The effect of temperature on the autofluorescence of scattering and non‐scattering tissue

Walsh, Alex J.; Masters, David B.; Jansen, E.; Welch, Ashley J.; Mahadevan‐Jansen, Anita

doi:10.1002/lsm.22080

Cited by 10 publications

(8 citation statements)

References 27 publications

(43 reference statements)

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“…Once the integrity of the cardiac muscle cells is destroyed due to RF or other means of ablation, the NADH levels irreversibly decline 13 . The secondary fluorophores found in cardiac muscle cells include flavins, flavoproteins, lipids, lipofuscin, and lipid-protein conjugates 18,22 . They fluoresce at longer wavelengths (< 500 nm), but their overall signal from the unablated muscle is weaker compared to the NADH signal.…”

Section: Resultsmentioning

confidence: 99%

“…Yet it is possible that in vivo, a larger contribution from endocardial cells will be seen. Notably, one should not confuse ablation-induced NADH loss from viable cells present within the endocardium with a transient decrease in collagen autofluorescence upon heating 22 . In contrast to irreversible NADH decline in injured cells, collagen autofluorescence bounces back when the tissue cools to its original temperature.…”

Section: Discussionmentioning

confidence: 99%

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Key factors behind autofluorescence changes caused by ablation of cardiac tissue

Muselimyan

Asfour

Sarvazyan

2020

Sci Rep

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Radiofrequency ablation is a commonly used clinical procedure that destroys arrhythmogenic sources in patients suffering from atrial fibrillation and other types of cardiac arrhythmias. To improve the success of this procedure, new approaches for real-time visualization of ablation sites are being developed. One of these promising methods is hyperspectral imaging, an approach that detects lesions based on changes in the endogenous tissue autofluorescence profile. To facilitate the clinical implementation of this approach, we examined the key variables that can influence ablation-induced spectral changes, including the drop in myocardial NADH levels, the release of lipofuscin-like pigments, and the increase in diffuse reflectance of the cardiac muscle beneath the endocardial layer. Insights from these experiments suggested simpler algorithms that can be used to acquire and post-process the spectral information required to reveal the lesion sites. Our study is relevant to a growing number of multilayered clinical targets to which spectral approaches are being applied.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Key factors behind autofluorescence changes caused by ablation of cardiac tissue

Muselimyan

Asfour

Sarvazyan

2020

Sci Rep

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“…With 75 mW of power irradiation, dermal fiber alteration first became apparent at 3 s. By 9 s obvious changes were seen in both the RCM and SHG + TPF imaging channels. We believe that during the laser treatment, both elastic and collagen fibers were denatured due to the increased temperature, which accounted for the loss of TPF + SHG signals [11][12]. Figure 2b shows representative RCM and SHG + TPF images comparing before and after targeted treatment as monitored at different tissue depths.…”

Section: Resultsmentioning

confidence: 99%

Imaging directed photothermolysis through two‐photon absorption demonstrated on mouse skin – a potential novel tool for highly targeted skin treatment

Wang

Zandi

Lee

et al. 2013

Journal of Biophotonics

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One-photon absorption based traditional laser treatment may not necessarily be selective at the microscopic level, thus could result in un-intended tissue damage. Our objective is to test whether two-photon absorption (TPA) could provide highly targeted tissue alteration of specific region of interest without damaging surrounding tissues. TPA based laser treatments (785 nm, 140 fs pulse width, 90 MHz) were performed on ex vivo mouse skin using different average power levels and irradiation times. Reflectance confocal microscopy (RCM) and combined second-harmonic-generation (SHG) and two-photon fluorescence (TPF) imaging channels were used to image before, during, and after each laser treatment. The skin was fixed, sectioned and H & E stained after each experiment for histological assessment of tissue alterations and for comparison with the non-invasive imaging assessments. Localized destruction of dermal fibers was observed without discernible epidermal damage on both RCM and SHG + TPF images for all the experiments. RCM and SHG + TPF images correlated well with conventional histological examination. This work demonstrated that TPA-based light treatment provides highly localized intradermal tissue alteration. With further studies on optimizing laser treatment parameters, this two-photon absorption photothermolysis method could potentially be applied in clinical dermatology.

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“…These samples were processed at room temperature (25 °C) after which sections were allowed to dry on microscope slides. However, temperature or hydration of the tissue may affect fluorescence yield and warrant further exploration [27,28]. The fluorescent intensities from the epidermis, hair follicles and sebaceous glands captured in images acquired with conventional microscopy tracked the yield trend of endogenous fluorescence from individual donors and provided qualitative comparatives to the measurements (Figs.…”

Section: Discussionmentioning

confidence: 99%

Characterization of human cutaneous tissue autofluorescence: implications in topical drug delivery studies with fluorescence microscopy

Hermsmeier¹,

Jeong

Yamamoto³

et al. 2018

Biomed. Opt. Express

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In pharmacokinetic studies of topical drugs, fluorescence microscopy methods can enable the direct visualization and quantification of fluorescent drugs within the skin. One potential limitation of this approach, however, is the strong endogenous fluorescence of skin tissues that makes straightforward identification of specific drug molecules challenging. To study this effect and quantify endogenous skin fluorescence in the context of topical pharmacokinetics, an integrating sphere-based screening tool was designed to collect fluorescence yield data from human skin specimens. Such information could be utilized to select specific donors in the investigation of drug uptake and distribution. Results indicated human facial skin specimens from a group of more than 35 individuals exhibited an at least 6fold difference in endogenous fluorescence. In visualizing drug distributions, the negative impact of autofluorescence could be exacerbated in cases where there are overlapping spatial distributions or spectral emission profiles between endogenous fluorophores and the exogenous fluorophore of interest. We demonstrated the feasibility of this approach in measuring the range of tissue endogenous fluorescence and selecting specimens for the study of drug pharmacokinetics with fluorescence microscopy.

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The effect of temperature on the autofluorescence of scattering and non‐scattering tissue

Cited by 10 publications

References 27 publications

Key factors behind autofluorescence changes caused by ablation of cardiac tissue

Key factors behind autofluorescence changes caused by ablation of cardiac tissue

Imaging directed photothermolysis through two‐photon absorption demonstrated on mouse skin – a potential novel tool for highly targeted skin treatment

Characterization of human cutaneous tissue autofluorescence: implications in topical drug delivery studies with fluorescence microscopy

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