Intraoperative Optical Coherence Tomography Imaging Research Articles

Identification and Management of a Central Type 2 Big Bubble in Deep Anterior Lamellar Keratoplasty

Purpose: The purpose of this study was to document a case of central type 2 bubble formation during deep anterior lamellar keratoplasty and discuss its intraoperative management. Methods: A rare case of central type 2 bubble formation with no peripheral extension beyond the trephination mark was documented with operative video and concurrent intraoperative optical coherence tomography imaging. Results: The type 2 bubble was decompressed with a needle intraoperatively, and deep anterior lamellar keratoplasty was successfully performed without perforation of Descemet membrane. Conclusions: Identifying formation of a type 2 bubble during deep anterior lamellar keratoplasty is crucial in avoiding perforation of Descemet membrane. This case shows that the behavior of type 2 bubbles can be different than what has been widely reported. It is hoped that this will aid the surgeon in identifying a type 2 bubble and in properly managing it intraoperatively.

Real-time intraoperative OCT imaging of the vitreolenticular interface during pediatric cataract surgery.

To report on the use of intraoperative optical coherence tomography (OCT) imaging of the vitreolenticular interface (VLI) during pediatric cataract surgery and to determine the incidence of VLI dysgenesis and surgical difficulties. Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium. Retrospective cohort study. This study included 51 pediatric patients who underwent cataract surgery between April 2016 and December 2018. Video recordings and OCT images of the VLI were analyzed and compared. VLI dysgenesis was considered present when intraoperative OCT images demonstrated partial or total adhesions between the posterior lens capsule and the anterior hyaloid membrane. Video recordings were analyzed to describe surgical difficulties, more specifically: inability to create a calibrated primary posterior continuous curvilinear capsulorhexis (PPCCC), occurrence of vitreous prolapse, need for anterior vitrectomy, and complicated IOL implantation. Of the 51 patients included, VLI dysgenesis was demonstrated in 27 patients (52.9%). The incidence of VLI dysgenesis was greater in children with unilateral cataract (72.4%), and children with a posterior capsule plaque (90%). PPCCC was challenging in 20 patients. A defect of the anterior hyaloid membrane was found in 16 patients. Anterior vitrectomy or cutting vitreous strands with scissors was necessary in 10 patients. Intraoperative OCT images were an excellent tool to evaluate the VLI and to demonstrate the presence of VLI dysgenesis during pediatric cataract surgery. Performing a calibrated PPCCC was more challenging in the presence of VLI dysgenesis. This can subsequently expose a defect in the anterior hyaloid membrane, which may result in vitreous prolapse.

Intraoperative Optical Coherence Tomography Imaging in Corneal Surgery: A Literature Review and Proposal of Novel Applications.

Intraoperative optical coherence tomography (iOCT) is widely used in ophthalmic surgeries for cross-sectional imaging of ocular tissues. The greatest advantage of iOCT is its adjunct diagnostic efficacy, which facilitates to decision-making during surgery. Since the development of microscopic-integrated iOCT (MIOCT), it has been widely used mainly for vitreoretinal and anterior segment surgeries. In corneal transplantation, MIOCT allows surgeons to visualise structure underneath the turbid and distorted cornea, which are impossible to visualise with a usual microscope. Real-time visualisation of hard-to-see area reduces the operation time and leads to favorable surgical outcomes. The use of MIOCT is advantageous for a variety of corneal surgical procedures. Here, we have reviewed articles focusing on the utility of iOCT and MIOCT in penetrating keratoplasty, deep anterior lamellar keratoplasty, Descemet stripping automated endothelial keratoplasty, and Descemet membrane endothelial keratoplasty. The applications of MIOCT to corneal surgery in terms of surgical education for trainees, emergency surgery, and novel surgery are also discussed, with our cases performed using RESCAN® 700.

Intra-operative point-of-procedure delineation of oral cancer margins using optical coherence tomography

ObjectivesSurgical margin status is a significant determinant of treatment outcome in oral cancer. Negative surgical margins can decrease the loco-regional recurrence by five-fold. The current standard of care of intraoperative clinical examination supplemented by histological frozen section, can result in a risk of positive margins from 5 to 17 percent. In this study, we attempted to assess the utility of intraoperative optical coherence tomography (OCT) imaging with automated diagnostic algorithm to improve on the current method of clinical evaluation of surgical margin in oral cancer. Materials and methodsWe have used a modified handheld OCT device with automated algorithm based diagnostic platform for imaging. Intraoperatively, images of 125 sites were captured from multiple zones around the tumor of oral cancer patients (n = 14) and compared with the clinical and pathologic diagnosis. ResultsOCT showed sensitivity and specificity of 100%, equivalent to histological diagnosis (kappa, ĸ = 0.922), in detection of malignancy within tumor and tumor margin areas. In comparison, for dysplastic lesions, OCT-based detection showed a sensitivity of 92.5% and specificity of 68.8% and a moderate concordance with histopathology diagnosis (ĸ = 0.59). Additionally, the OCT scores could significantly differentiate squamous cell carcinoma (SCC) from dysplastic lesions (mild/moderate/severe; p ≤ 0.005) as well as the latter from the non-dysplastic lesions (p ≤ 0.05). ConclusionThe current challenges associated with clinical examination-based margin assessment could be improved with intra-operative OCT imaging. OCT is capable of identifying microscopic tumor at the surgical margins and demonstrated the feasibility of mapping of field cancerization around the tumor.

THE INTEGRATIVE SURGICAL THEATER: Combining Intraoperative Optical Coherence Tomography and 3D Digital Visualization for Vitreoretinal Surgery in the DISCOVER Study.

To evaluate the feasibility of integrating intraoperative optical coherence tomography (OCT) with a digital visualization platform for vitreoretinal surgery. The DISCOVER study is a prospective study examining microscope-integrated intraoperative OCT across multiple prototypes and platforms. For this assessment, a microscope-integrated OCT platform was combined with a three-dimensional (3D) surgical visualization system to allow for digital display of the OCT data stream on the large immersive display. Intraoperative OCT scans were obtained at various surgical milestones that were directly overlaid to the surgical view in a 55-inch passive 3D 4K high-definition display. Surgeon feedback was obtained related to system performance and integration into the surgical procedures through a prespecified surgeon questionnaire. Seven eyes of seven subjects were identified. Clinical diagnosis included epiretinal membrane (n = 3), macular hole (2), symptomatic vitreous opacity (1), and proliferative vitreoretinopathy (1). Optical coherence tomography images were successfully obtained and displayed on the 4K screen in all cases. Intraoperative OCT images facilitated identification of subtle retinal alterations. Surgeons reported that the 4K screen seemed to provide improved visualization of the OCT data stream compared with the semitransparent ocular view. Surgeons were able to examine the OCT data on the 4K screen without reverting to the external display system of the microscope. The system provided a uniform surgical visualization experience for both the surgeon and the assistant. In addition, the digital platform allowed all surgical personnel to simultaneously view both the OCT and the surgical field. All eyes underwent uneventful vitrectomy without reverting to the conventional microscope. No intraoperative adverse events occurred. Integration of OCT into the digital visualization system may enable unique opportunities for surgeon feedback of intraoperative diagnostics. The overlay of the OCT data onto the 4K monitor seemed to provide excellent visualization of OCT details. Further research is needed to compare the conventional microscope-based approach to the digital 3D screen approach in regards to intraoperative OCT.

FACTORS ASSOCIATED WITH DEVELOPMENT OF DISSOCIATED OPTIC NERVE FIBER LAYER APPEARANCE IN THE PIONEER INTRAOPERATIVE OPTICAL COHERENCE TOMOGRAPHY STUDY.

To assess the relationship of dissociated optic nerve fiber layer (DONFL) and intraoperative membrane-peeling dynamics as visualized using intraoperative optical coherence tomography (OCT), and to evaluate the functional implications of DONFL. This was a post hoc analysis of eyes undergoing membrane peeling for vitreomacular interface disorders in the prospective PIONEER intraoperative OCT study. Retinal layer measurements in preincision and postpeel intraoperative OCT images were obtained. The primary outcome was development of DONFL appearance on spectral domain OCT at 6-month follow-up. Secondary outcomes included correlation of DONFL with surgical technique, surgical indication, intraoperative OCT findings, and retinal sensitivity. Ninety-five eyes were included. The prevalence of DONFL at 6 months was 36%. Increased inner retinal layer thickness on intraoperative OCT immediately after membrane peeling was associated with development of DONFL (P < 0.01). Macular hole repair was significantly associated with DONFL appearance. Peel technique (forceps vs. diamond-dusted membrane scraper) was not associated with DONFL. There was no difference in retinal sensitivity or visual acuity between eyes with or without DONFL. Acute postpeel increase in inner retinal thickness and macular hole repair were associated with development of DONFL appearance. However, it is unclear whether the surgical indication (e.g., macular hole) or the surgical manipulations performed (e.g., internal limiting membrane peeling) is the major factor that has an impact on DONFL appearance. Overall, these findings suggest that one mechanism in the development of DONFL appearance may be intraoperative trauma to the inner retina, potentially during internal limiting membrane peeling (e.g., macular hole repair).

Clinical and surgical implications of intraoperative optical coherence tomography imaging for benign pediatric vocal fold lesions

IntroductionBenign vocal disorders in children include an extensive list of abnormalities creating a variety of debilitating levels of dysphonia. Precise delineation of the benign lesion type and margins may have significant public health implications in children. An innovative technology such as optical coherence tomography (OCT) is being explored to delineate pediatric benign laryngeal lesions. An accurate assessment of the subepithelial morphology may help towards tailoring more personalized therapeutic treatments. This study was established to highlight key morphological and optical features of benign pediatric laryngeal lesions using intraoperative OCT and to suggest clinical implications that arise from such optical imaging. Methods and materialsThis in vivo study was performed at Massachusetts Eye and Ear Infirmary. Intraoperative imaging was performed on twenty-five pediatric patients ranging from 1 year to 16 years of age presenting hoarseness. Three-dimensional OCT images of benign laryngeal lesions or a subsite of the lesion were acquired. ResultsHigh-resolution OCT images of 25 patients with benign laryngeal lesions such as nodules, cysts, Reinke's edema, vocalis sulcus, and papilloma revealed distinct and specific morphological differences with normal tissue. Nodules show a symmetrical superficial remodeling of the vocal fold epithelial layer and the basement membrane. Cysts have oval-like shape and are either superficial or deeply located in the lamina propria. Sulcus vocalis OCT imaging allows characterizing if the lesion is shallow or deep according to Ford's classification system. Reinke's edema of the mucosa can be observed and quantified, which may lead to suspicion on the underlying social and medical conditions. Finally, the ability to assess margins and depth of invasion of papilloma lesions is demonstrated, raising the possibility to use OCT with angiolytic lasers for patient-tailored treatments. ConclusionsOCT imaging of benign pediatric vocal lesions is promising as it could improve preoperative decision-making and possibly peroperative imaging-guidance for patient-tailored treatments. An assessment of the optical contrast between healthy and abnormal tissue may help towards a more qualitative and quantitative approach to current standard care, especially when diagnosis remains unclear.

Intraoperative Optical Coherence Tomography Imaging of the Peripheral Vitreous and Retina.

Intraoperative Optical Coherence Tomography Imaging of the Peripheral Vitreous and Retina.

Intraoperative OCT Imaging of the Argus II Retinal Prosthesis System.

Optimal placement of the Argus II Retinal Prosthesis System (Second Sight Medical Products, Sylmar, CA) is critical. Intraoperative optical coherence tomography (OCT) allows for intrasurgical visualization and confirmation of array placement. In this study, two different OCT systems were evaluated to assess the feasibility and utility of this technology during Argus II surgery. Intraoperative OCT was performed on five patients undergoing Argus II implantation at Cole Eye Institute from June 2015 to July 2016. The EnVisu portable OCT (Bioptigen, Morrisville, NC) and microscope-integrated RESCAN 700 (Zeiss, Oberkochen, Germany) intraoperative OCT systems were utilized. The EnVisu was used in three patients and the RESCAN 700 in three of the five patients. Following array tacking, intraoperative OCT was performed over the entire array including the edges and tack. Intraoperative OCT allowed for visualization of the array/retina interface. Microscope integration of the OCT system facilitated ease of focusing, real-time feedback, surgeon-directed OCT scanning to the areas of interest, and enhanced image quality at points of interest. Intraoperative imaging of the Argus II electrode array is feasible and provides information about electrode array-retina interface and distance to help guide a surgeon. Microscope integration of OCT appears to provide an optimal and efficient approach to intraoperative OCT during Argus II array placement. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:999-1003.].

Intraoperative Optical Coherence Tomography Imaging and Assessment of the Macula During Cataract Surgery: A Novel Technique.

The authors describe a technique to qualitatively analyze the posterior segment during cataract surgery using intraoperative optical coherence tomography (iOCT). Macular iOCT can be done before and after intraocular lens implantation after the media is rendered clear following phacoemulsification. A handheld irrigating planoconcave contact lens is placed over the cornea with the operating microscope in retroillumination mode. After focusing the microscope and upon getting a clear view of the posterior segment, iOCT is switched on, centered at the macula, and focused. This technique enables the surgeon to intraoperatively analyze and document the macular morphology and vitreoretinal interface. Potential uses of this technique include intraoperative decision-making regarding concurrent use of anti-vascular endothelial growth factor agents or steroids in cases with dense cataracts where preoperative OCT is difficult. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:846-847.].

Use of a new intra-ocular spectral domain optical coherence tomography in vitreoretinal surgery.

To describe the use of a novel intra-ocular side-scanning probe enabling the acquisition of spectral-domain optical coherence tomography (SD-OCT) images during surgery in a series of patients with complex forms of retinal detachment. A 23-gauge, side-scanning SD-OCT probe (C7 System; LightLab Imaging, Inc/St Jude Medical, St. Paul, MN, USA) in a 20-gauge catheter, was used to acquire the intra-operative OCT images in seven patients with vitreoretinal diseases. Twenty-five gauge pars plana vitrectomy (PPV) was performed in every patient in a standard fashion. After enlarging the temporal sclerotomy to a 20-gauge port, all the patients were scanned with intra-ocular side-scanning SD-OCT, during different steps of the surgery based on surgeon needs. Scans were recorded real time and directly evaluated on a screen during surgery. Optical coherence tomography (OCT) scans were judged beneficial when they would recognize structures otherwise not seen on biomicroscopy. The intra-ocular SD-OCT has been helpful in acquiring extra information during vitreoretinal surgery such as the detection of the presence of otherwise invisible membranes (epiretinal membrane, subretinal membrane), the location of small tears and the identification of the retinal plane under suboptimal conditions for visualization. The use of an intra-ocular SD-OCT can expand upon visual cues during surgery, helping in the decision-making process and allowing additional deliberate surgical manoeuvres aimed at improving surgical outcomes.

INTRAOPERATIVE OPTICAL COHERENCE TOMOGRAPHY DURING VITREORETINAL SURGERY FOR DENSE VITREOUS HEMORRHAGE IN THE PIONEER STUDY.

To evaluate the feasibility and utility of intraoperative optical coherence tomography (OCT) during pars plana vitrectomy surgery for dense vitreous hemorrhage. The Prospective Assessment of Intraoperative and Perioperative OCT for Ophthalmic Surgery study examined the utility of intraoperative OCT in ophthalmic surgery. Intraoperative scanning was performed with a microscope-mounted spectral domain OCT system. This report is a case series of those eyes undergoing pars plana vitrectomy for dense central vitreous hemorrhage that precluded preoperative OCT assessment. Intraoperative OCT images were qualitatively evaluated for retinal abnormalities that might impact intraoperative or perioperative management. Clinical variables were collected and assessed. Surgeon assessment of intraoperative OCT utility was also evaluated. Twenty-three eyes were identified and included. The etiology for the vitreous hemorrhage was proliferative diabetic retinopathy (19 eyes, 82.6%), horseshoe retinal tear (1 eye, 4.3%), retinal vein occlusion with neovascularization (1 eye, 4.3%), presumed polypoid choroidal vasculopathy (1 eye, 4.3%), and presumed retinal arterial macroaneurysm (1 eye, 4.3%). Intraoperative OCT revealed epiretinal membrane (14 eyes, 60.9%), macular edema (14 eyes, 60.9%), posterior hyaloid traction (1 eye, 4.3%), and retinal detachment (1 eye, 4.3%). Surgeon feedback suggested that intraoperative OCT impacted surgical decision making in eyes where membrane peeling was performed. Intraoperative OCT during pars plana vitrectomy for vitreous hemorrhage may provide physicians with clinically relevant information that may impact surgical management, perioperative management, and patient outcomes.

INTRAOPERATIVE SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY IMAGING AFTER INTERNAL LIMITING MEMBRANE PEELING IN IDIOPATHIC EPIRETINAL MEMBRANE WITH CONNECTING STRANDS.

To report the intraoperative optical coherence tomography findings in idiopathic epiretinal membrane (ERM) with connecting strands and to describe the postoperative outcomes. A retrospective, case series study within a prospective observational intraoperative optical coherence tomography imaging study was performed. Epiretinal membranes with connecting strands were characterized on preoperative spectral domain optical coherence tomography images and assessed against corresponding intraoperative (after internal limiting membrane [ILM] peeling) and postoperative spectral domain optical coherence tomography images. Eleven locations of the connecting strands in 7 eyes were studied. The connecting strands had visible connections from the inner retinal surface to the ERM in all locations, and the reflectivity was moderate in 8 locations and high in 3 locations. After ERM and ILM peeling, disconnected strands were identified in all of the intraoperative optical coherence tomography images. The reflectivity of the remaining intraoperative strands was higher than that of the preoperative lesions and appeared as "finger-like" and branching projections. The remaining disconnected lesions were contiguous with the inner retinal layers. Postoperatively, the intraoperative lesions disappeared completely in all locations, and recurrent formation of ERM was not identified in any eyes. In ERM eyes with connecting strands, intraoperative spectral domain optical coherence tomography imaging showed moderately to highly reflective sub-ILM finger-like lesions that persist immediately after membrane and ILM peeling. Postoperatively, the hyperreflective lesions disappeared spontaneously without localized nerve fiber layer loss. The sub-ILM connecting strands may represent glial retinal attachments.

The Prospective Intraoperative and Perioperative Ophthalmic ImagiNg With Optical CoherEncE TomogRaphy (PIONEER) Study: 2-Year Results

To evaluate the feasibility, safety, and utility of intraoperative optical coherence tomography (OCT) for use during ophthalmic surgery. Prospective, consecutive case series. A prospective, single-center, consecutive case series was initiated to assess intraoperative OCT in ophthalmic surgery. Intraoperative scanning was performed with a microscope-mounted spectral-domain OCT system. Disease-specific or procedure-specific imaging protocols (eg, scan type, pattern, size, orientation, density) were used for anterior and posterior segment applications. A surgeon feedback form was recorded as part of the study protocol to answer specific questions regarding intraoperative OCT utility immediately after the surgical procedure was completed. During the first 24 months of the PIONEER study, 531 eyes were enrolled (275 anterior segment cases and 256 posterior segment surgical cases). Intraoperative OCT imaging was obtained in 518 of 531 eyes (98%). Surgeon feedback indicated that intraoperative OCT informed surgical decision making and altered surgeon understanding of underlying tissue configurations in 69 of 144 lamellar keratoplasty cases (48%) and 63 of 146 membrane peeling procedures (43%). The most common anterior segment surgical procedure was Descemet stripping automated endothelial keratoplasty (DSAEK, n = 135). Vitrectomy with membrane peeling was the most common procedure for posterior segment surgery (n = 154). The median time that surgery was paused to perform intraoperative OCT was 4.9 minutes per scan session. No adverse events were specifically attributed to intraoperative OCT scanning during the procedure. Intraoperative OCT is feasible for numerous anterior and posterior segment ophthalmic surgical procedures. A microscope-mounted intraoperative OCT system provided efficient imaging during operative procedures. The information gained from intraoperative OCT may impact surgical decision making in a high frequency of both anterior and posterior segment cases.

The value of intraoperative optical coherence tomography imaging in vitreoretinal surgery

To evaluate the role of intraoperative optical coherence tomography (iOCT) in vitreoretinal surgery, assess the current state-of-the art, and to examine possible future directions in the field. Numerous vitreoretinal surgical conditions and procedures have been described utilizing iOCT. These conditions include macular holes, epiretinal membranes, retinal detachments, and retinopathy of prematurity. Significant alterations appear to occur during surgical manipulations in many of these conditions that can be identified with iOCT. The most common current systems used are portable OCT probes that are either mounted to a microscope or used in a handheld fashion. Prototypes are also being utilized that are integrated into the microscope to allow for true 'real-time' imaging of instrument-tissue interactions. Current generation surgical instrument materials (e.g., metal) limit optimal visualization with integrated OCT systems because of shadowing and light scattering properties. The role of iOCT in vitreoretinal surgery continues to be defined by active research and enhancements to integrative technologies. Further research is needed to better define the specific applications of iOCT that impact patient outcomes and surgical decision-making. Future advancements in integrative systems, OCT-friendly instrumentation, and software algorithms will further expand the horizon of iOCT in the vitreoretinal surgical theater. As OCT transformed the clinical management of the vitreoretinal conditions, iOCT has the potential to be a paradigm-shifting technology in the operating room.

Extravascular Optical Coherence Tomography

Extravascular optical coherence tomography (OCT), as a noninvasive imaging methodology with micrometer resolution, was evaluated in a murine model of carotid atherosclerosis by way of assessing the efficacy of pravastatin therapy. An OCT device was engineered for extravascular plaque imaging. Wild-type mice and apolipoprotein E-deficient (ApoE(-/-)) mice were randomized to 3 treatment groups: (1) wild-type on a diet of standard rodent chow (n=13); (2) ApoE(-/-) on a high-fat, atherosclerotic diet (HFD; n=13); and (3) ApoE(-/-) on a HFD given daily pravastatin (n=13). Mice were anesthetized and the left common carotid was surgically exposed. Three-dimensional (3D; 2 spatial dimensions+time) and 4D (3 spatial dimensions+time) OCT images of the vessel lumen patency were evaluated. After perfusion, in situ OCT imaging was performed for statistical comparison with the in vivo results and final histology. Intraoperative OCT imaging positively identified carotid plaque in 100% of ApoE(-/-) mice on HFD. ApoE(-/-) mice on HFD had a significantly decreased lumen patency when compared with that in wild-type mice (P<0.001). Pravastatin therapy was found to increase lumen patency significantly in ApoE(-/-) mice on HFD (P<0.01; compared with ApoE(-/-) on HFD). The findings were confirmed with OCT imaging after perfusion and histology. OCT imaging offers the potential for real-time, detailed vessel lumen evaluation, potentially improving surgical accuracy and outcomes during cerebrovascular neurosurgical procedures. Pravastatin significantly increases vessel lumen patency in the ApoE(-/-) mouse on HFD.

Intra-operative OCT devices for ophthalmic use: an overview

It is feasible to bring the currently most used examination method in ophthalmology, optical coherence tomography (OCT), into ophthalmic surgery to enhance information and control for the surgeon and increase outcome for the patient. In this overview, the currently commercially available OCT devices intending intra-operative OCT imaging are described. Further experience with these systems might not only aid in solving current problems but also open our minds to detect processes so far unknown and help answer questions so far unaddressed.

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

Abstract 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.

SEGMENTATION AND CORRELATION OF OPTICAL COHERENCE TOMOGRAPHY AND X-RAY IMAGES FOR BREAST CANCER DIAGNOSTICS

Pre-operative X-ray mammography and intraoperative X-ray specimen radiography are routinely used to identify breast cancer pathology. Recent advances in optical coherence tomography (OCT) have enabled its use for the intraoperative assessment of surgical margins during breast cancer surgery. While each modality offers distinct contrast of normal and pathological features, there is an essential need to correlate image-based features between the two modalities to take advantage of the diagnostic capabilities of each technique. We compare OCT to X-ray images of resected human breast tissue and correlate different tissue features between modalities for future use in real-time intraoperative OCT imaging. X-ray imaging (specimen radiography) is currently used during surgical breast cancer procedures to verify tumor margins, but cannot image tissue in situ. OCT has the potential to solve this problem by providing intraoperative imaging of the resected specimen as well as the in situ tumor cavity. OCT and micro-CT (X-ray) images are automatically segmented using different computational approaches, and quantitatively compared to determine the ability of these algorithms to automatically differentiate regions of adipose tissue from tumor. Furthermore, two-dimensional (2D) and three-dimensional (3D) results are compared. These correlations, combined with real-time intraoperative OCT, have the potential to identify possible regions of tumor within breast tissue which correlate to tumor regions identified previously on X-ray imaging (mammography or specimen radiography).

Abstract P4-03-04: The potential use of Optical Coherence Tomography for intraoperative breast tumour margin width estimation

Abstract Total mastectomy and lumpectomy with radiation have been shown to have equivalent patient outcomes, which has likely contributed to the more widespread adoption of breast conserving surgery (BCS) procedures. Assessment of breast lumpectomy margin widths in both an accurate and timely manner is essential to successful breast conservation procedures. Current BCS methodologies have been reported to result in reoperation rates of up to 20–60%, which represents a significant and unmet need for improved margin assessment. High reoperation rates present both increased treatment risk to patients and increased burden on healthcare systems. In the USA alone, over 150,000 lumpectomies are performed per year at an average cost between $11,000 and $19,000 USD per procedure. Assuming a relatively modest average repeat operation rate of 25%, potentially preventable repeat surgeries represent an approximate cost to the US healthcare system of $500M (USD) annually. Reducing the prevalence of repeat surgeries may be accomplished by providing faster and more accurate intraoperative tools for assessing margin widths during the time of the first surgery. One such potential technique involves the use of Optical Coherence Tomography (OCT) imaging, which uses light to produce images in much the same way that ultrasound produces images with sound. Compared to ultrasound, OCT provides decreased depth of penetration, but increased resolution capabilities. The increased resolution that OCT provides allows for the visualization of the internal cellular structure within a tissue sample and therefore, provides the potential ability to differentiate cancerous from normal or benign cells. We propose the use of an intraoperative OCT imaging system to provide near real-time imaging information about the internal structure of tissue samples excised during BCS procedures. Our hypothesis is that the overall rate of repeat operations can be reduced by providing a tool to assist surgeons with the task of margin width estimation during the time of surgery. We have developed an early stage prototype OCT imaging system that has completed laboratory phantom and preclinical studies. This paper will present the capabilities of an OCT imaging system to provide margin assessment information in biological breast tissue mimicking phantoms. The phantoms were designed to encompass imaging characteristics across a wide range of human breast densities. The paper will go on to describe preclinical imaging that was done in tumor specimens excised from human breast cancer rat models. The results obtained in the phantom and preclinical studies suggest the potential for OCT as a near-real time, intraoperative imaging tool to aid surgeons with breast lumpectomy margin width estimation. To help realize this potential, further research is required in to the use of OCT during BCS. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-03-04.