Breast-conserving surgery (BCS) for treatment of breast cancer requires complete removal of the tumor. 20-30% of patients undergoing BCS require multiple surgeries due to cancer at or near the boundary (margin) of the excised tissue as assessed by postoperative histopathology. Intraoperative detection of involved margins could significantly reduce the number of patients requiring repeat surgeries. We built and deployed a portable optical coherence elastography system capable of rapid, 3D imaging of whole margins (46x46 mm) of excised breast specimens (wide local excisions, WLEs) removed during BCS. The system produces images of the microstructure and stiffness of the tissue using a phase-sensitive, compression-based elastography approach. The goal of this study was to determine the diagnostic accuracy (sensitivity and specificity), using this system, of OCT versus OCT plus micro-elastography for detecting cancer within 0.75 mm of the margin of the excised tissue. >70 women undergoing BCS were enrolled in the study. We scanned two margins from each fresh, intact surgical specimen within 2 hours of excision. We selected 10x10x0.75mm regions of interest (ROIs) from each margin scanned that are representative of the makeup of breast tissue. Post-operative histology, co-registered with the scans, was used as a gold standard, and a pathologist determined the tissue types present within each ROI based on corresponding histology. Recruitment for the study is complete, and a blinded reader analysis of one ROI from each margin is being performed by two surgeons, a pathologist, a radiologist, and an engineer. Results for sensitivity and specificity will be presented.
Disease alters both the micro-structural and micro-mechanical properties of tissue. These changes in mechanical properties manifest at the macro-scale, enabling clinicians to diagnose disease through manual palpation. This has been a primary motivator for elastography, however, in the development of elastography, manual palpation’s key advantages of dexterity and simplicity are lost. Combining manual palpation and elastography would, potentially, preserve these advantages whilst also providing clinicians with quantitative, high-resolution imaging necessary to overcome the subjective and inherently low spatial resolution of manual palpation. Optical coherence elastography (OCE) is particularly well-suited to imaging subtle changes in mechanical properties owing to its high spatial resolution and sensitivity to nanometer-scale displacement. Additionally, as OCE is an optics-based technique, it is readily implemented in compact probes, such as those already demonstrated in needles and endoscopes. Here, we propose a finger-mounted OCE probe, based on quantitative micro-elastography (QME) in a forward-facing configuration, and using the operator’s finger to apply compressive loading. A compliant silicone layer, with known mechanical properties, is placed on the sample and enables quantification of the sample’s elasticity. This finger-mounted probe is designed to preserve the dexterity of manual palpation, whilst providing quantitative, high-resolution images. In this study, we demonstrate the accuracy of finger-mounted OCE to be >70% in measuring the elasticity of tissue mimicking phantoms, and highlight the ability to delineate materials with different mechanical properties. Further, we present results performed on kangaroo muscle tissue and outline the developments required to translate this into a clinically feasible diagnostic tool.