and dissemination of best practice measures.

Diagnostic accuracy of intraoperative margin assessment techniques in surgery for head and neck squamous cell carcinoma: A meta-analysis

BACKGROUND

Positive margins following head and neck squamous cell carcinoma (HNSCC) surgery lead to significant morbidity and mortality. Existing Intraoperative Margin Assessment (IMA) techniques are not widely used due to limitations in sampling technique, time constraints and resource requirements. We performed a meta-analysis of the diagnostic performance of existing IMA techniques in HNSCC, providing a benchmark against which emerging techniques may be judged.

METHODS

The study was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Studies were included if they reported diagnostic metrics of techniques used during HNSCC surgery, compared with permanent histopathology. Screening, manuscript review and data extraction was performed by multiple independent observers. Pooled sensitivity and specificity were estimated using the bivariate random effects model.

RESULTS

From an initial 2344 references, 35 studies were included for meta-analysis. Sensitivity (Sens), specificity (Spec), diagnostic odds ratio (DOR) and area under the receiver operating characteristic curve (AUROC) were calculated for each group (n, Sens, Spec, DOR, AUROC): frozen section = 13, 0.798, 0.991, 309.8, 0.976; tumour-targeted fluorescence (TTF) = 5, 0.957, 0.827, 66.4, 0.944; optical techniques = 10, 0.919, 0.855, 58.9, 0.925; touch imprint cytology = 3, 0.925, 0.988, 51.1, 0.919; topical staining = 4, 0.918, 0.759, 16.4, 0.833.

CONCLUSIONS

Frozen section and TTF had the best diagnostic performance. Frozen section is limited by sampling error. TTF shows promise but involves administration of a systemic agent. Neither is currently in widespread clinical use. Emerging techniques must demonstrate competitive diagnostic accuracy whilst allowing rapid, reliable, cost-effective results.

Intraoperative Imaging Techniques to Improve Surgical Resection Margins of Oropharyngeal Squamous Cell Cancer: A Comprehensive Review of Current Literature

Inadequate resection margins in head and neck squamous cell carcinoma surgery necessitate adjuvant therapies such as re-resection and radiotherapy with or without chemotherapy and imply increasing morbidity and worse prognosis. On the other hand, taking larger margins by extending the resection also leads to avoidable increased morbidity. Oropharyngeal squamous cell carcinomas (OPSCCs) are often difficult to access; resections are limited by anatomy and functionality and thus carry an increased risk for close or positive margins. Therefore, there is a need to improve intraoperative assessment of resection margins. Several intraoperative techniques are available, but these often lead to prolonged operative time and are only suitable for a subgroup of patients. In recent years, new diagnostic tools have been the subject of investigation. This study reviews the available literature on intraoperative techniques to improve resection margins for OPSCCs. A literature search was performed in Embase, PubMed, and Cochrane. Narrow band imaging (NBI), high-resolution microendoscopic imaging, confocal laser endomicroscopy, frozen section analysis (FSA), ultrasound (US), computed tomography scan (CT), (auto) fluorescence imaging (FI), and augmented reality (AR) have all been used for OPSCC. NBI, FSA, and US are most commonly used and increase the rate of negative margins. Other techniques will become available in the future, of which fluorescence imaging has high potential for use with OPSCC.

A prospective study of intraoperative assessment of mucosal squamous cell carcinoma margins in the head and neck

BACKGROUND

In head and neck cancers, tumor margin assessment has important prognostic and therapeutic implications. Frozen section control of margins is commonly employed intraoperatively. However, this is not without limitations. The aim of this study is to determine whether intraoperative slicing of the whole specimen is feasible and what impact this may have on tumor margin assessment and the requirement for postoperative radiotherapy.

METHODS

From September 2016 to August 2018, we recruited 22 patients as a pilot study looking at both the practicalities and the clinical relevance of whole margin tumor analysis intraoperatively. Our project is a prospective single arm study with historical controls.

RESULTS

Forty-one percent of our patients required further intraoperative resection for close or involved margins. Seven of these patients who otherwise would have required adjuvant radiotherapy due to their margin status did not, after our intervention.

CONCLUSIONS

We found that although requiring resources, this process was feasible without unduly increasing operative times and with potential patient benefit including reduced incidence of adjuvant radiotherapy.

A Compact High-Speed Image-Based Method for Measuring the Longitudinal Motion of Living Tissues

Intraoperative imaging of living tissue at the cell level by endomicroscopy might help surgeons optimize surgical procedures and provide individualized treatments. However, the resolution of the microscopic image is limited by the motion of living tissue caused by heartbeat and respiration. An active motion compensation (AMC) strategy has been recognized as an effective way to reduce, or even eliminate, the influence of tissue movement for intravital fluorescence microscopy (IVM). To realize the AMC system, a high-speed sensor for measuring the motion of tissues is needed. At present, state-of-the-art commercialized displacement sensors are not suitable to apply in minimally invasive imaging instruments to measure the motion of living tissues because of the size problem, range of measurement or the update rate. In this study, a compact high-speed image-based method for measuring the longitudinal motion of living tissues is proposed. The complexity of the proposed method is the same as that of the traditional wide-field fluorescent microscopy (WFFM) system, which makes it easy to be miniaturized and integrated into a minimally invasive imaging instrument. Experimental results reveal that the maximum indication error, range of measurement and the sensitivity of the laboratory-built experimental prototype is 150 μm, 6 mm and −211.46 mm−1 respectively. Experimental results indicate that the proposed optical method is expected to be used in minimally invasive imaging instruments to build an AMC system.

An Update on Surgical Margins in the Head Neck Squamous Cell Carcinoma: Assessment, Clinical Outcome, and Future Directions

PURPOSE OF REVIEW

Failure to achieve tumor-free margins is the single largest cause of death for head neck cancer patients. At the same time, it is the only factor that is in complete control of the surgeon. This review summarizes evidence for the definition, clinical implications, and methods to achieve optimal margins.

RECENT FINDINGS

The previous universally followed definition of adequate margin (5 mm in final histopathology) has been disputed. Various biological, optical, and imaging adjuncts can aid in achieving optimal margins. Extent of resection and margins in human papilloma virus (HPV)-positive oropharyngeal cancers and following induction chemotherapy remain controversial. Though practiced widely, frozen section-guided margin revision has not conclusively shown improved local control rates. The role of molecular assessment of margins is promising but not established. The definition of adequate margin differs according to the site in the head neck region. Currently, the 5-mm margin at final histopathology is the most commonly accepted definition of an "adequate" margin.

Targeted Polymer-Based Probes for Fluorescence Guided Visualization and Potential Surgery of EGFR-Positive Head-and-Neck Tumors

This report describes the design, synthesis and evaluation of tumor-targeted polymer probes to visualize epidermal growth factor receptor (EGFR)-positive malignant tumors for successful resection via fluorescence guided endoscopic surgery. Fluorescent polymer probes of various molecular weights enabling passive accumulation in tumors via enhanced permeability and retention were prepared and evaluated, showing an optimal molecular weight of 200,000 g/mol for passive tumor targeting. Moreover, poly(N-(2-hydroxypropyl)methacrylamide)-based copolymers labeled with fluorescent dyes were targeted with the EGFR-binding oligopeptide GE-11 (YHWYGYTPQNVI), human EGF or anti-EGFR monoclonal antibody cetuximab were all able to actively target the surface of EGFR-positive tumor cells. Nanoprobes targeted with GE-11 and cetuximab showed the best targeting profile but differed in their tumor accumulation kinetics. Cetuximab increased tumor accumulation after 15 min, whereas GE 11 needed at least 4 h. Interestingly, after 4 h, there were no significant differences in tumor targeting, indicating the potential of oligopeptide targeting for fluorescence-navigated surgery. In conclusion, fluorescent polymer probes targeted by oligopeptide GE-11 or whole antibody are excellent tools for surgical navigation during oncological surgery of head and neck squamous cell carcinoma, due to their relatively simple design, synthesis and cost, as well as optimal pharmacokinetics and accumulation in tumors.

Margin Analysis in Head and Neck Cancer: State of the Art and Future Directions

BACKGROUND

The status of surgical margins is the most important prognosticator for patients undergoing surgical resection of head and neck squamous cell carcinoma (HNSCC). Despite this, analysis of surgical margins is fraught with inconsistencies, including the ways in which margins are sampled and interpreted. Fundamentally, even the definition what constitutes a "clear" (or negative) margin may vary between institutions, surgeons, and pathologists.

METHODS

The PubMed database was queried for articles relevant to the topic, and experts in the field were consulted regarding key articles for inclusion. Abstracts were reviewed and the full text was accessed for articles of particular interest.

RESULTS

Data regarding various approaches to traditional margin analysis have been published without consensus. Several next-generation technologies have emerged in recent years that hold promise.

CONCLUSION

An overview and appraisal of traditional margin analysis techniques are provided. Additionally, we explore novel technologies that may assist in more accurate margin assessment, guide the extent of surgical resections intraoperatively, and inform decisions regarding adjuvant treatment postoperatively.

Rapid histology of laryngeal squamous cell carcinoma with deep-learning based stimulated Raman scattering microscopy

Maximal resection of tumor while preserving the adjacent healthy tissue is particularly important for larynx surgery, hence precise and rapid intraoperative histology of laryngeal tissue is crucial for providing optimal surgical outcomes. We hypothesized that deep-learning based stimulated Raman scattering (SRS) microscopy could provide automated and accurate diagnosis of laryngeal squamous cell carcinoma on fresh, unprocessed surgical specimens without fixation, sectioning or staining. Methods: We first compared 80 pairs of adjacent frozen sections imaged with SRS and standard hematoxylin and eosin histology to evaluate their concordance. We then applied SRS imaging on fresh surgical tissues from 45 patients to reveal key diagnostic features, based on which we have constructed a deep learning based model to generate automated histologic results. 18,750 SRS fields of views were used to train and cross-validate our 34-layered residual convolutional neural network, which was used to classify 33 untrained fresh larynx surgical samples into normal and neoplasia. Furthermore, we simulated intraoperative evaluation of resection margins on totally removed larynxes. Results: We demonstrated near-perfect diagnostic concordance (Cohen's kappa, κ > 0.90) between SRS and standard histology as evaluated by three pathologists. And deep-learning based SRS correctly classified 33 independent surgical specimens with 100% accuracy. We also demonstrated that our method could identify tissue neoplasia at the simulated resection margins that appear grossly normal with naked eyes. Conclusion: Our results indicated that SRS histology integrated with deep learning algorithm provides potential for delivering rapid intraoperative diagnosis that could aid the surgical management of laryngeal cancer.

Surgical margins in head and neck cancer: Intra- and postoperative considerations

OBJECTIVE

To provide a perspective on the significance of recent reports for optimizing cancer free surgical margins that have challenged standard practices.

METHODS

We conducted a review of the recent literature (2012-2018) using the keywords surgical margin analysis, frozen and paraffin section techniques, head and neck cancer, spectroscopy and molecular markers.

RESULTS

Of significance are the reports indicating superiority of tumor specimen directed sampling of margins compared to patient directed (tumor bed) sampling for frozen section control of oral cancers. With reference to optimal distance between tumor and the surgical margin, recent reports recommended cutoffs less than 5mm. Employment of new technologies such as light spectroscopy and molecular analysis of tissues, provide opportunities for a "real time" assessment of surgical margins.

CONCLUSIONS

The commonly practiced method of patient directed margin sampling involving previous studies raises concern over conclusions made regarding the efficacy of frozen section margin control. The recent studies that challenge the optimal distance for clear surgical margins are retrospective and address patient cohorts with inherently confounding factors. The use of novel ancillary techniques require further refinements, clinical trial validation, and justification based on the additional resources.

In Vivo Multimodal Optical Imaging: Improved Detection of Oral Dysplasia in Low-Risk Oral Mucosal Lesions

Early detection of oral cancer and oral premalignant lesions (OPL) containing dysplasia could improve oral cancer outcomes. However, general dental practitioners have difficulty distinguishing dysplastic OPLs from confounder oral mucosal lesions in low-risk populations. We evaluated the ability of two optical imaging technologies, autofluorescence imaging (AFI) and high-resolution microendoscopy (HRME), to diagnose moderate dysplasia or worse (ModDys⁺) in 56 oral mucosal lesions in a low-risk patient population, using histopathology as the gold standard, and in 46 clinically normal sites. AFI correctly diagnosed 91% of ModDys⁺ lesions, 89% of clinically normal sites, and 33% of benign lesions. Benign lesions with severe inflammation were less likely to be correctly diagnosed by AFI (13%) than those without (42%). Multimodal imaging (AFI+HRME) had higher accuracy than either modality alone; 91% of ModDys⁺ lesions, 93% of clinically normal sites, and 64% of benign lesions were correctly diagnosed. Photos of the 56 lesions were evaluated by 28 dentists of varied training levels, including 26 dental residents. We compared the area under the receiver operator curve (AUC) of clinical impression alone to clinical impression plus AFI and clinical impression plus multimodal imaging using k-Nearest Neighbors models. The mean AUC of the dental residents was 0.71 (range: 0.45-0.86). The addition of AFI alone to clinical impression slightly lowered the mean AUC (0.68; range: 0.40-0.82), whereas the addition of multimodal imaging to clinical impression increased the mean AUC (0.79; range: 0.61-0.90). On the basis of these findings, multimodal imaging could improve the evaluation of oral mucosal lesions in community dental settings. Cancer Prev Res; 11(8); 465-76. ©2018 AACR.

Raman Spectroscopy for Inverted Papilloma: A Proof-of-Concept Study

Inverted papillomas are tumors of the sinonasal tract with a propensity to recur. Raman spectroscopy can potentially identify inverted papillomas from other tissue based on biochemical signatures. A pilot study comparing Raman spectroscopy to histopathology for 3 types of sinonasal tissue was performed. Spectral data of biopsies from patients with normal sinonasal mucosa, chronic rhinosinusitis, and inverted papillomas are compared to histopathology using principal component analysis and linear discriminant analysis after data preprocessing. A total of 18 normal, 15 chronic rhinosinusitis, and 18 inverted papilloma specimens were evaluated. The model distinguished normal sinonasal mucosa, chronic rhinosinusitis, and inverted papilloma tissue with an overall accuracy of 90.2% (95% confidence interval, 0.86-0.94). In conclusion, Raman spectroscopy can distinguish inverted papilloma, normal sinonasal mucosa, and chronically rhinosinusitis tissue with acceptable accuracy.

In-vivo optical imaging in head and neck oncology: basic principles, clinical applications and future directions

Head and neck cancers become a severe threat to human's health nowadays and represent the sixth most common cancer worldwide. Surgery remains the first-line choice for head and neck cancer patients. Limited resectable tissue mass and complicated anatomy structures in the head and neck region put the surgeons in a dilemma between the extensive resection and a better quality of life for the patients. Early diagnosis and treatment of the pre-malignancies, as well as real-time in vivo detection of surgical margins during en bloc resection, could be leveraged to minimize the resection of normal tissues. With the understanding of the head and neck oncology, recent advances in optical hardware and reagents have provided unique opportunities for real-time pre-malignancies and cancer imaging in the clinic or operating room. Optical imaging in the head and neck has been reported using autofluorescence imaging, targeted fluorescence imaging, high-resolution microendoscopy, narrow band imaging and the Raman spectroscopy. In this study, we reviewed the basic theories and clinical applications of optical imaging for the diagnosis and treatment in the field of head and neck oncology with the goal of identifying limitations and facilitating future advancements in the field.

High-resolution microendoscopy: a point-of-care diagnostic for cervical dysplasia in low-resource settings

Cervical cancer is the third leading cause of cancer-related death among women in low-to-middle income countries. Pap testing and pathological services are difficult to implement under these settings. Alternative techniques for the diagnosis of cervical precancer in these settings are needed to reduce the burden of the disease. The objective of this study was to evaluate the diagnostic accuracy of a low-cost, high-resolution microendoscope imaging system in identifying precancerous lesions of the cervix in vivo. A retrospective study of 59 patients undergoing colposcopy for an abnormal Pap test was performed at Hospital de Câncer de Barretos in Brazil. All patients underwent colposcopy as per standard of care, and acetowhite lesions were recorded. High-resolution microendoscopy (HRME) images were obtained from one colposcopically normal region and from all lesions observed on colposcopy. Biopsies of abnormal areas were obtained and reviewed by three independent, blinded pathologists and compared with HRME findings. The mean nuclear area and the median nuclear eccentricity were calculated from HRME images acquired from each site. A diagnostic algorithm to distinguish histopathologically diagnosed cervical intraepithelial neoplasias of grade 2 or more severe lesions (high grade) from less severe lesions (low grade) was developed using these parameters. A test of trend was used to analyze the relationship between HRME positivity and severity of histopathogical diagnosis. Fisher's exact test was used to analyze differences in HRME positivity between high-grade and low-grade lesions. Evaluable images were obtained from 108 of 143 discrete sites. Of these, 71 sites were colposcopically normal or low grade according to histopathology and 37 were diagnosed as high grade on the basis of histopathology. Using the mean nuclear area and the median nuclear eccentricity, HRME images from 59 colposcopically abnormal sites were classified as high grade or low grade with 92% sensitivity and 77% specificity compared with histopathological findings. Increasing HRME positivity showed a significant trend with increasing severity of diagnosis (Ptrend<0.001). We found a strong association (P<0.001) between HRME positivity and a histopathological diagnosis of cervical intraepithelial neoplasia of grade 2 or higher. HRME demonstrated an accurate in-situ diagnosis of high-grade dysplasia. In low-resource settings in which colposcopy and histopathology services are severely limited or unavailable, HRME may provide a low-cost, accurate method for diagnosis of cervical precancer without the need for biopsy, allowing for a single 'screen-and-treat' approach.

A Proposal to Redefine Close Surgical Margins in Squamous Cell Carcinoma of the Oral Tongue

Importance

Resection of the primary tumor with negative margins is the gold standard treatment for squamous cell carcinoma of the oral tongue (SCCOT). A microscopically positive surgical margin is clearly associated with a higher risk for local recurrence, whereas a negative margin has traditionally been defined as greater than 5.0 mm clearance from the tumor, with lesser margins arbitrarily designated as close. The precise cutoff at which the risk for local recurrence with a close margin approximates that of a microscopically positive margin remains unclear.

Objective

To determine whether the arbitrarily defined close margin (<5.0 mm) would portend as high a risk for local recurrence as a positive margin after resection of SCCOT.

Design, Setting, and Participants

In this retrospective study, head and neck pathologists reviewed archived tumor specimens from 381 patients with SCCOT who underwent primary surgical resection at a tertiary care center from January 1, 2000, through December 31, 2012. Data were analyzed from November 15, 2015, to January 5, 2016. Time-dependent receiver operating characteristic curve analysis was used in patients who did not have a microscopically positive margin to determine an optimal margin cutoff for local recurrence-free survival (LRFS). Pathologic factors were assessed for LRFS in a multivariate Cox proportional hazards regression model.

Main Outcomes and Measures

The primary end point was evaluation of the margin distance associated with LRFS.

Results

Among the 381 patients included in the analysis (222 men [58.3%] and 159 women [41.7%]; mean [SD] age, 58 [14.7] years), the optimal cutoff associated with LRFS was determined to be 2.2 mm. This cutoff was compared with the traditionally accepted cutoff of 5.0 mm. Patients with a margin of 2.3 to 5.0 mm had similar LRFS as patients with a margin of greater than 5.0 mm (hazard ratio [HR], 1.31; 95% CI, 0.58-2.96), and all other comparisons were significantly different (HR for positive margin, 9.03; 95% CI, 3.45-23.67; HR for 0.01- to 2.2-mm margin, 2.83; 95% CI, 1.32-6.07). Based on this result, negative margins were redefined as those with a clearance of greater than 2.2 mm. In a multivariate model adjusting for pathologic factors, positive margins (adjusted HR, 5.73; 95% CI, 2.45-13.41) and margins of 0.01 to 2.2 mm (adjusted HR, 2.00; 95% CI, 1.13-3.55) were the variables most significantly associated with LRFS.

Conclusions and Relevance

In this study, local recurrence-free survival was significantly affected only with surgical margins of less than or equal to 2.2 mm in patients with SCCOT. This new definition of close margins stratifies the risk for local recurrence better than the arbitrary 5.0-mm cutoff that has been used.

Intraoperative assessment of laryngeal malignancy using elastic light single-scattering spectroscopy: A pilot study

OBJECTIVES/HYPOTHESIS

The elastic light single-scattering spectroscopy (ELSSS) system is a new tool for the real-time diagnosis of cancerous lesions. In the current study, we have employed ELSSS to investigate its ability in differentiation between normal and cancerous larynx tissues ex vivo.

STUDY DESIGN

Basic science study in assessment of laryngeal malignancy using spectroscopy.

METHODS

ELSSS spectra of the larynx tissue were acquired using a single-fiber optical probe. Ex vivo spectroscopic measurements were acquired on 95 laryngeal lesions of 40 patients. Average slopes of the spectra in the wavelength range of 450 to 750 nm were calculated. The signs of the spectral slopes were positive for benign and negative for cancerous larynx tissues. Histopathology results were used as a gold standard to define sensitivity and specificity.

RESULTS

The ELSSS system correctly defined 38 out of 41 malignant tissues as cancerous; three of them were misclassified as benign. All benign tissues were correctly classified. Moderate, severely dysplastic, and malignant tissues were correctly classified as cancerous. The system could not classify mild dysplastic tissues either benign or cancerous, whereas nearly half of them were classified as benign and the other half as malignant. The signs of the spectral slopes were used as a discrimination parameter between benign and cancerous (moderate, severely dysplastic, and malignant) lesions with a sensitivity and specificity of 94% and 100%, respectively.

CONCLUSIONS

The ELSSS system has the potential to be used as an adjunctive tool in the diagnosis of cancerous laryngeal tissues in real time and noninvasively. This new diagnostic technique may reduce the number of negative biopsies.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:611-615, 2017.

Enhancing in vivo tumor boundary delineation with structured illumination fluorescence molecular imaging and spatial gradient mapping

Fluorescence imaging, in combination with tumor-avid near-infrared (NIR) fluorescent molecular probes, provides high specificity and sensitivity for cancer detection in preclinical animal models, and more recently, assistance during oncologic surgery. However, conventional camera-based fluorescence imaging techniques are heavily surface-weighted such that surface reflection from skin or other nontumor tissue and nonspecific fluorescence signals dominate, obscuring true cancer-specific signals and blurring tumor boundaries. To address this challenge, we applied structured illumination fluorescence molecular imaging (SIFMI) in live animals for automated subtraction of nonspecific surface signals to better delineate accumulation of an NIR fluorescent probe targeting α4β1 integrin in mice bearing subcutaneous plasma cell xenografts. SIFMI demonstrated a fivefold improvement in tumor-to-background contrast when compared with other full-field fluorescence imaging methods and required significantly reduced scanning time compared with diffuse optical spectroscopy imaging. Furthermore, the spatial gradient mapping enhanced highlighting of tumor boundaries. Through the relatively simple hardware and software modifications described, SIFMI can be integrated with clinical fluorescence imaging systems, enhancing intraoperative tumor boundary delineation from the uninvolved tissue.