1. Articles from Andrea Curatolo

    1-24 of 30 1 2 »
    1. Feature Of The Week 04.26.2020: Diagnostic Accuracy of Quantitative Micro-Elastography for Margin Assessment in Breast-Conserving Surgery

      Feature Of The Week 04.26.2020: Diagnostic Accuracy of Quantitative Micro-Elastography for Margin Assessment in Breast-Conserving Surgery

      Inadequate margins in breast-conserving surgery (BCS) are associated with an increased likelihood of local recurrence of breast cancer. Currently, approximately 20% of BCS patients require repeat surgery due to inadequate margins at the initial operation. Implementation of an accurate, intraoperative margin assessment tool may reduce this re-excision rate. This study determined, for the first time, the diagnostic accuracy of quantitative micro-elastography (QME), an optical coherence tomography (OCT)–based elastography technique that produces images of tissue microscale elasticity, for detecting tumor within 1 mm of the margins of BCS specimens. Simultaneous OCT and QME were performed on the margins of intact ...

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    2. Diagnostic Accuracy of Quantitative Micro-Elastography for Margin Assessment in Breast-Conserving Surgery

      Diagnostic Accuracy of Quantitative Micro-Elastography for Margin Assessment in Breast-Conserving Surgery

      Inadequate margins in breast-conserving surgery (BCS) are associated with an increased likelihood of local recurrence of breast cancer. Currently, approximately 20% of BCS patients require repeat surgery due to inadequate margins at the initial operation. Implementation of an accurate, intraoperative margin assessment tool may reduce this re-excision rate. This study determined, for the first time, the diagnostic accuracy of quantitative micro-elastography (QME), an optical coherence tomography (OCT)–based elastography technique that produces images of tissue microscale elasticity, for detecting tumor within 1 mm of the margins of BCS specimens. Simultaneous OCT and QME were performed on the margins of intact ...

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    3. Handheld volumetric manual compression‐based quantitative micro‐elastography

      Handheld volumetric manual compression‐based quantitative micro‐elastography

      Compression optical coherence elastography 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 utilises bidirectional manual compression via the natural motion of the user's hand to induce strain to the sample, realising compact, actuator‐free, handheld compression optical coherence elastography. In this way, we are able to demonstrate rapid acquisition of three‐dimensional quantitative micro‐elastography (QME ...

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    4. Handheld probe for quantitative micro-elastography

      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 bulky, lab-based imaging systems. A compact, handheld imaging probe would accelerate clinical translation, however, to date, this 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 × 6 × 1 mm volume of tissue in 3.4 seconds. This handheld probe is enabled by a novel QME acquisition protocol that ...

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    5. Finger-mounted quantitative micro-elastography

      Finger-mounted quantitative micro-elastography

      We present a finger-mounted quantitative micro-elastography (QME) probe, capable of measuring the elasticity of biological tissue in a format that avails of the dexterity of the human finger. Finger-mounted QME represents the first demonstration of a wearable elastography probe. The approach realizes optical coherence tomography-based elastography by focusing the optical beam into the sample via a single-mode fiber that is fused to a length of graded-index fiber. The fiber is rigidly affixed to a 3D-printed thimble that is mounted on the finger. Analogous to manual palpation, the probe compresses the tissue through the force exerted by the finger. The resulting ...

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    6. Handheld optical palpation of turbid tissue with motion-artifact correction

      Handheld optical palpation of turbid tissue with motion-artifact correction

      Handheld imaging probes are needed to extend the clinical translation of optical elastography to in vivo applications, yet such probes have received little attention. In this paper, we present the first demonstration of optical palpation using a handheld probe. Optical palpation is a variant of optical elastography that uses three-dimensional optical coherence tomography (3D-OCT) to provide maps of stress at the tissue surface under static compression. Using this technique, stiff features present beneath the surface of turbid tissues are identified, providing mechanical contrast complementary to the optical contrast provided by OCT. However, during handheld operation, relative motion between the probe ...

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    7. Realistic simulation and experiment reveals the importance of scatterer microstructure in optical coherence tomography image formation

      Realistic simulation and experiment reveals the importance of scatterer microstructure in optical coherence tomography image formation

      Realistic simulation of image formation in optical coherence tomography, based on Maxwell’s equations, has recently been demonstrated for sample volumes of practical significance. Yet, there remains a limitation whereby reducing the size of cells used to construct a computational grid, thus allowing for a more realistic representation of scatterer microstructure, necessarily reduces the overall sample size that can be modelled. This is a significant problem since, as is well known, the microstructure of a scatterer significantly influences its scattering properties. Here we demonstrate that an optimized scatterer design can overcome this problem resulting in good agreement between simulated and ...

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    8. Wide-field quantitative micro-elastography of human breast tissue

      Wide-field quantitative micro-elastography of human breast tissue

      Currently, 20-30% of patients undergoing breast-conserving surgery require a second surgery due to insufficient surgical margins in the initial procedure. We have developed a wide-field quantitative micro-elastography system for the assessment of tumor margins. In this technique, we map tissue elasticity over a field-of-view of ~46 × 46 mm. We performed wide-field quantitative micro-elastography on thirteen specimens of freshly excised tissue acquired from patients undergoing a mastectomy. We present wide-field optical coherence tomography (OCT) images, qualitative (strain) micro-elastograms and quantitative (elasticity) micro-elastograms, acquired in 10 minutes. We demonstrate that wide-field quantitative micro-elastography can extend the range of tumors visible using OCT-based ...

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    9. Ultrahigh-Resolution Optical Coherence Elastography Images Cellular-Scale Stiffness of Mouse Aorta

      Ultrahigh-Resolution Optical Coherence Elastography Images Cellular-Scale Stiffness of Mouse Aorta

      Cellular-scale imaging of the mechanical properties of tissue has helped to reveal the origins of disease; however, cellular-scale resolution is not readily achievable in intact tissue volumes. Here, we demonstrate volumetric imaging of Young’s modulus using ultrahigh-resolution optical coherence elastography, and apply it to characterizing the stiffness of mouse aortas. We achieve isotropic resolution of better than 15 μ m over a 1-mm lateral field of view through the entire depth of an intact aortic wall. We employ a method of quasi-static compression elastography that measures volumetric axial strain and uses a compliant, transparent layer to measure surface axial stress ...

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    10. Depth-encoded optical coherence elastography for simultaneous volumetric imaging of two tissue faces

      Depth-encoded optical coherence elastography for simultaneous volumetric imaging of two tissue faces

      Depth-encoded optical coherence elastography (OCE) enables simultaneous acquisition of two three-dimensional (3D) elastograms from opposite sides of a sample. By the choice of suitable path-length differences in each of two interferometers, the detected carrier frequencies are separated, allowing depth-ranging from each interferometer to be performed simultaneously using a single spectrometer. We demonstrate depth-encoded OCE on a silicone phantom and a freshly excised sample of mouse liver. This technique minimizes the required spectral detection hardware and halves the total scan time. Depth-encoded OCE may expedite clinical translation in time-sensitive applications requiring rapid 3D imaging of multiple tissue surfaces, such as tumor ...

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    11. Quantifying the influence of Bessel beams on image quality in optical coherence tomography

      Quantifying the influence of Bessel beams on image quality in optical coherence tomography

      Light scattered by turbid tissue is known to degrade optical coherence tomography (OCT) image contrast progressively with depth. Bessel beams have been proposed as an alternative to Gaussian beams to image deeper into turbid tissue. However, studies of turbid tissue comparing the image quality for different beam types are lacking. We present such a study, using numerically simulated beams and experimental OCT images formed by Bessel or Gaussian beams illuminating phantoms with optical properties spanning a range typical of soft tissue. We demonstrate that, for a given scattering parameter, the higher the scattering anisotropy the lower the OCT contrast, regardless ...

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    12. Ultrahigh-resolution optical coherence elastography

      Ultrahigh-resolution optical coherence elastography

      Visualizing stiffness within the local tissue environment at the cellular and subcellular level promises to provide insight into the genesis and progression of disease. In this Letter, we propose ultrahigh-resolution optical coherence elastography (UHROCE), and demonstrate 3D imaging of local axial strain of tissues undergoing compressive loading. We combine optical coherence microscopy (OCM) and phase-sensitive detection of local tissue displacement to produce strain elastograms with resolution (

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    13. Investigation of optical coherence micro-elastography as a method to visualize cancers in human breast tissue

      Investigation of optical coherence micro-elastography as a method to visualize cancers in human breast tissue

      Accurate intraoperative identification of malignant tissue is a challenge in the surgical management of breast cancer. Imaging techniques that help address this challenge could contribute to more complete and accurate tumor excision, and thereby help reduce the current high re-excision rates without resorting to the removal of excess healthy tissue. Optical coherence micro-elastography (OCME) is a three-dimensional, high-resolution imaging technique that is sensitive to micro-scale variations of the mechanical properties of tissue. As tumor modifies the mechanical properties of breast tissue, OCME has the potential to identify, on the micro-scale, involved regions of fresh, unstained tissue. OCME is based on ...

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    14. Full wave model of image formation in optical coherence tomography applicable to general samples

      Full wave model of image formation in optical coherence tomography applicable to general samples

      We demonstrate a highly realistic model of optical coherence tomography, based on an existing model of coherent optical microscopes, which employs a full wave description of light. A defining feature of the model is the decoupling of the key functions of an optical coherence tomography system: sample illumination, light-sample interaction and the collection of light scattered by the sample. We show how such a model can be implemented using the finite-difference time-domain method to model light propagation in general samples. The model employs vectorial focussing theory to represent the optical system and, thus, incorporates general illumination beam types and detection ...

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    15. Analysis of image formation in optical coherence elastography using a multiphysics approach

      Analysis of image formation in optical coherence elastography using a multiphysics approach

      Image formation in optical coherence elastography (OCE) results from a combination of two processes: the mechanical deformation imparted to the sample and the detection of the resulting displacement using optical coherence tomography (OCT). We present a multiphysics model of these processes, validated by simulating strain elastograms acquired using phase-sensitive compression OCE, and demonstrating close correspondence with experimental results. Using the model, we present evidence that the approximation commonly used to infer sample displacement in phase-sensitive OCE is invalidated for smaller deformations than has been previously considered, significantly affecting the measurement precision, as quantified by the displacement sensitivity and the elastogram ...

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    16. Optical coherence micro-elastography: mechanical-contrast imaging of tissue microstructure

      Optical coherence micro-elastography: mechanical-contrast imaging of tissue microstructure

      We present optical coherence micro-elastography, an improved form of compression optical coherence elastography. We demonstrate the capacity of this technique to produce en face images, closely corresponding with histology, that reveal micro-scale mechanical contrast in human breast and lymph node tissues. We use phase-sensitive, three-dimensional optical coherence tomography (OCT) to probe the nanometer-to-micrometer-scale axial displacements in tissues induced by compressive loading. Optical coherence micro-elastography incorporates common-path interferometry, weighted averaging of the complex OCT signal and weighted least-squares regression. Using three-dimensional phase unwrapping, we have increased the maximum detectable strain eleven-fold over no unwrapping and the minimum detectable strain is 2 ...

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    17. Energy-efficient low-Fresnel-number Bessel beams and their application in optical coherence tomography

      Energy-efficient low-Fresnel-number Bessel beams and their application in optical coherence tomography

      Bessel beams feature a very large depth-of-focus (DOF) compared to conventional focusing schemes, but their central lobe carries only a small fraction of the total beam power, leading to a strongly reduced peak irradiance. This is problematic for power-limited applications, such as optical coherence tomography (OCT) or optical coherence microscopy, as it can result in a prohibitive reduction of the signal-to-noise ratio (SNR). Using scalar diffraction theory, we show that the trade-off between DOF and peak irradiance of Bessel beams depends solely on the Fresnel number N . We demonstrate the existence of a low-Fresnel-number regime, N < 10 , in which axicons ...

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    18. A Microscope in a Needle

      A Microscope in a Needle

      A microscope small enough to fit into a needle creates many new possibilities for optics in medicine. We have developed a range of optical coherence tomography (OCT) needle probes. Connected to an OCT scanner via a single mode fiber, the probes are constructed by fusing exact lengths of no-core fiber and graded-index fiber to focus a broadband light beam. We terminated the optics with anglepolished, gold-coated no-core fiber to deflect the beam. Encased in a needle (outer diameter 310 ?m), these probes are capable of 3-D imaging. However, the important developments of 2012 have been where we have taken these ...

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    19. Ultrasound-Guided Optical Coherence Tomography Needle Probe for the Assessment of Breast Cancer Tumor Margins

      Ultrasound-Guided Optical Coherence Tomography Needle Probe for the Assessment of Breast Cancer Tumor Margins

      OBJECTIVE.The purpose of this study was to evaluate a new imaging technique for the assessment of breast cancer tumor margins. The technique entails deployment of a high-resolution optical imaging needle under ultrasound guidance. Assessment was performed on fresh ex vivo tissue samples. CONCLUSION. Use of the ultrasound-guided optical needle probe allowed in situ assessment of fresh tissue margins. The imaging findings corresponded to the histologic findings.

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    20. Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography

      Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography

      We review the development of phantoms for optical coherence tomography (OCT) designed to replicate the optical, mechanical and structural properties of a range of tissues. Such phantoms are a key requirement for the continued development of OCT techniques and applications. We focus on phantoms based on silicone, fibrin and poly(vinyl alcohol) cryogels (PVA-C), as we believe these materials hold the most promise for durable and accurate replication of tissue properties.

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    21. Imaging of Breast Cancer with Optical Coherence Tomography Needle Probes: Feasibility and Initial Results

      Imaging of Breast Cancer with Optical Coherence Tomography Needle Probes: Feasibility and Initial Results

      Optical coherence tomography (OCT) is a high-resolution imaging modality with the potential to provide in situ assessment to distinguish normal from cancerous tissue. However, limited image penetration depth has restricted its utility. This paper demonstrates the feasibility of an OCT needle probe to perform interstitial imaging deep below the tissue surface. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within either a 22- or 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. We present the first published image of a human breast cancer tumor margin ...

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    22. Structured three-dimensional optical phantom for optical coherence tomography

      Structured three-dimensional optical phantom for optical coherence tomography
      We present a three-dimensional structured tissue-mimicking phantom for use in optical coherence tomography (OCT). The phantom was fabricated from a silicone matrix and titanium dioxide additive using a lithographic casting method capable of producing a wide range of well-defined geometries with optical contrast and mesoscopic feature sizes relevant to OCT. We describe the fabrication, characterization and OCT imaging of two phantoms and demonstrate their utility in assessing the performance of a spatial-diversity speckle reduction technique. Such phantoms will be important in the development of standards in OCT, as well as in enabling quantitative performance assessment.
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    23. 3D visualization of tissue microstructures using optical coherence tomography needle probes

      3D visualization of tissue microstructures using optical coherence tomography needle probes

      Optical coherence tomography (OCT) needle probes use miniaturized focusing optics encased in a hypodermic needle. Needle probes can scan areas of the body that are too deep to be imaged by other OCT systems. This paper presents an OCT needle probe-based system that is capable of acquiring three-dimensional scans of tissue structures. The needle can be guided to a target area and scans acquired by rotating and pulling-back the probe. The system is demonstrated using ex vivo human lymph node and sheep lung samples. Multiplanar reconstructions are shown of both samples, as well as the first published 3D volume rendering ...

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    24. In situ imaging of lung alveoli with an optical coherence tomography needle probe

      In situ imaging of lung alveoli with an optical coherence tomography needle probe

      In situ imaging of alveoli and the smaller airways with optical coherence tomography (OCT) has significant potential in the assessment of lung disease. We present a minimally invasive imaging technique utilizing an OCT needle probe. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within a 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. The probe was used to image an intact, fresh (not fixed) sheep lung filled with normal saline, and the results validated against a histological gold standard. We present the first published images ...

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    1-24 of 30 1 2 »
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    1. (29 articles) University of Western Australia
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