Determination of scattering properties and damage thresholds in tissue using ultrafast laser ablation

Martin, Chris; Ben‐Yakar, Adela

doi:10.1117/1.jbo.21.11.115004

Cited by 8 publications

(15 citation statements)

References 33 publications

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“…We determined an average porcine l s;ep ¼ 59.9 AE 4.1 μm, which is within 20% of our previous findings. 19 The negligible variation in F th;ep for N ≥ 12 is in agreement with Rosenfeld et al, 26 which states that F th reaches a steady state value for N > 20 in dielectric materials such as glass where ablation initiates as optical breakdown. In tissue ablation, there is an additional regime of ablation where low-density plasma can lead to ROS-initiated photodamage.…”

Section: Porcine Pulse Overlap Studysupporting

confidence: 84%

“…To measure the optical properties of excised human and canine VF samples, we used a laser ablation-based method that we recently developed. 19 Using this method, we can simultaneously determine both scattering lengths and ablation thresholds in multiple layers of a heterogenous tissue. The method relies on finding input energies required to initiate ablation at multiple depths in each tissue layer.…”

Section: Experimental Approachmentioning

confidence: 99%

“…Additionally, homogenization is known to decrease optical scattering, thus reducing similarity to native tissue. 18 Prior work by our group and others has shown variations in optical properties for different tissue layers, 16,[19][20][21] and a priori knowledge of the optical properties of individual tissue layers is required to implement subsurface void creation for the proposed scarred VF treatment method.…”

Section: Introductionmentioning

confidence: 99%

“…16 and expanded in Ref. 19, allows for simultaneous determination of scattering lengths and ablation thresholds of individual layers in thick, multilayer tissues without requiring any sample processing. Results, obtained from multiple human VF samples as well as canine, which is the animal model of choice for preclinical testing of laryngeal treatments, provide a guideline for designing the necessary laser surgery conditions for future clinical treatment.…”

Section: Introductionmentioning

confidence: 99%

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Scattering properties and femtosecond laser ablation thresholds of human and canine vocal folds at 776-nm wavelength

2019

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Ultrafast laser ablation may provide a treatment for vocal fold (VF) scarring. Optical properties of VFs must be known prior to clinical implementation to select appropriate laser surgery conditions. We present scattering lengths of epithelium l s;ep , superficial lamina propria l s;SLP , and ablation thresholds F th of human and canine VF tissues. Our experimental approach involves an image-guided, laser-ablation-based method that allows for simultaneous determination of l s and F th in these multilayered tissues. Studying eight canine samples, we found l s;ep ¼ 75.3 AE 5.7 μm, l s;SLP ¼ 26.1 AE 1.2 μm, F th;ep ¼ 1.58 AE 0.06 J∕cm 2 , and F th;SLP ¼ 1.55 AE 0.17 J∕cm 2. Studying five human samples, we found l s;ep ¼ 42.8 AE 3.3 μm and F th;ep ¼ 1.66 AE 0.10 J∕cm 2. We studied the effects of cumulative pulse overlap on ablation threshold and found no significant variations beyond 12 overlapping pulses. Interestingly, our studies about the effect of sample storage on the scattering properties of porcine VF show a 60% increase in l s;ep for fresh porcine VF when compared to the same sample stored in isotonic solution. These results provide guidelines for clinical implementation by enabling selection of optimal laser surgery parameters for subsurface ablation of VF tissues.

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Section: Porcine Pulse Overlap Studysupporting

confidence: 84%

Section: Experimental Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Scattering properties and femtosecond laser ablation thresholds of human and canine vocal folds at 776-nm wavelength

2019

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“…Both of these methods rely on the assumption that ballistic photons are mostly responsible for the signal acquired in the photon multiplier tube (PMT). In order to determine the optical properties at the excitation wavelength more precisely, creating small laser ablation spots has been suggested for turbid tissues 9,24 . In these studies, tissues are ablated at different depths with different pulse energies to determine the tissue optical properties and threshold energies for ablation in each tissue layer.…”

Section: Introductionmentioning

confidence: 99%

Functional imaging of visual cortical layers and subplate in awake mice with optimized three-photon microscopy

et al. 2019

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Two-photon microscopy is used to image neuronal activity, but has severe limitations for studying deeper cortical layers. Here, we developed a custom three-photon microscope optimized to image a vertical column of the cerebral cortex > 1 mm in depth in awake mice with low (<20 mW) average laser power. Our measurements of physiological responses and tissue-damage thresholds define pulse parameters and safety limits for damage-free three-photon imaging. We image functional visual responses of neurons expressing GCaMP6s across all layers of the primary visual cortex (V1) and in the subplate. These recordings reveal diverse visual selectivity in deep layers: layer 5 neurons are more broadly tuned to visual stimuli, whereas mean orientation selectivity of layer 6 neurons is slightly sharper, compared to neurons in other layers. Subplate neurons, located in the white matter below cortical layer 6 and characterized here for the first time, show low visual responsivity and broad orientation selectivity.

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Ultrafast laser surgery probe for sub-surface ablation to enable biomaterial injection in vocal folds

Andrus

Jeon

Pawłowski

et al. 2022

Sci Rep

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Creation of sub-epithelial voids within scarred vocal folds via ultrafast laser ablation may help in localization of injectable therapeutic biomaterials towards an improved treatment for vocal fold scarring. Several ultrafast laser surgery probes have been developed for precise ablation of surface tissues; however, these probes lack the tight beam focusing required for sub-surface ablation in highly scattering tissues such as vocal folds. Here, we present a miniaturized ultrafast laser surgery probe designed to perform sub-epithelial ablation in vocal folds. The requirement of high numerical aperture for sub-surface ablation, in addition to the small form factor and side-firing architecture required for clinical use, made for a challenging optical design. An Inhibited Coupling guiding Kagome hollow core photonic crystal fiber delivered micro-Joule level ultrashort pulses from a high repetition rate fiber laser towards a custom-built miniaturized objective, producing a 1/e2 focal beam radius of 1.12 ± 0.10 μm and covering a 46 × 46 μm2 scan area. The probe could deliver up to 3.8 μJ pulses to the tissue surface at 40% transmission efficiency through the entire system, providing significantly higher fluences at the focal plane than were required for sub-epithelial ablation. To assess surgical performance, we performed ablation studies on freshly excised porcine hemi-larynges and found that large area sub-epithelial voids could be created within vocal folds by mechanically translating the probe tip across the tissue surface using external stages. Finally, injection of a model biomaterial into a 1 × 2 mm2 void created 114 ± 30 μm beneath the vocal fold epithelium surface indicated improved localization when compared to direct injection into the tissue without a void, suggesting that our probe may be useful for pre-clinical evaluation of injectable therapeutic biomaterials for vocal fold scarring therapy. With future developments, the surgical system presented here may enable treatment of vocal fold scarring in a clinical setting.

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Determination of scattering properties and damage thresholds in tissue using ultrafast laser ablation

Abstract: , "Determination of scattering properties and damage thresholds in tissue using ultrafast laser ablation," J.

Cited by 8 publications

References 33 publications

Scattering properties and femtosecond laser ablation thresholds of human and canine vocal folds at 776-nm wavelength

Scattering properties and femtosecond laser ablation thresholds of human and canine vocal folds at 776-nm wavelength

Functional imaging of visual cortical layers and subplate in awake mice with optimized three-photon microscopy

Ultrafast laser surgery probe for sub-surface ablation to enable biomaterial injection in vocal folds

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