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OCT
Kinds of OCT Terms modified by OCT Selected AbstractsAssessment of Optical Coherence Tomography Imaging in the Diagnosis of Non-Melanoma Skin Cancer and Benign Lesions Versus Normal Skin: Observer-Blinded Evaluation by Dermatologists and PathologistsDERMATOLOGIC SURGERY, Issue 6 2009METTE MOGENSEN MD BACKGROUND Optical coherence tomography (OCT) is an optical imaging technique that may be useful in diagnosis of non-melanoma skin cancer (NMSC). OBJECTIVES To describe OCT features in NMSC such as actinic keratosis (AK) and basal cell carcinoma (BCC) and in benign lesions and to assess the diagnostic accuracy of OCT in differentiating NMSC from benign lesions and normal skin. METHODS AND MATERIALS OCT and polarization-sensitive (PS) OCT from 104 patients were studied. Observer-blinded evaluation of OCT images from 64 BCCs, 1 baso-squamous carcinoma, 39 AKs, two malignant melanomas, nine benign lesions, and 105 OCT images from perilesional skin was performed; 50 OCT images of NMSC and 50 PS-OCT images of normal skin were evaluated twice. RESULTS Sensitivity was 79% to 94% and specificity 85% to 96% in differentiating normal skin from lesions. Important features were absence of well-defined layering in OCT and PS-OCT images and dark lobules in BCC. Discrimination of AK from BCC had an error rate of 50% to 52%. CONCLUSION OCT features in NMSC are identified, but AK and BCC cannot be differentiated. OCT diagnosis is less accurate than clinical diagnosis, but high accuracy in distinguishing lesions from normal skin, crucial for delineating tumor borders, was obtained. [source] Barrett's esophagus: current and future role of endosonography and optical coherence tomographyDISEASES OF THE ESOPHAGUS, Issue 2 2004S. A. Faruqi SUMMARY., This paper reviews the role of endosonography and optical coherence tomography (OCT) for imaging of Barrett's esophagus (BE). The routine use of endoscopic ultrasound (EUS) to screen patients with BE is neither justified nor cost effective. EUS does appear to have a role in patients who have BE and high-grade dysplasia or intramucosal carcinoma, in whom a non-operative therapy is being contemplated. For patients with a diagnosis of esophageal cancer with or without BE, EUS is superior to computed tomography or magnetic resonance imaging for assessing esophageal wall penetration and for detecting regional lymph node involvement. In its current state, OCT is not yet ready for application in clinical practice. However, given its superior resolution compared with other modalities such as EUS, OCT has great potential as a powerful adjunct to standard endoscopy in surveillance of BE and may enhance the ability of endoscopists to detect high-grade dysplasia at an early stage. With further technical refinement, this technique may become a mainstay in the surveillance of BE and other premalignant conditions of the gastrointestinal tract. [source] Niobium Oxide Mesophases Obtained by Self-Assembly of an Aqueous Soluble Niobium Complex Precursor and Organic TemplatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2007Marcos A. Bizeto Abstract In this paper the use of triammonium trioxalato(oxido)niobate {(NH4)3[NbO(C2O4)3]} as an inorganic precursor to assemble organized hybrid niobium oxide mesophases using n -octylamine (OCT) and cetyltrimethylammonium (CTA) bromide as structure-directing agents is described for the first time. The niobium complex is water-soluble and its hydrolysis at controlled pH and in the presence of organic templates leads to the formation of hybrid mesophases. A lamellar mesophase is produced by a neutral route based on the interaction of hydrolyzed units with the octylamine micelles. On the other hand, a hexagonal (p6m) mesophase is obtained when hydrolyzed species interact with CTA micelles through a charge-matching route (ionic route). This is the first time that such an ionic route has been described for the production of organized niobium oxide hybrids.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Sweat gland epithelial and myoepithelial cells are vitamin D targetsEXPERIMENTAL DERMATOLOGY, Issue 2 2007Nobuo Koike Abstract:, Nuclear receptor binding of 1,25(OH)2 -vitamin D3 (vitamin D) in skin keratinocytes of epidermis, hair sheaths and sebaceous glands was discovered through receptor microscopic autoradiography. Extended experiments with 3H-1,25(OH)2 -vitamin D3 and its analog 3H-oxacalcitriol (OCT) now demonstrate nuclear receptor binding in sweat gland epithelium of secretory coils and ducts as well as in myoepithelial cells, as studied in paws of nude mice after i.v. injection. The results suggest genomic regulation of cell proliferation and differentiation, as well as of secretory and excretory functions, indicating potential therapies for impaired secretion as in hypohidrosis of aged and diseased skin. [source] Isotopic and petrological evidence of fluid,rock interaction at a Tethyan ocean,continent transition in the Alps: implications for tectonic processes and carbon transfer during early ocean formationGEOFLUIDS (ELECTRONIC), Issue 4 2007A. ENGSTRÖM Abstract We report overprinting stable isotope evidence of fluid,rock interaction below two detachment faults along which mantle rocks were exhumed to the seafloor, between the respective landward and seaward limits of oceanic and continental crust, at a Tethyan ocean,continent transition (OCT). This OCT, which is presently exposed in the Tasna nappe (south-eastern Switzerland) is considered an on-land analogue of the well-studied Iberian OCT. We compare our results with the fault architecture (fault core,damage zone,protolith) described by Caine et al. [Geology (1996) Vol. 24, pp. 1025,1028]. We confirm the existence of a sharp boundary between the fault core and damage zone based on isotopic data, but the boundary between the damage zone and protolith is gradational. We identify evidence for: (1) pervasive isotopic modification to 8.4 ± 0.1, which accompanied or post-dated serpentinization of these mantle rocks at an estimated temperature of 67,109°C, (2) either (i) partial isolation of some highly strained regions [fault core(s) and mylonite] from this pervasive isotopic modification, because of permeability reduction (Caine et al.) or (ii) subsequent isotopic modification caused by structurally channelled flow of warm fluids within these highly strained regions, because of permeability enhancement, and (3) isotopic modification, which is associated with extensive calcification at T = 54,100°C, primarily beneath the younger of the two detachment faults and post-dating initial serpentinization. By comparing the volumetric extent of calcification with an experimentally verified model for calcite precipitation in veins, we conclude that calcification could have occurred in response to seawater infiltration, with a calculated flux rate of 0.1,0.2 m year,1 and a minimum duration of 0.2,4.0 × 104 years. The associated time-averaged uptake flux of carbon during this period was 8,120 mol m,2 year,1. By comparison with the estimated area of exhumed mantle rocks at the Iberian OCT, we calculate a maximum annual uptake flux for carbon of 2,30 Tg year,1. This is an order of magnitude greater than that for carbon exchange at the mid-ocean ridges and 0.1,1.4% of the global oceanic uptake flux for carbon. [source] Clinical value of optical coherence tomography in laryngologyHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 12 2008Marcel Kraft MD Abstract Background. Optical coherence tomography (OCT) is a new, noninvasive imaging technology for the evaluation of superficial lesions. The objective of this study is to evaluate microlaryngoscopy in combination with OCT compared with microlaryngoscopy alone (ie, without OCT) in supplying a specific diagnosis, predicting invasive tumor growth and epithelial dysplasia in the larynx. Methods. This was a prospective study including 217 laryngeal lesions in a total of 193 patients undergoing surgery. Intraoperative suspicion diagnosis gained by microlaryngoscopy with and without OCT was compared with conventional histopathology after excisional biopsy. Results. Microlaryngoscopy with OCT supplied a specific diagnosis in 89% of cases, but in only 80% of cases with microlaryngoscopy alone. In particular, our results in malignant and benign pathologies were correct in 93% each, and the exact grade of dysplasia could be predicted in 71% of precancerous lesions. Microlaryngoscopy with OCT presented a higher sensitivity than microlaryngoscopy alone in predicting invasive tumor growth (93% vs 87%) and epithelial dysplasia (78% vs 66%), but the specificity and accuracy were comparable in both methods. Conclusions. OCT is a simple, rapid, and reliable aid in the diagnostic investigation and intraoperative monitoring of laryngeal disease. © 2008 Wiley Periodicals, Inc. Head Neck, 2008 [source] pH-induced alterations in stratum corneum propertiesINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2003K. P. Ananthapadmanabhan Synopsis Skin-cleansing compositions based on alkyl carboxylates (soaps) have a higher irritation potential than those based on syndet surfactants such as alkyl isethionates or alkyl ether sulphates. Contributing factors include inherent differences in the irritation potential of soaps and syndet surfactants, pH-induced changes in surfactant solution chemistry, and the direct effects of pH on the physical properties of the stratum corneum (SC). Past work has not directly addressed the effect of solution pH on the SC itself and its potential role in cleanser-induced skin irritation. In the current work, alterations to SC properties induced by buffered pH solutions and two strongly ionizable surfactants, sodium dodecyl sulphate and sodium lauryl ether sulphate, at different pH values are measured. By utilizing optical coherence tomography (OCT) and infrared (IR) spectroscopy we have directly measured physical changes in SC proteins and lipids. Our results indicate that SC swelling, which reflects alterations to SC structural proteins, is increased significantly at pH 10, compared to pH 4 and 6.5. The transition temperature (Tm) of SC lipids is found to increase at pH 10, compared to pH 4 and 6.5, suggesting a more rigid SC lipid matrix. Surfactants cause a further increase in swelling and lipid rigidity. Some aspects of what these results mean for SC physical properties as well as their implications to potential mechanisms of surfactant-induced skin irritation are discussed. Résumé Les compositions nettoyantes pour la peau à base d'alkyl carboxylates (savons) ont un potentiel irritant supérieur à celles à base de syndet tensioactifs tels que les alkyl isothionates ou les alkyl ether sulfates. Les facteurs en cause comprennent les différences de potentiel irritant inhérentes aux savons et aux syndet tensioactifs, les modifications de la chimie de la solution de tensioactif dues aux pH, et les effets directs du pH sur les propriétés physiques de la couche cornée (CC). Les travaux antérieurs n'ont pas traité directement l'effet du pH de la solution sur la couche cornée elle-même et son rôle potentiel dans l'irritation de la peau due à la solution nettoyante. Dans la présente étude on a mesuré les altérations des propriétés de la CC causées par des solutions à pH tamponné et deux tensioactifs fortement ionisables, le dodecyl sulfate de sodium et le lauryl ether sulfate de sodium, à différentes valeurs de pH. En utilisant la tomographie optique (OCT) et la spectroscopie à infrarouge (IR) on a mesuré directement les modifications physiques des protéines et des lipides de la CC. Nos résultats montrent que le gonflement de la CC, qui traduit des altérations des protéines structurales de la CC, augmente significativement à pH 10, par comparaison au pH 4 et 6.5. On observe que la température de transition (Tm) des lipides de la CC augmente à pH 10, par comparaison au pH 4 et 6.5, suggérant une matrice lipidique de la CC plus rigide. Les tensioactifs provoquent une augmentation plus importante du gonflement et de la rigidité lipidique. On aborde certains aspects de la signification de ces résultats vis-à-vis des propriétés physiques de la couche cornée ainsi que leurs conséquences sur les mécanismes potentiels de l'irritation de la peau causée par les tensioactifs. [source] Monitoring of glucose permeability in monkey skin in vivo using Optical Coherence TomographyJOURNAL OF BIOPHOTONICS, Issue 1-2 2010Mohamad G. Ghosn Abstract Topical trans-dermal delivery of drugs has proven to be a promising route for treatment of many dermatological diseases. The aim of this study is to monitor and quantify the permeability rate of glucose solutions in rhesus monkey skin noninvasively in vivo as a primate model for drug diffusion. A time-domain Optical Coherence Tomography (OCT) system was used to image the diffusion of glucose in the skin of anesthetized monkeys for which the permeability rate was calculated. From 5 experiments on 4 different monkeys, the permeability for glucose-20% was found to be (4.41 ± 0.28) 10,6 cm/sec. The results suggest that OCT might be utilized for the noninvasive study of molecular diffusion in the multilayered biological tissues in vivo. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Imaging engineered tissues using structural and functional optical coherence tomographyJOURNAL OF BIOPHOTONICS, Issue 11 2009Xing Liang Abstract As the field of tissue engineering evolves, there will be an increasingly important need to visualize and track the complex dynamic changes that occur within three-dimensional constructs. Optical coherence tomography (OCT), as an emerging imaging technology applied to biological materials, offers a number of significant advantages to visualize these changes. Structural OCT has been used to investigate the longitudinal development of engineered tissues and cell dynamics such as migration, proliferation, detachment, and cell-material interactions. Optical techniques that image functional parameters or integrate multiple imaging modalities to provide complementary contrast mechanisms have been developed, such as the integration of optical coherence microscopy with multiphoton microscopy to image structural and functional information from cells in engineered tissue, optical coherence elastography to generate images or maps of strain to reflect the spatially-dependent biomechanical properties, and spectroscopic OCT to differentiate different cell types. From these results, OCT demonstrates great promise for imaging and visualizing engineered tissues, and the complex cellular dynamics that directly affect their practical and clinical use. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] AM,FM techniques in the analysis of optical coherence tomography signalsJOURNAL OF BIOPHOTONICS, Issue 6-7 2009Costas Pitris Abstract The subtle tissue changes associated with the early stages of malignancies, such as cancer, are not clearly discernible even at the current, improved, resolution of optical coherence tomography (OCT) systems. However, these changes directly affect the spectral content of the OCT image that contains information regarding these unresolvable features. Spectral analysis of OCT signals has recently been shown to provide additional information, resulting in improved contrast, directly related to scatterer size changes. Amplitude modulation,frequency modulation (AM,FM) analysis, a fast and accurate technique for the estimation of the instantaneous frequency, phase, and amplitude of a signal, can also be applied to OCT images to extract scatterer-size information. The proposed technique could make available an extremely valuable tool for the investigation of disease characteristics that now remain below the resolution of OCT and could significantly improve the technology's diagnostic capabilities. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] OCT imaging of skin cancer and other dermatological diseasesJOURNAL OF BIOPHOTONICS, Issue 6-7 2009Mette Mogensen Abstract Optical coherence tomography (OCT) provides clinicians and researchers with micrometer-resolution, in vivo, cross-sectional images of human skin up to several millimeter depth. This review of OCT imaging applied within dermatology covers the application of OCT to normal skin, and reports on a large number of applications in the fields of non-melanoma skin cancer, malignant melanomas, psoriasis and dermatitis, infestations, bullous skin diseases, tattoos, nails, haemangiomas, and other skin diseases. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Use of optical coherence tomography for assessment of dental caries: quantitative procedureJOURNAL OF ORAL REHABILITATION, Issue 12 2001B. T. Amaechi A method for quantitative assessment of dental caries using optical coherence tomography (OCT) was demonstrated. Development of caries lesions in 15 bovine teeth, by demineralization in acidic buffer solution, was quantitatively assessed daily for 3 days, using OCT. An OCT system which can collect A-scans (depth versus reflectivity curve), B-scans (longitudinal images) and C-scans (transverse images at constant depth) was used. While the B- and C-scans qualitatively described the lesion detected, the A-scan which showed the depth (mm) resolved reflectivity (dB) of the tooth tissue was used for the quantitative analysis. After a simple normalization procedure to determine the actual depth the light travelled into the tooth tissue, the area (R) under the A-scan was quantified as a measure of the degree of reflectivity of the tissue. The result showed that R (dB mm) decreased with increasing demineralization time. The percentage reflectivity loss (R%) in demineralized tissue, which related to the amount of mineral loss, was also calculated, and it was observed that R% increased with increasing demineralization time. It was concluded that with the above procedure, OCT could quantitatively monitor the mineral changes in a caries lesion on a longitudinal basis. [source] High-resolution imaging of progressive articular cartilage degenerationJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2006Samuel B. Adams Jr Abstract The objective of this study was to develop and verify a new technique for monitoring the progression of osteoarthritis (OA) by combining a rat model with the imaging modality optical coherence tomography (OCT). Time-sequential, in vivo, OCT imaging was performed on the left femoral condyles of 12 Wistar rats following sodium,iodoacetic acid-induced OA progression. The right femoral condyles (untreated) were also imaged and served as controls. Imaging was performed on days 0, 10, 20, 30, and 60 with an OCT system capable of acquiring images at four frames per second and an axial resolution of 5 µm. Progressive changes were analyzed using an OA scoring system. OCT successfully identified progressive cartilage degeneration as well as alteration of the cartilage/bone interface. Significant changes to both of these structures were observed in the sodium,iodoacetic acid-injected condyles. Structural changes detected with OCT were confirmed histologically. OCT in combination with a well-known model used in arthritis research represents a powerful tool for following degenerative joint disease progression in a given animal by detecting changes to the cartilage/bone interface and articular cartilage. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Imaging pharmaceutical tablets with optical coherence tomographyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2010Jakob M.A. Mauritz Abstract Optical coherence tomography (OCT) is a recently developed optical technique that produces depth profiles of three-dimensional objects. It is a nondestructive interferometric method responding to refractive index variation in the sample under study and can reach a penetration depth of a few millimetres. OCT employs near-infrared (NIR) light and therefore provides a link between NIR spectroscopy and Terahertz (THz) measurements that are often used to characterise tablets. In this article we assess the potential of OCT as a reliable and practical tool in the analysis of pharmaceutical tablets and coatings. A variety of tablets were tested with different shapes, formulations and coatings. We consider the origins of contrast in the obtained images and demonstrate that it correlates strongly with the expected tablet structure. The influence of absorption and scattering are considered for the wavelength ranges used. The results show that OCT is a promising diagnostic tool with an important role to play in the tablet and coating technologies. The high measurement speed of OCT and its relative ease of implementation make it also an attractive candidate technology for in-line quality control during manufacturing. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:385,391, 2010 [source] Clinicopathologic Evaluation of Hepatic Lipidosis in Periparturient Dairy CattleJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2007Emmanouil Kalaitzakis Background: Fatty change of the liver (FCL) is very common in dairy cattle periparturiently. Many laboratory methods have been implicated in order to assist the diagnosis. Hypothesis: To investigate whether FCL in dairy cattle could be evaluated by assessment of ornithine carbamoyl transferase (OCT) by means of an assay modified for bovine serum, other enzyme activity, serum bile acids (SBA) concentration, or other biochemical constituents. Animals: A total of 187 dairy cattle were included: 106 were suspected to have liver dysfunction and were examined after referral by veterinarians; 70 were clinically healthy with mild FCL; and 11 were clinically healthy without FCL. Methods: Blood and liver biopsy samples were obtained after clinical examination. Histologic examination by light microscopy and classification of samples according to the severity of FCL was done, and total lipid and triglyceride concentration was measured. In serum, OCT, aspartate aminotransferase (AST), alanine aminotransferase (ALT), sorbitol dehydrogenase (SDH), glutamate dehydrogenase (GDH), alkaline phosphatase (ALP), and ,-glutamyltransferase (,-GT) activity as well as SBA, glucose, ketones, total bilirubin (tBIL), and nonesterified fatty acids (NEFA) concentration were measured. Results: OCT and AST activity and tBIL concentration correlate well with the degree of FCL. SBA concentration does not contribute well to FCL diagnosis. The majority of FCL cases appeared within the first 21 days-in-milk (DIM). The majority of moderate-to-severe and severe FCL cases arose in the first 7 DIM. Conclusions and Clinical Importance: Except for OCT, AST, and tBIL, none of the biochemical tests used, including SBA, had sufficient discriminatory power to differentiate reliably between mild and severe FCL because of poor sensitivity. A weak correlation between clinical signs and the extent of FCL was evident. [source] Cultured mammary epithelial monolayers (BME-UV) express functional organic anion and cation transportersJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2009M. M. AL-BATAINEH There is ongoing concern about the potential adverse effects of xenobiotic residues in cows' milk to the human consumer. Although drugs that are intentionally administered to lactating dairy cattle are rigorously regulated to prevent harmful residues, there are numerous other potential sources of exposure that are not as easily controlled. For example, cattle may be exposed to mycotoxins, pesticides and/or persistent organic pollutants through feed, water and inhalation of polluted air. Accurate estimates of the rate and extent of excretion of these compounds into milk is important to assess the risk of exposure through cows' milk. In the present study, the expression of carrier mediated transport processes in cultured monolayers of an immortalized bovine mammary epithelial cell line (BME-UV) was determined using a flow-through diffusion cell system, selective substrates and inhibitors of organic cation transporters (OCT) and organic anion transporters (OAT). The basal-to-apical (BL-to-Ap) flux of tetraethylammonium and estrone sulfate significantly exceeded their flux in the opposite direction. The addition of selective inhibitors to the donor compartment significantly decreased the BL-to-Ap flux of either selective substrate. These results suggest that both OCT and OAT are functionally expressed by BME-UV cells. [source] Plant photonics: application of optical coherence tomography to monitor defects and rots in onionLASER PHYSICS LETTERS, Issue 4 2010I.V. Meglinski Abstract The incidence of physiological and/or pathological defects in many fresh produce types is still unacceptably high and accounts for a large proportion of waste. With increasing interest in food security their remains strong demand in developing reliable and cost effective technologies for non-destructive screening of internal defects and rots, these being deemed unacceptable by consumers. It is well recognized that the internal defects and structure of turbid scattering media can be effectively visualized by using optical coherence tomography (OCT). In the present study, the high spatial resolution and advantages of OCT have been demonstrated for imaging the skins and outer laminae (concentric tissue layers) of intact whole onion bulbs with a view to non-invasively visualizing potential incidence/severity of internal defects. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Quantification of glycerol diffusion in human normal and cancer breast tissues in vitro with optical coherence tomographyLASER PHYSICS LETTERS, Issue 4 2010H.Q. Zhong Abstract Optical coherence tomography (OCT) holds great promise as a routine research tool for analysis of identifying the boundaries between normal and diseased breast tissue in vitro and in vivo. However, despite the depth penetration afforded by this imaging modality, light attenuation in tissues imposes limitations. Here we studied the optical clearing effect of glycerol in human cancer and normal breast tissues with OCT for functional imaging to monitor. Depth- and time-resolved profiles for OCT signal enhancement were presented. The results show that the OCT imaging depth and imaging contrast of breast tissues have been improved after application of 60% glycerol in the 2-D OCT images. The OCT slope signals of breast tissues decreased as glycerol diffusion into tissues, therefore, the water and intercellular fluids were drawn out from tissues. Then the reverse process due to water was drawn back into the cells as a result of its affinity for water. The permeability coefficient of 60% glycerol was (3.14 ± 0.07) × 10,5 cm/s in breast cancer tissues, and (0.89 ± 0.02) × 10,5 cm/s in normal breast tissues, respectively. The permeability coefficient of glycerol in cancer tissues was 3.54-fold than that in normal tissues. These results demonstrate that the optical clearing of normal and cancer breast tissues are improved after application of glycerol. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Magneto-motive detection of tissue-based macrophages by differential phase optical coherence tomographyLASERS IN SURGERY AND MEDICINE, Issue 3 2007Junghwan Oh PhD Abstract Background and Objectives A novel method to detect tissue-based macrophages using a combination of superparamagnetic iron oxide (SPIO) nanoparticles and differential phase optical coherence tomography (DP-OCT) with an external oscillating magnetic field is reported. Study Design/Material and Methods Magnetic force acting on iron-laden tissue-based macrophages was varied by applying a sinusoidal current to a solenoid containing a conical iron core that substantially focused and increased magnetic flux density. Results Nanoparticle motion was detected with DP-OCT, which can detect tissue movement with nanometer resolution. Frequency response of iron-laden tissue movement was twice the modulation frequency since the magnetic force is proportional to the product of magnetic flux density and gradient. Conclusions Results of our experiments indicate that DP-OCT can be used to identify tissue-based macrophage when excited by an external focused oscillating magnetic field. Lasers Surg. Med. 39:266,272, 2007. © 2007 Wiley-Liss, Inc. [source] Mechanistic comparison of blood undergoing laser photocoagulation at 532 and 1,064 nmLASERS IN SURGERY AND MEDICINE, Issue 2 2005John F. Black PhD Abstract Background and Objectives We seek to compare and contrast the mechanisms of blood photocoagulation under 532 and 1,064 nm laser irradiation in vitro in order to better understand the in vivo observations. We also seek to validate a finite element model (FEM) developed to study the thermodynamics of coagulation. Study Design/Materials and Methods We study the photocoagulation of whole blood in vitro at 532 and 1,064 nm using time-domain spectroscopic and optical coherence tomography (OCT)-based imaging techniques. We model the coagulation using an FEM program that includes the latent heat of vaporization (LHV) of water, consideration of the pulse shape of the laser, and the bathochromic shift in the hemoglobin absorption spectrum. Results We find significant similarities in the spectroscopic, chemical, and structural changes occurring in hemoglobin and in the blood matrix during photocoagulation despite the very large difference in the absorption coefficients. The more uniform temperature profile developed by the deeper-penetrating 1,064 nm laser allows us to resolve the structural phase transition in the red blood cells (going from biconcave disc to spherocyte) and the chemical transition creating met-hemoglobin. We find that the RBC morphology transition happens first, and that the met-Hb transition happens at a much higher temperature (,>,90°C) than is found in slow bath heating. The FEM analysis with the LHV constraint and bathochromic shift predicts accurately the imaging results in both cases, and can be used to show that at 1,064 nm there is the potential for a runaway increase in absorption during the laser pulse. Conclusions Photothermally mediated processes dominate the in vitro coagulation dynamics in both regimes despite the difference in absorption coefficients. There is a significant risk under 1,064 nm irradiation of vascular lesions in vivo that the dynamic optical properties of blood will cause runaway absorption and heating. This may in turn explain some recent results at this wavelength where full-thickness burns resulted from laser treatment. Lasers Surg. Med. 36:155,165, 2005. © 2005 Wiley-Liss, Inc. [source] Technical Note: Method for estimating volume of subretinal fluid in cases of localized retinal detachment by OCT ophthalmoscopyOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2007Hideto Nakajima Abstract The volume of the subretinal fluid can be used to assess the condition of different types of retinal and macular disorders. The purpose of this report is to introduce a method to measure the volume of the subretinal fluid with the images of the optical coherence tomography (OCT) Ophthalmoscope in three cases of central serous chorioretinopathy and one case of retinal pigment epithelial detachment. We used the topography-mode program of the OCT Ophthalmoscope and measured the average height of the retinal detachment. By multiplying the size of the area of the retinal detachment and the average height of the retinal detachment, the volume of subretinal fluid could be determined. Examples are given to show the results of volume measurement of subretinal fluid in cases of localized retinal detachments. [source] Comparison of optical coherence tomography and fundus photography for measuring the optic disc sizeOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2006Aljoscha S. Neubauer Abstract Purpose:, To assess the agreement and repeatability of optic nerve head (ONH) size measurements by optical coherence tomography (OCT) as compared to conventional planimetry of fundus photographs in normal eyes. Methods:, For comparison with planimetry the absolute size of the ONH of 25 eyes from 25 normal subjects were measured by both OCT and digital fundus photography (Zeiss FF camera 450). Repeatability of automated Stratus OCT measurements were investigated by repeatedly measuring the optic disc in five normal subjects. Results:, Mean disc size was 1763 ± 186 vertically and 1632 ± 160 ,m horizontally on planimetry. On OCT, values of 1772 ± 317 ,m vertically (p = 0.82) and a significantly smaller horizontal diameter of 1492 ± 302 ,m (p = 0.04) were obtained. The 95% limits of agreement were (,546 ,m; +527 ,m) for vertical and (,502 ,m; +782 ,m) for horizontal planimetric compared to OCT measurements. In some cases large discrepancies existed. Repeatability of automatic measurements of the optic disc by OCT was moderately good with intra-class correlation coefficients (ICC) of 0.78 horizontally and 0.83 vertically. The coefficient of repeatability indicating instrument precision was 80 ,m for horizontal and 168 ,m for vertical measurements. Conclusions:, OCT can be used to determine optic disc margins in moderate agreement with planimetry in normal subjects. However, in some cases significant disagreement with photographic assessment may occur making manual inspection advisable. Automatic disc detection by OCT is moderately repeatable. [source] Molecular Contrast Optical Coherence Tomography: A Review,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Changhuei Yang ABSTRACT This article reviews the current state of research on the use of molecular contrast agents in optical coherence tomography (OCT) imaging techniques. After a brief discussion of the basic principle of OCT and the importance of incorporating molecular contrast agent usage into this imaging modality, we shall present an overview of the different molecular contrast OCT (MCOCT) methods that have been developed thus far. We will then discuss several important practical issues that define the possible range of contrast agent choice, the design criteria for engineered molecular contrast agent and the implementability of a given MCOCT method for clinical or biological applications. We will conclude by outlining a few areas of pursuit that deserve a greater degree of research and development. [source] Seeing right through you: Applications of optical imaging to the study of the human brainPSYCHOPHYSIOLOGY, Issue 4 2003Gabriele Gratton Abstract A new set of techniques allows for the study of brain function by near-infrared light, exploiting two optical phenomena: Changes in light absorption are determined by changes in the concentration of substances like oxy- and deoxy-hemoglobin, and changes in light scattering occur as a consequence of variations of properties of membranes and corpuscles in the neural tissue. Methods based on light absorption can be used to study hemodynamic changes in the brain, whereas those based on light scattering can be used to study neuronal activity and to provide anatomical information at a cellular and subcellular level. Three optical imaging approaches can be used to study living tissue: reflection, optical coherence tomography (OCT), and photon migration. These three approaches vary in their penetration (from less than a millimeter for reflection to up to 3,5 cm for photon migration) and spatial resolution (from a micron level for reflection and OCT to a millimeter and centimeter level for photon migration). This issue includes a collection of articles reviewing applications of these technologies to the study of brain and other bodily functions in humans. [source] Longitudinal study of vision and retinal nerve fiber layer thickness in multiple sclerosisANNALS OF NEUROLOGY, Issue 6 2010Lauren S. Talman BA Objective Cross-sectional studies of optical coherence tomography (OCT) show that retinal nerve fiber layer (RNFL) thickness is reduced in multiple sclerosis (MS) and correlates with visual function. We determined how longitudinal changes in RNFL thickness relate to visual loss. We also examined patterns of RNFL thinning over time in MS eyes with and without a prior history of acute optic neuritis (ON). Methods Patients underwent OCT measurement of RNFL thickness at baseline and at 6-month intervals during a mean follow-up of 18 months at 3 centers. Low-contrast letter acuity (2.5%, 1.25% contrast) and visual acuity (VA) were assessed. Results Among 299 patients (593 eyes) with ,6 months follow-up, eyes with visual loss showed greater RNFL thinning compared to eyes with stable vision (low-contrast acuity, 2.5%: p < 0.001; VA: p = 0.005). RNFL thinning increased over time, with average losses of 2.9,m at 2 to 3 years and 6.1,m at 3 to 4.5 years (p < 0.001 vs 0.5,1-year follow-up interval). These patterns were observed for eyes with or without prior history of ON. Proportions of eyes with RNFL loss greater than test-retest variability (,6.6,m) increased from 11% at 0 to 1 year to 44% at 3 to 4.5 years (p < 0.001). Interpretation Progressive RNFL thinning occurs as a function of time in some patients with MS, even in the absence of ON, and is associated with clinically significant visual loss. These findings are consistent with subclinical axonal loss in the anterior visual pathway in MS, and support the use of OCT and low-contrast acuity as methods to evaluate the effectiveness of putative neuroprotection protocols. ANN NEUROL 2010;67:749,760 [source] Neuroplasticity predicts outcome of optic neuritis independent of tissue damageANNALS OF NEUROLOGY, Issue 1 2010Thomas M. Jenkins MRCP Objectives To determine whether lateral occipital complex (LOC) activation with functional magnetic resonance imaging (fMRI) predicts visual outcome after clinically isolated optic neuritis (ON). To investigate the reasons behind good recovery following ON, despite residual optic nerve demyelination and neuroaxonal damage. Methods Patients with acute ON and healthy volunteers were studied longitudinally over 12 months. Structural MRI, visual evoked potentials (VEPs), and optical coherence tomography (OCT) were used to quantify acute inflammation, demyelination, conduction block, and later to estimate remyelination and neuroaxonal loss over the entire visual pathway. The role of neuroplasticity was investigated using fMRI. Multivariable linear regression analysis was used to study associations between vision, structure, and function. Results Greater baseline fMRI responses in the LOCs were associated with better visual outcome at 12 months. This was evident on stimulation of either eye (p = 0.007 affected; p = 0.020 fellow eye), and was independent of measures of demyelination and neuroaxonal loss. A negative fMRI response in the LOCs at baseline was associated with a relatively worse visual outcome. No acute electrophysiological or structural measures, in the anterior or posterior visual pathways, were associated with visual outcome. Interpretation Early neuroplasticity in higher visual areas appears to be an important determinant of recovery from ON, independent of tissue damage in the anterior or posterior visual pathway, including neuroaxonal loss (as measured by MRI, VEP, and OCT) and demyelination (as measured by VEP). ANN NEUROL 2010;67:99,113 [source] USING OPTICAL COHERENCE TOMOGRAPHY TO EXAMINE THE SUBSURFACE MORPHOLOGY OF CHINESE GLAZESARCHAEOMETRY, Issue 5 2009M.-L. YANG Optical coherence tomography (OCT), a new method for ceramics research, is a nondestructive, three-dimensional tomography system, which provides subsurface morphology visualization of samples based on the refractive index or dielectric constant differences in the target specimen. In this study, seven shards from different Chinese kilns of Song and Yuan dynasties (10,14th centuries) were scanned to visualize the subsurface morphology of their glazes. The images revealed unique phase assemblage modes in different samples. The results suggest OCT may be used to identify ceramics and provide information about their manufacturing technology. [source] Clinical optical coherence tomography of early articular cartilage degeneration in patients with degenerative meniscal tearsARTHRITIS & RHEUMATISM, Issue 5 2010Constance R. Chu Objective Quantitative and nondestructive methods for clinical diagnosis and staging of articular cartilage degeneration are important to the evaluation of potential disease-modifying treatments in osteoarthritis (OA). Optical coherence tomography (OCT) is a novel imaging technology that can generate microscopic-resolution cross-sectional images of articular cartilage in near real-time. This study tested the hypotheses that OCT can be used clinically to identify early cartilage degeneration and that OCT findings correlate with magnetic resonance imaging (MRI) T2 values and arthroscopy results. Methods Patients undergoing arthroscopy for degenerative meniscal tears were recruited under Institutional Review Board,approved protocols. Thirty consecutive subjects completing preoperative 3.0T MRI, arthroscopy, and intraoperative OCT comprised the study group. Qualitative and quantitative OCT results and MRI T2 values were compared with modified Outerbridge cartilage degeneration scores (0,4 scale) assigned at arthroscopy. Results Arthroscopic grades showed cartilage abnormality in 23 of the 30 patients. OCT grades were abnormal in 28 of the 30 patients. Both qualitative and quantitative OCT strongly correlated with the arthroscopy results (P = 0.004 and P = 0.0002, respectively, by Kruskal-Wallis test). Neither the superficial nor the deep cartilage T2 values correlated with the arthroscopy results. The quantitative OCT results correlated with the T2 values in the superficial cartilage (Pearson's r = 0.39, P = 0.03). Conclusion These data show that OCT can be used clinically to provide qualitative and quantitative assessments of early articular cartilage degeneration that strongly correlate with arthroscopy results. The correlation between the quantitative OCT values and T2 values for the superficial cartilage further supports the utility of OCT as a clinical research tool, providing quantifiable microscopic resolution data on the articular cartilage structure. New technologies for nondestructive quantitative assessment of human articular cartilage degeneration may facilitate the development of strategies to delay or prevent the onset of OA. [source] Evaluation of the atrophogenic potential of different glucocorticoids using optical coherence tomography, 20-MHz ultrasound and profilometry; a double-blind, placebo-controlled trialBRITISH JOURNAL OF DERMATOLOGY, Issue 4 2006M. Coßmann Summary Background, Skin atrophy is one of the main side-effects of topical corticosteroid therapy. Although the use of high-frequency ultrasound is an established method that has been studied previously, it allows measurements of the slow-reacting dermal thickness only. Objectives, To investigate the decreasing epidermal thickness, which occurs earlier, we used optical coherence tomography (OCT), a high-resolution noninvasive imaging technique, and compared it with 20-MHz ultrasound and profilometry. Patients/methods, In this double-blind placebo-controlled trial 20 healthy volunteers applied four different corticosteroids and the cream base formulation as placebo to the volar part of both arms once a day over a 4-week period. The epidermal thickness, the dermal thickness and the skin surface roughness were assessed using OCT, high-frequency ultrasound and profilometry. Results, Each of the three methods allowed the detection and monitoring of significant corticosteroid-induced skin atrophy and its reversibility. The changes correlated with the potency of the steroids. The epidermal thickness decreased significantly in all test areas, even in the placebo and the untreated fields. As expected, the reduction in epidermal thickness was more pronounced and could be detected earlier by OCT than the reduction of dermal thickness using ultrasound. The epidermal surface roughness investigated using profilometry showed a slight smoothing. Conclusions, OCT allows a simple, fast and noninvasive in vivo measurement of the epidermal thickness. To evaluate the atrophogenic potential of corticosteroids it is more suitable than high-frequency ultrasound as epidermal thickness decreases earlier. In addition, epidermal thickness is a more sensitive indicator of steroid atrophy as the degree of thinning is much higher compared with the dermal atrophy. Profilometry might give further information; however, it would not be suitable for clinical use as the results were generally less pronounced. In the future, OCT might be useful to detect corticosteroid-induced side-effects at the beginning for monitoring the therapy. [source] Histology of highly echolucent regions in optical coherence tomography images from two patients with sirolimus-eluting stent restenosis,CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 6 2010Hiroyuki Nagai MD Abstract We report on two patients with sirolimus-eluting stent (SES) restenosis lesions who showed highly echolucent regions by optical coherence tomography (OCT) and who could be assessed histologically after removal by directional coronary atherectomy (DCA). One restenosis lesion had a bilayer structure of hyperechoic outer layers and highly echolucent inner layers on OCT images and histologically exhibited myxomatous neointima tissue in the highly echolucent regions; another restenosis case showed patchy and highly echolucent regions throughout the layers and its histology revealed fibrin thrombosis. We should be aware that patterns of echolucent on OCT images may have various histology. OCT allows the visualization of fine lesions that conventional intravascular ultrasound (IVUS) cannot provide. The OCT images of drug-eluting stent restenosis lesions often show echolucent regions [Shuzoh et al., EuroInterv 2006;1:484]. However, no histological study of the lesions has been reported to date. Here we report on two patients with SES restenosis lesions that showed highly echolucent regions by OCT and that could be assessed histologically after removal by DCA. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||