3D Optical Tomography Research Articles

Evidence-Based Definition of Region of Interest (ROI) for Abdominal DIBH Surface-Guided Radiotherapy

<h3>Purpose/Objective(s)</h3> To define and evaluate the appropriate abdominal region of interest (ROI) as a surrogate of both body and diaphragm positioning in deep-inspiration breath-hold (DIBH) for surface-guided radiotherapy (SGRT) using 3D optical surface imaging (OSI). <h3>Materials/Methods</h3> Six simulated abdominal ROIs were evaluated to calculate the correlations with the diaphragm position using 4DCT images of 20 abdominal patients. Twelve points of interest (POIs) were defined (6 on the central soft tissue and 6 on the bilateral ribs) at 3 superior-inferior levels between the xiphoid and umbilicus, and different sub-groups represented different ROIs. ROI-1 was the largest, containing all 12 POIs while ROI-2 had only 8 inferior POIs, ROI-3 had 6 lateral POIs, and ROI-4 had 4 superior-lateral POIs over the ribs, ROI-5 contained 6 central and 2 most inferior-lateral POIs, and ROI-6 contained 6 central and 4 inferior-lateral POIs. The lateral body midlines defined the ROI coverages to represent body position. Internally, the right diaphragm dome positions were measured in 4DCT (0% and 50% phases). The Pearson correlation coefficients were calculated between the diaphragm and all 12 external POIs individually or grouped as 6 ROIs. The quality of the abdominal ROIs was evaluated as potential internal surrogates and, therefore, potential ROIs for SGRT DIBH setup. <h3>Results</h3> The four most inferior POIs show the highest mean correlation (r=0.75) with diaphragmatic motion, and the correlation decreases as POIs move superiorly. The mean correlations are higher at r=0.67 for ROI-2, r=0.64 for ROI-5, and r=0.63 for ROI-6, while ROI-1 has r=0.60, ROI-3 has r=0.50, and ROI-4 has only r=0.28. <h3>Conclusion</h3> This study demonstrates that the rectangular/triangular soft-tissue ROI is the optimal surrogate for body positioning and diaphragmatic motion, even when treating tumors under the rib cage. This evidence-based ROI definition should be utilized when treating abdominal cancers with FB and/or DIBH setup.

Comparative analysis of signal-to-noise ratio in correlation plenoptic imaging architectures

Correlation plenoptic imaging (CPI) is a scanning-free diffraction-limited 3D optical imaging technique exploiting the peculiar properties of correlated light sources. CPI has been further extended to samples of interest to microscopy, such as fluorescent or scattering objects, in a modified architecture named correlation light-field microscopy (CLM). Interestingly, experiments have shown that the noise performances of CLM are significantly improved over the original CPI scheme, leading to better images and faster acquisition. In this work, we provide a theoretical foundation to such advantage by investigating the properties of both the signal-to-noise and the signal-to-background ratios of CLM and the original CPI setup.

Comparative evaluation of the accuracy of the dental arch display using modern intraoral three-dimensional scanners

BACKGROUND: At present, modern dentists used dental intraoral three-dimensional (3D) scanners routinely in their daily work. Obtaining an optical 3D image of the teeth and dentition helps avoid errors at the stage of obtaining traditional silicone impressions and significantly reduces the level of discomfort during dental procedures. Intraoral scanner systems are commercially available today. Despite their advantages over traditional silicone impressions, the accuracy of the optical impressions obtained during total and subtotal prosthetics on the upper and lower jaw are still questionable.&#x0D; AIM: This study aimed to evaluate the accuracy of scanning models of the patients dentition obtained using intraoral scanners and to determine the currently available models of digital devices that are optimal in terms of price and quality.&#x0D; MATERIAL AND METHODS: The reference scan (master model) was an optical image of the reference model of the upper jaw of a patient with a full dentition made by additive 3D-printing technology obtained using a laboratory scanner. To level out the shrinkage errors of photopolymerization materials, the resulting model was scanned on the same day using intraoral scanners selected for the study. The obtained scan results were compared with the reference scan of the control group. Based on the measurements made at reference points, the average error value relative to the master model and its precision were calculated for each scanner. In addition to the average values, the error parameters of the scanners in the frontal and chewing sections were calculated, as well as the arc error, which was equal to the difference in the values of the discrepancy at the reference points at which the maximum and minimum values were obtained. The cost and availability of scanners on the domestic market, under the sanctions policy of foreign countries, were also considered.&#x0D; RESULTS: The CEREC Primescan AC scanner showed the best accuracy according to the results of model discrepancies. It has an average error of 13.727.34. The arc error was 18.8 microns, and the discrepancies in the frontal area and chewing area were 18 and 6.8 microns, respectively. 3Shape Trios 3 scanner has the closest accuracy, with an average error of 16.285.94 microns. The error value of Aoralscan 3 was 42.0818.34 microns, its arc accuracy was 65 microns, and the discrepancies in the frontal and chewing areas were 33 and 55.1 microns, respectively. Emerald S Mode C had an average error of 35.8422.29 microns, which was higher than that of Medit i500 and Aoralscan 3; however, Aoralscan 3 showed better precision (18.34 microns versus 22.29 microns). According to the comparison results of the models in the MeshLab program, CEREC Primescan AC showed the smallest median of distances (18 microns). The TRIOS 3 and Emerald S Mode C differed from the standard by an average of 29 microns, and Aoralscan 3 scanners had of 33 microns and Medit i500 had 41 microns.&#x0D; CONCLUSION: The precision of Aoralscan 3 scanner, which is the best among its analogs in the price category, makes it the most affordable scanner for dental surgical, orthodontic, and orthopedic fields. CEREC Primescan AC is the leader of the premium scanners involved in the study and available in the dental market.

Evidence-based region of interest (ROI) definition for surface-guided radiotherapy (SGRT) of abdominal cancers using deep-inspiration breath-hold (DIBH).

To define and evaluate the appropriate abdominal region of interest (ROI) as a surrogate of diaphragm positioning in deep-inspiration breath-hold (DIBH) for surface-guided radiotherapy (SGRT) of abdominal cancers using 3D optical surface imaging (OSI). Six potential abdominal ROIs were evaluated to calculate their correlations with the diaphragm position using 4DCT images of 20 abdominal patients. Twelve points of interest (POIs) were defined (six on the central soft tissue and six on the bilateral ribs) at three superior-inferior levels, and different sub-groups represented different ROIs. ROI-1 was the largest, containing all 12 POIs from the xiphoid to the umbilicus and between the lateral body midlines while ROI-2 had only eight inferior POIs, ROI-3 had six lateral POIs, and ROI-4 had four superior-lateral POIs over the ribs, ROI-5 contained six central and two most inferior-lateral POIs and ROI-6 contained six central and four inferior-lateral POIs. Internally, the right diaphragm dome was used to represent its positions in 4DCT (0% and 50% within the cycle). The Pearson correlation coefficients were calculated between the diaphragm dome and all 12 external POIs individually or grouped as six ROIs. The quality of the abdominal ROIs was evaluated as potential internal surrogates and, therefore, potential ROIs for SGRT DIBH setup. The four most inferior POIs show the highest mean correlation (r=0.75) with diaphragmatic motion, and the correlation decreases as POIs move superiorly. The mean correlations are the highest for ROIs with little or no rib support: r=0.67 for ROI-2, r=0.64 for ROI-5, and r=0.63 for ROI-6, while lower for ROIs with rib support: ROI-1 has r=0.60, ROI-3 has r=0.50, and ROI-4 has only r=0.28. This study demonstrates that the rectangular/triangular soft-tissue ROI (with little rib support) is an optimal surrogate for body positioning and diaphragmatic motion, even when treating tumors under the rib cage. This evidence-based ROI definition should be utilized when treating abdominal cancers with free-breathing (FB) and/or DIBH setup.

Bullseye: preclinical evaluation of a novel structured light-based imaging workflow to inform glenoid implant positioning in total shoulder arthroplasty

BackgroundAccurate glenoid component positioning during total shoulder arthroplasty (TSA) is critical for prosthesis longevity and postoperative function. Glenoid component positioning in many TSA procedures depends on the insertion of a guide pin through the glenoid vault. However, up to 48% of TSA procedures involve guide pin malpositioning. The aim of this study was to evaluate the ability of a novel structured light imaging system to visualize glenoid guide pin position and trajectory in surgically exposed cadaveric shoulders. Computed tomography (CT)-based and magnetic resonance imaging (MRI)-based workflows and subchondral bone–based and glenoid cartilage–based workflows were compared. MethodsPreoperative cone-beam CT (CBCT) and MRI images were acquired for 5 intact cadaveric shoulders. Following deltopectoral surgical exposure, a glenoid vault guide pin was inserted through the glenoid vault of each scapula as in a clinical TSA procedure. A 3D printed optical tracker was placed over the guide pin, and a 3D optical surface image of the glenoid and tracker was acquired using a handheld structured light sensor. A postprocedural CBCT was acquired for each shoulder to verify guide pin position and trajectory. The imaging procedure was repeated after débridement of the glenoid cartilage to expose subchondral bone. The guide pin was segmented from the postprocedural CBCT image (actual guide pin). A virtual model of the tracker was aligned with a co-linear representation of the intraoperative guide pin (predicted guide pin). A series of image registrations aligned the actual and predicted guide pin positions to yield visualization accuracy, defined as the trajectory and offset errors between predicted and actual guide pins. ResultsThe mean guide pin trajectory and offset errors based on the subchondral bone were 2.22 ± 1.27° and 1.27 ± 0.46 mm for the CT-based workflow and 2.27 ± 1.72° and 1.78 ± 0.92 mm for the MRI-based workflow, respectively. Registration of the cartilage surface models visualized in the MRI images reduced accuracy to a trajectory error of 3.89 ± 1.57° (P = .147) and offset error of 2.28 ± 1.33 mm (P = .217). ConclusionThe Bullseye structured light imaging system presented an accurate approach for glenoid guide pin verification and adjustment during TSA using preoperative MRI or CT. Future development for the implementation of the Bullseye system should focus on improving surface segmentations and automation of the computer vision algorithm needed to facilitate clinical translation.

Three-Dimensional Reconstruction of Printed Circuit Boards: Comparative Study between 3D Femtosecond Laser Serial Sectioning and Optical Imaging versus 3D X-Ray Computed Tomography

Three-Dimensional Reconstruction of Printed Circuit Boards: Comparative Study between 3D Femtosecond Laser Serial Sectioning and Optical Imaging versus 3D X-Ray Computed Tomography - Volume 28 Issue S1

Three-dimensional (3D) optical imaging of electron beam and X-rays from medical linear accelerators (LINAC) using a plastic scintillator plate in water

Although optical imaging of electron beams and X-rays from medical linear accelerators (LINAC) is a possible method for dose distribution measurements, it has been limited to two-dimensional (2D) projection images. For the precise measurement of an optical image of electron beams and X-rays, three-dimensional (3D) imaging is desired. To measure 3D dose distributions, we conducted imaging of electron beams and X-rays using a plastic scintillator plate set in a water phantom. When this plate was immersed in the water phantom, irradiation with electron beams or X-rays was carried out from along the plate's sides. Optical images of the scintillator plate were acquired using a charge-coupled device (CCD) camera from the side during irradiation with electron beams and X-rays. Measurements were conducted at 6 MeV, 9 MeV and 12 MeV for electron beams and at 6 MV and 10 MV for X-rays. The imaging system was set on the bed of the LINAC and moved at 10-mm steps perpendicular to the beam direction to acquire a set of sliced optical images of the beams. A set of these sliced images were stacked and interpolated to form 3D optical images. For the 3D images, after the correction of the Cherenkov-light component in the images, the relative depth and lateral doses were evaluated. From the relative depth doses of electron beams, the half-value depths could be evaluated within an error of 1.3 mm. Lateral widths could be evaluated within an error of less than 2 mm parallel to the plastic scintillator and less than 6.5 mm perpendicular to it. From the relative depth doses of X-rays, the average difference between the measured value and that by a planning system was within an error of 2 %. Lateral widths could be evaluated within an error of less than 0.68 mm parallel to the plastic scintillator and less than 2.6 mm perpendicular to it. We confirmed that 3D imaging of electron beams and X-rays using plastic scintillator plate is feasible and is a promising method for measuring dose images at any position.

From 1901 to 2022, how far are we from truly understanding the pathogenesis of age-related dementia?

From the first described AD case in 1901 to the current year 2022, understanding the pathogenesis of Alzheimer's disease (AD) and dementia has undergone a long and tortuous journey. Many mechanisms of AD etiology have been proposed and studied. However, current medications and FDA-approved treatments cannot cure AD and AD-related dementias (AD/ADRD). Recently, brain hypoperfusion associated with neurovascular dysfunction was recognized as one of the causal factors in the development of AD dementia. Arteriosclerotic changes were observed in the first AD case. A recent study reported that the functional hyperemic response to whisker stimulation was reduced in 9-12months old atherosclerotic mice. Interestingly, they found that evoked hemodynamic responses were not altered in age-matched AD mice or AD mice with superimposed atherosclerosis using 2D-optical imaging spectroscopy in chronic studies. However, functional hyperemia was impaired in AD mice using the same approach in an acute study. It is essential to scrutinize the available data critically since different genetic backgrounds, ages, sexes of studied animal models, and different approaches used for the same function even structural examination may provide opposite information. We certainly are closer to truly understanding the pathogenesis of dementia. We expect positive results from using aducanumab (Aduhelm®) as the first FDA-approved anti-amyloid monoclonal antibody as a treatment for AD/ADRD. We hope to identify and develop new drugs targeting other potential contributing mechanisms such as the cerebral vascular pathways.

Optical clearing-based 3D-imaging of vascularization and mineralization of human degenerative osteochondral tissue

Optical clearing-based 3D-imaging of vascularization and mineralization of human degenerative osteochondral tissue

The neuroprotective effects of oxygen therapy in Alzheimer’s disease: a narrative review

Alzheimer’s disease (AD) is a degenerative neurological disease that primarily affects the elderly. Drug therapy is the main strategy for AD treatment, but current treatments suffer from poor efficacy and a number of side effects. Non-drug therapy is attracting more attention and may be a better strategy for treatment of AD. Hypoxia is one of the important factors that contribute to the pathogenesis of AD. Multiple cellular processes synergistically promote hypoxia, including aging, hypertension, diabetes, hypoxia/obstructive sleep apnea, obesity, and traumatic brain injury. Increasing evidence has shown that hypoxia may affect multiple pathological aspects of AD, such as amyloid-beta metabolism, tau phosphorylation, autophagy, neuroinflammation, oxidative stress, endoplasmic reticulum stress, and mitochondrial and synaptic dysfunction. Treatments targeting hypoxia may delay or mitigate the progression of AD. Numerous studies have shown that oxygen therapy could improve the risk factors and clinical symptoms of AD. Increasing evidence also suggests that oxygen therapy may improve many pathological aspects of AD including amyloid-beta metabolism, tau phosphorylation, neuroinflammation, neuronal apoptosis, oxidative stress, neurotrophic factors, mitochondrial function, cerebral blood volume, and protein synthesis. In this review, we summarized the effects of oxygen therapy on AD pathogenesis and the mechanisms underlying these alterations. We expect that this review can benefit future clinical applications and therapy strategies on oxygen therapy for AD.

The effects of locomotion on sensory-evoked haemodynamic responses in the cortex of awake mice

Investigating neurovascular coupling in awake rodents is becoming ever more popular due, in part, to our increasing knowledge of the profound impacts that anaesthesia can have upon brain physiology. Although awake imaging brings with it many advantages, we still do not fully understand how voluntary locomotion during imaging affects sensory-evoked haemodynamic responses. In this study we investigated how evoked haemodynamic responses can be affected by the amount and timing of locomotion. Using an awake imaging set up, we used 2D-Optical Imaging Spectroscopy (2D-OIS) to measure changes in cerebral haemodynamics within the sensory cortex of the brain during either 2 s whisker stimulation or spontaneous (no whisker stimulation) experiments, whilst animals could walk on a spherical treadmill. We show that locomotion alters haemodynamic responses. The amount and timing of locomotion relative to whisker stimulation is important, and can significantly impact sensory-evoked haemodynamic responses. If locomotion occurred before or during whisker stimulation, the amplitude of the stimulus-evoked haemodynamic response was significantly altered. Therefore, monitoring of locomotion during awake imaging is necessary to ensure that conclusions based on comparisons of evoked haemodynamic responses (e.g., between control and disease groups) are not confounded by the effects of locomotion.

Dynamic Tomographic Phase Microscopy by Double Six-Pack Holography.

Three-dimensional (3D) optical imaging of rapidly moving biological cells is difficult to achieve as such samples cannot be scanned over time. Here, we present a dynamic scan-free optical tomography approach for stain-free 3D imaging of biological cells using our new double six-pack tomography technique, whereby 12 off-axis holograms are captured in a single camera exposure without sacrificing resolution or field of view. The proposed system illuminates the sample from 12 angles simultaneously, and 3D refractive index (RI) tomograms are reconstructed from each recorded video frame of the dynamic sample. The technique is verified experimentally by recording flowing silica beads, 3 μm in diameter, with the resulting tomogram RI accuracy being 98.5%. A live swimming sperm cell is also imaged, and dynamic 3D imaging results for both beads and sperm cell are presented. The proposed technique represents a 12-fold increase in dynamic holographic data for tomography.

Deep Learning Model Based on 3D Optical Coherence Tomography Images for the Automated Detection of Pathologic Myopia.

Pathologic myopia causes vision impairment and blindness, and therefore, necessitates a prompt diagnosis. However, there is no standardized definition of pathologic myopia, and its interpretation by 3D optical coherence tomography images is subjective, requiring considerable time and money. Therefore, there is a need for a diagnostic tool that can automatically and quickly diagnose pathologic myopia in patients. This study aimed to develop an algorithm that uses 3D optical coherence tomography volumetric images (C-scan) to automatically diagnose patients with pathologic myopia. The study was conducted using 367 eyes of patients who underwent optical coherence tomography tests at the Ophthalmology Department of Incheon St. Mary’s Hospital and Seoul St. Mary’s Hospital from January 2012 to May 2020. To automatically diagnose pathologic myopia, a deep learning model was developed using 3D optical coherence tomography images. The model was developed using transfer learning based on four pre-trained convolutional neural networks (ResNet18, ResNext50, EfficientNetB0, EfficientNetB4). Grad-CAM was used to visualize features affecting the detection of pathologic myopia. The performance of each model was evaluated and compared based on accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC). The model based on EfficientNetB4 showed the best performance (95% accuracy, 93% sensitivity, 96% specificity, and 98% AUROC) in identifying pathologic myopia.

Comparison of 2D Optical Imaging and 3D Microtomography Shape Measurements of a Coastal Bioclastic Calcareous Sand.

This article compares measurements of particle shape parameters from three-dimensional (3D) X-ray micro-computed tomography (μCT) and two-dimensional (2D) dynamic image analysis (DIA) from the optical microscopy of a coastal bioclastic calcareous sand from Western Australia. This biogenic sand from a high energy environment consists largely of the shells and tests of marine organisms and their clasts. A significant difference was observed between the two imaging techniques for measurements of aspect ratio, convexity, and sphericity. Measured values of aspect ratio, sphericity, and convexity are larger in 2D than in 3D. Correlation analysis indicates that sphericity is correlated with convexity in both 2D and 3D. These results are attributed to inherent limitations of DIA when applied to platy sand grains and to the shape being, in part, dependent on the biology of the grain rather than a purely random clastic process, like typical siliceous sands. The statistical data has also been fitted to Johnson Bounded Distribution for the ease of future use. Overall, this research demonstrates the need for high-quality 3D microscopy when conducting a micromechanical analysis of biogenic calcareous sands.

A pilot study of a novel method to visualize three-dimensional dose distribution on skin surface images to evaluate radiation dermatitis

Predicting the radiation dose‒toxicity relationship is important for local tumor control and patients’ quality of life. We developed a first intuitive evaluation system that directly matches the three-dimensional (3D) dose distribution with the skin surface image of patients with radiation dermatitis (RD) to predict RD in patients undergoing radiotherapy. Using an RGB-D camera, 82 3D skin surface images (3DSSIs) were acquired from 19 patients who underwent radiotherapy. 3DSSI data acquired included 3D skin surface shape and optical imaging of the area where RD occurs. Surface registration between 3D skin dose (3DSD) and 3DSSI is performed using the iterative closest point algorithm, then reconstructed as a two-dimensional color image. The developed system successfully matched 3DSSI and 3DSD, and visualized the planned dose distribution onto the patient's RD image. The dose distribution pattern was consistent with the occurrence pattern of RD. This new approach facilitated the evaluation of the direct correlation between skin-dose distribution and RD and, therefore, provides a potential to predict the probability of RD and thereby decrease RD severity by enabling informed treatment decision making by physicians. However, the results need to be interpreted with caution due to the small sample size.

Characterization of biofilm structure and properties via processing of 2D optical coherence tomography images in BISCAP.

Processing of Optical Coherence Tomography (OCT) biofilm images is currently restricted to a set of custom-made MATLAB scripts. None of the tools currently available for biofilm image processing (including those developed for Confocal Laser Scanning Microscopy-CLSM) enable a fully automatic processing of 2D OCT images. A novel software tool entitled Biofilm Imaging and Structure Classification Automatic Processor (BISCAP) is presented. It was developed specifically for the automatic processing of 2D OCT biofilm images. The proposed approach makes use of some of the key principles used in CLSM image processing, and introduces a novel thresholding algorithm and substratum detection strategy. Two complementary pixel continuity checks are executed, enabling very detailed pixel characterizations. BISCAP delivers common structural biofilm parameters and a set of processed images for biofilm analysis. A novel biofilm 'compaction parameter' is suggested. The proposed strategy was tested on a set of 300 images with highly satisfactory results obtained. BISCAP is a Python-based standalone application, not requiring any programming knowledge or property licenses, and where all operations are managed via an intuitive Graphical User Interface. The automatic nature of this image processing strategy decreases biasing problems associated to human-perception and allows a reliable comparison of outputs. BISCAP and a collection of biofilm images obtained from OCT scans can be found at: https://github.com/diogonarciso/BISCAP. Supplementary data are available at Bioinformatics online.

Three-dimensional morphometric analysis of human kidney nephron structures in health and disease

Background and Hypothesis: Chronic kidney disease (CKD) is very common and affects as many as 37 million people in the United States. Diabetes and hypertension are the most common causes of CKD. The pathogenesis of CKD is not fully elucidated. Morphological changes such as glomerulosclerosis and tubular atrophy are commonly observed with advanced disease. However, it is unclear if such changes occur at earlier stages of disease, a time when therapeutic interventions are likely to have the most benefit. Measurements of glomerular, vascular and tubular dimensions have been typically derived from thin section, but a pipeline for acquiring these morphometric measurements in 3-dimentions have not been performed. Using enhanced tissue clearing, confocal 3D imaging and volumetric segmentation and analysis, we aimed at developing an approach to measure the dimensions of various structures within the human kidney. Our overarching hypothesis is that such approach could allow the detection of morphometric changes in early disease. &#x0D; Experimental Design or Project Methods: Kidney tissue were used either from donor nephrectomies or stored frozen biopsies from Biobank Biopsy Cohort of Indiana (BBCI). Enhanced tissue clearing and staining for nuclei, endothelium and proximal tubules were performed. Optical sectioning and 3D Imaging was done using confocal microscopy. Volume rendering, segmentation and analysis were done using the Imaris Software (Bitplane). Various built in and customized segmentation approaches were used.&#x0D; Results: Volumes spanning 200 µm in thickness encompassing entire glomeruli and tubules were obtained. 3D Rendering of these volumes allowed visualization and enabled 3D segmentation. Dimensions of entire human glomeruli (maximum and minimum diameters, glomerular volumes and cellular densities), tubules and vessels were defined in control and samples with diabetic kidney disease.&#x0D; Conclusion and Potential Impact: Our studies established an approach for accurate measurements of the dimensions of nephronal structures preserved in their 3D environment within tissue. We also established the feasibility of this approach in comparing changes with disease vs. control. Such methodology will open up a new line of investigations to better understand the pathogenesis of CKD, particularly at its early stages.

Automatic Segmentation of the Retinal Nerve Fiber Layer by Means of Mathematical Morphology and Deformable Models in 2D Optical Coherence Tomography Imaging.

Glaucoma is a neurodegenerative disease process that leads to progressive damage of the optic nerve to produce visual impairment and blindness. Spectral-domain OCT technology enables peripapillary circular scans of the retina and the measurement of the thickness of the retinal nerve fiber layer (RNFL) for the assessment of the disease status or progression in glaucoma patients. This paper describes a new approach to segment and measure the retinal nerve fiber layer in peripapillary OCT images. The proposed method consists of two stages. In the first one, morphological operators robustly detect the coarse location of the layer boundaries, despite the speckle noise and diverse artifacts in the OCT image. In the second stage, deformable models are initialized with the results of the previous stage to perform a fine segmentation of the boundaries, providing an accurate measurement of the entire RNFL. The results of the RNFL segmentation were qualitatively assessed by ophthalmologists, and the measurements of the thickness of the RNFL were quantitatively compared with those provided by the OCT inbuilt software as well as the state-of-the-art methods.

3D sub-cellular localization of upconverting nanoparticles through hyperspectral microscopy

Hyperspectral microscopy is an intriguing technique combining spectroscopy with optical microscopy that can be used to simultaneously obtain spectral and spatial information. The relevance of hyperspectral imaging in biomedical applications such as the monitoring of bioimaging agents, the identification of pathogens and cancerous cells, and the cellular uptake of nanoparticles has emerged recently, due to recent advances in optical reconstruction. The location and tracking of particles within the cell structure have been analyzed by 2D hyperspectral imaging of non-fluorescence objects, being examples of 3D localization uncommon. Here, we report the synthesis of Yb3+/Er3+-codoped Gd2O3 nanoparticles, their structural and luminescence characterization, and their biocompatibility assessments in Human melanoma (MNT-1 and A375) cell lines. The internalization of the particles by MNT-1 cells and their 3D localization in a fixed configuration are addressed through 2D optical images acquired in different planes along with the cell culture depth. 2D hyperspectral imaging is used to unequivocally identify the nuclei and the nanoparticles. The results indicate that the particles are distributed in distinct planes deep in the cell volume in the cytoplasmic and perinuclear regions. Furthermore, the emission signature of the nanoparticles enabled the determination of the intracellular temperature.

Single-shot real-time compressed ultrahigh-speed imaging enabled by a snapshot-to-video autoencoder

Single-shot 2D optical imaging of transient scenes is indispensable for numerous areas of study. Among existing techniques, compressed optical-streaking ultrahigh-speed photography (COSUP) uses a cost-efficient design to endow ultrahigh frame rates with off-the-shelf CCD and CMOS cameras. Thus far, COSUP’s application scope is limited by the long processing time and unstable image quality in existing analytical-modeling-based video reconstruction. To overcome these problems, we have developed a snapshot-to-video autoencoder (S2V-AE)—which is a deep neural network that maps a compressively recorded 2D image to a movie. The S2V-AE preserves spatiotemporal coherence in reconstructed videos and presents a flexible structure to tolerate changes in input data. Implemented in compressed ultrahigh-speed imaging, the S2V-AE enables the development of single-shot machine-learning assisted real-time (SMART) COSUP, which features a reconstruction time of 60 ms and a large sequence depth of 100 frames. SMART-COSUP is applied to wide-field multiple-particle tracking at 20,000 frames per second. As a universal computational framework, the S2V-AE is readily adaptable to other modalities in high-dimensional compressed sensing. SMART-COSUP is also expected to find wide applications in applied and fundamental sciences.