Horizontal Scanning Research Articles

3D LIDAR based on FPCB mirror

This paper presents the first 3D LIDAR (light detection and ranging) constructed from two 1D FPCB (flexible printed circuit board) oscillation mirrors and one single-point LIDAR with a very low total cost of ∼$150 (assuming no additional angle sensor used). One FPCB mirror is for vertical scanning and the other is for horizontal scanning. The low cost is realized because of the low cost 1D FPCB mirror (a few dollars), as well as the widely available and relatively easy to make single-point LIDAR (<$100 cost for mass production). The 3D LIDAR can be used to obtain 3D map for navigation and obstacle avoidance of AGVs (automated guidance vehicles) subject to low speed and low acceleration. The FPCB mirror in this paper evolves from FPCB micromirrors previously developed but has a large aperture (20 × 20 mm). The achieved performance is: horizontal and vertical FOV (field of view) of 38° and 24°, respectively, 12.5 or 25 horizontal scanning lines, refreshing rate of 2, 4 or 8 fps (frames per second), 0.2∼20 m detection distance for low reflectivity object, and 1, 250∼5,000 points/frame when using the standard single-point LIDAR (TF03). If using a customized single-point LIDAR, the distance would be increased to 50∼80 m with 10 times more points/frame. The 3D LIDAR is suitable for AGV's navigation and obstacle avoidance. Modeling, prototyping and testing are presented.

An on-road examination of daytime and evening driving on rural roads: physiological, subjective, eye gaze, and driving performance outcomes.

Experiencing sleepiness when driving is associated with increased crash risk. An increasing number of studies have examined on-road driver sleepiness; however, these studies typically assess the effect of sleepiness during the late night or early morning hours when sleep pressure is approaching its greatest. An on-road driving study was performed to assess how a range of physiological and sleepiness measures are impacted when driving during the daytime and evening when moderate sleepiness is experienced. In total, 27 participants (14 women and 13 men) completed a driving session in a rural town lasting approximately 60 minutes, while physiological sleepiness (heart rate variability), subjective sleepiness, eye tracking data, vehicle kinematic data and GPS speed data were recorded. Daytime driving sessions began at 12:00 or 14:00, with the evening sessions beginning at 19:30 or 20:30; only a subset of participants (n = 11) completing the evening sessions (daytime and evening order counterbalanced). The results suggest reductions in the horizontal and vertical scanning ranges occurred during the initial 40 minutes of driving for both daytime and evening sessions, but with evening sessions reductions in scanning ranges occurred across the entire driving session. Moreover, during evening driving there was an increase in physiological and subjective sleepiness levels. The results demonstrate meaningful increases in sleepiness and reductions in eye scanning when driving during both the daytime and particularly in the evening. Thus, drivers need to remain vigilant when driving during the daytime and the evening.

An Intensity-Augmented LiDAR-Inertial SLAM for Solid-State LiDARs in Degenerated Environments

With development of LiDAR technology, solid-state LiDARs receive a lot of attention for their high reliability, low cost and light weight. However, compared with traditional rotating LiDARs, these solid-state LiDARs pose new challenges on simultaneous localization and mapping (SLAM) due to their small field of view (FoV) in horizontal direction and irregular scanning pattern, which arises the issue of degeneracy in indoor environments. To this end, we propose an accurate, robust and real-time LiDAR-inertial SLAM method for solid-state LiDARs. Firstly, a novel feature extraction based on geometry and intensity is proposed, which is the core of handling with degeneracy. To make full use of extracted features, two multi-weighting functions are designed for planar and edge points respectively in the process of pose optimization. Lastly, a map management module using an image processing method is developed not only to keep time efficiency and space efficiency but also to reduce edge intensity outliers in line map. Qualitative and quantitative evaluations on public and recorded datasets show that the proposed method exhibits similar and even better accuracy with state-of-the-art SLAM methods in wellconstrained scenarios, while only the proposed method can survive in the robustness test towards degenerated indoor lab environment.

Mechanistic Insights into the Pathogenesis of Proliferative and Nonproliferative Vitreomacular Traction

To describe the vitreoretinal interface in vitreomacular traction (VMT) by using novel optical coherence tomography (OCT) methods; wide-angle montage, and pseudomotion OCT imaging systems. Observational case series. Wide-angle montage OCT images of horizontal and vertical scans through the fovea were acquired in 50 eyes of 46 consecutive patients with VMT. Baseline fundus scans were obtained. These were followed by scans acquired with an eye-tracking system performed immediately after vertical and horizontal eye movements. Three scans were then superimposed to compare changes in the contour and position of the posterior vitreous. The subjects were classified as VMT with ("proliferative"; 48.0%) and without ("nonproliferative"; 52.0%) thickened posterior vitreous. Epiretinal membrane was observed in 26.9% of nonproliferative and 95.8% of proliferative VMT eyes (P=3.6×10-7). No eye of proliferative and 57.7% of nonproliferative VMT eyes had wavy contoured posterior vitreous (P=4.0×10-6). None with proliferative VMT, but 91.7% of nonproliferative VMT eyes, showed motion induced changes of posterior vitreous following eye movement (P=2.0×10-8). The posterior vitreous detachment extended beyond the scanned area in 34.6% of nonproliferative and 8.3% of proliferative VMT eyes (P=.040). By dynamically evaluating the vitreoretinal interface of patients with VMT, the static contraction forces of a thickened posterior vitreous at the macula are implicated in proliferative VMT. This contractile force is not strongly implicated in the majority of VMT eyes with nontaut and more mobile vitreous (nonproliferative VMT). VMT and its associated complications are determined by at least 2 different pathophysiological mechanisms.

Assessment of Scleral Contour Changes in High Myopia by Optical Coherence Tomography.

PurposeThis study aimed to establish and validate optical coherence tomography (OCT) based diagnostic criteria of high myopia.MethodsThis was a cross-sectional study including 100 eyes of high myopia with axial length larger than 26.5 mm and 100 control eyes, which were examined by spectral-domain OCT. Vertical and horizontal OCT of 9 mm scanning across fovea were analyzed. OCT characteristics including mirror artifact, scleral sink due to steep inclination of posterior sclera, scleral visibility, abnormality of outer retinal layer, foveoschisis, and dome-shaped macula were assessed in each group.ResultsThe mean axial length was 28.65 ± 2.07 mm (range, 26.51–34.59 mm) in high myopia group and 23.79 ± 0.99 mm (range, 21.26–25.94 mm) in control group. Among the OCT characteristics noted at high frequency in the eyes with high myopia, three criteria achieving high sensitivity and specificity were determined: scleral sink over 500 μm, scleral visibility over 100 μm, and dome-shaped macula. Under conditions of presence of any of three criteria in either horizontal or vertical OCT scanning, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value for high myopia were found to be 95.0%, 98.0%, 98.0%, and 95.1%, respectively. In a new set of OCT images from 50 eyes with high myopia and 50 eyes of nonhigh myopia cases, the OCT-based criteria also proved similar level of diagnostic validity.ConclusionsThe OCT-based criteria, which directly addressed posterior scleral contour changes, may lead to an intuitive and accurate diagnosis of high myopia. Also, the criteria may contribute to early detection and monitoring of eyes that cannot be defined as high myopia but can progress. OCT may be useful for monitoring high myopia patients as OCT can detect myopia-associated retinal pathologies as well as scleral contour changes.

Calibration of X-Band Radar for Extreme Events in a Spatially Complex Precipitation Region in North Peru: Machine Learning vs. Empirical Approach

Cost-efficient single-polarized X-band radars are a feasible alternative due to their high sensitivity and resolution, which makes them well suited for complex precipitation patterns. The first horizontal scanning weather radar in Peru was installed in Piura in 2019, after the devastating impact of the 2017 coastal El Niño. To obtain a calibrated rain rate from radar reflectivity, we employ a modified empirical approach and draw a direct comparison to a well-established machine learning technique used for radar QPE. For both methods, preprocessing steps are required, such as clutter and noise elimination, atmospheric, geometric, and precipitation-induced attenuation correction, and hardware variations. For the new empirical approach, the corrected reflectivity is related to rain gauge observations, and a spatially and temporally variable parameter set is iteratively determined. The machine learning approach uses a set of features mainly derived from the radar data. The random forest (RF) algorithm employed here learns from the features and builds decision trees to obtain quantitative precipitation estimates for each bin of detected reflectivity. Both methods capture the spatial variability of rainfall quite well. Validating the empirical approach, it performed better with an overall linear regression slope of 0.65 and r of 0.82. The RF approach had limitations with the quantitative representation (slope = 0.44 and r = 0.65), but it more closely matches the reflectivity distribution, and it is independent of real-time rain-gauge data. Possibly, a weighted mean of both approaches can be used operationally on a daily basis.

Inner Retinal Layer Thickness Alterations in Early Age Related Macular Degeneration in Eyes with Subretinal Drusenoid Deposits or Conventional Drusen.

The purpose of this study was to evaluate central and parafoveal inner retinal layer thickness in patients with subretinal drusenoid deposits (SDD) or conventional drusen (CD). Participants underwent comprehensive ophthalmoscopic examination. Evidence of SDD or CD was evaluated with near infrared reflectance and spectral domain optical coherence tomography. Quantification of subfoveal lesions was made through a qualitative analysis of vertical and horizontal SD-OCT scans centered on the fovea. Inner retinal layer macular thickness measurements were obtained for central circles with 1, 3, and 5 mm diameter. Continuous variables were compared by the analysis of covariance (ANCOVA) with post-hoc Tukey HSD correction for multiple comparison analysis. Fifty-five patients were included in the study; 18 eyes with SDD alone, 19 eyes with CD alone, and 18 eyes of healthy age-matched subjects. Eight eyes with SDD (44%) and 13 eyes with CD (68%) had subfoveal lesions. There was significant reduction in the inner retinal layer thickness in the central 1mm area and in the superior 3 mm area in the SDD and CD group compared to controls. In conclusion the inner retinal layer is thinner in the central macula and in the superior parafovea in eyes.

Posterior Vitreous Detachment in Normal Healthy Subjects Younger Than Age Twenty.

PurposeTo describe the initiation of posterior vitreous detachment (PVD) in the eyes of normal individuals, under 20 years of age, using wide-angle optical coherence tomography (OCT).MethodsThis is an observational cross-sectional study. Montaged images of horizontal and vertical OCT scans were obtained in 63 healthy eyes of 35 consecutive subjects ranging in age from 4 to 17 years.ResultsForty-five eyes (71.4%) had obvious PVD, defined as a contiguous line of posterior cortical vitreous separated from the surface of the retina. Eighteen eyes (28.6%) had no PVD. The mean age of the individuals without PVD was significantly younger than those with PVD (P = 0.008). The spatial distribution of PVD initiation was highest in the superior quadrants, with the nasal, inferior, septum papillomaculae, and temporal quadrants following in descending order of frequency (P < 0.001). PVD was observed to begin anterior to the premacular liquefied lacuna, where the vitreous gel directly adheres to the vitreoretinal interface. In the majority of subjects (80.6%), PVD was initiated anterior to the vascular arcades.ConclusionsPVD can be observed by OCT to begin in the first and second decade of life. It begins in the mid-peripheral vitreous, most frequently in the superior quadrants anterior to the vascular arcades. In this study, all PVDs originated outside of the macular liquefied lacunae, where the vitreous gel adheres directly to the retina.

The effect of a ytterbium-doped fiber laser on titanium fused to ceramic

Aim: The aim of our study is to compare the application of fiber lasers with aluminum oxide sandblasting and CoJet, which is one of the other surface roughening methods used for the first time in this study. Investigating the effect of titanium–porcelain bond strength is another aim of this study. Methodology: In total, 96 samples of titanium discs (6 mm in diameter and 3 mm in height) were prepared in a CAD/CAM device. Samples were divided into six groups (n: 10), including the control group, according to the applied surface treatments: one-way (horizontal) scanning with a Yb fiber laser, two-way (horizontal–vertical) scanning with a Yb fiber laser, three-way (horizontal–vertical–hypotenuse) scanning with a Yb fiber laser, CoJet, sandblasting, and the control group. After using the different surface treatments on the titanium discs, SEM imaging, a wettability test, and a profilometer test were applied to the samples in each group. After the surface treatments were applied to the titanium discs, including those in the control group, low heat porcelain (VITA Titanium Porcelain), which was 4 mm in diameter and 3 mm in height, was applied according to the manufacturer's instructions. Afterwards, porcelain samples prepared with titanium inlays were placed in acrylic blocks and kept in 37°C (±1°C) distilled water for 24 hours. Shear tests were applied to the samples embedded in prepared acrylic blocks, and the results were evaluated. Results: In the statistical evaluation of the obtained data, one-way analysis of variance (one-way ANOVA) was used to compare the statistical differences of the mean values of the bond strength between titanium and porcelain. In our study, Tukey’s HSD and Dunnett’s multiple comparison statistical tests were used to determine the differences among the groups. Conclusion: According to the results of our study, the highest average bond strength values were obtained from sandblasting and three-way fiber laser roughness. As a result, no statistically significant difference was found among the groups. Although Yb fiber laser application was not found to have a statistically significant effect on titanium porcelain bond strength, this method could be useful for titanium porcelain bonding. How to cite this article: Tepe IH, Nigiz R, Seyfioglu Polat Z, Mutluay Unal S. The effect of a ytterbium-doped fiber laser on titanium fused to ceramic. Int Dent Res 2021;11(Suppl.1):128-36. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.20 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Estimating Tree Diameters from an Autonomous Below-Canopy UAV with Mounted LiDAR

Below-canopy UAVs hold promise for automated forest surveys because their sensors can provide detailed information on below-canopy forest structures, especially in dense forests, which may be inaccessible to above-canopy UAVs, aircraft, and satellites. We present an end-to-end autonomous system for estimating tree diameters using a below-canopy UAV in parklands. We used simultaneous localization and mapping (SLAM) and LiDAR data produced at flight time as inputs to diameter-estimation algorithms in post-processing. The SLAM path was used for initial compilation of horizontal LiDAR scans into a 2D cross-sectional map, and then optimization algorithms aligned the scans for each tree within the 2D map to achieve a precision suitable for diameter measurement. The algorithms successfully identified 12 objects, 11 of which were trees and one a lamppost. For these, the estimated diameters from the autonomous survey were highly correlated with manual ground-truthed diameters (R2=0.92, root mean squared error = 30.6%, bias = 18.4%). Autonomous measurement was most effective for larger trees (&gt;300 mm diameter) within 10 m of the UAV flight path, for medium trees (200–300 mm diameter) within 5 m, and for trees with regular cross sections. We conclude that fully automated below-canopy forest surveys are a promising, but still nascent, technology and suggest directions for future research.

A Study on the Large-Area Image Acquisition Using Stage Transfer Synchronization Method in a Low-Energy Microcolumn System

We studied the stage transfer synchronization method to improve the low throughput which is the biggest drawback of the raster scan method when applied to image acquisition in a low energy microcolumn system. Through preliminary experiments, we were able to acquire some sample images and some images of the measured samples by applying the synchronization method to a conventional single-microcolumn system. The image acquired in this preliminary experiment was three times larger than that acquired by the raster scan method in the vertical direction. In this study, we tested two types of the synchronization method: the first method acquires an image by horizontal electron beam scanning followed by a vertical stage transfer, and the second one acquires an image by vertical electron beam scanning followed by a horizontal stage transfer. By applying the vertical stage transfer synchronization method, we could acquire a larger image than that acquired by the conventional raster scan method. The vertical stage transfer synchronization method image was 1.8 times larger in the horizontal direction and 6 times larger in the vertical direction. In addition, a larger image approximately nine times in the horizontal direction and five times in the vertical direction was acquired by applying the horizontal stage transfer synchronization method.

Repeatability and Reproducibility of Macular Hole Size Measurements Using Optical Coherence Tomography.

The purpose of this study was to assess the repeatability and reproducibility of measuring the minimum linear diameter (MLD) of macular holes (MHs) using horizontal linear and radial scan modes in optical coherence tomography (OCT). Patients with concurrent sets of radial and horizontal linear OCT volume scans were included. The MLD was measured twice in both scan modes by six raters of three different experience levels (groups). Outcome measures were the reliability and repeatability of MLD measurements. Fifty patients were included. Mean MLD was 317.21(±170.63) µm in horizontal linear and 364.52 (±161.71) µm in radial mode, a difference of 47.31 (±26.48) µm (p < 0.001). In the radial scan mode, MLD was identified within 15° of the horizontal meridian in 27% and within 15° of the vertical meridian in 26.7%, with the remainder (46.3%) in oblique meridians. The intra-group coefficients of repeatability (CR) for horizontal linear mode were 23 µm, 33 µm and 45 µm, and for radial mode 25 µm, 44 µm and 57 µm for groups 1, 2 and 3, respectively. The inter-group CR, taking group 1 as reference standard for groups 2 and 3, were 74 µm and 71 µm for the linear mode, and 62 µm and 78 µm for radial mode. The radial mode provides good repeatability and reliability for measurement of MLD. In a majority of cases the MLD does not lie in the horizontal meridian and would be underestimated using a horizontal OCT mode.

DROACOR® REFLECTANCE RETRIEVAL FOR HYPERSPECTRAL MINERAL EXPLORATION USING A GROUND-BASED ROTATING PLATFORM

Abstract. The acquisition of imaging spectroscopy data from ground based rotating stages is a novel approach which is more and more used in open pit mines for prospection and controlling. The special radiometric situation of such data sets asks for new processing approaches for geometric processing as well as for reflectance retrieval. Herein, a new method for atmospheric correction and relative reflectance retrieval is presented which is optimized for the special horizontal scanning situation by hyperspectral instruments from rotating ground based platforms. The method is implemented within the recently developed drone atmospheric correction framework DROACOR®. It combines a physical inversion of a radiative transfer code with semi-empirical correction approaches for illumination and spectral absorption. Sample results from two open pit mines show that mineral detection after reflectance retrieval allows the discrimination of iron minerals and that the retrieved spectra are well comparable to standard library spectra.

Контроль зазоров в конструкциях технических изделий в процессе вибрационных испытаний

Introduction. A fair number of technical structures have gaps (backlashes) which can be contingently divided into two types. One of them is the gaps in connections between substructures which are introduced so that the connections may operate correctly. Sizes of such gaps are usually normalized. Another type is the backlashes which occur during operation. Due to the normalized gaps usually expand while operating, both of the types may lead to increased loading and wear of mechanical parts, an alteration in dynamical characteristics and a deterioration in a technical state of mechanical structures. It explains the necessity to control the gaps. When the ground vibration testing of the structures is performed, it seems appropriate to use these tests to detect such gaps. Research Objective: developing the method to control the gaps in the technical structures during the ground vibration testing based on distortions of portraits of forced oscillations. Research Technique. The steady-state forced oscillations of the technical structures, which were measured by acceleration sensors, are excited by means of shakers. The sensor signals are represented as the portraits: the vertical scanning is proportional to the signal and the horizontal scanning – to its first harmonic with the phase shift of π/2. In case of a linear system, the portraits are circles. The presence of the gaps distorts the portraits of oscillations specifically. To estimate the distortions numerically, the first harmonic is subtracted from the Fourier series of the portrait of oscillations, the absolute maximum of the residue is calculated over the oscillation period and used subsequently as the distortion parameter Ψ. The value of the parameter Ψ is normalized and denoted as ξ. The ξ distributions are plotted on controlled objects. The locations of the gaps are determined through the positions of the local maxima of the distortions. While calculating the parameter ξ, the two types of normalization, which were conditionally named the global and local ones, are being used. In case of the global normalization, the value of Ψ is related to the amplitude of the first harmonic at the control point of the structure. The local normalization means that the magnitude of Ψ is related to the amplitude of the first harmonic of the sensor where that parameter was previously calculated. The global normalization is required to analyze the distortion distribution of the portraits of oscillations of the entire technical structure. The local normalization of the distortions of the portraits of oscillations is utilized to establish the locations of the gaps in the mechanical parts and structural connections. The ground vibration tests were carried out via Test.Lab software. The subprogram is integrated into the software interface in order to analyze the portraits of oscillations. It enabled one to calculate the distortions of the portraits of oscillations, plot the distortion distributions of the structure and save it for further use. It allowed one to control the gaps during vibration strength tests, as well as while the structures being used, by means of comparing the distortion distributions of the parameter ξ related to different states of the structure. Additionally, the plotting of the distortion distributions of the portraits of oscillations for each structural component is added to the subprogram so as to control the defects subsequently. Not only the locations of the gaps are determined in the force-displacement application systems but also the equation is given to calculate its magnitudes. The practical recommendations on using that equation are presented. Results and Discussion. The possibility of detecting the gaps by the distortions of the portraits of oscillations is illustrated with the example of the diagnostics of the layout of the control wiring and the airplanes during the ground vibration testing as well as the open-type spacecraft structures. It is shown that the developed method enables one to detect all the gaps in the testing object which distort the portraits of oscillations.

Visualization of elastin using cardiac magnetic resonance imaging after myocardial infarction as inflammatory response

The aim of this study was to investigate the merits of magnetic resonance imaging (MRI) using an elastin-binding contrast agent after myocardial infarction in mouse models with deletions of monocyte populations. Permanent ligation of the left anterior descending (LAD) artery was conducted in 10 wild-type mice and 10 each of three knockout models: CX3CR−/−, CCR2−/−, and MCP-1−/−. At 7 days and 30 days after permanent ligation, cardiac MRI was performed with a 7 T-Bruker horizontal scanner for in vivo detection of elastin with an elastin/tropoelastin-specific contrast agent (ESMA). Histology was performed with staining for elastin, collagen I and III, and F4/80. Real-time PCR was conducted to quantify the expression of genes for collagen I and III, F4/80, and tumor necrosis factor alpha (TNFα). Histological and ESMA-indicated elastin areas were strongly correlated (r = 0.8). 30 days after permanent ligation, CCR2-deficient mice demonstrated higher elastin levels in the scar relative to MCP-1−/− (p < 0.04) and wild-type mice (p < 0.02). The ejection fraction was lower in CCR2-deficient mice. In vivo MRI in mouse models of MI can detect elastin deposition after myocardial infarction, highlighting the pivotal role of elastin in myocardial remodeling in mouse models with deletions of monocyte populations.

The adaptation and investigation of cone-beam CT reconstruction algorithms for horizontal rotation fixed-gantry scans of rabbits

Fixed-gantry radiation therapy has been proposed as a low-cost alternative to the conventional rotating-gantry radiation therapy, that may help meet the rising global treatment demand. Fixed-gantry systems require gravitational motion compensated reconstruction algorithms to produce cone-beam CT (CBCT) images of sufficient quality for image guidance. The aim of this work was to adapt and investigate five CBCT reconstruction algorithms for fixed-gantry CBCT images. The five algorithms investigated were Feldkamp–Davis–Kress (FDK), prior image constrained compressed sensing (PICCS), gravitational motion compensated FDK (GMCFDK), motion compensated PICCS (MCPICCS) (a novel CBCT reconstruction algorithm) and simultaneous motion estimation and iterative reconstruction (SMEIR). Fixed-gantry and rotating-gantry CBCT scans were acquired of 3 rabbits, with the rotating-gantry scans used as a reference. Projections were sorted into rotation bins, based on the angle of rotation of the rabbit during image acquisition. The algorithms were compared using the structural similarity index measure root mean square error, and reconstruction time. Evaluation of the reconstructed volumes showed that, when compared with the reference rotating-gantry volume, the conventional FDK algorithm did not accurately reconstruct fixed-gantry CBCT scans. Whilst the PICCS reconstruction algorithm reduced some motion artefacts, the motion estimation reconstruction methods (GMCFDK, MCPICCS and SMEIR) were able to greatly reduce the effect of motion artefacts on the reconstructed volumes. This finding was verified quantitatively, with GMCFDK, MCPICCS and SMEIR reconstructions having RMSE 17%–19% lower and SSIM 1% higher than a conventional FDK. However, all motion compensated fixed-gantry CBCT reconstructions had a 56%–61% higher RMSE and 1.5% lower SSIM than FDK reconstructions of conventional rotating-gantry CBCT scans. The results show that motion compensation is required to reduce motion artefacts for fixed-gantry CBCT reconstructions. This paper further demonstrates the feasibility of fixed-gantry CBCT scans, and the ability of CBCT reconstruction algorithms to compensate for motion due to horizontal rotation.

Comparison of Central Macular Fluid Volume With Central Subfield Thickness in Patients With Diabetic Macular Edema Using Optical Coherence Tomography Angiography

Diabetic macular edema (DME) is the predominant cause of visual impairment in patients with type 1 or 2 diabetes. Automated fluid volume measurements using optical coherence tomography (OCT) may improve the diagnostic accuracy of DME screening. To assess the diagnostic accuracy of an automated central macular fluid volume (CMFV) quantification using OCT for DME. A cross-sectional observational study was conducted at a tertiary academic center among 215 patients with diabetes (1 eye each) enrolled from January 26, 2015, to December 23, 2019. All participants underwent comprehensive examinations, 6 × 6-mm macular structural OCT horizontal raster scans, and 6 × 6-mm macular OCT angiography volumetric scans. From January 1 to March 30, 2020, 2 retinal specialists reviewed the structural OCT scans independently and diagnosed DME if intraretinal or subretinal fluid was present. Diabetic macular edema was considered center involved if fluid was present within the central fovea (central 1-mm circle). A third retinal specialist arbitrated any discrepancy. The mean central subfield thickness (CST) within the central fovea was measured on structural OCT horizontal raster scans. A deep learning algorithm automatically quantified fluid volumes on 6 × 6-mm OCT angiography volumetric scans and within the central foveas (CMFV). The area under the receiver operating characteristic curve (AUROC) and the sensitivity and specificity of CST and CMFV for DME diagnosis. We enrolled 1 eye each of 215 patients with diabetes (117 women [54.4%]; mean [SD] age, 59.6 [12.4] years). Diabetic macular edema was present in 136 eyes; 93 cases of DME were center involved. The AUROC of CMFV for diagnosis of center-involved DME (0.907 [95% CI, 0.861-0.954]) was greater than the AUROC of CST (0.832 [95% CI, 0.775-0.889]; P = .02). With the specificity set at 95%, the sensitivity of CMFV for detection of center-involved DME (78.5% [95% CI, 68.8%-86.3%]) was higher than that of CST (53.8% [95% CI, 43.1%-64.2%]; P = .002). Center-involved DME cases not detected by CST but detected by CMFV were associated with a thinner CST (290.8 μm [95% CI, 282.3-299.3 μm] vs 369.4 μm [95% CI, 347.1-391.7 μm]; P < .001), higher proportion of previous macular laser treatment (11 of 28 [39.3%; 95% CI, 21.5%-59.4%] vs 12 of 65 [18.5%; 95% CI, 9.9%-30.0%]; P = .03), and female sex (20 of 28 [71.4%; 95% CI, 51.3%-86.8%] vs 31 of 65 [47.7%; 95% CI, 35.1%-60.5%]; P = .04). These findings suggest that an automated CMFV is a more accurate diagnostic biomarker than CST for DME and may improve screening for DME.

Noninvasive transcranial classification of stroke using a portable eddy current damping sensor

Existing paradigms for stroke diagnosis typically involve computed tomography (CT) imaging to classify ischemic versus hemorrhagic stroke variants, as treatment for these subtypes varies widely. Delays in diagnosis and transport of unstable patients may worsen neurological status. To address these issues, we describe the development of a rapid, portable, and accurate eddy current damping (ECD) stroke sensor. Copper wire was wound to create large (11.4 cm), medium (4.5 cm), and small (1.5 cm) solenoid coils with varying diameters, with each connected to an inductance-to-digital converter. Eight human participants were recruited between December 15, 2019 and March 15, 2020, including two hemorrhagic stroke, two ischemic stroke, one subarachnoid hemorrhage, and three control participants. Observers were blinded to lesion type and location. A head cap with 8 horizontal scanning paths was placed on the patient. The sensor was tangentially rotated across each row on the patient’s head circumferentially. Consent, positioning, and scanning with the sensor took roughly 15 min from start to end for each participant and all scanning took place at the patient bedside. The ECD sensor accurately classified and imaged each of the varying stroke types in each patient. The sensor additionally detected ischemic and hemorrhagic lesions located deep inside the brain, and its range is selectively tunable during sensor design and fabrication.

Measurement of Iris Thickness at Different Regions in Healthy Chinese Adults.

Purpose To study the variation of iris thicknesses in different regions and explore the possible correlations with age and gender. Methods Healthy Chinese adults were recruited; the anterior segment of their eyes was imaged by swept-source optical coherence tomography (SS-OCT). The horizontal scan of the right eye was selected, and the thicknesses of both the nasal and temporal irises were measured at 199 evenly spaced points. Results A total of 233 subjects with an average age of 36.79 ± 10.04 years (range 19 to 62) were included in the final analysis. The mean iris thicknesses of the temporal and nasal sides were 364.79 ± 47.58 μm and 372.44 ± 43.75 μm, respectively. The mean nasal iris thickness was positively correlated with age (β = 0.9 μm/year; P = 0.002), but the temporal one was not (β = 0.077 μm/year; P = 0.806). At 139 points of the nasal iris and 146 points of the temporal iris, the iris thickness was significantly correlated with age (P < 0.05). The thicknesses of the peripheral and pupillary parts were positively correlated with age, while the middle part was negatively correlated with age. No significant difference was observed in the mean iris thickness between genders (temporal: t = 1.597, P = 0.112; nasal: t = 1.870, P = 0.063), but females had a thicker iris than males at 50 points in the temporal side and 49 points in the nasal side (P < 0.05); no point in males was observed to have thicker iris compared to females. Conclusion Using SS-OCT and the novel method, thicknesses of the iris at different regions were measured. The thicknesses of the peripheral and pupillary irises increase with age, while the thicknesses of the middle part decrease.

Vertical open-bore MRI scanners generate significantly less radiofrequency heating around implanted leads: A study of deep brain stimulation implants in 1.2T OASIS scanners versus 1.5T horizontal systems.

Patients with active implants such as deep brain stimulation (DBS) devices are often denied access to MRI due to safety concerns associated with the radiofrequency (RF) heating of their electrodes. The majority of studies on RF heating of conductive implants have been performed in horizontal close-bore MRI scanners. Vertical MRI scanners which have a 90° rotated transmit coil generate fundamentally different electric and magnetic field distributions, yet very little is known about RF heating of implants in this class of scanners. We performed numerical simulations as well as phantom experiments to compare RF heating of DBS implants in a 1.2T vertical scanner (OASIS, Hitachi) compared to a 1.5T horizontal scanner (Aera, Siemens). Simulations were performed on 90 lead models created from post-operative CT images of patients with DBS implants. Experiments were performed with wires and commercial DBS devices implanted in an anthropomorphic phantom. We found significant reduction of 0.1 g-averaged specific absorption rate (30-fold, P < 1 × 10-5 ) and RF heating (9-fold, P < .026) in the 1.2T vertical scanner compared to the 1.5T conventional scanner. Vertical MRI scanners appear to generate lower RF heating around DBS leads, providing potentially heightened safety or the flexibility to use sequences with higher power levels than on conventional systems.