Measurement of optical properties of pig esophagus by using a modified spectrometer set‐up

Hohmann, Martin; Lengenfelder, Benjamin; Kanawade, Rajesh; Klämpfl, Florian; Douplik, Alexandre; Albrecht, Heinz

doi:10.1002/jbio.201600187

Cited by 11 publications

(8 citation statements)

References 28 publications

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“…For tissue temperature and corresponding thermal damage calculations, an esophageal tissue model with a uniform 3D grid system of 300 × 300 × 180 with a grid size of 10 μm of each dimension was used. The depth of the modeled tissue was determined by the sum of mucosa layer thickness (0.54 mm), submucosa layer thickness (0.55 mm), and muscularis layer thickness (0.63 mm) . Thermal properties of the tissue and optical properties at a wavelength of 1.5 μm have been compiled from the literature.…”

Section: Resultsmentioning

confidence: 99%

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Tozburun

2020

Journal of Biophotonics

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Superficial photothermal laser ablation (SPLA) may be useful as a therapeutic approach producing a depth of injury that is sufficient to eliminate mucosal lesion but not deep enough to induce thermal effects in deeper tissue layers. The purpose of this preliminary study is twofold: (a) to describe design steps of a fiber probe capable of delivering a tightly focused laser beam, including Monte-Carlobased simulations, and (b) to complete the initial testing of the probe in a sheep esophagus model, ex vivo. The cone-shaped (tapered) fiber tip was obtained by chemical etching of the optical fiber. A 1505 nm diode laser providing power up to 500 mW was operated in continuous wave. The successful SPLA of the sheep mucosa layer was demonstrated for various speed-power combinations, including 300 mW laser power at a surface scanning rate of 0.5 mm/s and 450 mW laser power at a surface scanning rate of 2.0 mm/s. Upon further development, this probe may be useful for endoscopic photothermal laser ablation of the mucosa layer using relatively low laser power. K E Y W O R D S chemical etching, fiber probe, Monte Carlo, mucosa, photothermal ablation

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Section: Resultsmentioning

confidence: 99%

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Tozburun

2020

Journal of Biophotonics

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“…The data from Holmer et al 25 is used due to the fact that Holmer et al 25 measured the optical properties from carcinoma and from healthy oesophagus. However, there is a high chance that the measurements from Holmer et al 25 have a systematic error as shown by Hohmann et al 26 . Despite the fact that they use cryo-homogenisation, this should not influence the optical properties 27 .…”

Section: Methodsmentioning

confidence: 98%

“…For the simulation, a carcinoma in oesophageal tissue is simulated due to the fact that the optical properties (μ a , μ s or g) of these tissue types is known. The optical properties are taken from the study from Holmer et al 25 instead of the own optical properties 26 . The data from Holmer et al 25 is used due to the fact that Holmer et al 25 measured the optical properties from carcinoma and from healthy oesophagus.…”

Section: Methodsmentioning

confidence: 99%

Factors influencing the accuracy for tissue classification in multi spectral in-vivo endoscopy for the upper gastro-internal tract

Hohmann

Albrecht

Lengenfelder

et al. 2020

Sci Rep

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Hyper spectral imaging is a possible way for disease detection. However, for carcinoma detection most of the results are ex-vivo. However, in-vivo results of endoscopic studies still show fairly low accuracies in contrast to the good results of many ex-vivo studies. To overcome this problem and to provide a reasonable explanation, Monte-Carlo simulations of photon trajectories are proposed as a tool to generate multi spectral images including inter patient variations to simulate 40 patients. Furthermore, these simulations have the huge advantage that the position of the carcinoma is known. Due to this, the effect of mislabelled data can be studied. As shown in this study, a percentage of 30–35% of mislabelled data might lead to significant decrease of the accuracy from around 90% to around 70–75%. Therefore, the main focus of hyper spectral imaging has to be the exact characterization of the training data in the future.

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“…A uniform grid system (i.e., 100 × 100 × 100) with a mesh size of 40 × 40 × 40 µm 3 constituted the 3D structure. The thickness of the tissue sample was determined to be 4 mm, which is the sum of mucosal layer thickness (0.54 mm), submucosal layer thickness (0.55 mm), muscularis layer thickness (0.63 mm), and muscle layer (>2 mm) 9 . The third module simulated the time‐dependent heat diffusion generated by laser power density (i.e., laser irradiance) utilized as a heat source.…”

Section: Methodsmentioning

confidence: 99%

Guide mapping for effective superficial photothermal coagulation of the esophagus using computer simulations with ex vivo sheep model validation study

et al. 2022

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Objectives The transfer and widespread acceptance of laser‐induced thermal therapy into gastroenterology remain a topic of interest. However, a practical approach to the quantitative effect of photothermal injury in the esophagus needs further investigation. Here, we aim to perform computer simulations that simulate laser scanning and calculate the laser‐induced thermal damage area. The simulation engine offers the results in a guide map for laser coagulation with a well‐confined therapeutic area according to laser irradiance and surface scanning speed. The study also presents validation experiments that include histology analyses in an ex vivo sheep esophagus model. Methods The simulation engine was developed based on the Monte‐Carlo method and the Arrhenius damage integral. The computational model mimicked laser scanning by shifting the position of the calculated heat source in the grating system along the axis to be scanned. The performance of the simulations was tested in an ex vivo sheep esophagus model at a laser wavelength of 1505 nm. Histological analysis, hematoxylin–eosin staining, light microscope imaging, and block‐face scanning electron microscopy were used to assess thermal damage to the tissue model. Results The developed simulation engine estimated the photothermal coagulation area for a surface scanning speed range of 0.5–8 mm/second and laser power of up to 0.5 W at a 0.9‐nm laser diameter in a tissue model with a volume of 4 × 4 × 4 mm3. For example, the optimum laser irradiation for effective photothermal coagulation in the mucosa and superficial submucosa depths was estimated to be between 16.4 and 31.8 W/cm2, 23.2 and 38.1 W/cm2 at 0.5 and 1 mm/second, respectively. The computational results, summarized as a guide map, were directly compared with the results of ex vivo tissue experiments. In addition, it was pointed out that the comparative theoretical and experimental data overlap significantly in terms of energy density. Conclusions Our results suggest that the developed simulation approach could be a seed algorithm for further preclinical and clinical trials and a complementary tool to the laser‐induced photothermal coagulation technique for superficial treatments in the gastrointestinal tract. In future preclinical studies, it is thought that the simulation engine can be enriched by combining it with an in vivo model for different laser wavelengths.

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Measurement of optical properties of pig esophagus by using a modified spectrometer set‐up

Cited by 11 publications

References 28 publications

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Superficial photothermal laser ablation of ex vivo sheep esophagus using a cone‐shaped optical fiber tip

Factors influencing the accuracy for tissue classification in multi spectral in-vivo endoscopy for the upper gastro-internal tract

Guide mapping for effective superficial photothermal coagulation of the esophagus using computer simulations with ex vivo sheep model validation study

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