Compound metalens-based miniature two-photon microscope for large-FOV imaging in freely behaving animals

SummaryIn vivo two-photon deep imaging with a broad field of view has revealed functional connectivity among brain regions. Here, we developed a novel observation method that utilizes a polyethylene-oxide-coated CYTOP (PEO-CYTOP) nanosheet with a thickness of ∼130 nm that exhibited a water retention effect and a hydrophilized adhesive surface. PEO-CYTOP nanosheets firmly adhered to brain surfaces, which suppressed bleeding from superficial veins. By taking advantage of the excellent optical properties of PEO-CYTOP nanosheets, we performed in vivo deep imaging in mouse brains at high resolution. Moreover, PEO-CYTOP nanosheets enabled to prepare large cranial windows, achieving in vivo imaging of neural structure and Ca2+ elevation in a large field of view. Furthermore, the PEO-CYTOP nanosheets functioned as a sealing material, even after the removal of the dura. These results indicate that this method would be suitable for the investigation of neural functions that are composed of interactions among multiple regions.

Advanced image sensor and powerful parallel data acquisition chip can be used to collect more detailed and comprehensive light field information. Using multiple single aperture and high resolution sensor record light field data, and processing the light field data real time, we can obtain wide field-of-view (FOV) and high resolution image. Wide FOV and high-resolution imaging has promising application in areas of navigation, surveillance and robotics. Qualityenhanced 3D rending, very high resolution depth map estimation, high dynamic-range and other applications we can obtained when we post-process these large light field data. The FOV and resolution are contradictions in traditional single aperture optic imaging system, and can't be solved very well. We have designed a multi-camera light field data acquisition system, and optimized each sensor's spatial location and relations. It can be used to wide FOV and high resolution real-time image. Using 5 megapixel CMOS sensors, and field programmable Gate Array (FPGA) acquisition light field data, paralleled processing and transmission to PC. A common clock signal is distributed to all of the cameras, and the precision of synchronization each camera achieved 40ns. Using 9 CMOSs build an initial system and obtained high resolution 360°×60° FOV image. It is intended to be flexible, modular and scalable, with much visibility and control over the cameras. In the system we used high speed dedicated camera interface CameraLink for system data transfer. The detail of the hardware architecture, its internal blocks, the algorithms, and the device calibration procedure are presented, along with imaging results.

ASSESSMENT OF CBCT IMAGE ARTIFACTS GENERATED BY IMPLANTS LOCATED IN THE EXOMASS

HomeRadiology: Imaging CancerVol. 2, No. 3 PreviousNext Research HighlightsFree AccessPreclinical Model of Optical Coherence Tomography for High-Resolution Deep-Brain Imaging for Laser AblationAdeline N. BoettcherAdeline N. BoettcherAdeline N. BoettcherPublished Online:May 29 2020https://doi.org/10.1148/rycan.2020204016MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked InEmail Take-Away Points■ Major Focus: Preclinical in vivo imaging of the deep brain using an optical coherence tomography (OCT) needle for tissue visualization and laser ablation.■ Key Result: OCT imaging in a murine model was capable of producing high-resolution images of the deep brain before and after laser ablation at a resolution of 1.7 μm (axial) × 5.7 μm (lateral).■ Impact: Development of this tool for deep-brain imaging and ablation would allow for more precise and real-time imaging during ablation procedures in clinical practice.High-resolution three-dimensional imaging would be beneficial for viewing solid organs for planning and monitoring of cancer ablation therapies. Typical laser ablation procedures require MRI to determine where the target lesion is located, to confirm placement of the ablation probe, and to observe the effect of ablation during the procedure. For sensitive imaging areas, such as the brain, time needed for MRI to verify probe positioning and possible repositioning increases risk of injury to the patient. Together, a real-time high-resolution imaging technique that could overcome these issues would be beneficial for planning and monitoring of solid organ ablation procedures.In this study, Yuan et al assembled an 800-nm optical coherence tomography (OCT) imaging needle that was capable of high-resolution imaging (1.7 μm [axial] × 5.7 μm [lateral]). Additionally, this needle was equipped with a near-infrared laser for tissue ablation. For their first proof-of-concept study, the group imaged brain tissue in mice by introducing the microneedle through two burr holes made in the skull. Three-dimensional, color-coded images were generated by imaging a 4.5-mm-long cylindrical volume in the deep brain. Images detected even filament bundles in deep brain tissues. The authors also successfully imaged brain tumors marked with green fluorescent protein. Images from both normal and malignant brain tissue showed high concordance to histology.To demonstrate potential imaging laser ablation procedures in patients, the authors imaged mouse brains before and immediately after laser ablation. By assessing volumetric OCT brain images, the authors verified successful laser ablation of the target volume demonstrated by histology. Taken together, the authors show exciting first steps toward developing an OCT microneedle for real-time high-resolution clinical imaging and precision laser ablation of solid organ tumors, such as glioblastomas.Highlighted ArticleYuan W, Chen D, Sarabia-Estrada R, et al. Theranostic OCT microneedle for fast ultrahigh-resolution deep-brain imaging and efficient laser ablation in vivo. Sci Adv 2020;6(15):eaaz9664. doi: 10.1126/sciadv.aaz9664Highlighted ArticleYuan W, Chen D, Sarabia-Estrada R, et al. Theranostic OCT microneedle for fast ultrahigh-resolution deep-brain imaging and efficient laser ablation in vivo. Sci Adv 2020;6(15):eaaz9664. doi: 10.1126/sciadv.aaz9664 Crossref, Medline, Google ScholarArticle HistoryPublished online: May 29 2020 FiguresReferencesRelatedDetailsRecommended Articles Image-guided Microinvasive Percutaneous Treatment of Breast Lesions: Where Do We Stand?RadioGraphics2021Volume: 41Issue: 4pp. 945-966Effects of a Thermal Accelerant Gel on Microwave Ablation Zone Volumes in Lung: A Porcine StudyRadiology2019Volume: 291Issue: 2pp. 504-510Development of Multispectral Optoacoustic Tomography as a Clinically Translatable Modality for Cancer ImagingRadiology: Imaging Cancer2020Volume: 2Issue: 6High-Intensity Focused Ultrasound for Pain Management in Patients with CancerRadioGraphics2018Volume: 38Issue: 2pp. 603-623Focused Ultrasound Hyperthermia for Targeted Drug Release from Thermosensitive Liposomes: Results from a Phase I TrialRadiology2019Volume: 291Issue: 1pp. 232-238See More RSNA Education Exhibits Diagnostic and Procedural Intraoperative Ultrasound: Technique, Tips, and Tricks for Optimizing ResultsDigital Posters2019Novel Image-Guided Micro-Invasive Percutaneous Treatments of Breast Lesions: Where Do We Stand?Digital Posters2019Five Stages of Artifacts: Denial, Anger, Bargaining, Depression, and AcceptanceDigital Posters2019 RSNA Case Collection Cerebral Air EmboliRSNA Case Collection2021Medial Temporal Lobe EncephaloceleRSNA Case Collection2021Trigeminal schwannomaRSNA Case Collection2020 Vol. 2, No. 3 Metrics Downloaded 156 times Altmetric Score PDF download

Adaptive Optics (AO) retinal imaging is revealing microscopic structures of the eye in a non-invasive way. Due to anisoplanatism, conventional AO systems are efficient on small 1°x1° field of view (FoV). We present a lens-based AO scanning laser ophthalmoscope (SLO) set-up with 2 deformable mirrors (DM), providing high-resolution retinal imaging on a 4°x4° FoV, for an eye pupil diameter of 7 mm. The first DM is in a pupil plane and is driven using a Shack-Hartmann (SH). The second DM is conjugated to a plane located 0.7 mm in front of the retina, to correct for aberrations varying within the FoV. Its shape is optimized using sensorless AO technique. The performance of this set-up was characterized in-vivo by measuring the eyes of four healthy volunteers. The obtained image quality was satisfactory and uniform over the entire FoV. Foveal cones could be resolved and no image distortion was detected. Furthermore, a 10°x10° FoV image was acquired at the fovea of one volunteer, by stitching 9 images recorded at different eccentricities. Finally, different layers of the retina were imaged. In addition to the photoreceptors mosaic, small capillaries and nerve fibers were clearly identified. The presented AO-SLO instrument provides high-resolution images of the retina on a relatively large FoV in reasonable time. With 2 DMs, one SH and no guide star, the system stays quite simple. The imaging performance of the set-up was validated on 4 healthy volunteers and we are currently imaging patients with different eye diseases.

Imaging systems with a wide field-of-view (FOV) and high-resolution, which can provide abundant target information, are always desired in various applications including target detection, environment monitoring, marine rescue, etc. Various approaches to realizing the wide FOV and high-resolution imaging have been developed, for example, fisheye lens imaging system, and panoramic optical annular staring imaging technology. In these single aperture imaging systems, the maximum resolution and FOV are determined by either the geometric aberration or the diffraction limit of the optics. Multi-scale monocentric ball-lens imaging system is of particular importance due to its high real-time ability, small image distortion, and wide FOV. The complete geometrical symmetry of multilayer monocentric ball-lens makes it possible to compensate for the geometric aberration with no need of additional assistance. However, the major problem in designing imaging system based on multi-scale monocentric ball-lens is that there are too many variables needed to be set for a ball-lens imaging structure and the problems of high time cost and computation complexity.For simplifying the design process, in this manuscript, we apply the computational imaging theory to optical system design, thereby developing a geometric aberration optimization function to determine the initial values of the desired system by the sound computation rather than repetitive iterations by using the optical system design software. Function development starts from the aberration theory. Since the monocentric ball lens does not bring in the aberrations relating to FOV, only spherical aberration and chromatic aberration are needed to be considered. The optimization function is then founded according to the principle of minimizing the spherical aberration and chromatic aberration. And then with the determined initial parameters, ZEMAX is employed to globally optimize the residual geometric aberrations, which is time-efficient. After required parameters are finally determined, the system performance is evaluated via the modulation transmission function, the spot diagram distribution, the field-curve and distortion value and the ray fan curve. Favorable results are obtained, which demonstrates the feasibility of the developed system designing approach. Imaging results from the finished prototype system are pretty satisfactory with wide FOV and high resolution which is captured through only one frame. The multi-scale wide FOV and high-resolution computation imaging system not only solves the conflict between the wide FOV and high resolution, but also provides the research foundation for computational imaging.

Evaluation of Cone-beam Computed Tomography Artifacts Produced by Metal Objects Located Within and Outside the Field of View

Curved imaging sensors bring significant size, weight and cost reduction to imaging systems while mitigating off-axis optical aberrations, as opposed to current flat sensors. Unlocking these key features has captured the interest of major players over the last two decades. SILINA has been developing a CMOS Image Sensor (CIS) curving process, which adapts to various sensor characteristics. This enables to maximize the optical performance of every single imaging system. We have demonstrated the manufacturing of curved CMOS Front-Side Illuminated (FSI) and Back Side Illuminated (BSI), opening a new area of compact, fast, wide-angle and high-resolution optical lenses. This new degree of freedom offered to optical designer can significantly simplify optical systems through a significant improvement of the optical performance while simplifying the system architecture in many different ways. The field of view (FOV), the contrast, the aperture can be increased while optical aberrations can be minimized. At the end, the different costs related to manufacturing, metrology, integration, and alignment are reduced. This is of great importance for applications requiring compact and high resolution lens, notably in low-light environment. To quantify the gain brought by curved image sensor for smartphone camera lens, we are performing several comparative optical lens designs. We compare traditional flat-image sensor based camera lens to camera lens optimized specifically with a curved image sensor. In this paper, we present the result obtained on wide-angle smartphone camera lens design considering a spherical concave image sensor. We compare the optical characteristics and performance with a reference optical design using a flat image sensor. We discuss the various benefits in terms of optical performance and Z-stack reduction.

Multiphoton microscopy combined with optogenetic photostimulation is a powerful technique in neuroscience enabling precise control of cellular activity to determine the neural basis of behavior in a live animal. Two-photon patterned photostimulation has taken this further by allowing interrogation at the individual neuron level. However, it remains a challenge to implement imaging of neural activity with spatially patterned two-photon photostimulation in a freely moving animal. We developed a miniature microscope for high resolution two-photon fluorescence imaging with patterned two-photon optogenetic stimulation. The design incorporates a MEMS scanner for two-photon imaging and a second beam path for patterned two-photon excitation in a compact and lightweight design that can be head-attached to a freely moving animal. We demonstrate cell-specific optogenetics and high resolution MEMS based two-photon imaging in a freely moving mouse. The new capabilities of this miniature microscope design can enable cell-specific studies of behavior that can only be done in freely moving animals.

Training to improve the standardization of subjective assessments in biological science is crucial to improve and maintain accuracy. However, in reproductive science there is no standardized training tool available to assess sperm morphology. Sperm morphology is routinely assessed subjectively across several species and is often used as grounds to reject or retain samples for sale or insemination. As with all subjective tests, sperm morphology assessment is liable to human bias and without appropriate standardization these assessments are unreliable. This proof-of-concept study aimed to develop a standardized sperm morphology assessment training tool that can train and test students on a sperm-by-sperm basis. The following manuscript outlines the methods used to develop a training tool with the capability to account for different microscope optics, morphological classification systems, and species of spermatozoa assessed. The generation of images, their classification, organization, and integration into a web interface, along with its design and outputs, are described. Briefly, images of spermatozoa were generated by taking field of view (FOV) images at 40× magnification on DIC optics, amounting to a total of 3,600 FOV images from 72 rams (50 FOV/ram). These FOV images were cropped to only show one sperm per image using a novel machine-learning algorithm. The resulting 9,365 images were labelled by three experienced assessors, and those with 100% consensus on all labels (4821/9365) were integrated into a web interface able to provide both (i) instant feedback to users on correct/incorrect labels for training purposes, and (ii) an assessment of user proficiency. Future studies will test the effectiveness of the training tool to educate students on the application of a variety of morphology classification systems. If proven effective, it will be the first standardized method to train individuals in sperm morphology assessment and help to improve understanding of how training should be conducted.

Digital rock imaging plays an important role in studying the microstructure and macroscopic properties of rocks, where microcomputed tomography (MCT) is widely used. Due to the inherent limitations of MCT, a balance should be made between the field of view (FOV) and resolution of rock MCT images-a large FOV at low resolution (LR) or a small FOV at high resolution (HR). However, large FOV and HR are both expected for reliable analysis results in practice. Super-resolution (SR) is an effective solution to break through the mutual restriction between the FOV and resolution of rock MCT images, for it can reconstruct an HR image from a LR observation. Most of the existing SR methods cannot produce satisfactory HR results on real-world rock MCT images. One of the main reasons for this is that paired images are usually needed to learn the relationship between LR and HR rock images. However, it is challenging to collect such a dataset in a real scenario. Meanwhile, the simulated datasets may be unable to accurately reflect the model in actual applications. To address these problems, we propose a cycle-consistent generative adversarial network (CycleGAN)-based SR approach for real-world rock MCT images, namely, SRCycleGAN. In the off-line training phase, a set of unpaired rock MCT images is used to train the proposed SRCycleGAN, which can model the mapping between rock MCT images at different resolutions. In the on-line testing phase, the resolution of the LR input is enhanced via the learned mapping by SRCycleGAN. Experimental results show that the proposed SRCycleGAN can greatly improve the quality of simulated and real-world rock MCT images. The HR images reconstructed by SRCycleGAN show good agreement with the targets in terms of both the visual quality and the statistical parameters, including the porosity, the local porosity distribution, the two-point correlation function, the lineal-path function, the two-point cluster function, the chord-length distribution function, and the pore size distribution. Large FOV and HR rock MCT images can be obtained with the help of SRCycleGAN. Hence, this work makes it possible to generate HR rock MCT images that exceed the limitations of imaging systems on FOV and resolution.

A meteorological moderate resolution sensor requires large field of view (FOV) and low distortion imaging. At present, a fixed-focus camera combined with a whiskbroom scanning mechanism or a fixed-focus multi-camera combined with pushbroom scanning mechanism is being used. Owing to the fixed focal length of the camera, a large FOV causes the difference of imaging distance and ground imaging angle between the nadir point and the edge of the FOV to be significantly large, resulting in a large difference in the resolution between the nadir point and the edge of the FOV. The study proposes to simultaneously adopt a distributed zoom concentric multiscale system to realize a large FOV, low distortion, and high quality imaging to coordinate with different compensation lenses to achieve a different FOV corresponding to different focal lengths, where the resolution drop between the nadir point and the edge of the FOV is reduced. To ensure the same illumination of the entire FOV, the entire system possesses the same F# with different FOVs exhibiting different entrance pupil diameters. The study analyzes the principle of aberration compensation of a concentric multiscale system when both the FOV and entrance pupil diameter are changed and completes three groups of optical design of different focal lengths with uniform F#. The results indicate that the system has advantages of low distortion and high imaging quality in the entire FOV. Moreover, the resolution drop in the entire FOV is reduced to approximately 50% of the traditional design scheme. To verify the implementability of the system, a set of prototype manufacturing and imaging experiments are conducted to prove that the system has satisfactory implementability, and the imaging quality is also satisfactory.

Diffractive lenses (DLs) can realize high-resolution imaging with light weight and compact size. Conventional DLs suffer large chromatic and off-axis aberrations, which significantly limits their practical applications. Although many achromatic methods have been proposed, most of them are used for designing small aperture DLs, which have low diffraction efficiencies. In the designing of diffractive achromatic lenses, increasing the aperture and improving the diffraction efficiency have become two of the most important design issues. Here, a novel phase-coded diffractive lens (PCDL) for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally, and it also possesses wide field-of-view (FOV) imaging at the same time. The phase distribution of the conventional phase-type diffractive lens (DL) is coded with a cubic function to expand both the working bandwidth and the FOV of conventional DL. The proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm, a focal length of 100 mm, and a cubic phase coding parameter of 30π. Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16° with over 8% focusing efficiency, which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical predictions. This work provides a novel way for implementing the achromatic, wide FOV, and high-efficiency imaging with large aperture DL.

目的 探讨扫描野大小与CT图像质量之间关系.方法分别采用25 cm×25 cm、35 cm×35 cm、42 cm×42 cm扫描野对空间分辨率模体和密度分辨率模体进行扫描,测量出各扫描野时空间分辨率和密度分辨率;对20例病人分别采用25 cm×25 cm和35 cm×35 cm扫描野进行扫描,并请有多年临床经验的医师,采用双盲法对图像质量进行比较.结果不同的扫描野其图像空间分辨率和密度分辨率不同,25 cm×25 cm扫描野的图像空间分辨率最高,可以分辨4个直径0.6 mm 小孔,其密度分辨率也最高,可以分辨5个直径2.5mm 小孔;扫描野为25 cm×25 cm时,临床应用CT扫描的图像明显比35 cm×35 cm的图像清晰(P＜0.05).结论 CT常用的扫描野范围内,当扫描野为25 cm×25cm时,其图像的空间分辨率和密度分辨率最佳。

Currently, a serious problem obstructing the large-scale clinical applications of fluorescence technique is the shallow penetration depth. Two-photon fluorescence microscopic imaging with excitation in the longer-wavelength near-infrared (NIR) region (>1100 nm) and emission in the NIR-I region (650-950 nm) is a good choice to realize deep-tissue and high-resolution imaging. Here, we report ultradeep two-photon fluorescence bioimaging with 1300 nm NIR-II excitation and NIR-I emission (peak ∼810 nm) based on a NIR aggregation-induced emission luminogen (AIEgen). The crab-shaped AIEgen possesses a planar core structure and several twisting phenyl/naphthyl rotators, affording both high fluorescence quantum yield and efficient two-photon activity. The organic AIE dots show high stability, good biocompatibility, and a large two-photon absorption cross section of 1.22 × 103 GM. Under 1300 nm NIR-II excitation, in vivo two-photon fluorescence microscopic imaging helps to reconstruct the 3D vasculature with a high spatial resolution of sub-3.5 μm beyond the white matter (>840 μm) and even to the hippocampus (>960 μm) and visualize small vessels of ∼5 μm as deep as 1065 μm in mouse brain, which is among the largest penetration depths and best spatial resolution of in vivo two-photon imaging. Rational comparison with the AIE dots manifests that two-photon imaging outperforms the one-photon mode for high-resolution deep imaging. This work will inspire more sight and insight into the development of efficient NIR fluorophores for deep-tissue biomedical imaging.