Bladder tissue characterization using probe‐based Raman spectroscopy: Evaluation of tissue heterogeneity and influence on the model prediction

Abstract

Existing approaches for early-stage bladder tumor diagnosis largely depend on invasive and time-consuming procedures, resulting in hospitalization, bleeding, bladder perforation, infection and other health risks for the patient. The reduction of current risk factors, while maintaining or even improving the diagnostic precision, is an underlying factor in clinical instrumentation research. For example, for clinic surveillance of patients with a history of noninvasive bladder tumors real-time tumor diagnosis can enable immediate laser-based removal of tumors using flexible cystoscopes in the outpatient clinic. Therefore, novel diagnostic modalities are required that can provide real-time in vivo tumor diagnosis. Raman spectroscopy provides biochemical information of tissue samples ex vivo and in vivo and without the need for complicated sample preparation and staining procedures. For the past decade there has been a rise in applications to diagnose and characterize early cancer in different organs, such as in head and neck, colon and stomach, but also different pathologies, for example, inflammation and atherosclerotic plaques. Bladder pathology has also been studied but only with little attention to aspects that can influence the diagnosis, such as tissue heterogeneity, data preprocessing and model development. The present study presents a clinical investigative study on bladder biopsies to characterize the tumor grading ex vivo, using a compact fiber probe-based imaging Raman system, as a crucial step towards in vivo Raman endoscopy. Furthermore, this study presents an evaluation of the tissue heterogeneity of highly fluorescent bladder tissues, and

Morpho-molecular ex vivo detection and grading of non-muscle-invasive bladder cancer using forward imaging probe based multimodal optical coherence tomography and Raman spectroscopy

“…3). The described method has previously been reported in Cordero et al 67 Multivariate curve resolution alternating least squares (MCR-ALS) for collagen distribution of Raman data Initially, the pure components for each biopsy were determined by using an orthogonal projection approach (OPA) algorithm. This function extracts the initial 'pure' components of the set of spectra based on spectral dissimilarity of the data set.…”

Raman Spectroscopy to Characterize Bladder Tissue for Multidimensional Diagnostics of Cancer in Urology

“…The detection of the drug is consistent with PDT treatment of bladder cancer which induced necrosis. In fact, elevated Raman bands of fibrous proteins in cancer tissues in figure 2 rather point to necrotic tissue than to cancer when compared to another study [10]. 16 additional data sets were collected from eight patients with identical parameters and are expected to give more details about bladder tissue features.…”

“…The authors reported that the probe collected mainly signal from deeper tissue layers whereas early changes in the upper urothelial layer were not detected. A recent study collected Raman images from 67 bladder biopsies of 28 patients using a fiber-probe system [10]. After extensive pre-processing to suppress high tissue autofluorescence in Raman spectra, noncancer tissue, low-grade and high-grade cancer were classi-*Corresponding author: C. Krafft: Leibniz IPHT, Albert-Einstein-Str.…”

Advances in real‐time fiber‐optic Raman spectroscopy for early cancer diagnosis: Pushing the frontier into clinical endoscopic applications

“…Recent technical advancements in compact NIR diode lasers, high‐throughput Raman imaging spectrographs with holographic gratings, deep‐depletion charge‐coupled device (CCD) camera, notch filters/sharp‐edged long‐pass Raman filters and miniaturized fiber‐optic Raman probe designs have permitted the rapid acquisition of NIR tissue Raman spectra in clinical settings [22–24]. Accumulating evidences of NIR Raman spectroscopy for tissue characterization and diagnosis have been reported in a number of organ sites (eg, skin [25–28], breast [29–31], oral cavity [32], larynx/nasopharynx [33–36], esophagus and gastric [37–41], colon [37, 42], lung [11, 43, 44], bladder [45–51], prostate [37, 49, 52], cervix [53, 54], brain [48, 55–58], bone [59, 60], artery [61, 62] etc.). Encouraged by the promising results of ex vivo Raman studies as well as the latest advancement in NIR Raman technologies, substantial progress has been made in translating NIR Raman spectroscopy into real‐time in vivo endoscopic applications.…”