Dual-coil magnetomotive optical coherence tomography for contrast enhancement in liquids.
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ABSTRACT:
SUBMITTER: Kim J
PROVIDER: S-EPMC3635698 | biostudies-other | 2013 Mar
REPOSITORIES: biostudies-other
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Project description:BackgroundCoronary revascularization using imaging guidance is rapidly becoming the standard of care. Intravascular optical coherence tomography uses near-infrared light to obtain high resolution intravascular images. Standard optical coherence tomography imaging technique employs iodinated contrast dye to achieve the required blood clearance during acquisition. We sought to systematically evaluate the technical performance of saline as an alternative to iodinated contrast for intravascular optical coherence tomography assessment.Methods and resultsWe performed bench top optical coherence tomography analysis on nylon tubing with sequential contrast/saline dilutions to empirically derive adjustment coefficients. We then applied these coefficients in vivo in an established rabbit abdominal stenting model with both saline and contrast optical coherence tomography imaging. In this model, we assessed the impact of saline on both quantitative and qualitative vessel assessment. Nylon tubing assessment demonstrated a linear relationship between saline and contrast for both area and diameter. We then derived adjustment coefficients, allowing for accurate calculation of area and diameter when converting saline into both contrast and reference dimensions. In vivo studies confirmed reduced area with saline versus contrast [7.43 (5.67-8.36) mm2 versus 8.2 (6.34-9.39) mm2, p = 0.001] and diameter [3.08 mm versus 3.23 mm, p = 0.001]. Following correction, a strong relationship was achieved in vivo between saline and contrast in both area and diameter without compromising image quality, artefact, or strut assessment.ConclusionSaline generates reduced dimensions compared to contrast during intravascular optical coherence tomography imaging. The relationship across physiologic coronary diameters is linear and can be corrected with high fidelity. Saline does not adversely impact image quality, artefact, or strut assessment.
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Project description:PurposeTo investigate gold nanorods (GNRs) as a contrast agent to enhance Doppler optical coherence tomography (OCT) imaging of the intrascleral aqueous humor outflow.MethodsA serial dilution of GNRs was scanned with a spectral-domain OCT device (Bioptigen, Durham, NC) to visualize Doppler signal. Doppler measurements using GNRs were validated using a controlled flow system. To demonstrate an application of GNR enhanced Doppler, porcine eyes were perfused at constant pressure with mock aqueous alone or 1.0×10(12) GNR/mL mixed with mock aqueous. Twelve Doppler and volumetric SD-OCT scans were obtained from the limbus in a radial fashion incremented by 30°, forming a circular scan pattern. Volumetric flow was computed by integrating flow inside non-connected vessels throughout all 12 scans around the limbus.ResultsAt the GNR concentration of 0.7×10(12) GNRs/mL, Doppler signal was present through the entire depth of the testing tube without substantial attenuation. A well-defined laminar flow profile was observed for Doppler images of GNRs flowing through the glass capillary tube. The Doppler OCT measured flow profile was not statistically different from the expected flow profile based upon an autoregressive moving average model, with an error of -0.025 to 0.037 mm/s (p = 0.6435). Cross-sectional slices demonstrated the ability to view anterior chamber outflow ex-vivo using GNR-enhanced Doppler OCT. Doppler volumetric flow measurements were comparable to flow recorded by the perfusion system.ConclusionsGNRs created a measureable Doppler signal within otherwise silent flow fields in OCT Doppler scans. Practical application of this technique was confirmed in a constant pressure ex-vivo aqueous humor outflow model in porcine eyes.
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Project description:This article introduces a new functional imaging paradigm that uses optical coherence tomography (OCT) to detect rehydrated, lyophilized platelets (RL platelets) that are in the preclinical trial stage and contain superparamagnetic iron oxides (SPIOs) approved by the U.S. Food and Drug Administration. Platelets are highly functional blood cells that detect and adhere to sites of vascular endothelial damage by forming primary hemostatic plugs. By applying magnetic gradient forces, induced nanoscale displacements (magnetomotion) of the SPIO-RL platelets are detected as optical phase shifts in OCT. In this article, we characterize the iron content and magnetic properties of SPIO-RL platelets, construct a model to predict their magnetomotion in a tissue medium, and demonstrate OCT imaging in tissue phantoms and ex vivo pig arteries. Tissue phantoms containing SPIO-RL platelets exhibited >3 dB contrast/noise ratio at ?1.5 × 10(9) platelets/cm(3). OCT imaging was performed on ex vivo porcine arteries after infusion of SPIO-RL platelets, and specific contrast was obtained on an artery that was surface-damaged (P < 10(-6)). This may enable new technologies for in vivo monitoring of the adherence of SPIO-RL platelets to sites of bleeding and vascular damage, which is broadly applicable for assessing trauma and cardiovascular diseases.
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Project description:BackgroundInflammatory skin diseases, such as psoriasis, atopic eczema, and contact dermatitis pose diagnostic challenges due to their diverse clinical presentations and the need for rapid and precise diagnostic assessment.ObjectiveWhile recent studies described non-invasive imaging devices such as Optical coherence tomography and Line-field confocal OCT (LC-OCT) as possible techniques to enable real-time visualization of pathological features, a standardized analysis and validation has not yet been performed.MethodsOne hundred forty lesions from patients diagnosed with atopic eczema (57), psoriasis (50), and contact dermatitis (33) were imaged using OCT and LC-OCT. Statistical analysis was employed to assess the significance of their characteristic morphologic features. Additionally, a decision tree algorithm based on Gini's coefficient calculations was developed to identify key attributes and criteria for accurately classifying the disease groups.ResultsDescriptive statistics revealed distinct morphologic features in eczema, psoriasis, and contact dermatitis lesions. Multivariate logistic regression demonstrated the significance of these features, providing a robust differentiation between the three inflammatory conditions. The decision tree algorithm further enhanced classification accuracy by identifying optimal attributes for disease discrimination, highlighting specific morphologic criteria as crucial for rapid diagnosis in the clinical setting.ConclusionThe combined approach of descriptive statistics, multivariate logistic regression, and a decision tree algorithm provides a thorough understanding of the unique aspects associated with each inflammatory skin disease. This research offers a practical framework for lesion classification, enhancing the interpretability of imaging results for clinicians.
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