This article describes the results of experimental studies using optical methods for in vitro estimation of the composition of bile obtained from patients with different etiologies of obstructive jaundice. Experimental studies were carried out using spectrophotometry and Raman spectroscopy methods to study and compare optical properties of bile from patients with obstructive jaundice caused either by choledocholithiasis or malignant tumors. The results show that the selected methods are suitable for studying the composition and optical properties of bile and can provide additional diagnostic information. Averaged Raman spectra, as well as absorption spectra of bile, corresponding to different etiologies of jaundice origin were demonstrated.
At the moment, percutaneous needle biopsy (PNB) remains the gold standard for diagnosing liver cancer. However, the relatively high probability of false-negative results can still be an issue with the method. The introduction of real-time feedback for the precise navigation of the biopsy tool is an up-and-coming technology to immensely reduce the mistakes in taking relevant tissue samples. This work presents the technical details of the developed optical biopsy system, which implements fluorescence lifetime and diffuse reflectance measurements. Also, we demonstrate the most recent results of measurements by the system equipped with a novel needle optical probe, compatible with the 17.5G biopsy needle standard. At the first stage, measurements were verified in the murine model with inoculated hepatocellular carcinoma (HCC). With that model, we demonstrate that the registered set of independent diagnostic parameters allows us to reliably distinguish the HCC tissue, liver tissue in the control and the metabolically changed liver tissues of animals with the developed HCC tumour. At the second stage, the optical biopsy system was tested during the routing procedure of the transcutaneous biopsy in humans with suspected cancerous processes in the liver. Our results demonstrate that the developed technique can reliably discriminate malignant tumours of different nature (primary HCC and adenocarcinoma metastasis) from liver tissues. We conclude that, being supported by machine learning approaches, the presented technique can significantly decrease the rate of false-negative results for transcutaneous biopsy.
In this paper we demonstrate results of combined measurements by diffuse reflectance and fluorescence lifetime measuring techniques for real time liver cancer differentiation using a needle optical probe.
The article describes the development of the optical phantom mimicking flavin adenine dinucleotide (FAD) and skin collagen fluorescence. The results of experimental studies using fluorescence imaging and fluorescence spectroscopy methods are demonstrated. The method of optical phantom production for quick calibration of fluorescence imaging devices for further application in clinical practice is proposed.
The paper describes the results of experimental studies using custom developed optical biopsy system for diagnostics in vivo during the procedure of fine needle aspiration biopsy. Experimental studies were conducted in laboratory mice with inoculated hepatocellular carcinoma. The measurements were carried out using fluorescence spectroscopy and diffuse reflectance spectroscopy methods to reveal metabolic and morphological changes in tissues. The results show that the developed approach is sensitive for cancer detection. Quantified differences in the maximum of fluorescence spectra and diffuse reflectance spectra between tumor and normal tissues were demonstrated and approved with morphological analysis.
The aim of the study was to compare the metabolic activity of brain cortex after the acute hypoxia caused by the impairment of breathing or blood circulation. Male Wistar rats were randomized in two groups: impaired breathing and blood circulation failure groups. Fluorescence under 365 and 450 nm excitation and diffuse reflectance intensity at 550-820 nm range were estimated. We found that after long-term hypoxic conditions, notable metabolic changes occur. We suppose that oxygen deficiency causes an activation of the GABA shunt mechanism. In cases of blood circulation failure, fluorescence intensity changes faster than in cases of breathing impairment.
The paper describes the methodology and technical implementation of a multimodal approach for optical diagnostics in hepatopancreatobiliary organs focal and diffuse neoplasms. Fine needle aspiration biopsy technique and following cytological examination show its effectiveness and safety but its performing takes several days. However, the problem of real-time analysis of pathological changes in tissues remains relevant. The solution suggested is implementing of optical biopsy methods (namely fluorescence spectroscopy and diffuse reflectance spectroscopy) in the form of fiber-optic probe compatible with standard biopsy fine needles. The special device was designed for this purpose to conduct optical measurements and compare the results with ones obtained by conventional biopsy. The proposed methodology seems promising for developing new diagnostic criteria for clinical practice.
The paper presents the results of in vivo experimental measurements of the endogenous fluorescence and blood perfusion in common bile duct tissues in obstructive jaundice patients during minimally invasive surgical operations. Nowadays the type of interventions become more widespread for treating hepatopancreatobiliary pathologies. An effective feedback which can be established by one or more optical diagnostic channels integrated into the standard instruments for minimally invasive manipulations would be of particular value to practical surgeons. To collect reference data, an experimental study has been conducted using a fiber optical probe with fluorescence spectroscopy and laser Doppler flowmetry channels. For every measurement, the areas of interest were different areas of common bile duct obstructed by a malignant tumor. Obtained results demonstrated significant variety registered intensities of fluorescence spectra and values of blood perfusion. Tested fiber optical endoscopic system showed sensitivity to the tissue state in the investigated area, so the two modal approach seems to be promising for further research and implementation in clinical practice.
Fine needle aspiration biopsy technique and following histological examination show its effectiveness and safety but its performing takes several time. However, the problem of real-time analysis of pathological changes in tissues remains relevant. We demonstrate optical fine-needle biopsy method, combining a fine needle (17.5G) and a fiber-optic probe (1 mm diameter) for minimally invasive interrogation of tissue in vivo. During rat tumor experiment, we collected spectrally-resolved diffuse reflectance and fluorescence. Quantified differences between tumor and normal tissues were demonstrated and approved with morphological analysis. The proposed methodology seems promising for developing new diagnostic criteria for clinical practice.
At present, minimally invasive interventions become more widespread for treating hepatopancreatoduodenal area pathologies. However, new methods and approaches are necessary for obtaining more diagnostic information in real time. Several methods within the framework of “optical biopsy” concept are considered. The features and areas of application of each method are reviewed to find out which of them can be used in further studies to assess the possibility of intraoperative use in minimally invasive abdominal surgery. Preliminary measurements with fluorescence spectroscopy method have been performed at excitation wavelengths 365 nm and 450 nm. Areas of interest were common bile duct, gallbladder and liver abscess. In our opinion, the obtained results can be a basis for further research and provide a deeper understanding of pathological processes of abdominal cavity organs tissues.
This article presents the results of the study of the pressure applied on optical diagnostic probes as a significant factor affecting the results of measurements. During stepwise increasing and decreasing of local pressure on skin we conducted measurements using the methods of laser Doppler flowmetry and fluorescence spectroscopy. It was found out that pressure on optical probe has sufficient impact on skin microcirculation to affect registered fluorescence intensity. Data obtained in this study are of interest for design and development of diagnostic technologies for wearable devices. This data will also inform further investigation into issues of compensation of blood absorption influence on fluorescence spectrum, allowing increased accuracy and reproducibility of measurements by fluorescence spectroscopy methods in optical diagnosis.
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