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Optical Biopsies (optical + biopsy)
Selected AbstractsOptical biopsy: a promising approach for real-time liver steatosis gradingLIVER INTERNATIONAL, Issue 3 2009Giovanni Bottiroli No abstract is available for this article. [source] Multiphoton microscopy in life sciencesJOURNAL OF MICROSCOPY, Issue 2 2000K. König Near infrared (NIR) multiphoton microscopy is becoming a novel optical tool of choice for fluorescence imaging with high spatial and temporal resolution, diagnostics, photochemistry and nanoprocessing within living cells and tissues. Three-dimensional fluorescence imaging based on non-resonant two-photon or three-photon fluorophor excitation requires light intensities in the range of MW cm,2 to GW cm,2, which can be derived by diffraction limited focusing of continuous wave and pulsed NIR laser radiation. NIR lasers can be employed as the excitation source for multifluorophor multiphoton excitation and hence multicolour imaging. In combination with fluorescence in situ hybridization (FISH), this novel approach can be used for multi-gene detection (multiphoton multicolour FISH). Owing to the high NIR penetration depth, non-invasive optical biopsies can be obtained from patients and ex vivo tissue by morphological and functional fluorescence imaging of endogenous fluorophores such as NAD(P)H, flavin, lipofuscin, porphyrins, collagen and elastin. Recent botanical applications of multiphoton microscopy include depth-resolved imaging of pigments (chlorophyll) and green fluorescent proteins as well as non-invasive fluorophore loading into single living plant cells. Non-destructive fluorescence imaging with multiphoton microscopes is limited to an optical window. Above certain intensities, multiphoton laser microscopy leads to impaired cellular reproduction, formation of giant cells, oxidative stress and apoptosis-like cell death. Major intracellular targets of photodamage in animal cells are mitochondria as well as the Golgi apparatus. The damage is most likely based on a two-photon excitation process rather than a one-photon or three-photon event. Picosecond and femtosecond laser microscopes therefore provide approximately the same safe relative optical window for two-photon vital cell studies. In labelled cells, additional phototoxic effects may occur via photodynamic action. This has been demonstrated for aminolevulinic acid-induced protoporphyrin IX and other porphyrin sensitizers in cells. When the light intensity in NIR microscopes is increased to TW cm,2 levels, highly localized optical breakdown and plasma formation do occur. These femtosecond NIR laser microscopes can also be used as novel ultraprecise nanosurgical tools with cut sizes between 100 nm and 300 nm. Using the versatile nanoscalpel, intracellular dissection of chromosomes within living cells can be performed without perturbing the outer cell membrane. Moreover, cells remain alive. Non-invasive NIR laser surgery within a living cell or within an organelle is therefore possible. [source] New perspectives in retinal imaging: fundus autofluorescence and age-related macular degenerationACTA OPHTHALMOLOGICA, Issue 2007F HOLZ Fundus Autofluorescence (FAF) imaging using confocal scanning laser ophthalmoscopy is a non-invasive method to to accurately record the topographic distribution of RPE lipofuscin in the human eye in vivo. Excessive lipofuscin accumkulation in the RPE is a common downstream pathogenetic pathway in various complex and monogenetic retinal diseases. Toxic compounds and molecular mechanisms of interference with normal cellular functions have been identified including the dominant fluorophore A2-E. Alterations in fundus autofluorescence (FAF) appearance in eyes with early and late age-related macular degeneration (AMD) can be striking. FAF patterns and distribution do not necessarily correlate with the features of interest in color or angiographic images of eyes with early or late AMD. In the prospective, multicenter FAM study distinct patterns of abnormal FAF were identified and classified in the junctional zone of geographic atrophy (GA). Areas of increased FAF outside GA were associated with variable degrees of loss of retinal sensitivity when tested with microperimetry which suggests a functional correlate of lipofuscin accumulation. Increased FAF preceded the development and enlargement of outer retinal atrophy associated with spread of absolute scotoma in eyes with AMD. Longitudinal examinations showed that the abnormal phenotypic FAF patterns serve as novel prognostic determinants which allows to distinguish fast vs. slow progressors. These findings are relevant and now used to design and carry out interventional trials with agents aimed at slowing down spread of atrophy, e.g. using visual cycle modulators to influence lipofuscinogenesis. Hereby FAF imaging also serves as a mean to accurately delineate and measure areas of GA over time in an automated fashion. A phenotype-genotype correlation was identified for a distinct FAF phenotype subset which was found to represent late-onset Stargardt macular dystrophy mimicking late-stage atrophic AMD. New imaging technologies were recently applied including simultaneous recordings of FAF images and high-resolution, spectral-domain optical coherence tomography (OCT) which allows to identify morphological correlates of abnormal FAF signals in optical biopsies. [source] MAGNIFYING ENDOSCOPY FOR THE DIAGNOSIS OF EARLY GASTRIC CANCERDIGESTIVE ENDOSCOPY, Issue 2002Yasumasa Niwa Magnifying endoscopy of stomach cancer requires observation of minute structure and minute vessel patterns of the mucosal surface. The small pits, various-sized pits, irregularly branched pits and irregular vessels were found to be characteristics as the surface structure of early gastric cancer. Small pits were commonly observed on the differentiated type of early gastric cancer (88%) compared with the undifferentiated type (50%). We found it important to analyze not only the minute vessel patterns, but also the minute surface structure to ensure magnifying endoscopic observation using 0.1% indigo-carmine and the binarized images would be effective in determining the margin of the lesion. The relationship between the findings of magnifying endoscopy in cancer and the histology should now be investigated. Applying the techniques mentioned above, more delicate observation in the regular endoscopy and prudent photographing to obtain clear images might be promoted. Thus, this would contribute to endoscopy with a concept similar to optical biopsy, and which can depend on the usual biopsy methods. [source] Miniaturization of Fluorescence Microscopes Using Fibre OpticsEXPERIMENTAL PHYSIOLOGY, Issue 6 2002Fritjof Helmchen In both medical research and diagnostics characterization of biological tissue on the cellular level relies on high-resolution optical microscopy. In most cases, however, tissue is excised for microscopic investigation, in part because conventional microscopes are bulky instruments. Imaging of cells in the intact living organism has been difficult. Over the last decade several groups have developed miniature confocal microscopes that use fibre optics to deliver light to the specimen and to measure either reflected or excited fluorescence light. In addition, two-photon excitation recently has been employed in a small portable ,fibrescope'. A potential clinical application of these microscope probes is their endoscopic use for optical biopsy of inner organs or guidance of conventional biopsy. As a mobile research tool they may permit imaging of neuronal activity in the brain of awake, behaving animals. Here, we review technological approaches to build miniaturized fluorescence microscopes and discuss their potential applications. [source] Photodiagnostic techniques for the endoscopic detection of premalignant gastrointestinal lesionsDIGESTIVE ENDOSCOPY, Issue 3 2003Ralph S. DaCosta Considerable attention is given to the clinical diagnosis of gastrointestinal (GI) malignancies as they remain the second leading cause of cancer-associated deaths in developed countries. Detection and intervention at an early stage of preneoplastic development significantly improve patient survival. High-risk assessment of asymptomatic patients is currently performed by strict endoscopic surveillance biopsy protocols aimed at early detection of dysplasia and malignancy. However, poor sensitivity associated with frequent surveillance programs incorporating conventional screening tools, such as white light endoscopy and multiple random biopsy, is a significant limitation. Recent advances in biomedical optics are illuminating new ways to detect premalignant lesions of the GI tract with endoscopy. The present review presents a summary report on the newest developments in modern GI endoscopy, which are based on novel optical endoscopic techniques: fluorescence endoscopic imaging and spectroscopy, Raman spectroscopy, light scattering spectroscopy, optical coherence tomography, chromoendoscopy, confocal fluorescence endoscopy and immunofluorescence endoscopy. Relying on the interaction of light with tissue, these ,state-of-the-art' techniques potentially offer an improved strategy for diagnosis of early mucosal lesions by facilitating targeted excisional biopsies. Furthermore, the prospects of real-time ,optical biopsy' and improved staging of lesions may significantly enhance the endoscopist's ability to detect subtle preneoplastic mucosal changes and lead to curative endoscopic ablation of these lesions. Such advancements within this specialty will be rewarded in the long term with improved patient survival and quality of life. [source] | ||||||||||