Modifying a commercially available HD OCT device using a 60-D lens resulted in a high-resolution image of the angle of the front chamber. In addition to the sclera spur, we were able to identify a new imaging marker for the angle, namely the end of the endothelium/descemet membrane at the swallow line. The classification of an angle as open or closed according to the affixing of the iris to the area between these landmarks (where the trabecular network is located) would thus be possible. In addition, the relationship between partial closure of the trabecular mesh and intraocular pressure could be studied. This is a distinct advantage over AS-OCT angle imaging, where only the sclerary spur is visible (although only in about 70% to 80% of images) and the angle shutter is diagnosed based on the presence of contact between the iris and the angular wall in front of the sclerotic spur. Tearney GJ, Brezinski ME, Bouma BE, et al. In vivo endoscopic optical biopsy with optical coherence tomography. Science 1997;276:2037-2039. Changes in interstitial volume corresponding to the tubular volume. In OCT images, there is a marked difference in signal intensity between tubular lumen (low backscatter) and interstitial tissues or parenchymas (high backscatter). Therefore, we can segment the tubular lumen using intensity thresholds applied to individual OCT cross-sectional images. We then use 3D visualization and volumetric rendering software (Amira) to visualize the tubular networks.
The total luminal volume of the tubules is quantified by multiplying the total number of pixels in the segmented 3D image and the pixel size (750 to 750 to 2200âÎ1/4m3/5123=9.22âÎ1/4m3 pixels). In this experiment, the goal was to find out if OCT could document changes in the urethra that occur during kidney storage before transplantation. Our previous studies have shown that such changes correlate with the post-transplantation function of cold-preserved kidneys.17 The kidneys were rinsed in situ with a renal preservation solution consisting of a phosphate buffered solution containing sucrose 150âmOsm (i.e. PBSuc 150)24, 26, 27 and stored at 0â4°C for 48°C. During the first hours of cold storage, the tubular lumens remained patented and appeared to be free of cytoplasmic deposits (Figure 10a). However, unlike normothermic ischemia, cold-preserved renal tubules also showed an increased signal (increased brightness) from the salivary mucosa (Figure 10a). Although it is not known exactly what this amplified reflection represents, these regions seem to distinguish the tubular walls from the intermediate peritubular capillary lumens (Figure 10a). As storage time progresses, this amplified reflective aspect of tubular walls is lost and there is a significant change in tubular dimensions, similar to that observed in response to normothermic ischemia (Figure 10b). Adler DC, Huber R, Fujimoto JG.
Phase sensitive optical coherence tomography with up to 370,000 lines per second with buffered Fourier domain locked lasers. Opt Lett 2007;32:626â628. The A, Sivak MV, Chak A, et al. High-resolution endoscopic imaging of the gastrointestinal tract: a comparative study of optical coherence tomography vs. high-frequency catheter probe EUS. Gastrointes Endosc 2001;54:219â224. A high-resolution optical coherence tomography scan showing a gap between the iris and the angular wall (arrow); However, the quadrant was classified as closed on gonioscopy. Other visible structures are the sclerary spur (SS), the end of the Descemet membrane (Schwalbe line [SL]) and the trabecular lattice (TM).
Chen Y, Aguirre AD, Hsiung P, et al. Ultrahigh resolution optical coherence tomography of Barrett`s esophagus preliminary descriptive clinical trial correlating images with histology. Endoscopy 2007;39:599â605. In the present study, we investigated the ability of high-velocity OCT to image the live kidney in situ and its responses to renal ischemia, mannitolin fusion, and cold storage conservation. A Munich-Wistar rat kidney model was chosen because it has superficial glomeruli accessible to observation,23 and served as the in vivo model of choice for previous in situ microscopic imaging studies documenting the response of the living kidney to mannitolin fusion and renal ischemia.16 With OCT, we were able to image 300 to 400 m in the renal parenchyma. which is deep enough to see three or more layers of superficial urine daggers. This is much deeper than our previous study using a tandem scanning confocal microscope, which could only image a single superficial layer of urine daggers.16 Li X, Chudoba C, Ko T, et al. Imaging needle for optical coherence tomgraphy. Opt Lett 2000;25:1520â1522. Additional contributions: We thank Wing Kee Damon Wong, PhD, Annan Li, PhD, and Ai Ping Yow, BSc of the A*STAR Institute for infocomm research for 3-dimensional reconstruction from CT scans of skin scans. They did not receive more remuneration for their work than they received for the normal course of their employment. Results: Twenty-three percent of all cases studied with Stratus OCT and 1.9% of cases studied with Cirrus OCT had a signal strength of less than 6 (P = 0.01).
In cases where the signal strength was ≥6, the mean signal strength of Cirrus OCT was higher than that of Stratus OCT (P = 0.01). The RNFL measurements of Cirrus were thicker than those of Stratus OCT (P < 0.05). AUCs were 0.829 for Stratus and 0.837 for Cirrus OCT (P = 0.706) for the world GNI average. The RLs were similar in both OCTs in the global classification of GNI, but varied from quadrant to quadrant. The widths of the concordance limits ranged from 42.16 to 97.79 μm. There was almost perfect agreement (κ = 0.82) in the mean GNDR classification. Intravenous infusion of mannitol results in a significant increase in glomerular filtration rate,42 which has been shown to result in an increase in luminal tubule diameter.16 In the current study, high-speed OCT imaging showed these increases in luminal renal tubule diameter in response to mannitol infusion. Mannitol also protects against renal ischemia by acting as an unintentional osmotic agent to prevent ischemia-induced cell swelling.24 This protection is due to the presence of the imermean osmotic agent, mannitol, in the lumens of the tubule, which counteracts the osmotic gradient resulting from the accumulation of small ions in tubular cells during ischemia (GibbsâDonnan equilibrium). In the current study, high-speed OCT imaging documented the protection of mannitolin fusion against induction of normothermic renal ischemia. In particular, the rats received an intravenous infusion of mannitol 10âmin before the kidneys became ischemic due to renal artery clamping. This mannitol treatment prevented the rapid and dramatic cell swelling that otherwise led to a reduction and loss of tubule lumen in rats that had not received mannitole fusion. Tissue samples are imagined using a pair of mirrors mounted on XY scanning galvanometers (Cambridge Technology, MA, USA) and a microscope objective.
A polarization controller and a spatial aperture are used to adjust the power of the reference arm. The sensitivity of the system is 93°B with 6 mW of incident average power on the sample. Dispersion compensation glasses (SFL6) are inserted into the reference arm to compensate for the collimation and focusing optics in the sample arm required to achieve optimal image resolution. The resolution of the imaging system is 8°1/4m (in the tissue) in the axial direction (Z) and 5°1/4m in the transverse direction (XY). Unique OCT cross-sectional (XZ) images, consisting of 512 axial scans, are generated at a speed of 50 frames per second over areas 0.75 mm in length (X, 512 horizontal pixels) and 2.2 inches deep (Z, axial 512 pixels). Successive images of the OCO on different planes along the Y direction are digitized to create a 3D volume. The image area in Y is also 0.75mm with 512 XZ images. Therefore, each 3D volume contains 512 to 512 to 512 pixels with XYZ dimensions of 0.75 to 0.75 to 2.2 mm.
OCO software captures a series of cross-sectional images of the OCO for each 3D volume in approximately 10¢s and can display both cross-sectional (XZ) and surface (XY) images immediately after image acquisition. In addition to direct morphological analysis of tubular and glomerular dimensions (average of open luminal dimensions in a representative image), 3D OCT data were imported into separate advanced 3D visualization software (Amira, Mercury Computer Systems Inc., Berlin, Germany) to produce volumetric 3D views.