Raman spectroscopy of bladder tissue in the presence of 5-aminolevulinic acid
ABSTRACT Raman spectroscopy has the ability to provide differential diagnosis of different cancers with high sensitivity and specificity. A major limitation in its clinical application is the weak nature of Raman signal, which inhibits scanning large surface areas of tissues. In bladder cancer diagnosis, fluorescence-guided endoscopy with 5-aminolevulinic acid (5-ALA) has gained interest as a technique that can provide such spatial differentiation, thus improving early detection and more complete removal of superficial tumors. However, several studies have demonstrated the poor specificity of this modality. Combining fluorescence with Raman spectroscopy could improve its diagnostic capability. However, little is known about the effect of agents such as 5-ALA on Raman spectra of tissue. In this paper, we present measuring Raman spectroscopy from benign and malignant bladder tissues in the presence of 5-ALA and attempt to evaluate the potential to discriminate between different pathologies. Raman spectra were recorded from 92 bladder biopsies without 5-ALA and 38 biopsies with 5-ALA using a Raman microspectrometer system at 830nm excitation. Empirical and multivariate statistical techniques were used for data analysis. Algorithms were developed to determine the effect of 5-ALA on tissue and its influence on the prediction ability of a preliminary benign/malignant prediction model. In samples with 5-ALA, an overall decrease in Raman intensity was observed when compared to the Raman spectra from samples without 5-ALA. Additionally, differences in relative intensities at 1270 and 1330cm(-1) were also noted. However, significant differences were observed in the Raman spectra of benign and malignant samples with 5-ALA indicating the potential of using Raman spectroscopy for discriminating bladder cancer in the presence of 5-ALA. The Principal-Component fed Linear-Discriminant Analysis (PCA/LDA) algorithm derived from biopsies in the absence of 5-ALA used to predict biopsies in the presence of 5-ALA resulted in an overall sensitivity and specificity of 42.6% and 71.1%, respectively. This suggests the presence of 5-ALA in tissue affects the Raman spectra. A PCA/LDA algorithm based on fluorescence information (i.e. PpIX fluorescence positive or negative) and the Raman spectrum of 5-ALA biopsies, had a sensitivity and specificity of 100% and 80.8%, respectively. This study demonstrates that applying 5-ALA affects the Raman spectra of bladder tissues. However, benign/malignant differentiation can be accomplished with a preliminary PCA/LDA algorithm, suggesting the potential of a combined diagnostic modality in vivo.
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- "Presently, white light cystoscopy, which is most often used to diagnose bladder cancer, has sensitivities and specificities between 62 – 84% and 43 – 98%, respectively  , whereas Raman-based cystoscopy has shown a sensitivity of 85% and specificity of 79% within the first in vivo study  , and sensitivity and specificity of 85.7% and 100% using a confocal fiber-optic probe ex vivo  . Fluorescence cystoscopy using 5-aminolevulinic acid (5-ALA) or its hexyl ester, hexaminolevulinate (HAL), has previously been shown to achieve sensitivities and specificities of 76 – 97% and 43 – 79% respectively  ; when fluorescence and Raman spectroscopy modalities are combined, 100% sensitivity and specificity has been demonstrated  . Urine cytology has the advantage of being entirely non-invasive but its low sensitivity, particularly for low-grade tumors, which represent the bulk of cases, has meant that it is generally not used as a primary diagnostic tool. "
ABSTRACT: Biomolecular changes associated with cancer progression can be identified using Raman spectroscopy, allowing for this technique to be utilized as a non-invasive tool for the diagnosis of bladder cancer. Applications of Raman spectroscopy for diagnostics in real-time have consistently produced higher sensitivities and specificities than current clinical methods. This technique can be applied in vivo during bladder visualization (cystoscopic) procedures as an “optical biopsy” or in vitro to cells obtained from urine cytology specimens. This review follows the evolution of studies in this field from the first in vitro experiment to the most recent in vivo application, identifies how diagnostic algorithms are developed, and provides molecular information associated with the etiology of the biochemical continuum of disease progression. Future prospects for the application of Raman spectroscopy in bladder cancer diagnostics are also discussed.Photonics and Lasers in Medicine 05/2014; 3(3):2193-0643. DOI:10.1515/plm-2014-0004
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- "Raman spectroscopy is an optical technique that has been proposed as a discriminating/diagnostic tool in the life sciences      . This technique is based upon the inelastic scattering interactions between light and matter. "
ABSTRACT: Raman spectroscopy has been used for the diagnosis of various eye diseases. A diagnostic tool based on Raman spectroscopy has been developed to discriminate endophthalmitis from uveitis in vitreous tissues of rabbits' eyes in vitro. Twenty-two New Zealand rabbits suffering from endophthalmitis induced by Staphylococcus aureus (n=10), non-infectious uveitis induced by lipopolysaccharide from Escherichia coli (LPS) (n=10 animals) and control (n=2) were included in the study. After eye inoculation, vitreous tissues were dissected and a fragment was submitted to dispersive Raman spectroscopy using near-infrared laser excitation (830 nm, 100 mW) and spectrograph/CCD camera for detection of Raman signal with integration time of 50 s. A routine was developed to classify the spectra of endophthalmitis and uveitis using principal components analysis (PCA) and Mahalanobis distance. The mean Raman spectra of tissues with uveitis and endophthalmitis showed several bands in the region of 800-1800 cm(-1), which have been attributed to nucleic acids, amino acids and proteins from inflamed tissue and proliferating bacteria. The bands at 1004, 1258, 1339, 1451 and 1635 cm(-1) showed statistically significant differences between both diseases. It was observed that principal components PC1, PC3 and PC4 showed statistically significant differences for the two tissue types, indicating that these PCs can be used to discriminate between the two groups. The diagnostic model showed 94% sensitivity, 95% specificity and 95% accuracy using PC3×PC4. The Raman spectroscopy technique has been shown to be useful in differentiating uveitis and endophthalmitis in vitreous tissues in vitro, and these results may be clinically relevant for differentiating vitreous tissues to optimise the diagnosis of inflammatory and infectious vitreoretinal diseases.Journal of photochemistry and photobiology. B, Biology 12/2011; 107(1):73-8. DOI:10.1016/j.jphotobiol.2011.12.001 · 2.96 Impact Factor
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ABSTRACT: New developments in optical diagnostics have a potential for less invasive and improved detection of bladder cancer. To provide an overview of the technology and diagnostic yield of recently developed optical diagnostics for bladder cancer and to outline their potential future applications. A PubMed literature search was performed, and papers on Raman spectroscopy (RS), optical coherence tomography (OCT), photodynamic diagnosis (PDD) and narrow-band imaging (NBI) regarding bladder cancer were reviewed. Technology, clinical evidence, and future applications of the techniques are discussed. With RS, the molecular components of tissue can be measured objectively in qualitative and quantitative ways. The first studies demonstrating human in vivo applicability are still awaited. OCT produces high-resolution, cross-sectional images of tissue, comparable with histopathology, and provides information about depth of tumour growth. The first in vivo studies of OCT demonstrated promising diagnostic accuracy. RS and OCT are not suitable for scanning the entire bladder. PDD is a technique using fluorescence to indicate pathologic tissue. Several studies have shown that PDD increases the detection rate of bladder tumours and improves resection, resulting in fewer early recurrences. The relatively low specificity of PDD remains a problem. NBI enhances contrast of mucosal surface and microvascular structures. The NBI technique has clear advantages over PDD, and the two studies published to date have shown promising preliminary results. PDD and NBI do not contribute to histopathologic diagnosis. RS and OCT aim at providing a real-time, minimally invasive, objective prediction of histopathologic diagnosis, while PDD and NBI aim at improving visualisation of bladder tumours. For RS, OCT, and NBI, more research has to be conducted before these techniques can be implemented in the management of bladder cancer. All techniques might be of value in specific clinical scenarios.European Urology 04/2009; 56(2):287-96. DOI:10.1016/j.eururo.2009.02.033 · 13.94 Impact Factor