Laser-induced fluorescence spectroscopy at endoscopy: tissue optics, Monte Carlo modeling, and in vivo measurements

Qu, Jianan Y.; MacAulay, Calum E.; Lam, Stephen; Palcic, Branko

doi:10.1117/12.212917

Cited by 124 publications

(94 citation statements)

References 5 publications

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“…The current MC model neglects all polarization effects that might result in anisotropic fluorescence emission [7]. Therefore, the fluorescence photons are emitted isotropically from the source points, this agrees with the assumptions proposed in [16][17][18][19][20][21][22][23]. Figure 4.…”

Section: Fluorescence Simulationsupporting

confidence: 85%

Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

Churmakov

Meglinski

Piletsky

et al. 2003

J. Phys. D: Appl. Phys.

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A novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account the spatial distribution of fluorophores, which would arise due to the structure of collagen fibres, compared to the epidermis and stratum corneum where the distribution of fluorophores is assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed in the near-infrared spectral region, whereas the spatial distribution of fluorescence sources within a sensor layer embedded in the epidermis is localized at an 'effective' depth.

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Section: Fluorescence Simulationsupporting

confidence: 85%

Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

Churmakov

Meglinski

Piletsky

et al. 2003

J. Phys. D: Appl. Phys.

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“…Monte Carlo simulations have been used to evaluate the effect of scattering and absorption changes on light propagation in a two-layer model of the cervix 17,18 and in multilayered models of the colon 19 and bronchial tissue. 20 As a clinically relevant example, we explore the application of this model to describe fluorescence spectra of oral tissue, using physiologically realistic input parameters and tissue geometries for normal oral tissue and for benign and precancerous oral lesions.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo model to describe depth selective fluorescence spectra of epithelial tissue: applications for diagnosis of oral precancer

et al. 2008

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We present a Monte Carlo model to predict fluorescence spectra of the oral mucosa obtained with a depth-selective fiber optic probe as a function of tissue optical properties. A model sensitivity analysis determines how variations in optical parameters associated with neoplastic development influence the intensity and shape of spectra, and elucidates the biological basis for differences in spectra from normal and premalignant oral sites. Predictions indicate that spectra of oral mucosa collected with a depth-selective probe are affected by variations in epithelial optical properties, and to a lesser extent, by changes in superficial stromal parameters, but not by changes in the optical properties of deeper stroma. The depth selective probe offers enhanced detection of epithelial fluorescence, with 90% of the detected signal originating from the epithelium and superficial stroma. Predicted depth-selective spectra are in good agreement with measured average spectra from normal and dysplastic oral sites. Changes in parameters associated with dysplastic progression lead to a decreased fluorescence intensity and a shift of the spectra to longer emission wavelengths. Decreased fluorescence is due to a drop in detected stromal photons, whereas the shift of spectral shape is attributed to an increased fraction of detected photons arising in the epithelium.

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“…Specifically, the loss of autofluorescence is believed to reflect a complex mixture of alterations to intrinsic tissue fluorophore distribution, such as the breakdown of the collagen matrix and a decrease in flavin adenine dinucleotide concentration due to tissue remodeling and increased metabolism associated with neoplastic development. Correspondingly, structural changes in tissue morphology associated with neoplastic development in both the epithelium and lamina propria (e.g., thickening of the epithelium, hyperchromatism and increased cellular/ nuclear pleomorphism, or increased microvascularity), lead to increased absorption and/or scattering of light, which in turn, reduces and modifies the detectable autofluorescence (16,17,19,20).…”

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confidence: 99%

Fluorescence Visualization Detection of Field Alterations in Tumor Margins of Oral Cancer Patients

Poh

Zhang²,

Anderson³

et al. 2006

Clinical Cancer Research

262

250

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Purpose: Genetically altered cells could become widespread across the epithelium of patients with oral cancer, often in clinically and histologically normal tissue, and contribute to recurrent disease. Molecular approaches have begun to yield information on cancer/risk fields; tissue optics could further extend our understanding of alteration to phenotype as a result of molecular change. Experimental Design: We used a simple hand-held device in the operating room to directly visualize subclinical field changes around oral cancers, documenting alteration to fluorescence. A total of 122 oral mucosa biopsies were obtained from 20 surgical specimens with each biopsy being assessed for location, fluorescence visualization (FV) status, histology, and loss of heterozygosity (LOH; 10 markers on three regions: 3p14, 9p21, and 17p13). Results: All tumors showed FV loss (FVL). For 19 of the 20 tumors, the loss extended in at least one direction beyond the clinically visible tumor, with the extension varying from 4 to 25 mm. Thirty-two of 36 FVL biopsies showed histologic change (including 7 squamous cell carcinoma/carcinomas in situ, 10 severe dysplasias, and 15 mild/moderate dysplasias) compared with 1of the 66 FV retained (FVR) biopsies. Molecular analysis on margins with low-grade or no dysplasia showed a significant association of LOH in FVL biopsies, with LOH at 3p and/or 9p (previously associated with local tumor recurrence) present in 12 of 19 FVL biopsies compared with 3 of 13 FVR biopsies (P = 0.04). Conclusions: These data have, for the first time, shown that direct FV can identify subclinical high-risk fields with cancerous and precancerous changes in the operating room setting.

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Laser-induced fluorescence spectroscopy at endoscopy: tissue optics, Monte Carlo modeling, and in vivo measurements

Cited by 124 publications

References 5 publications

Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

Monte Carlo model to describe depth selective fluorescence spectra of epithelial tissue: applications for diagnosis of oral precancer

Fluorescence Visualization Detection of Field Alterations in Tumor Margins of Oral Cancer Patients

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