Urothelial carcinoma (UC) is the most common type of bladder cancer, and its treatment depends from both tumour invasiveness (stage) and aggressiveness (grade). The gold standard for detecting UC is white-light cystoscopy, followed by tissue biopsy and histopathological examination; however, such process is invasive, time-consuming, operatordependent and prone to sampling errors. In this framework, optical spectroscopy techniques could be a promising solution for fast and label-free diagnosis of bladder tissues and for early detection of UC. Thus, we combined autofluorescence, diffuse reflectance and Raman spectroscopy in a compact and transportable setup based on an optical fibrebundle probe. This experimental setup was used for studying fresh biopsies of urothelial tumour (140 samples) and healthy bladder (50 samples) collected from 90 patients undergoing Transurethral Resection of Bladder Tumours (TURBT). The aim of this study was to develop an automated classification of the examined tissues based on the intrinsic spectral information provided by all three techniques. We found that healthy and diseased tissues showed significant spectral differences for each technique, resulting in high accuracy (up to 90%) from a Linear Discriminant Analysis (LDA) routine. In particular, fluorescence spectroscopy – excited either with blue or UV light – provided very good results in detecting UC. However, tumour grading and staging proved to be more challenging tasks, for which no single spectroscopic technique could provide sufficient sensitivity and specificity. Therefore, we found that a multimodal approach can improve significantly the diagnosis of UC stages and grades.
Urothelial carcinoma (UC) is the most common type of bladder cancer, and its treatment depends from both tumour invasiveness (stage) and aggressiveness (grade). The gold standard for detecting UC is white-light cystoscopy, followed by tissue biopsy and histopathological examination; however, such process is invasive, time-consuming, operatordependent and prone to sampling errors. In this framework, optical spectroscopy techniques can provide a fast, label-free and non-invasive tool for improving diagnosis. Thus, we combined auto-fluorescence, diffuse reflectance and Raman spectroscopy in a compact and transportable setup based on an optical fibre-bundle probe. This experimental setup was used for studying fresh biopsies of urothelial tumour (129 samples) and healthy bladder (40 samples) collected from 78 patients undergoing Transurethral Resection of Bladder Tumours (TURBT). The recorded data were analysed using Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) for obtaining an automated classification of the examined samples based on the intrinsic spectral information provided by all three techniques. We found that healthy and diseased tissues showed significant spectral differences for each technique, resulting in high accuracy (up to 90%) from PCA-LDA routines. While fluorescence spectroscopy seems sensitive enough for detecting UC, we found that a multimodal approach is crucial for obtaining high discriminating capability (<80%) in grading and staging tumour biopsies. In conclusion, the presented strategy generates results similar to gold standard histology, but in a fast and labelfree way, offering the potential for endoscopic in vivo applications.
The most common type of bladder cancer is urothelial carcinoma (UC), whose treatment depends from both tumour extension (stage) and aggressiveness (grade). The gold standard for detecting UC is white-light cystoscopy, followed by tissue biopsy and pathological examination for determining tumour stage and grade. However, such process is invasive, time-consuming and prone to sampling errors. In this framework, optical spectroscopy techniques provide fast, label-free and non-invasive alternatives to standard histopathology. Thus, we combined auto-fluorescence, diffuse reflectance and Raman spectroscopy in a compact and transportable setup based on an optical fibre-probe. The latter was coupled to three laser diodes (emitting at 378 nm, 445 nm and 785 nm) and to a halogen lamp for exciting and collecting autofluorescence, Raman and reflectance spectra, respectively. This experimental setup was used for studying fresh biopsies of urothelial tumour (103 samples) and healthy bladder (34 samples) collected from 63 patients undergoing Transurethral Resection of Bladder Tumours (TURBT). All spectral recordings were done within 30 minutes from surgical resection, and optical inspection required less than 2 minutes for each sample. The recorded data were analysed using Principal Component Analysis (PCA) for obtaining an automated classification of the examined samples based on the intrinsic spectral information provided by all three techniques. We found that multimodal spectroscopy provides high-sensitivity, high-specificity discriminating capability for UC detection, grading and staging. The presented strategy generates results similar to gold standard histology, but in a fast and label-free way, offering the potential for endoscopic in vivo applications.
Urothelial carcinoma (UC) is the most common type of bladder cancer. Its treatment depends from both tumour extension (stage) and aggressiveness (grade). The gold standard for detecting UC is white-light cystoscopy, followed by tissue biopsy and pathological examination for determining tumour stage and grade. However, such process is invasive, time-consuming and prone to sampling errors. In this framework, optical spectroscopy techniques provide fast, label-free and non-invasive alternatives to standard histopathology. Thus, we combined auto-fluorescence, diffuse reflectance and Raman spectroscopies in a compact and transportable setup based on an optical fibre-probe. The latter was coupled to three laser diodes (emitting at 378 nm, 445 nm and 785 nm) and to a halogen lamp for exciting and collecting autofluorescence, Raman and reflectance spectra, respectively. This experimental setup was used for studying fresh biopsies of urothelial tumour (82 samples) and healthy bladder (32 samples) collected from 49 patients undergoing Transurethral Resection of Bladder Tumours (TURBT). All spectral recordings were done within 30 minutes from surgical resection, and optical inspection required less than 2 minutes for each sample. The recorded data were analysed using Principal Component Analysis (PCA) for obtaining an automated classification of the examined samples based on the intrinsic spectral information provided by all three techniques. We found that multimodal spectroscopy provides high-sensitivity, high-specificity discriminating capability for UC detection, grading and staging. The presented strategy generates results similar to gold standard histology, but in a fast and label-free way, offering the potential for endoscopic in vivo applications.
Urothelial carcinoma (UC) is the most common type of bladder cancer. The gold standard for detecting UC is white-light cystoscopy, which is followed by tissue biopsy and pathological examination. However, such process is invasive, timeconsuming and prone to sampling errors. In this framework, optical spectroscopy techniques provide fast, label-free and non-invasive alternatives to standard histopathology. Thus, the aim of this study is to discriminate normal bladder tissues from urothelial tumours, and to identify the different stages of the disease, by means of combined auto-fluorescence, diffuse reflectance and Raman spectroscopy. In fact, these techniques were implemented in a compact and transportable setup based on two optical fibre probes: one coupled to fluorescence and reflectance excitation sources, while the other one to the 785 nm laser. Raman, fluorescence and reflected light signals were collected though the same probe used for excitation and sent to a spectrograph. We used this experimental setup for studying fresh biopsies of urothelial tumour and healthy bladder collected from 32 patients undergoing Transurethral Resection of Bladder Tumours (TURBT). Scoring methods based on ratiometric approach and Principal Component Analysis (PCA) allowed not only to discriminate healthy biopsies from tumour ones, but also to recognize three tumour stages.
An optical fiber probe for multimodal spectroscopy was designed, developed and used
for tissue diagnostics. The probe, based on a fiber bundle with optical fibers of various size and
properties, allows performing spectroscopic measurements with different techniques, including
fluorescence, Raman, and diffuse reflectance, using the same probe. Two visible laser diodes were
used for fluorescence spectroscopy, a laser diode emitting in the NIR was used for Raman
spectroscopy, and a fiber-coupled halogen lamp for diffuse reflectance. The developed probe was
successfully employed for diagnostic purposes on various tissues, including brain and bladder. In
particular, the device allowed discriminating healthy tissue from both tumor and dysplastic tissue
as well as to perform tumor grading. The diagnostic capabilities of the method, determined using a
cross-validation method with a leave-one-out approach, demonstrated high sensitivity and
specificity for all the examined samples, as well as a good agreement with histopathological
examination performed on the same samples. The obtained results demonstrated that the
multimodal approach is crucial for improving diagnostic capabilities with respect to what can be
obtained from individual techniques. The experimental setup presented here can improve
diagnostic capabilities on a broad range of tissues and has the potential of being used clinically for
guiding surgical resection in the near future.
The gold standard for the detection of bladder cancer is white light cystoscopy, followed by an invasive biopsy and
pathological examination. Tissue pathology is time consuming and often prone to sampling errors. Recently, optical
spectroscopy techniques have evolved as promising techniques for the detection of neoplasia. The specific goal of this
study is to evaluate the application of combined auto-fluorescence (excited using 378 nm and 445 nm wavelengths)
and diffuse reflectance spectroscopy to discriminate normal bladder tissue from tumor at different grades. The
fluorescence spectrum at both excitation wavelengths showed an increased spectral intensity in tumors with respect
to normal tissues. Reflectance data indicated an increased reflectance in the wavelength range 610 nm - 700 nm for
different grades of tumors, compared to normal tissues. The spectral data were further analyzed using principal
component analysis for evaluating the sensitivity and specificity for diagnosing tumor. The spectral differences
observed between various grades of tumors provides a strong genesis for the future evaluation on a larger patient
population to achieve statistical significance. This study indicates that a combined spectroscopic strategy,
incorporating fluorescence and reflectance spectroscopy, could improve the capability for diagnosing bladder tumor
as well as for differentiating tumors in different grades.
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