Nanobomb optical coherence elastography

Liu, Chih-Hao; Nevozhay, Dmitry; Schill, Alexander; Singh, Manmohan; Das, Susobhan; Nair, Achuth; Han, Zhaolong; Aglyamov, Salavat R.; Larin, Kirill V.; Sokolov, Konstantin

doi:10.1364/ol.43.002006

Cited by 28 publications

(32 citation statements)

References 26 publications

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“…For example, features with a lateral length of 20 μm in excised mouse aorta were observed with a measured equivalent Gaussian FWHM lateral feature resolution of approximately 10 μm to 15 μm [27], which is consistent with our framework. However, the diameter of many animal cells lies below 10 μm [49], and to study cells with a feature resolution below this limit will likely require solving more complex mechanical models, or indeed employing techniques that localize deformation [19][20][21][22]. The limit on achievable resolution may result in compression OCE being most useful in studying the mechanical properties over the entirety of the cell and the interactions between the cell and its environment over relatively large fields-of-view.…”

Section: Discussionmentioning

confidence: 99%

Analysis of spatial resolution in phase-sensitive compression optical coherence elastography

Hepburn¹,

Wijesinghe²,

Chin³

et al. 2019

Biomed. Opt. Express

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Optical coherence elastography (OCE) is emerging as a method to image the mechanical properties of tissue on the microscale. However, the spatial resolution, a main advantage of OCE, has not been investigated and is not trivial to evaluate. To address this, we present a framework to analyze resolution in phase-sensitive compression OCE that incorporates the three main determinants of resolution: mechanical deformation of the sample, detection of this deformation using optical coherence tomography (OCT), and signal processing to estimate local axial strain. We demonstrate for the first time, through close correspondence between experiment and simulation of structured phantoms, that resolution in compression OCE is both spatially varying and sample dependent, which we link to the discrepancies between the model of elasticity and the mechanical deformation of the sample. We demonstrate that resolution is dependent on factors such as feature size and mechanical contrast. We believe that the analysis of image formation provided by our framework can expedite the development of compression OCE.

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Section: Discussionmentioning

confidence: 99%

Analysis of spatial resolution in phase-sensitive compression optical coherence elastography

Hepburn¹,

Wijesinghe²,

Chin³

et al. 2019

Biomed. Opt. Express

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“…The nanodroplets were synthetized from a liquid dodecafluoropentane core coated by a mixture of phospholipids and Cyanine 3 (Cy3) dye molecules. The formulation was adopted from a previously described protocol [28]. Briefly, 1,2-distearoyl-sn-glycero-3phosphocholine (DSPC), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxypolyethyleneglycol-2000 (DSPE-PEG-2000), and cholesterol (all from Avanti Polar Lipids, Inc.) were dissolved in 2 mL of chloroform at a weight ratio of 90:8.5:1.5, respectively, and the total mass of 20 mg.…”

Section: Synthesis and Assessment Of Nanodropletsmentioning

confidence: 99%

“…In these studies, excitation of the nanodroplets occurs with nanosecond laser pulses, which are matched with the absorption band of an embedded dye, followed by a liquid to gas transition of the PFC core which elicits a strong photoacoustic signal. Using this principle, we recently demonstrated that the phase changing PFC nanodroplets can also be used to create localized, high frequency elastic waves in optical coherence elastography measurements [28,29]. PFC with relatively low boiling temperatures, e.g.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporally controlled nano-sized third harmonic generation agents

Nevozhay¹,

Weiger²,

Friedl³

et al. 2019

Biomed. Opt. Express

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Here, we present a new class of third harmonic generation (THG) imaging probes that can be activated with precise spatiotemporal control using non-linear excitation. These probes consist of lipid-coated perfluorocarbon nanodroplets with embedded visible chromophores. The droplets undergo phase transition from liquid to gas upon heating mediated by two-photon absorption of NIR light by the embedded dyes. Resulting microbubbles provide a sharp, local refractive index mismatch, which makes an excellent source of THG signal. Potential applications of these probes include activatable THG agents for biological imaging and "on-demand" delivery of various compounds under THG monitoring.

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“…To generate the elastic wave, the laser pulse should be efficiently absorbed and converted into heat by the tissue. Different techniques have been used to enhance the absorption of pulsed laser energy by the sample, such as the injection of nanoparticles, [35][36][37] droplets of perfluorocarbon, 38 and doping with graphite. 34 Naturally, the endogenous mechanism of the elastic wave generation would be preferred for many biological and clinical applications.…”

Section: Introductionmentioning

confidence: 99%

Laser-induced elastic wave classification: thermoelastic versus ablative regimes for all-optical elastography applications

et al. 2020

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Significance: Shear wave optical coherence elastography is an emerging technique for characterizing tissue biomechanics that relies on the generation of elastic waves to obtain the mechanical contrast. Various techniques, such as contact, acoustic, and pneumatic methods, have been used to induce elastic waves. However, the lack of higher-frequency components within the elastic wave restricts their use in thin samples. The methods also require moving parts and/or tubing, which therefore limits the extent to which they can be miniaturized. Aim: To overcome these limitations, we propose an all-optical approach using photothermal excitation. Depending on the absorption coefficient of the sample and the laser pulse energy, elastic waves are generated either through a thermoelastic or an ablative process. Our study aimed to experimentally determine the boundary between the thermoelastic and the ablative regimes for safe all-optical elastography applications. Approach: Tissue-mimicking graphite-doped phantoms and chicken liver samples were used to investigate the boundary between thermoelastic and ablative regimes. A pulsed laser at 532 nm was used to induce elastic waves in the samples. Laser-induced elastic waves were detected using a line field low coherence holography instrument. The shape of the elastic wave amplitude was analyzed and used to determine the transition point between thermoelastic and ablative regimes. Results: The transition from the thermoelastic to the ablative regime is accompanied by the nonlinear increase in surface wave amplitude as well as the transformation of the wave shape. Correlation between the absorption coefficient and the transition point energy was experimentally determined using graphite-doped phantoms and applied to biological samples ex vivo. Conclusions: Our study described a methodology for determining the boundary region between thermoelastic and ablative regimes of elastic wave generation. These can be used for the development of a safe method for completely noncontact, all-optical microscale assessment of tissue biomechanics using laser-induced elastic waves.

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Nanobomb optical coherence elastography

Cited by 28 publications

References 26 publications

Analysis of spatial resolution in phase-sensitive compression optical coherence elastography

Analysis of spatial resolution in phase-sensitive compression optical coherence elastography

Spatiotemporally controlled nano-sized third harmonic generation agents

Laser-induced elastic wave classification: thermoelastic versus ablative regimes for all-optical elastography applications

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