Optical palpation for the visualization of tumor in human breast tissue

Australian Research Council; Cancer Council Western Australia; Department of Health, Government of Western Australia; OncoResMedical; William and Marlene Schrader Trust of The University of Western AustraliaAccurate and effective removal of tumor in one operation is an important goal of breast-conserving surgery. However, it is not always achieved. Surgeons often utilize manual palpation to assess the surgical margin and/or the breast cavity. Manual palpation, however, is subjective and has relatively low resolution. Here, we investigate a tactile imaging technique, optical palpation, for the visualization of tumor. Optical palpation generates maps of the stress at the surface of tissue under static preload compression. Stress is evaluated by measuring the deformation of a contacting thin compliant layer with known mechanical properties using optical coherence tomography. In this study, optical palpation is performed on 34 freshly excised human breast specimens. Wide field-of-view (up to ~46 × 46 mm) stress images, optical palpograms, are presented from four representative specimens, demonstrating the capability of optical palpation to visualize tumor. Median stress reported for adipose tissue, 4 kPa, and benign dense tissue, 8 kPa, is significantly lower than for invasive tumor, 60 kPa. In addition, we demonstrate that optical palpation provides contrast consistent with a related optical technique, quantitative micro-elastography. This study demonstrates that optical palpation holds promise for visualization of tumor in breast-conserving surgery.PostprintPeer reviewe

Coherence function-encoded optical palpation

Funding: Australian Research Council, the National Health and Medical Research Council (Australia), OncoRes Medical, Australia.Optical palpation maps stress at the surface of biological tissue into 2D images. It relies on measuring surface deformation of a compliant layer, which to date has been performed with optical coherence tomography (OCT). OCT-based optical palpation holds promise for improved clinical diagnostics; however, the complexity and cost hinder broad adoption. In this Letter, we introduce coherence function-encoded optical palpation (CFE-OP) using a novel optical profilometry technique that exploits the envelope of the coherence function rather than its peak position, which is typically used to retrieve depth information. CFE-OP utilizes a Fabry–Perot laser diode (bandwidth, 2.2 nm) and a single photodiode in a Michelson interferometer to detect the position along the coherence envelope as a function of path length. This technique greatly reduces complexity and cost in comparison to the OCT-based approach. We perform CFE-OP on phantom and excised human breast tissue, demonstrating comparable mechanical contrast to OCT-based optical palpation and the capability to distinguish stiff tumor from soft benign tissue.PostprintPeer reviewe

Handheld probe for quantitative micro-elastography

Funding: Australian Research Council (ARC); Department of Health, Western Australia; Cancer Council, Western Australia; OncoRes Medical.Optical coherence elastography (OCE) has been proposed for a range of clinical applications. However, the majority of these studies have been performed using bulks, lab based imaging systems. A compact. handheld imaging probe would accelerate clinical translation, however, to date. tins had been inhibited by the slow scan rates of compact devices and the motion artifact induced by the user's hand. In this paper, we present a proof-of-concept. handheld quantitative micro-elastography (QME) probe capable of scanning a 6 x 6 x 1 mm volume of tissue in 3.4 seconds. This handheld probe is enabled by a novel QME acquisition protocol that incorporates a custom bidirectional scan pattern driving a microelectromechanical system (MEMS) scanner, synchronized with the sample deformation induced by an annular PZT actuator. The custom scan pattern reduces the total acquisition time and the time difference between B-scans used to generate displacement maps. minimizing the impact of motion artifact. We test the feasibility of the handheld QME probe on a tissue-mimicking silicone phantom, demonstrating comparable image quality to a bench-mounted setup. In addition, we present the first handheld QME scans performed on human breast tissue specimens. For each specimen, quantitative micro-elastograms are co-registered with, and validated by, histology, demonstrating the ability-to distinguish stiff cancerous tissue from surrounding soft benign tissue.Publisher PDFPeer reviewe

Coherence function-encoded optical palpation

Optical palpation maps stress at the surface of biological tissue into 2D images. It relies on measuring surface deformation of a compliant layer, which to date has been performed with optical coherence tomography (OCT). OCT-based optical palpation holds promise for improved clinical diagnostics; however, the complexity and cost hinder broad adoption. In this Letter, we introduce coherence function-encoded optical palpation (CFE-OP) using a novel optical profilometry technique that exploits the envelope of the coherence function rather than its peak position, which is typically used to retrieve depth information. CFE-OP utilizes a Fabry–Perot laser diode (bandwidth, 2.2 nm) and a single photodiode in a Michelson interferometer to detect the position along the coherence envelope as a function of path length. This technique greatly reduces complexity and cost in comparison to the OCT-based approach. We perform CFE-OP on phantom and excised human breast tissue, demonstrating comparable mechanical contrast to OCT-based optical palpation and the capability to distinguish stiff tumor from soft benign tissue

Handheld probe for quantitative micro-elastography

Optical coherence elastography (OCE) has been proposed for a range of clinical applications. However, the majority of these studies have been performed using bulks, lab based imaging systems. A compact. handheld imaging probe would accelerate clinical translation, however, to date. tins had been inhibited by the slow scan rates of compact devices and the motion artifact induced by the user's hand. In this paper, we present a proof-of-concept. handheld quantitative micro-elastography (QME) probe capable of scanning a 6 x 6 x 1 mm volume of tissue in 3.4 seconds. This handheld probe is enabled by a novel QME acquisition protocol that incorporates a custom bidirectional scan pattern driving a microelectromechanical system (MEMS) scanner, synchronized with the sample deformation induced by an annular PZT actuator. The custom scan pattern reduces the total acquisition time and the time difference between B-scans used to generate displacement maps. minimizing the impact of motion artifact. We test the feasibility of the handheld QME probe on a tissue-mimicking silicone phantom, demonstrating comparable image quality to a bench-mounted setup. In addition, we present the first handheld QME scans performed on human breast tissue specimens. For each specimen, quantitative micro-elastograms are co-registered with, and validated by, histology, demonstrating the ability-to distinguish stiff cancerous tissue from surrounding soft benign tissue.</p

Optical palpation for tumor margin assessment in breast-conserving surgery

Intraoperative margin assessment is needed to reduce the re-excision rate of breastconserving surgery. One possibility is optical palpation, a tactile imaging technique that maps stress (force applied across the tissue surface) as an indicator of tissue stiffness. Images (optical palpograms) are generated by compressing a transparent silicone layer on the tissue and measuring the layer deformation using optical coherence tomography (OCT). This paper reports, for the first time, the diagnostic accuracy of optical palpation in identifying tumor within 1 mm of the excised specimen boundary using an automated classifier. Optical palpograms from 154 regions of interest (ROIs) from 71 excised tumor specimens were obtained. An automated classifier was constructed to predict the ROI margin status by first choosing a circle diameter, then searching for a location within the ROI where the circle was ≥ 75% filled with high stress (indicating a positive margin). A range of circle diameters and stress thresholds, as well as the impact of filtering out non-dense tissue regions, were tested. Sensitivity and specificity were calculated by comparing the automated classifier results with the true margin status, determined from co-registered histology. 83.3% sensitivity and 86.2% specificity were achieved, compared to 69.0% sensitivity and 79.0% specificity obtained with OCT alone on the same dataset using human readers. Representative optical palpograms show that positive margins containing a range of cancer types tend to exhibit higher stress compared to negative margins. These results demonstrate the potential of optical palpation for margin assessment

Handheld volumetric manual compression-based quantitative microelastography

This research was supported by grants and fellowships from the Australian Research Council, the National Health and Medical Research Council (Australia), the National Breast Cancer Foundation (Australia), the Department of Health, Western Australia, the Cancer Council, Western Australia and through a research contract with OncoRes Medical, Australia.Compression optical coherence elastography (OCE) typically requires a mechanical actuator to impart a controlled uniform strain to the sample. However, for handheld scanning, this adds complexity to the design of the probe and the actuator stroke limits the amount of strain that can be applied. In this work, we present a new volumetric imaging approach that utilizes bidirectional manual compression via the natural motion of the user's hand to induce strain to the sample, realizing compact, actuator‐free, handheld compression OCE. In this way, we are able to demonstrate rapid acquisition of three‐dimensional quantitative microelastography (QME) datasets of a tissue volume (6 × 6 × 1 mm3) in 3.4 seconds. We characterize the elasticity sensitivity of this freehand manual compression approach using a homogeneous silicone phantom and demonstrate comparable performance to a benchtop mounted, actuator‐based approach. In addition, we demonstrate handheld volumetric manual compression‐based QME on a tissue‐mimicking phantom with an embedded stiff inclusion and on freshly excised human breast specimens from both mastectomy and wide local excision (WLE) surgeries. Tissue results are coregistered with postoperative histology, verifying the capability of our approach to measure the elasticity of tissue and to distinguish stiff tumor from surrounding soft benign tissue.PostprintPeer reviewe

De noodzaak van verheffing - Over mateloosheid en de hegemonie van de 'eigen keuze'-doctrine

Wide-field quantitative_micro-elastography of a freshly excised mastectomy specimen containing ductal carcinoma in situ