Mortality and cardiac arrest rates of emergency surgery in developed and developing countries: a systematic review and meta-analysis.

BACKGROUND: The magnitude of the risk of death and cardiac arrest associated with emergency surgery and anesthesia is not well understood. Our aim was to assess whether the risk of perioperative and anesthesia-related death and cardiac arrest has decreased over the years, and whether the rates of decrease are consistent between developed and developing countries. METHODS: A systematic review was performed using electronic databases to identify studies in which patients underwent emergency surgery with rates of perioperative mortality, 30-day postoperative mortality, or perioperative cardiac arrest. Meta-regression and proportional meta-analysis with 95% confidence intervals (CIs) were performed to evaluate global data on the above three indicators over time and according to country Human Development Index (HDI), and to compare these results according to country HDI status (low vs. high HDI) and time period (pre-2000s vs. post-2000s). RESULTS: 35 studies met the inclusion criteria, representing more than 3.09 million anesthetic administrations to patients undergoing anesthesia for emergency surgery. Meta-regression showed a significant association between the risk of perioperative mortality and time (slope: -0.0421, 95%CI: from - 0.0685 to -0.0157; P = 0.0018). Perioperative mortality decreased over time from 227 per 10,000 (95% CI 134-380) before the 2000s to 46 (16-132) in the 2000-2020 s (p < 0-0001), but not with increasing HDI. 30-day postoperative mortality did not change significantly (346 [95% CI: 303-395] before the 2000s to 292 [95% CI: 201-423] in the 2000s-2020 period, P = 0.36) and did not decrease with increasing HDI status. Perioperative cardiac arrest rates decreased over time, from 113 per 10,000 (95% CI: 31-409) before the 2000s to 31 (14-70) in the 2000-2020 s, and also with increasing HDI (68 [95% CI: 29-160] in the low-HDI group to 21 [95% CI: 6-76] in the high-HDI group, P = 0.012). CONCLUSIONS: Despite increasing baseline patient risk, perioperative mortality has decreased significantly over the past decades, but 30-day postoperative mortality has not. A global priority should be to increase long-term survival in both developed and developing countries and to reduce overall perioperative cardiac arrest through evidence-based best practice in developing countries.

Flow-Diverting Devices in the Treatment of Vertebral Artery Aneurysms: Insights into Efficacy and Safety from a Systematic Review and Meta-analysis.

The objective of this study is to conduct a systematic review and meta-analysis aimed at evaluating the efficacy and safety of flow-diverting devices (FDs) treatment for intracranial vertebral artery (VA) aneurysms. We searched PubMed, Web of Science, OVID, and Embase for English-language studies up to February 2024 and included clinical studies on FD treatment of intracranial VA aneurysms. Sensitivity analysis evaluated outcome stability. Of 2273 articles, 29 studies involving 541 aneurysms treated with FDs were included. Based on the Methodological Index for Non-Randomized Studies (MINORS), six were high-quality and 23 moderate quality. FD treatment showed a 95% rate of favorable clinical outcomes (95% CI, 89-99%), 81% (95% CI, 74-88%) complete aneurysmal occlusion, 4% (95% CI, 2-7%) ischemic complication incidence, 1% (95% CI, 0-3%) hemorrhagic complication incidence, 95% (95% CI, 87-100%) posterior inferior cerebellar artery (PICA) preservation, and 6% (95% CI, 3-10%) in-stent stenosis or occlusion across clinical and angiographic follow-up periods of 13.62 months (95% CI, 10.72-16.52) and 11.85 months (95% CI, 9.36-14.33), respectively. Subgroup analyses, based on a 12-month angiographic follow-up threshold, indicated no statistically significant differences in rates of complete aneurysm occlusion, PICA preservation, or in-stent stenosis or occlusion incidence (p > 0.05) between subgroups. Moreover, significant differences were observed in clinical and angiographic outcomes between ruptured and unruptured aneurysms, particularly in hemorrhagic complications (p < 0.05), without significant disparity in ischemic complications (p > 0.05). The results' stability was confirmed via sensitivity analysis. FDs treatment for VA aneurysms is efficacious and safe, offering high rates of positive clinical and angiographic outcomes with minimal complications, underscoring FDs' viability as a treatment option for VA aneurysms. The study was registered with PROSPERO (registration number: CRD42024499894).

Differences and Correlations of Morphological and Hemodynamic Parameters between Anterior Circulation Bifurcation and Side-wall Aneurysms.

OBJECTIVE: The objective of this research was to explore the difference and correlation of the morphological and hemodynamic features between sidewall and bifurcation aneurysms in anterior circulation arteries, utilizing computational fluid dynamics as a tool for analysis. METHODS: In line with the designated inclusion criteria, this study covered 160 aneurysms identified in 131 patients who received treatment at Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, China, from January 2021 to September 2022. Utilizing follow-up digital subtraction angiography (DSA) data, these cases were classified into two distinct groups: the sidewall aneurysm group and the bifurcation aneurysm group. Morphological and hemodynamic parameters in the immediate preoperative period were meticulously calculated and examined in both groups using a three-dimensional DSA reconstruction model. RESULTS: No significant differences were found in the morphological or hemodynamic parameters of bifurcation aneurysms at varied locations within the anterior circulation. However, pronounced differences were identified between sidewall and bifurcation aneurysms in terms of morphological parameters such as the diameter of the parent vessel (Dvessel), inflow angle (θF), and size ratio (SR), as well as the hemodynamic parameter of inflow concentration index (ICI) (P<0.001). Notably, only the SR exhibited a significant correlation with multiple hemodynamic parameters (P<0.001), while the ICI was closely related to several morphological parameters (R>0.5, P<0.001). CONCLUSIONS: The significant differences in certain morphological and hemodynamic parameters between sidewall and bifurcation aneurysms emphasize the importance to contemplate variances in threshold values for these parameters when evaluating the risk of rupture in anterior circulation aneurysms. Whether it is a bifurcation or sidewall aneurysm, these disparities should be considered. The morphological parameter SR has the potential to be a valuable clinical tool for promptly distinguishing the distinct rupture risks associated with sidewall and bifurcation aneurysms.

Rapamycin inhibits B16 melanoma cell viability invitro and invivo by inducing autophagy and inhibiting the mTOR/p70­S6k pathway.

Rapamycin is an immunosuppressant that has been shown to prevent tumor growth following organ transplantation. However, its exact mode of antitumor action remains unknown. The present study used the B16-F10 (B16) murine melanoma model to explore the antitumor mechanism of rapamycin, and it was revealed that rapamycin reduced B16 cell viability in vitro and in vivo. In addition, in vitro and in vivo, the results of western blotting showed that rapamycin reduced Bcl2 expression, and enhanced the protein expression levels of cleaved caspase 3 and Bax, indicating that it can induce the apoptosis of B16 melanoma cells. Furthermore, the results of cell cycle analysis and western blotting showed that rapamycin induced B16 cell cycle arrest in the G1 phase, based on the reduction in the protein expression levels of CDK1, cyclin D1 and CDK4, as well as the increase in the percentage of cells in G1 phase. Rapamycin also significantly increased the number of autophagosomes in B16 melanoma cells, as determined by transmission electron microscopy. Furthermore, the results of RT-qPCR and western blotting showed that rapamycin upregulated the protein expression levels of microtubule-associated protein light chain 3 (LC3) and Beclin-1, while downregulating the expression of p62 in vitro and in vivo, thus indicating that rapamycin could trigger cellular autophagy. The present study revealed that rapamycin in combination with chloroquine (CQ) further increased LC3 expression compared with that in the CQ group, suggesting that rapamycin induced an increase in autophagy in B16 cells. Furthermore, the results of western blotting showed that rapamycin blocked the phosphorylation of p70 ribosomal S6 kinase (p70-S6k) and mammalian target of rapamycin (mTOR) proteins in vitro and in vivo, thus suggesting that rapamycin may exert its antitumor effect by inhibiting the phosphorylation of the mTOR/p70-S6k pathway. In conclusion, rapamycin may inhibit tumor growth by inducing cellular G1 phase arrest and apoptosis. In addition, rapamycin may exert its antitumor effects by inducing the autophagy of B16 melanoma cells in vitro and in vivo, and the mTOR/p70-S6k signaling pathway may be involved in this process.

Efficacy of esketamine for the treatment of postpartum depression and pain control following cesarean section: a randomized, double-blind, controlled clinical trial.

BACKGROUND: Postpartum depression (PPD) following a cesarean delivery is a frequently seen complication. Despite the prophylactic effects of ketamine, the impact of esketamine on PPD in women undergoing cesarean section remains uncertain. This study aimed to assess the effectiveness of esketamine as an adjunct to patient-controlled intravenous analgesia (PCIA) in preventing PPD in women undergoing caesarean section. METHODS: A total of 275 parturients undergoing caesarean section and subsequent patient-controlled intravenous analgesia (PCIA) were randomly assigned to receive either the control treatment (sufentanil 2 µg/kg + tropisetron 10 mg) or the experimental treatment with additional esketamine (1.5 mg/kg). The primary outcome measured was the incidence of postpartum depression (PPD), classified by Edinburgh Postnatal Depression Scale (EPDS) scores equal to or greater than 13 indicating PPD. Secondary outcomes included cumulative sufentanil consumption during specific time periods (0-24 h, 24-48 h, and 0-48 h) after the surgical procedure and numerical rating scale (NRS) scores at rest and during movements. RESULTS: The final analysis included a total of 246 postpartum women who had undergone caesarean delivery. On postoperative day 42, the incidence of depression among the control group was 17.6%, which was significantly higher compared to the esketamine group with a rate of 8.2% (P = 0.02). The EPDS scores also showed a significant difference between the two groups, with a mean score of 9.02 ± 2.21 in the control group and 6.87 ± 2.14 in the esketamine group (p < 0.0001). In terms of pain management, the esketamine group showed lower sufentanil consumption in the 0-24 h (42.5 ± 4.58 µg vs. 50.15 ± 5.47 µg, P = 0.04) and 0-48 h (87.40 ± 9.51 µg vs. 95.10 ± 9.36 µg, P = 0.04) postoperative periods compared to the control group. Differences in movement were also observed between the two groups at 24 and 48 h after the cesarean Sect. (3.39 ± 1.57 vs. 4.50 ± 0.80, P = 0.02; 2.43 ± 0.87 vs. 3.56 ± 0.76, P = 0.02). It is worth noting that the frequency of side effects observed in both groups was comparable. CONCLUSIONS: Esketamine at a dose of 1.5 mg/kg, when used as a supplement in PCIA, has been shown to significantly reduce the occurrence of PPD within 42 days. Additionally, it has been found to decrease cumulative consumption of sufentanil over a 48-hour period following cesarean operation, all without increasing the rate of adverse effects. TRIAL REGISTRATION: Registered in the Chinese Clinical Trial Registry (ChiCTR2200067054) on December 26, 2022.

Navigating complexity: a comprehensive review of microcatheter shaping techniques in endovascular aneurysm embolization.

The endovascular intervention technique has gained prominence in the treatment of intracranial aneurysms due to its minimal invasiveness and shorter recovery time. A critical step of the intervention is the shaping of the microcatheter, which ensures its accurate placement and stability within the aneurysm sac. This is vital for enhancing coil placement and minimizing the risk of catheter kickback during the coiling process. Currently, microcatheter shaping is primarily reliant on the operator's experience, who shapes them based on the curvature of the target vessel and aneurysm location, utilizing 3D rotational angiography or CT angiography. Some researchers have documented their experiences with conventional shaping methods. Additionally, some scholars have explored auxiliary techniques such as 3D printing and computer simulations to facilitate microcatheter shaping. However, the shaping of microcatheters can still pose challenges, especially in cases with complex anatomical structures or very small aneurysms, and even experienced operators may encounter difficulties, and there has been a lack of a holistic summary of microcatheter shaping techniques in the literature. In this article, we present a review of the literature from 1994 to 2023 on microcatheter shaping techniques in endovascular aneurysm embolization. Our review aims to present a thorough overview of the various experiences and techniques shared by researchers over the last 3 decades, provides an analysis of shaping methods, and serves as an invaluable resource for both novice and experienced practitioners, highlighting the significance of understanding and mastering this technique for successful endovascular intervention in intracranial aneurysms.

Case Report: A novel heterozygous nonsense mutation in KRIT1 cause hereditary cerebral cavernous malformation.

Cerebral cavernous malformation (CCM) is a vascular malformation of the central nervous system and mainly characterized by enlarged capillary cavities without intervening brain parenchyma. Genetic studies have identified three disease-causing genes (CCM1/KRIT1, CCM2/MGC4607 and CCM3/PDCD10) responsible for CCM. Here, we characterized a four-generation family diagnosed with CCM and identified a novel heterozygous mutation c.1159C>T, p.Q387X in KRIT1 gene by whole exome sequencing and Sanger sequencing. The Q387X mutation resulted in premature termination of KRIT1 protein, which was predicted to be deleterious by the ACMG/AMP 2015 guideline. Our results provide novel genetic evidence support that KRIT1 mutations cause CCM, and are helpful to the treatment and genetic diagnosis of CCM.

Utility of low-profile visualized intraluminal support (LVIS™) stent for treatment of acutely ruptured bifurcation aneurysms: A single-center study.

Objective: Stent-assisted coiling has been increasingly used in the treatment of intracranial aneurysms. However, its application in ruptured bifurcation aneurysms remains controversial and challenging. This study aimed to present the safety and feasibility of low-profile visualized intraluminal support (LVIS™, LVIS, and LVIS Jr.) stent for acutely ruptured bifurcation aneurysms. Methods: A total of 41 patients with acutely ruptured intracranial aneurysms arising at the bifurcation were treated with LVIS™ stent-assisted coiling in our hospital between January 2017 and December 2021. The clinical data and angiographic results of the patients were analyzed. Results: Among these patients, all stents were successfully implanted. According to the immediate angiographic results, 29 aneurysms (70.7%) were completely occluded. Intraoperative thrombosis and hemorrhage occurred in two and one cases, respectively. No post-operative thrombosis or rebleeding events were observed. The clinical follow-up of all patients revealed that 38 (92.7%) cases had favorable outcomes (modified Rankin scale: 0-2). The angiographic results available for the 36 patients during the follow-up period revealed complete occlusion was achieved in 30 patients (83.3%) and residual neck in six patients. Conclusion: The LVIS™ stent-assistant coiling is a safe and feasible option for acutely ruptured bifurcation aneurysms. Further studies with a prospective design, a larger sample size, and long-term follow-up are needed to validate these findings.

Sacral Nerve Stimulation in Patients With Refractory Pudendal Neuralgia.

BACKGROUND: Pudendal neuralgia (PN) is one of the most common forms of genital pain. Only 42.2% of PN patients respond to the first-line treatment. Novel neuromodulation techniques in the treatment of refractory PN patients are urgently required. OBJECTIVES: The aim of this study was to evaluate the treatment effects and adverse events of sacral nerve stimulation (SNS) for patients with refractory PN. STUDY DESIGN: A prospective nonrandomized study. SETTING: This prospective analysis included 33 patients who received the phase II surgical implantation. METHODS: A total of 55 eligible PN patients were recruited for SNS treatment after informed consent, and 33 of 55 patients with a minimum 50% improvement were candidates for surgical implantation. Visual Analog Scale (VAS) scores, Self-rating Anxiety and Depression Scale, Quality of life score (SF-36), and sleep monitoring indicators before and after surgery were used to assess the effects of SNS on patients with refractory PN. RESULTS: Thirty-three patients were included in the final analysis, involving 24 women and 9 men with a mean age of 49.5 years (26-70 years). There was a favorable decrease in pain severity (VAS scores) from 7.1 ± 1.1 at baseline to 6.1 ± 1.0 on postoperative day 1, and 2.8 ± 0.7 at 1 week, 1.7 ± 0.5 at 1 month, 1.1 ± 0.7 at 6 months, and 1.0 ± 0.6 at 12 months after surgery, respectively (P < 0.05). The mean score of each section of SF-36 after SNS was significantly higher than that at baseline (P < 0.05). Total sleep time and sleep time in each period were significantly prolonged after SNS implantation compared with that before surgery (6 months vs Pre, total: 5.32 ± 1.49 hours vs 3.66 ± 1.19 hours, deep: 2.52 ± 0.63 hours vs 1.36 ± 0.43 hours, light: 1.78 ± 0.42 hours vs 0.99 ± 0.30 hours, rapid eye movement: 1.41 ± 0.29 hours vs 0.89 ± 0.27 hours, P < 0.05). No serious device complications were reported during the follow-up period. LIMITATIONS: Large-scale randomized clinical trials are warranted to evaluate the risk factors for prediction of refractory PN. CONCLUSIONS: These data imply that SNS can have beneficial effects on patients with refractory PN.

The immunometabolite S-2-hydroxyglutarate exacerbates perioperative ischemic brain injury and cognitive dysfunction by enhancing CD8+ T lymphocyte-mediated neurotoxicity.

BACKGROUND: Metabolic dysregulation and disruption of immune homeostasis have been widely associated with perioperative complications including perioperative ischemic stroke. Although immunometabolite S-2-hydroxyglutarate (S-2HG) is an emerging regulator of immune cells and thus triggers the immune response, it is unclear whether and how S-2HG elicits perioperative ischemic brain injury and exacerbates post-stroke cognitive dysfunction. METHODS: Perioperative ischemic stroke was induced by transient middle cerebral artery occlusion for 60 min in C57BL/6 mice 1 day after ileocecal resection. CD8+ T lymphocyte activation and invasion of the cerebrovascular compartment were measured using flow cytometry. Untargeted metabolomic profiling was performed to detect metabolic changes in sorted CD8+ T lymphocytes after ischemia. CD8+ T lymphocytes were transfected with lentivirus ex vivo to mobilize cell proliferation and differentiation before being transferred into recombination activating gene 1 (Rag1-/-) stroke mice. RESULTS: The perioperative stroke mice exhibit more severe cerebral ischemic injury and neurological dysfunction than the stroke-only mice. CD8+ T lymphocyte invasion of brain parenchyma and neurotoxicity augment cerebral ischemic injury in the perioperative stroke mice. CD8+ T lymphocyte depletion reverses exacerbated immune-mediated cerebral ischemic brain injury in perioperative stroke mice. Perioperative ischemic stroke triggers aberrant metabolic alterations in peripheral CD8+ T cells, in which S-2HG is more abundant. S-2HG alters CD8+ T lymphocyte proliferation and differentiation ex vivo and modulates the immune-mediated ischemic brain injury and post-stroke cognitive dysfunction by enhancing CD8+ T lymphocyte-mediated neurotoxicity. CONCLUSION: Our study establishes that S-2HG signaling-mediated activation and neurotoxicity of CD8+ T lymphocytes might exacerbate perioperative ischemic brain injury and may represent a promising immunotherapy target in perioperative ischemic stroke.

Correction to: Comparison of analgesic effect of oxycodone and morphine on patients with moderate and advanced cancer pain: a meta-analysis.

After publication of this article [1], the authors noted that the corresponding email address is incorrect.

Comparison of analgesic effect of oxycodone and morphine on patients with moderate and advanced cancer pain: a meta-analysis.

BACKGROUND: Morphine and oxycodone are considered as wide-spreadly used opioids for moderate/severe cancer pain. However, debate exists about the evidence regarding their relative tolerability and underlying results. METHODS: A systematic search of online electronic databases, including PubMed, Embase, Cochrane library updated on October 2017 were conducted. The meta-analysis was performed including the studies that were designed as randomized controlled trials. RESULTS: In total, seven randomized clinical trials met our inclusion criteria. No statistical differences in analgesic effect between oxycodone and morphine were observed. Both the pooled analysis of API (MD =0.01, 95% CI -0.22 - 0.23; p = 0.96) and WPI (MD = - 0.05, 95% CI -0.21 - 0.30; p = 0.72) demonstrated clinical non-inferiority of the efficacy of morphine compared with oxycodone, respectively. Additionally, no significant difference in PRR response was observed in either oxycodone or morphine that were used in patients (MD =0.99, 95% CI -0.88 - 1.11; p = 0.87). With the pooled result of AEs indicating the comparable safety profiles between the 2 treatment groups, the meta-analysis on the nausea (OR = 1.20, 95% CI 0.90-1.59; p = 0.22), vomiting (OR = 1.33, 95% CI 0.75-2.38; p = 0.33), somnolence (OR = 1.35, 95% CI 0.95-1.93; p = 0.10), diarrhea (OR = 1.01, 95% CI 0.60-1,67; p = 0.98), and constipation (OR = 1.04, 95% CI 0.77-1.41; p = 0.79) was conducted, respectively. CONCLUSIONS: In the current study, no remarkable difference was identified either in analgesic efficacy or in tolerability of oxycodone and morphine as the first-line therapy for patients with moderate to severe cancer pain. Thus, no sufficient clinical evidence on the superior effects of oxycodone to morphine was provided in this experimental hypothesis.

Solving Fourier ptychographic imaging problems via neural network modeling and TensorFlow.

Fourier ptychography is a recently developed imaging approach for large field-of-view and high-resolution microscopy. Here we model the Fourier ptychographic forward imaging process using a convolutional neural network (CNN) and recover the complex object information in a network training process. In this approach, the input of the network is the point spread function in the spatial domain or the coherent transfer function in the Fourier domain. The object is treated as 2D learnable weights of a convolutional or a multiplication layer. The output of the network is modeled as the loss function we aim to minimize. The batch size of the network corresponds to the number of captured low-resolution images in one forward/backward pass. We use a popular open-source machine learning library, TensorFlow, for setting up the network and conducting the optimization process. We analyze the performance of different learning rates, different solvers, and different batch sizes. It is shown that a large batch size with the Adam optimizer achieves the best performance in general. To accelerate the phase retrieval process, we also discuss a strategy to implement Fourier-magnitude projection using a multiplication neural network model. Since convolution and multiplication are the two most-common operations in imaging modeling, the reported approach may provide a new perspective to examine many coherent and incoherent systems. As a demonstration, we discuss the extensions of the reported networks for modeling single-pixel imaging and structured illumination microscopy (SIM). 4-frame resolution doubling is demonstrated using a neural network for SIM. The link between imaging systems and neural network modeling may enable the use of machine-learning hardware such as neural engine and tensor processing unit for accelerating the image reconstruction process. We have made our implementation code open-source for researchers.

Terapixel hyperspectral whole-slide imaging via slit-array detection and projection.

Digital pathology via whole-slide imaging (WSI) systems has recently been approved for the primary diagnostic use in the US. Acquiring whole-slide images with spectral information at each pixel permits the use of multiplexed antibody labeling and allow for the measurement of cellularly resolved chemical information. Here, we report the development of a high-throughput terapixel hyperspectral WSI system using prism-based slit-array dispersion. We demonstrate a slit-array detection scheme for absorption-based measurements and a slit-array projection scheme for fluorescence-based measurements. The spectral resolution and spectral range in the reported schemes can be adjusted by changing the orientation of the slit-array mask. We use our system to acquire 74 5-megapixel brightfield images at different wavelengths in ∼1 s, corresponding to a throughput of 0.375 gigapixels / s. A terapixel whole-slide spatial-spectral data cube can be obtained in ∼45 min. The reported system is compatible with existing WSI systems and can be developed as an add-on module for whole-slide spectral imaging. It may find broad applications in high-throughput chemical imaging with multiple antibody labeling. The use of slit array for structured illumination may also provide insights for developing high-throughput hyperspectral confocal imaging systems.

Transform- and multi-domain deep learning for single-frame rapid autofocusing in whole slide imaging.

A whole slide imaging (WSI) system has recently been approved for primary diagnostic use in the US. The image quality and system throughput of WSI is largely determined by the autofocusing process. Traditional approaches acquire multiple images along the optical axis and maximize a figure of merit for autofocusing. Here we explore the use of deep convolution neural networks (CNNs) to predict the focal position of the acquired image without axial scanning. We investigate the autofocusing performance with three illumination settings: incoherent Kohler illumination, partially coherent illumination with two plane waves, and one-plane-wave illumination. We acquire ~130,000 images with different defocus distances as the training data set. Different defocus distances lead to different spatial features of the captured images. However, solely relying on the spatial information leads to a relatively bad performance of the autofocusing process. It is better to extract defocus features from transform domains of the acquired image. For incoherent illumination, the Fourier cutoff frequency is directly related to the defocus distance. Similarly, autocorrelation peaks are directly related to the defocus distance for two-plane-wave illumination. In our implementation, we use the spatial image, the Fourier spectrum, the autocorrelation of the spatial image, and combinations thereof as the inputs for the CNNs. We show that the information from the transform domains can improve the performance and robustness of the autofocusing process. The resulting focusing error is ~0.5 µm, which is within the 0.8-µm depth-of-field range. The reported approach requires little hardware modification for conventional WSI systems and the images can be captured on the fly without focus map surveying. It may find applications in WSI and time-lapse microscopy. The transform- and multi-domain approaches may also provide new insights for developing microscopy-related deep-learning networks. We have made our training and testing data set (~12 GB) open-source for the broad research community.

13-fold resolution gain through turbid layer via translated unknown speckle illumination.

Fluorescence imaging through a turbid layer holds great promise for various biophotonics applications. Conventional wavefront shaping techniques aim to create and scan a focus spot through the turbid layer. Finding the correct input wavefront without direct access to the target plane remains a critical challenge. In this paper, we explore a new strategy for imaging through turbid layer with a large field of view. In our setup, a fluorescence sample is sandwiched between two turbid layers. Instead of generating one focus spot via wavefront shaping, we use an unshaped beam to illuminate the turbid layer and generate an unknown speckle pattern at the target plane over a wide field of view. By tilting the input wavefront, we raster scan the unknown speckle pattern via the memory effect and capture the corresponding low-resolution fluorescence images through the turbid layer. Different from the wavefront-shaping-based single-spot scanning, the proposed approach employs many spots (i.e., speckles) in parallel for extending the field of view. Based on all captured images, we jointly recover the fluorescence object, the unknown optical transfer function of the turbid layer, the translated step size, and the unknown speckle pattern. Without direct access to the object plane or knowledge of the turbid layer, we demonstrate a 13-fold resolution gain through the turbid layer using the reported strategy. We also demonstrate the use of this technique to improve the resolution of a low numerical aperture objective lens allowing to obtain both large field of view and high resolution at the same time. The reported method provides insight for developing new fluorescence imaging platforms and may find applications in deep-tissue imaging.

Dual light-emitting diode-based multichannel microscopy for whole-slide multiplane, multispectral and phase imaging.

We report the development of a multichannel microscopy for whole-slide multiplane, multispectral and phase imaging. We use trinocular heads to split the beam path into 6 independent channels and employ a camera array for parallel data acquisition, achieving a maximum data throughput of approximately 1 gigapixel per second. To perform single-frame rapid autofocusing, we place 2 near-infrared light-emitting diodes (LEDs) at the back focal plane of the condenser lens to illuminate the sample from 2 different incident angles. A hot mirror is used to direct the near-infrared light to an autofocusing camera. For multiplane whole-slide imaging (WSI), we acquire 6 different focal planes of a thick specimen simultaneously. For multispectral WSI, we relay the 6 independent image planes to the same focal position and simultaneously acquire information at 6 spectral bands. For whole-slide phase imaging, we acquire images at 3 focal positions simultaneously and use the transport-of-intensity equation to recover the phase information. We also provide an open-source design to further increase the number of channels from 6 to 15. The reported platform provides a simple solution for multiplexed fluorescence imaging and multimodal WSI. Acquiring an instant focal stack without z-scanning may also enable fast 3-dimensional dynamic tracking of various biological samples.

Rapid focus map surveying for whole slide imaging with continuous sample motion.

Whole slide imaging (WSI) has recently been cleared for primary diagnosis in the U.S. A critical challenge of WSI is to perform accurate focusing in high speed. Traditional systems create a focus map prior to scanning. For each focus point on the map, a sample needs to be static in the x-y plane, and axial scanning is needed to maximize the contrast. Here we report a novel focus map surveying method for WSI. In this method, we illuminate the sample with two LEDs and recover the focus points based on 1D autocorrelation analysis. The reported method requires no axial scanning, no additional camera and lens, works for stained and transparent samples, and allows continuous sample motion in the surveying process. By using a 20× objective lens, we demonstrate a mean focusing error of ∼0.08 µm in the static mode and ∼0.17 µm in the continuous motion mode. The reported method may provide a turnkey solution for most existing WSI systems due to its simplicity, robustness, accuracy, and high speed. It may also standardize the imaging performance of WSI systems for digital pathology and find other applications in high-content microscopy, such as time-lapse live-cell imaging.

Angular light modulator using optical blinds.

Spatial light modulator (SLM) is widely used in imaging applications for modulating light intensity and phase delay. In this paper, we report a novel device concept termed angular light modulator (ALM). Different from the SLM, the reported ALM employs a tunable blind structure to modulate the angular components of the incoming light waves. For spatial-domain light modulation, the ALM can be directly placed in front of an image sensor for selecting different angular light components. In this case, we can sweep the slat angle of the blind structure and capture multiple images corresponding to different perspectives. These images can then be back-projected for 3D tomographic refocusing. By using a fixed slat angle, we can also convert the incident-angle information into intensity variations for wavefront sensing or introduce a translational shift to the defocused object for high-speed autofocusing. For Fourier-domain light modulation, the ALM can be placed at the pupil plane of an optical system for reinforcing the light propagating trajectories. We show that a pupil-plane-modulated system is able to achieve a better resolution for out-of-focus objects while maintaining the same resolution for in-focus objects. The reported ALM can be fabricated on the chip level and controlled by an external magnetic field. It may provide new insights for developing novel imaging and vision devices.

Motion-corrected Fourier ptychography.

Fourier ptychography (FP) is a recently proposed computational imaging technique for high space-bandwidth product imaging. In real setups such as endoscope and transmission electron microscope, the common sample motion largely degrades the FP reconstruction and limits its practicability. In this paper, we propose a novel FP reconstruction method to efficiently correct for unknown sample motion. Specifically, we adaptively update the sample's Fourier spectrum from low spatial-frequency regions towards high spatial-frequency ones, with an additional motion recovery and phase-offset compensation procedure for each sub-spectrum. Benefiting from the phase retrieval redundancy theory, the required large overlap between adjacent sub-spectra offers an accurate guide for successful motion recovery. Experimental results on both simulated data and real captured data show that the proposed method can correct for unknown sample motion with its standard deviation being up to 10% of the field-of-view scale. We have released our source code for non-commercial use, and it may find wide applications in related FP platforms such as endoscopy and transmission electron microscopy.