![]() ![]() 90% in the case of fluorescein isothiocyanate (FITC)) to areas of interest. However naturally-occurring fluorophores occur in very low concentrations and exhibit very low quantum yield, limiting the effectiveness of AFE for example FAD, the main contributor to autofluorescence emission exhibits a quantum yield of only 7% 18, 19.Īn alternative approach, which enhances the effectiveness of fluorescence endoscopy, involves binding exogenous label fluorophores exhibiting very high quantum yield (e.g. An advantage of AFE is that it avoids introduction of foreign material, eliminating the risk of toxicity or other unwanted interaction with the biological system under investigation 14. Autofluorescence endoscopy (AFE) takes advantage of the fact that the concentration of endogenous fluorophores such as flavin adenine dinucleotide (FAD) and other extracellular matrices such as collagen and elastin in cancerous tissue can be up to three times lower than that of normal tissue 7, 15, 16, 17. These fluorophores can occur naturally within human tissue (endogenous) and are utilised in autofluorescence endoscopy, or can be introduced externally as labels to the biological system (exogenous) for use in targeted-fluorescence endoscopy 7, 14. In this study, we focus on fluorescence imaging as a modality that has great promise for integration with current standard capsule endoscopy for the small bowel.įluorescence endoscopy exploits the natural phenomenon whereby specific molecules (fluorophores) absorb the excitation energy of blue light (380–500 nm wavelength) and then re-emit some of that energy in the form of green light (490–590 nm) 13. Robotic technologies to control capsule position and therefore enhance diagnostic and therapeutic capability are also being studied 10, 11, 12. New methods of improving detection rates within the lower part of the GI tract by means of software processing and 3D representation of captured WLI video are also being investigated. This drawback was overcome for the upper GI tract and duodenum by the introduction of multimodal imaging endoscopy that employs WLI, fluorescence imaging (FI) and narrow band imaging (NBI) in combination to significantly improve the detection rate from 53% to 90% 2, 7, 8, 9. However, both WLE and CE suffer from low detection rate. Similar to WLE, CE uses white light imaging (WLI) and is potentially capable of viewing ailments including tumours, obscure gastrointestinal bleeding and Crohn’s disease within the small bowel 3, 5, 6. This changed after the approval of capsule endoscopy (CE) for medical use by the US Food and Drug Administration (FDA) in 2001 3, 4. However, until recently, the small bowel was an obscure region requiring invasive intervention for diagnosis and treatment. White light endoscopy (WLE), has been a standard technique for diagnosis of disease pathology in the upper and lower part of the gastrointestinal (GI) tract for several decades 1, 2. We also demonstrated the utility of marker identification by imaging a 20 μM fluorescein isothiocyanate (FITC) labelling solution on mammalian tissue. To demonstrate the performance of our capsule, we imaged fluorescence phantoms incorporating principal tissue fluorophores (flavins) and absorbers (haemoglobin). The device has the potential to replace highly power-hungry intrusive optical fibre based endoscopes and to extend the range of clinical examination below the duodenum. When in use the capsule consumes only 30.9 mW and deploys very low-level 468 nm illumination. The capsule incorporates a state-of-the-art complementary metal oxide semiconductor single photon avalanche detector imaging array, miniaturised optical isolation, wireless technology and low power design. With enhanced sensitivity compared to existing technology we have demonstrated that the capsule can be successfully used to image tissue autofluorescence and targeted fluorescence via fluorophore labelling of tissues. Here we present a miniaturised wireless fluorescence endoscope capsule with low power consumption that will pave the way for future FI systems and applications. ![]() Current FI devices that are used either for in-vivo or in-vitro studies are expensive, bulky and consume substantial power, confining the technique to laboratories and hospital examination rooms. Fluorescence Imaging (FI) is a powerful technique in biological science and clinical medicine. ![]()
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