Kimberly A. Cradock

Real-time imaging of the resection bed using a handheld probe to reduce incidence of microscopic positive margins in cancer surgery

Wide local excision (WLE) is a common surgical intervention for solid tumors such as those in melanoma, breast, pancreatic, and gastrointestinal cancer. However, adequate margin assessment during WLE remains a significant challenge, resulting in surgical reinterventions to achieve adequate local control. Currently, no label-free imaging method is available for surgeons to examine the resection bed in vivo for microscopic residual cancer. Optical coherence tomography (OCT) enables real-time high-resolution imaging of tissue microstructure. Previous studies have demonstrated that OCT analysis of excised tissue specimens can distinguish between normal and cancerous tissues by identifying the heterogeneous and disorganized microscopic tissue structures indicative of malignancy. In this translational study involving 35 patients, a handheld surgical OCT imaging probe was developed for in vivo use to assess margins both in the resection bed and on excised specimens for the microscopic presence of cancer. The image results from OCT showed structural differences between normal and cancerous tissue within the resection bed following WLE of the human breast. The ex vivo images were compared with standard postoperative histopathology to yield sensitivity of 91.7% [95% confidence interval (CI), 62.5%-100%] and specificity of 92.1% (95% CI, 78.4%-98%). This study demonstrates in vivo OCT imaging of the resection bed during WLE with the potential for real-time microscopic image-guided surgery.

Intraoperative optical coherence tomography for assessing human lymph nodes for metastatic cancer

BackgroundEvaluation of lymph node (LN) status is an important factor for detecting metastasis and thereby staging breast cancer. Currently utilized clinical techniques involve the surgical disruption and resection of lymphatic structure, whether nodes or axillary contents, for histological examination. While reasonably effective at detection of macrometastasis, the majority of the resected lymph nodes are histologically negative. Improvements need to be made to better detect micrometastasis, minimize or eliminate lymphatic disruption complications, and provide immediate and accurate intraoperative feedback for in vivo cancer staging to better guide surgery.MethodsWe evaluated the use of optical coherence tomography (OCT), a high-resolution, real-time, label-free imaging modality for the intraoperative assessment of human LNs for metastatic disease in patients with breast cancer. We assessed the sensitivity and specificity of double-blinded trained readers who analyzed intraoperative OCT LN images for presence of metastatic disease, using co-registered post-operative histopathology as the gold standard.ResultsOur results suggest that intraoperative OCT examination of LNs is an appropriate real-time, label-free, non-destructive alternative to frozen-section analysis, potentially offering faster interpretation and results to empower superior intraoperative decision-making.ConclusionsIntraoperative OCT has strong potential to supplement current post-operative histopathology with real-time in situ assessment of LNs to preserve both non-cancerous nodes and their lymphatic vessels, and thus reduce the associated risks and complications from surgical disruption of lymphoid structures following biopsy.

In vivo intra-operative breast tumor margin detection using a portable OCT system with a handheld surgical imaging probe

Breast-conserving surgery is a frequent option for women with stage I and II breast cancer, and with radiation treatment, can be as effective as a mastectomy. However, adequate margin detection remains a challenge, and too often additional surgeries are required. Optical coherence tomography (OCT) provides a potential method for real-time, high-resolution imaging of breast tissue during surgery. Intra-operative OCT imaging of excised breast tissues has been previously demonstrated by several groups. In this study, a novel handheld surgical probe-based OCT system is introduced, which was used by the surgeon to image in vivo, within the tumor cavity, and immediately following tumor removal in order to detect the presence of any remaining cancer. Following resection, study investigators imaged the excised tissue with the same probe for comparison. We present OCT images obtained from over 15 patients during lumpectomy and mastectomy surgeries. Images were compared to post-operative histopathology for diagnosis. OCT images with micron scale resolution show areas of heterogeneity and disorganized features indicative of malignancy, compared to more uniform regions of normal tissue. Video-rate acquisition shows the inside of the tumor cavity as the surgeon sweeps the probe along the walls of the surgical cavity. This demonstrates the potential of OCT for real-time assessment of surgical tumor margins and for reducing the unacceptably high re-operation rate for breast cancer patients.

Intraoperative determination of tumor aggressiveness by real-time label-free nonlinear imaging and characterization of tumor-associated extracellular vesicles (Conference Presentation)

Tumor-associated extracellular vesicles (TEVs), which represent a unique kind of inter-cellular communication carrier, have been found to play vital roles in directing the invasion and metastasis of tumor cells. However, because the human tumor microenvironment and TEVs significantly degrade or lose vitality over relatively brief periods of time after breast cancer surgical excision, lab-based studies with fresh human tissue specimens cannot provide accurate TEV information. By designing and building a portable label-free nonlinear imaging system, we have been able to conduct intraoperative imaging of fresh, unstained breast tissue specimens immediately after excision. Various features of the breast tumor microenvironment from multimodal nonlinear images were characterized to indicate tumor progression, invasiveness, and tumor grade, such as tumor-accommodating collagen structure visualized using second harmonic generation imaging, fibroblasts shown by two photon auto-fluorescence, and TEVs highlighted using third harmonic generation imaging. In particular, we found TEV count as a promising biomarker of tumor aggressiveness and margin distance. A decreasing trend of TEV counts with larger margin distance and lower cancer aggressiveness grades was revealed among 18 breast cancer cases. In addition, clear differences in TEV counts between images collected from breast cancer cases and healthy breast reduction cases, in another aspect, validate the potential of identifying TEVs using our imaging method. Acquisition and interpretation of these intraoperative image data not only provided assessment of the human tumor microenvironment, but also offered the potential to intraoperatively assess tumor margin distance and determine tumor aggressiveness.

Abstract 3038: Intraoperative breast cancer margin detection via polarization-sensitive optical coherence tomography

Current standard-of-care for breast conserving surgery (BCS) procedures relies on post-operative histopathology to provide a microscopic view and assessment of surgical margins. To avoid high reoperation rates there has been a great interest in developing new imaging solutions to visualize tissue intraoperatively, and provide real-time feedback on the margin status. Optical coherence tomography (OCT) is a high-resolution label-free, imaging technology that is the optical analogue to ultrasound imaging, except images are based on backscattered near-infrared light. Fundamentally, the contrast mechanism of OCT relies on the light scattering properties associated with different tissue structures. Unlike normal tissue with well-organized tissue structure, the structure of cancer tissue is often disorganized and typically characterized by variable cell sizes, abnormal shapes, and enlarged nuclei, resulting in different optical scattering properties, and enabling OCT to reveal differences between normal and cancerous tissues with high spatial resolution. We have previously demonstrated OCT for in vivo label-free intraoperative assessment of the breast conserving surgery (BCS) with a hand-held OCT probe that is integrated with a portable OCT system. Despite the technological advance to achieve in vivo OCT imaging during BCS, there remains a critical need to improve the OCT-based detection, differentiation, and diagnosis of breast tumor tissue. Polarization-sensitive optical coherence tomography (PS-OCT) is a functional extension of standard OCT that maps changes in the polarization state of light induced by anisotropic tissue properties. By exploiting the interaction between the polarization state of light and tissue, additional structural and functional information can be extracted. Form birefringence is the main optical property present in tissues responsible for altering the polarization state of light. In breast tissue, birefringent structures include the connective tissue or normal stroma, composed largely of collagen fibers. In the presence of breast cancer, the birefringent collagen fibers are degraded, displaced, reorganized, and/or disrupted in ways that dramatically alter the PS-OCT signal, serving as a fundamentally new optical imaging biomarker for the presence of cancer in the breast. In this study, we report data from 23 cancer surgeries, compared with healthy breast tissue samples obtained from the breast reduction surgeries. Our results show strong correlation of observed tissue birefringence and collagen fiber density, and the lack of the tissue birefringence, due to low collagen fiber density, in the cancerous areas. Our PS-OCT imaging system provides faster and more informative intraoperative tumor margin assessment. It has the potential to determine margin status in real-time during the surgical procedure and reduce reoperation rates. Citation Format: Marina Marjanovic, Jianfeng Wang, Yang Xu, Eric J. Chaney, Darold R. Spillman, Anna M. Higham, Natasha N. Luckey, Kimberly A. Cradock, George Z. Liu, Stephen A. Boppart. Intraoperative breast cancer margin detection via polarization-sensitive optical coherence tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3038.

Intraoperative in vivo assessment of lymph nodes with optical coherence tomography

Techniques have been developed to localize sentinel lymph nodes during cancer surgery and for post-operative histology. Intraoperative OCT, however, uniquely offers microscopic label-free in vivo assessment of lymph nodes for metastatic disease.

Abstract P1-01-23: Intraoperative optical coherence tomography for the assessment of metastatic disease in human lymph nodes

The status of lymph nodes is an important factor in staging cancer since the transport of primary cancer cells via the lymphatic system is one of the main pathways of metastasis to distant organs. During cancer surgery, lymph node status is evaluated via sentinel lymph node biopsy (SLNB), which involves the removal and analysis of the first (or sentinel) nodes along the lymphatic chain of nodes draining the primary tumor. The sentinel nodes are identified through the accumulation of a radioactive agent (technetium-99) and/or isosulfan blue dye within the nodes, frequently resulting in the resection of multiple nodes for subsequent, often time-consuming, histopathological analysis. The majority of these resected nodes are found by histological analysis to be normal, leading to unnecessary complications, including increased risk of lymphedema. Thus, a method for the in situ assessment of node status could reduce the number of normal lymph nodes that are resected. In this study we evaluated the sensitivity and specificity of three-dimensional optical coherence tomography (OCT) for the intraoperative assessment of metastatic disease in lymph nodes. OCT is the optical analogue to ultrasound imaging, except images are based on the optical scattering properties of near-infrared light. Real-time OCT with micron-scale resolution affords optical biopsies of tissue for immediate feedback. Intraoperative OCT imaging was conducted on human lymph nodes resected from 49 subjects during breast and, head and neck cancer surgeries. Three-dimensional OCT datasets were recorded ex vivo from one or more locations per node, and marked with surgical ink for subsequent correlation to histology. These lymph nodes then underwent the standard histological processing. A double-blinded study was performed comparing the assessment of OCT datasets to the co-registered histological findings. Three-dimensional -OCT datasets from 206 sites were independently analyzed by six observers and classified as cancerous or non-cancerous. Seventy-nine sets were identified as unsuitable for OCT analysis due to insufficient nodal tissue within the imaged field-of-view. Early training classification results from three of the six observers resulted in a sensitivity of 64.8% and a specificity of 73.3% for identifying metastatic lymph nodes intraoperatively, in real-time, compared to the gold standard of post-operative histopathology. Final study results are expected to improve with observer training and a decision tree for interpreting OCT images. Our initial imaging studies of resected lymph nodes in human cancer subjects demonstrate the potential of OCT as a technique for real-time optical biopsy of lymph nodes for the intraoperative staging of cancer. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-23.

Abstract P2-03-11: In situ imaging of the tumor cavity during breast lumpectomy using optical coherence tomography

Re-operation rates for breast lumpectomy procedures are exceedingly high, often over 30%, depending on the institution and surgical technique. Because current standard-of-care relies on post-operative histopathology to provide a microscopic view and assessment of surgical margins, there has been great interest in developing new imaging solutions to visualize tissues intraoperatively with high-resolution, and provide real-time feedback on the margin status. While it is possible to use a variety of microscopic imaging methods in the operating suite, including frozen-section histology, touch-prep cytology, confocal or scattering-based microscopy, all these techniques are limited to visualizing margins on ex vivo resected specimens, and do not provide a means for visualizing the in situ tumor cavity for evidence of positive margins or residual disease. Optical coherence tomography (OCT) is a high-resolution, real-time, optical biomedical imaging technology that is the optical analogue to ultrasound imaging, except images are based on backscattered near-infrared light. OCT is capable of performing optical biopsies of in situ tissue at resolutions that approach those in histopathology. With the use of an advanced computed imaging technique called ISAM (Interferometric Synthetic Aperture Microscopy), even higher imaging resolution over larger depths is possible, commensurate with the depths (1-2 mm) visualized by pathologists to determine negative, close, or positive margins. Past studies by our group and others have demonstrated the feasibility of intraoperative OCT for assessing tumor margin and lymph node status during breast cancer surgery, but to date, all studies have been performed on resected lumpectomy tissue. In this study, we report the development of a novel handheld surgical imaging probe that enables 2-D and 3-D OCT/ISAM imaging of the in situ tumor cavity, in addition to the margins of excised specimens. To date, this handheld OCT/ISAM probe has been used in 10 breast cancer surgeries where both in situ and ex vivo imaging was performed. Four of these cases involved in situ imaging of the cavity margin after a suspicious area was visually and tactically identified, and was subsequently resected, followed by ex vivo imaging and validating post-operative histopathology. Representative cases included fibroadipose tissue, fibroadenomas, and high-grade ductal carcinoma in situ . Distinct microstructural features identified on OCT/ISAM and confirmed with histopathology demonstrate that this technique can visualize the in situ tumor cavity, as well as the surgical margins on resected specimens, with micron-scale resolution. OCT/ISAM has the potential to determine margin status in real-time during the surgical procedure, when further surgical resection to establish clear margins and reduce re-operation rates is possible. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-03-11.

Abstract OT2-1-04: Intraoperative assessment of tumor margins with a new optical imaging technology: A multi-center, randomized, blinded clinical trial

Background: Partial mastectomy is the most commonly performed procedure for invasive breast cancer and is associated with a reexcision rate commonly ranging from 20% to 40% in the literature. This high rate of reexcision is associated with significant additional cost (estimated over

Impact of Systematic Cavity Shave Margins in Breast Conserving Surgery at a Large Community Hospital

4,000 per reexcision) and lower quality outcomes. Optical coherence tomography (OCT) is a high-resolution imaging technology that images tissue structure with micron-scale resolution – on the same scale as histopathology. It is similar to ultrasound except it uses near infra-red light waves instead of sound waves to create detailed images several millimeters deep into tissue. Although widely used in ophthalmology with growing use in cardiovascular imaging, high-resolution OCT imaging has a narrow depth of focus and requires instrumentation that is not well suited for intraoperative use. Drawing from OCT technology, interferometric synthetic aperture microscopy (ISAM) is a computational imaging technique that creates high-resolution, always in-focus images in software with basic optical instrumentation. A high-resolution ISAM probe and imaging system has been developed for intraoperative imaging of tissue structure and has the potential to broadly impact intraoperative assessment of tumor margins. Intraoperative ISAM imaging of the excised breast cancer specimen margins and in vivo imaging within the surgical cavity may reduce the high rate of reexcision associated with partial mastectomy. Trial Design: The trial design is a prospective, multi-center, randomized, double arm study comparing the reexcision rate of standard of care partial mastectomy versus the reexcision rate of standard of care partial mastectomy plus intraoperative ISAM imaging. Inclusion Criteria: Women histologically diagnosed with invasive carcinoma of the breast (invasive ductal or lobular) Undergoing partial mastectomy (lumpectomy) procedure Age 18 years or more Exclusion Criteria Multicentric disease Bilateral disease Neoadjuvant systemic therapy All T4 tumors Previous radiation in the operated breast Prior surgical procedure in the same quadrant Implants in the operated breast Pregnancy Lactation Participating in any other investigational study which can influence collection of valid data Primary Endpoints Measure of surgical reexcision rate Rate of tumor at final surgical margins Secondary Endpoints Volume of tissue excised Clinical and economic measures of addressing asymmetry Statistical Methods: The trial is designed to show superiority of the ISAM imaging arm to the standard of care. Statistical design is two group, continuity corrected chi-squared test of equal proportions with 90% power and alpha=0.05. The trial design assumes a baseline reoperation rate in the standard of care arm of 24% with at least a 50% reduction in the ISAM imaging arm. Present Accrual and Target Accrual Not yet recruiting. Target accrual is 230 patients in the partial mastectomy + imaging arm and 230 patients in the standard of care partial mastectomy arm. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT2-1-04.