Cross-sectional Optical Coherence Tomography Images Research Articles

Validation of swept source optical coherence tomography (SS-OCT) for the diagnosis of smooth surface caries in vitro

ObjectiveAn accurate evaluation of the extent of dental caries and possible progress of the lesion from enamel into dentin is very important in clinical dentistry. Dentists need an imaging technology that can noninvasively and reliably quantify the extent of caries. This study aimed to evaluate the effectiveness of non-polarized swept source optical coherence tomography (OCT) in evaluating the extent of caries on smooth enamel surfaces. MethodsOne-hundred and twenty-seven investigation sites on the enamel surfaces of 93 extracted teeth were selected randomly and examined visually. The presence and extent of caries were scored by experienced and inexperienced dentists using each observation method (0: no caries; 1: enamel demineralization without surface breakdown; 2: enamel breakdown due to caries; 3: deep caries involving the dentin). The same locations were then examined using OCT, following which the teeth were sectioned using a diamond saw and viewed directly under a confocal laser scanning microscope (CLSM). Sensitivity and specificity indices for OCT and VI were calculated and compared. The results were analysed statistically using receiver operating characteristic (ROC) curves. ResultsEnamel and dentin caries were outlined by a visible boundary on the cross-sectional OCT images. The modality showed superior results for the detection of dentinal caries; higher sensitivity and Az values could be obtained in the ROC curves, especially by experienced dentists. ConclusionsCross-sectional imaging of the natural caries lesions on smooth enamel surface by OCT enables efficient diagnosis of the lesion type, extent and dentin involvement. Clinical significanceSS-OCT can demonstrate the cross-sectional image of smooth surface enamel caries as highlighted zone in tomogram. It is crucial to determine the extent of the lesion, whether it reaches beyond DEJ or not by a non-invasive and safe technique. OCT can give clinicians information about internal tooth structure and will help clinical decision making on surgical intervention.

Morphologic and Functional Changes in Retinal Vessels Associated with Branch Retinal Vein Occlusion

To study the morphologic and functional changes in retinal veins of eyes affected with branch retinal vein occlusion (BRVO) by thin sectioning with optical coherence tomography (OCT). Prospective, observational, cross-sectional study. Twenty-five consecutive patients (25 eyes) with acute BRVO. Major retinal veins, arteries, and arteriovenous (A/V) crossing were examined by sequential thin sectioning by Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). The retinal blood flow was mimicked in vitro and scanned with Spectralis HRA+OCT. Morphologic characteristics of normal and BRVO-affected retinal vessels seen in OCT sections. Cross-sectional OCT images revealed physiologic retinal vessels as oval configurations with 4 distinctive hyperreflectivities in a line. The vessel walls showed the innermost and outermost hyperreflectivity, and the blood flow showed internal paired hyperreflectivities with an hourglass shape. No eye with disturbed blood flow due to BRVO showed this internal hyperreflectivity pattern. In vitro, OCT sections of the blood within the glass tube without flow showed homogeneous reflectivities. Increased blood flow velocity resulted in the development of heterogeneous internal reflectivity and hourglass-shaped hyperreflectivities. In all eyes with acute BRVO, sequential sectioning with OCT visualized 3-dimensional vascular architecture and the intravascular conditions at the A/V crossing. At the affected A/V crossing, arterial overcrossing was seen in 17 eyes and venous overcrossing was seen in 8 eyes. In eyes with arterial overcrossing, the retinal vein seemed to run deep under the artery at the A/V crossing, and the venous lumen often appeared to be preserved even at the A/V crossing. In all eyes with venous overcrossing, the retinal vein appeared to be compressed and choked between the internal limiting membrane and the arterial wall at the A/V crossing. Optical coherence tomography sectioning showed intravenous thrombi in 21 eyes, and the thrombi were detected downstream of the A/V crossing in all the cases. The detection of thrombus was significantly associated with ischemic pattern in BRVO (P=0.036). In eyes with BRVO, sequential thin sections with OCT visualized 3-dimensional retinal vasculature. The present OCT findings suggest that BRVO may occur by 2 different mechanisms, depending on the relative anatomic positions of the crossing vessels. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Multiscale multimodal imaging with multiphoton microscopy and optical coherence tomography

A multiscale multiphoton microscopy (MPM) and optical coherence tomography (OCT) system has been developed using a sub-10 fs Ti:sapphire laser. The system performs cross-sectional OCT imaging over millimeter field-of-view and en-face high-resolution MPM imaging with submicrometer resolution from the same sample location. With fish cornea, we have demonstrated cross-sectional imaging of cornea tissue layers using OCT, and the zoom-in imaging of cells and collagen fibers in each layer using MPM. The multiscale MPM/OCT system shows the potential of a rapid coarse scan to search for abnormal regions and the subsequent fine zoom-in imaging for diagnosis.

Abstract 17117: In Vitro Monitoring of Microbubble Mediated Clot Dissolution Using Optical Coherence Tomography (OCT)

Background: Thrombolysis using ultrasound (US) induced destruction of systemically injected microbubbles (MBs) is a potential targeted treatment for acute myocardial infarction or ischemic stroke. The physical mechanisms underlying MB mediated clot lysis are incompletely elucidated, partly due to limitations in methods to characterize morphologic and volumetric changes in a thrombus resulting from MB destruction. Here, we explore possibilities for 3D quantitative assessment of sonothrombolysis using optical coherence tomography (OCT), a high resolution imaging modality. Methods: Thrombi were formed in polyethylene tubing (1.67 mm i.d.) from recalcified porcine blood using silk suture as a nidus for thrombosis. Lipid shell MBs suspended in saline and tissue plasminogen activator (rt-PA, 3 μ g/ml) were perfused through the tube (22 μ l/min, 2x107 MBs/ml) using a syringe pump while US pulses (1 MHz, 1.0 MPa, 100 cycles) were delivered over 30 min to the clot from a single element transducer every 5 sec to ensure MB replenishment between destructive pulses. 3D OCT images of clots were obtained before and after US treatment, rt-PA alone, or saline alone (n=3/condition). Clot volume was measured using clot boundary determination by thresholding pixel intensity of each cross-sectional OCT image. Results: Thrombi treated with US + MBs + rt-PA decreased in volume by 55.7% (0.02 mm3; p=0.02). rt-PA alone resulted in a 25.6% (0.009 mm3; p=0.39) decrease in volume and treatment with saline alone did not change clot volume (0.003 mm3; p=0.94). OCT images qualitatively showed greatest change in clot shape and volume in regions closest to the source of US (Fig 1). Conclusion: 3D OCT can quantify thrombolysis. As expected, the addition of US and MBs enhanced the lytic effect of rt-PA. OCT imaging may reveal the physical effects of contrast US on thrombus structure, thereby yielding insights into mechanisms of sonothrombolysis that can be used to optimize treatment regimens.

Sirolimus‐eluting stent fracture detection by three‐dimensional optical coherence tomography

Stent fracture has emerged as a complication of drug-eluting stent and is now recognized as contributing to in-stent restenosis and possibly stent thrombosis. Although optical coherence tomography (OCT) can detect stent fractures in the absence of circumference struts, it is challenging to visualize stent fractures with only cross-sectional OCT images. We describe two cases of restenosis with stent fracture detected by a novel three-dimensional OCT image reconstruction technique. This technique allows identification of a single stent fracture even in the absence of angiographic signs.

Three-Dimensional Optical Coherence Tomography on Endoscopic Mucosal Resection Specimens Confirms Identification of Malignant From Metaplastic Lesions in Patients With Barrett's Esophagus

BACKGROUND/AIMS: Endoscopic mucosal resection (EMR) has been an effective method to assess patients with esophageal nodules arising in Barrett's esophagus (BE). Optical Coherence Tomography (OCT) enables real-time, three-dimensional (3D) imaging of tissue microstructure, with resolution approaching histology and can be used to evaluate pathological features both In Vivo and within EMR specimens. In comparison, the latter is difficult to assess on confocal endoscopy which depends on In Vivo fluorescein to achieve optimal images . METHODS: A prototype OCT imaging system was developed in collaboration with the LightLab imaging Inc., providing images with an axial resolution of ~5um in tissue and ~15um along the transverse dimension. The OCT system has an axial scanning rate of ~59kHz and the system sensitivity is 103dB. The in-house developed fiberoptic imaging probe (2.5mm in diameter) can pass through the working channel of the endoscope. A 3DOCT dataset covering an imaging area of 20 mm x 8 mm x 2 mm can be acquired in 20s. Standard EMR was performed on 12 patients using Duette (Cook Medical, Inc.). Twentyfour EMR specimens, including 9 benign, 6 BE, 2 BE with low-grade dysplasia, 1 BE with high grade dysplasia, and 6 early adenocarcinomas, were subsequently imaged with 3DOCT and sent for standard H&E histology. Imaging features identified in the OCT images were then compared with matching histology. RESULTS: Cross-sectional and en face images could be reconstructed from the 3D-OCT dataset. Cross-sectional OCT image showed features matching with the corresponding histology. BE glands were observed at regions over the lamina propria layer while both the lamina propria layer and the muscular mucosa were preserved in 87% of OCT imaging dataset. En face OCT highlighted the distribution of the glandular structures in Barrett's esophagus and allowed quantification of BE gland density. In lesions with intramucosal and invasive adenocarcinoma, the muscular mucosa layer was less distinct or lost in the OCT images. This may be due to the destruction of tissue architecture or the thickened mucosa from the tumor. No lamina propria layer is identified in the datasets of 6 early adenocarcinomas. In addition, the shape and the distribution of the glandular structures were irregular compared to those of the BE glands. These distinctive patterns associated with adenocarcinoma were observed in both cross-sectional and en face OCT images. CONCLUSIONS: We demonstrated 3D-OCT images of EMR specimens of human esophagus ranging from benign nodules, BE with LGD, BE with HGD to adenocarcinoma. These studies comparing 3D-OCT images with histology are promising in improving In Vivo evaluation of esophageal nodules in the future. ACKNOWLEDGEMENT: NIH 5R01CA075289-14 and AFOSR FA9550-07-1-0101.

Reversibility of Optical-Cleared Porcine Ileal Specimens Enables Integration of 3-Dimensional Microscopy With the Standard H&E Tissue Analysis

BACKGROUND/AIMS: Endoscopic mucosal resection (EMR) has been an effective method to assess patients with esophageal nodules arising in Barrett's esophagus (BE). Optical Coherence Tomography (OCT) enables real-time, three-dimensional (3D) imaging of tissue microstructure, with resolution approaching histology and can be used to evaluate pathological features both In Vivo and within EMR specimens. In comparison, the latter is difficult to assess on confocal endoscopy which depends on In Vivo fluorescein to achieve optimal images . METHODS: A prototype OCT imaging system was developed in collaboration with the LightLab imaging Inc., providing images with an axial resolution of ~5um in tissue and ~15um along the transverse dimension. The OCT system has an axial scanning rate of ~59kHz and the system sensitivity is 103dB. The in-house developed fiberoptic imaging probe (2.5mm in diameter) can pass through the working channel of the endoscope. A 3DOCT dataset covering an imaging area of 20 mm x 8 mm x 2 mm can be acquired in 20s. Standard EMR was performed on 12 patients using Duette (Cook Medical, Inc.). Twentyfour EMR specimens, including 9 benign, 6 BE, 2 BE with low-grade dysplasia, 1 BE with high grade dysplasia, and 6 early adenocarcinomas, were subsequently imaged with 3DOCT and sent for standard H&E histology. Imaging features identified in the OCT images were then compared with matching histology. RESULTS: Cross-sectional and en face images could be reconstructed from the 3D-OCT dataset. Cross-sectional OCT image showed features matching with the corresponding histology. BE glands were observed at regions over the lamina propria layer while both the lamina propria layer and the muscular mucosa were preserved in 87% of OCT imaging dataset. En face OCT highlighted the distribution of the glandular structures in Barrett's esophagus and allowed quantification of BE gland density. In lesions with intramucosal and invasive adenocarcinoma, the muscular mucosa layer was less distinct or lost in the OCT images. This may be due to the destruction of tissue architecture or the thickened mucosa from the tumor. No lamina propria layer is identified in the datasets of 6 early adenocarcinomas. In addition, the shape and the distribution of the glandular structures were irregular compared to those of the BE glands. These distinctive patterns associated with adenocarcinoma were observed in both cross-sectional and en face OCT images. CONCLUSIONS: We demonstrated 3D-OCT images of EMR specimens of human esophagus ranging from benign nodules, BE with LGD, BE with HGD to adenocarcinoma. These studies comparing 3D-OCT images with histology are promising in improving In Vivo evaluation of esophageal nodules in the future. ACKNOWLEDGEMENT: NIH 5R01CA075289-14 and AFOSR FA9550-07-1-0101.

Semiautomated analysis of optical coherence tomography crystalline lens images under simulated accommodation

Presbyopia is an age related, gradual loss of accommodation, mainly due to changes in the crystalline lens. As part of research efforts to understand and cure this condition, ex vivo, cross-sectional optical coherence tomography images of crystalline lenses were obtained by using the Ex-Vivo Accommodation Simulator (EVAS II) instrument and analyzed to extract their physical and optical properties. Various filters and edge detection methods were applied to isolate the edge contour. An ellipse is fitted to the lens outline to obtain central reference point for transforming the pixel data into the analysis coordinate system. This allows for the fitting of a high order equation to obtain a mathematical description of the edge contour, which obeys constraints of continuity as well as zero to infinite surface slopes from apex to equator. Geometrical parameters of the lens were determined for the lens images captured at different accommodative states. Various curve fitting functions were developed to mathematically describe the anterior and posterior surfaces of the lens. Their differences were evaluated and their suitability for extracting optical performance of the lens was assessed. The robustness of these algorithms was tested by analyzing the same images repeated times.

Closure of Sclerotomies after 25- and 23-Gauge Transconjunctival Sutureless Pars Plana Vitrectomy Evaluated by Optical Coherence Tomography

Aims: To evaluate sclerotomy closure after 25- and 23-gauge transconjunctival sutureless pars plana vitrectomy using optical coherence tomography (OCT). Methods: Forty-eight eyes (20 with a macular hole and 28 with an epiretinal membrane) of 47 patients (mean age, 66.5 years) who underwent one of the two procedures were included. Three sclerotomy sites in each eye were measured by cross-sectional OCT images vertical and parallel to the limbus on weeks 1 and 2 and months 1, 2 and 3 postoperatively. Results: After 25-gauge vitrectomy, the scleral wounds evaluated by OCT closed in 40.6% of the eyes at 1 week, 53.3% at 2 weeks, 60.5% at 1 month, 63.6% at 2 months and 63.9% at 3 months. There were significant differences in the closure rates between 1 week and 1 month (p = 0.015), 2 months (p = 0.007) and 3 months (p = 0.006) postoperatively. After 23-gauge vitrectomy, the scleral wounds closed in 31.6% of the eyes at 1 week, 50.0% at 2 weeks, 57.4% at 1 month, 63.0% at 2 months, and 61.1% at 3 months postoperatively. There were significant differences in the closure rates between 1 week and 1 month (p = 0.011), 2 months (p = 0.001) and 3 months (p = 0.002) postoperatively. The wound closure rates did not differ significantly between the two procedures. Conclusions: Scleral wounds after 25- and 23-gauge transconjunctival sutureless pars plana vitrectomy can be evaluated with OCT. Wound healing seems to be complete 2 weeks postoperatively.

Drusen with Accompanying Fluid underneath the Sensory Retina

To investigate whether confluent drusen may be accompanied by fluid accumulation underneath the sensory retina and to determine if the detection of subretinal fluid on spectral-domain optical coherence tomography (OCT) in patients with coalescent drusen is indicative of choroidal neovascularization (CNV). Prospective, noncomparative case series. Seventy-four eyes of 57 patients with large, confluent drusen. The retinal structure of patients with coalescent drusen was studied by spectral-domain OCT. Optical coherence tomography reflectivity and outer retina topography maps were created and compared with fluorescein angiography (FA) and indocyanine green angiography (ICGA) images as well as with microperimetry. Optical coherence tomography-derived retinal morphologic features. What appears to be fluid beneath the sensory retina was found on spectral-domain OCT in 8 eyes of 7 patients. The outer retina topography maps demonstrated that fluid accumulates only in the concavity between clustering soft drusen, not on their outward slopes. The maps also revealed a reduced distance between the retinal pigment epithelium (RPE) and the photoreceptor inner/outer segment (IS/OS) junction over large drusen and tiny elevations of the IS/OS junction around drusen of all sizes. Microperimetry showed decreased retinal light sensitivity at the site of diminished distance between the RPE and the IS/OS junction. Seven eyes of 6 patients who were followed up were found to have no retinal changes other than confluent drusen along with subretinal fluid during the entire observational period (12-27 months). There was no evidence of CNV on FA or ICGA in any of the patients. Large, confluent drusen may be accompanied by subretinal spaces that appear to be filled with fluid. Specific distribution of the fluid limited to the depression between adjacent drusen may indicate that the cluster of coalescent drusen produces mechanical strain to the outer retinal layers that locally pulls the sensory retina away from its normal position. Consequently, the appearance of fluid within subretinal compartment between coalescent drusen in OCT cross-sectional images may not be a reliable marker for the presence of CNV.

Robust High-Resolution Fine OCT Needle for Side-Viewing Interstitial Tissue Imaging

Fine optical coherence tomography (OCT) imaging needles that can be integrated with a standard biopsy needle have been developed with a new optics design to improve the optical quality and mechanical robustness, where a fiber-optic lens (that is spliced to a single-mode fiber) and a microreflector are encased within a microglass tube. The design also minimizes the cylindrical lens effect induced by the glass tube and eases the needle assembly process. Real-time cross-sectional OCT imaging of various tissue samples were performed ex vivo using the miniature-imaging needle along with a 1300-nm swept-source OCT system. The preliminary results demonstrate the improved mechanical and optical performance and suggest the potential of the fine OCT needle for minimally invasive interstitial imaging and image-guided biopsy.

Selective involvement of ERK and JNK MAP kinases in the synovial tissue of patients with early arthritis

<h3>Background and purpose</h3> During carotid artery stenting (CAS) with the use of closed cell design stents for unstable plaques, tissue prolapse between stent struts was evaluated by optical coherence tomography...

Simultaneous Measurement of Tear Film Dynamics Using Wavefront Sensor and Optical Coherence Tomography

PURPOSE. To investigate tear film dynamics using simultaneous measurements of ocular aberrations and lower tear meniscus. METHODS. Simultaneous measurements of wavefront aberration and lower tear meniscus were performed for 11 normal eyes and 7 eyes with short tear film break-up time (SBUT) dry eye, with a tear film break-up time shorter than 5 seconds, using a wavefront sensor and an anterior segment optical coherence tomography (OCT). During the measurement, the subjects were instructed to blink every 6 seconds for a total of 30 seconds. From the measured aberration, root mean square (RMS) wavefront error and volume modulation transfer function (vMTF) induced by changes in tear film dynamics were calculated for a 5-mm pupil. Lower tear meniscus height (TMH) and area (TMA) were estimated from the cross-sectional OCT images of lower tear meniscus. RESULTS. There was a positive correlation between RMS and tear meniscus dimensions and a negative correlation between vMTF and tear meniscus in both groups. There were moderate negative correlations between the postblink initial RMS change and baseline TMH (R = -0.61) and TMA (R = -0.54) in SBUT dry eyes that were stronger than in normal eyes (R = -0.37, R = -0.38). CONCLUSIONS. Tear meniscus dimensions increase with RMS over time, and tear quantity before blink has a significant role in maintaining initial optical integrity, especially in SBUT dry eye. Simultaneous measurement of optical quality and tear meniscus has the potential to improve understanding of tear stability in normal eyes and dry eyes.

Evaluation in 3 Months Duration of Neointimal Coverage After Zotarolimus-Eluting Stent Implantation by Optical Coherence Tomography: The ENDEAVOR OCT Trial

We performed this study to investigate the vascular response in early period after zotarolimus-eluting stent (ZES) (Endeavor Sprint, Medtronic CardioVascular, Minneapolis, Minnesota) implantation. The ZES has different characteristics, with biocompatible polymer and rapid drug-elution, compared with the first-generation drug-eluting stents (DES). The ENDEAVOR OCT (Evaluation in 3 Months Duration of Neointimal Coverage after Zotarolimus-Eluting Stent Implantation by Optical Coherence Tomography) trial is a prospective, single-center study evaluating vascular healing patterns with optical coherence tomography (OCT) at 3 months after stent implantation. A total of 31 ZES in 30 patients underwent serial OCT at immediate post-intervention and 3 months. Neointimal growth and malapposition were analyzed at each stent strut of cross-sectional OCT images with 0.5-mm intervals. The incidence of malapposition at post-intervention and 3 months was 6.0% and 0.2%, respectively. However, late acquired malapposition was not detected at 3 months. Of 31 stents, 27 stents (87.1%) were covered completely with neointima, but the remaining 4 stents had 2 (0.8%), 4 (0.9%), 4 (1.2%), and 6 (1.4%) uncovered struts. Overall mean percentage of covered stent struts was 99.9 ± 0.4%. This finding was consistent among groups with acute coronary syndrome and stable angina pectoris (99.9 ± 0.3% vs. 99.9 ± 0.4%, p = 0.92). Intracoronary thrombus was documented in 1 stent (3.2%) among 31 stents. Most of the stent struts were covered with neointima, and late acquired malapposition was not found at 3 months after ZES implantation. Therefore, the current study demonstrated that ZES might have a favorable in vivo vascular response at 3 months after stent implantation. (Evaluation of Zotarolimus Eluting Stent at 3 Months Using Optical Coherence Tomography [ENDEAVOR OCT]; NCT00815139)

Automated quantification of microstructural dimensions of the human kidney using optical coherence tomography (OCT)

Optical coherence tomography (OCT) is a rapidly emerging imaging modality that can non-invasively provide cross-sectional, high-resolution images of tissue morphology in situ and in real-time. We previously demonstrated that OCT is capable of visualizing characteristic kidney anatomic structures, including blood vessels, uriniferous tubules, glomeruli, and renal capsules on a Munich-Wistar rat model. Because the viability of a donor kidney is closely correlated with its tubular morphology, and a large amount of image datasets are expected when using OCT to scan the entire kidney to provide a global assessment of its viability, it is necessary to develop automatic image analysis methods to quantify the spatially-resolved morphometric parameters such as tubular diameter to provide potential diagnostic information. In this study, we imaged the human kidney in vitro and quantified the diameters of hollow structures such as blood vessels and uriniferous tubules automatically. The microstructures were first segmented from cross-sectional OCT images. Then the spatially-isolated region-of-interest (ROI) was automatically selected to quantify its dimension. This method enables the automatic selection and quantification of spatially-resolved morphometric parameters. The quantification accuracy was validated, and measured features are in agreement with known kidney morphology. This work can enable studies to determine the clinical utility of OCT for kidney imaging, as well as studies to evaluate kidney morphology as a biomarker for assessing kidney's viability prior to transplantation.

Dual optical coherence tomography/fluorescence microscopy for monitoring of Drosophila melanogaster larval heart

This article demonstrates a combined instrument of two imaging modalities to acquire information on cardiac function in larval Drosophila melanogaster: optical coherence tomography (OCT) and laser scanning fluorescence microscopy (LSFM). For this purpose, a dedicated imaging instrument able to sequentially provide cross-sectional OCT and C-scan LSFM images has been developed. With this dual-imaging system, the heart can be easily located and visualized within the specimen and the change of the heart shape in a cardiac cycle can be monitored.

3.04] First experiences with catheter-based intraluminal optical coherence tomography of the human upper urinary tract in vivo

Objective Catheter-based intraluminal optical coherence tomography (OCT) with near-infrared light provides cross-sectional images of hollow organs and vessels, with a lateral resolution of 10–20 μm. We evaluated the technical success rate and demonstration of different wall layers of the human upper urinary tract (UUT) in OCT images obtained in vivo. Materials and methods The study protocol was approved by the local hospital ethics committee. The OCT probe (diameter: 0.014 in) was introduced into the UUT of 14 patients either through a cystoscope and urinary catheter, or through an uretero-renoscope to obtain single-slice cross-sectional images. OCT images were evaluated for delineation of ureteral wall layers by means of OCT software (M2, LightLab, Inc., Westford, MA). Results Catheter-based OCT of the UUT in vivo was technically successful in 14 out of 14 patients (100%). A total of 190 cross-sectional OCT images (760 quadrants) were obtained. Image quality allowed for tissue differentiation in 656/760 quadrants (86.3%). OCT distinguished urothelium and lamina propria in 552/656 quadrants (84.1%), lamina propria and muscle layer in 643/656 quadrants (98.0%), inner and outer muscle layer in 288/656 quadrants (43.9%), and different cell layers within the urothelium in 33/656 quadrants (5.0%) of cross-sectional images in healthy sections of the UUT. Urothelial cancer was presented as a thickening of the urothelium with distortion of the lamina propria. The histological sections confirmed the OCT findings. Conclusion Using OCT it appears to be possible to distinguish between different wall layers of the human upper urinary tract in vivo. Urothelial cancer involves a tumorous thickening of the urothelial layer and distortion of deeper tissue layers.

Advanced Neointimal Growth is Not Associated With a Low Risk of In-Stent Thrombus Optical Coherence Tomographic Findings After First-Generation Drug-Eluting Stent Implantation

There is a hypothesis that advanced neointimal stent coverage may protect against stent thrombosis. In the present study, differences in neointimal growth and prevalence of in-stent thrombus between paclitaxel- and sirolimus-eluting stent (PES and SES) were evaluated by optical coherence tomography (OCT). Follow-up angiographic and OCT examinations at approximately 6 months were performed for 40 patients (20 PES, 20 SES). Late loss was measured by quantitative coronary angiography. Neointimal hyperplasia (NIH) thickness on stent struts was measured by cross-sectional OCT images at 1 mm intervals. After measuring the NIH area in each cross-section, NIH volume was calculated as integral of NIH area within the stent. Late loss, NIH thickness, and NIH volume were greater for PES than for SES (0.42 +/-0.44 vs 0.13 +/-0.12 mm, 118 +/-141 vs 31 +/-39 mum, 53.2 +/-30.5 vs 24.3 +/-14.0 mm(3); P<0.05, respectively). In-stent thrombus was found more frequently in PES than in SES (50 vs 15%; P=0.02). Although the degree of neointimal growth in PES was generally greater, in-stent thrombus was more common compared with SES. Presence of thrombus in first-generation drug-eluting stents was not related to advanced neointimal growth.

Line-Field Optical Coherence Tomography Using Frequency-Sweeping Source

In this paper, we propose a line-field optical coherence tomography (OCT) with frequency-sweeping source, which uses imaging optics to form a line focus on the sample and obtains cross-sectional OCT images of biological tissues without any mechanical scanning. Therefore, real-time imaging becomes possible even when the sweeping rate of the source is not high. Moreover, a full 3-D volume image can be acquired by simply incorporating 1-D mechanical scanning. Our line-field OCT using frequency-sweeping source has a sensitivity of ~88 dB, an axial resolution of 8.3 mum, and an acquisition speed of 45 fps.

Optical Coherence Tomography for the Inspection of Plasma-Sprayed Ceramic Coatings

Optical coherence tomography (OCT) is evaluated as a potential technique for microstructure characterization of plasma-sprayed ceramic coatings. OCT combines the principles of low-coherence interferometry and optical heterodyne detection to obtain both a high axial resolution and a high sensitivity to weakly backscattered light. It can be used to accurately locate interfaces where the refractive index changes abruptly within translucent materials. Therefore, OCT should be sensitive to interlamellar pores and splat interfaces within plasma-sprayed ceramic coatings. In the present work, OCT cross-sectional images of thin yttria-stabilized zirconia (YSZ) coatings are considered. The interferogram envelopes forming the collected images are analyzed individually to successfully gather information related to light attenuation inside the coatings. This light attenuation is shown to be related to the density of interfaces within the coatings as well as to the material oxidation state. The envelope analysis also allows the evaluation of the refractive index of the YSZ nontransformable tetragonal phase.