Contrast Imaging Research Articles

Neuromuscular Electrostimulation Increases Microcirculatory Flux in Mixed Etiology Leg Ulcers.

To determine if intermittent neuromuscular electrostimulation (NMES) of the common peroneal nerve increases microvascular flow and pulsatility in and around the wound bed of patients with combined venous and arterial etiology. Seven consenting participants presenting with mixed etiology leg ulcers participated in this study. Microvascular flow and pulsatility was measured in the wound bed and in the skin surrounding the wound using laser speckle contrast imaging. Measurements were made at baseline and when the venous pumps of the leg were activated by 1 Hz intermittent neuromuscular stimulation of the common peroneal nerve. The nerve was stimulated transdermally at the head of the fibula. When activated by NMES, wound bed flux increased by 38% (95% CI, 11%-73%; P = .023), and periwound flux increased by 19% (95% CI, 9%-32%; P = .009). Pulsatility increased in the wound bed by 214% (95% CI, 51%-985%; P = .017) and in the periwound by 122% (95% CI, 38%-299%; P = .014). The results indicate that NMES is effective in augmenting microvascular flow in leg ulcers with combined venous and arterial etiology.

Expression of Plasma Levels of miRNA-181b and miRNA-21 in Patients With Abdominal Aortic Aneurysms and Their Effect on Clinical Outcome After Endovascular Treatment.

Abdominal aortic aneurysms (AAA) are major causes of morbidity and mortality in the elderly population. Endovascular aneurysm repair (EVAR) is associated with lower complications rates than conventional treatment; however, rigorous follow-up with contrast imaging is required to confirm aneurysmal sac exclusion. The main objective of this study was to quantify and evaluate miRNA expression response to EVAR based on serum dosages at the 6-month follow-up. 47 patients with indication for EVAR were recruited and 10 patients without comorbidities. miRNA-181b and miRNA-21 were selected for this study and their serum dosages were measured at two time points: preoperatively and after 6 months of follow-up, and only once in the control group. Demographic profiles, clinical follow-ups, and imaging examinations with angiotomography performed preoperatively and after 6 months were collected. Overexpression of miRNA-181b and miRNA-21 was observed in the whole blood of patients with AAA. EVAR of patients with AAA resulted in decreased expression of the studied miRNAs, indicating that exclusion of the aneurysmal sac alters the expression of these markers. In addition, the expressions of miRNAs did not correlate with endoleaks or the diameter of the aneurysm or with the different types of devices used for the EVAR. The overexpression of miRNA-181b, miRNA-21 with its reduction after EVAR, may suggest the use of these molecules as potential biomarkers in the follow-up of these patients. However, miRNAs were not able to identify possible endoleaks or discriminate them into subtypes. The clinical application of the use of biomarkers in other areas such as oncology is already well established. In endovascular surgery it is still incipient although with great potential in daily practice, in order to anticipate or schedule possible interventions in patients with endoleak. In addition, understand the mechanisms of action of miRNAs in Atherosclerotic diseases and aortic syndromes could provide a better understanding of the pathophysiology as well as pharmacological development for AAA prevention as well as remodeling of the aneurysm sac after EVAR.

State-dependent neurovascular modulation induced by transcranial ultrasound stimulation.

Previous studies reported baseline state-dependent effects on neural and hemodynamic responses to transcranial ultrasound stimulation. However, due to neurovascular coupling, neither neural nor hemodynamic baseline alone can fully explain the ultrasound-induced responses. In this study, using a general linear model, we aimed to investigate the roles of both neural and hemodynamic baseline status as well as their interactions in ultrasound-induced responses. Thirty Sprague-Dawley rats were randomly assigned to Hypoxia, Hyperoxia, and Normoxia groups. The baseline states were altered by changing the oxygen concentrations. Micro-electrode and laser speckle contrast imaging were used to record local field potentials and cerebral blood flow during resting, before, and after ultrasound stimulation, respectively. We found that baseline neural activity played a positive role in neural response (Coefficient = 0.634, t = 1.748, p = 0.096, = 0.133), but a negative role in hemodynamic response (Coefficient = 0.060, t = 1.996, p = 0.060, = 0.166). Baseline hemodynamic activity also had a significantly negative correlation with the hemodynamic response (Coefficient = 0.760, t = 3.947, p 0.001, = 0.438). This study enriched our understanding of state-dependent effects underlying the neurovascular activation by ultrasound stimulation.

Programmable scanning diffuse speckle contrast imaging of cerebral blood flow.

Cerebral blood flow (CBF) imaging is crucial for diagnosing cerebrovascular diseases. However, existing large neuroimaging techniques with high cost, low sampling rate, and poor mobility make them unsuitable for continuous and longitudinal CBF monitoring at the bedside. We aimed to develop a low-cost, portable, programmable scanning diffuse speckle contrast imaging (PS-DSCI) technology for fast, high-density, and depth-sensitive imaging of CBF in rodents. The PS-DSCI employed a programmable digital micromirror device (DMD) for remote line-shaped laser (785nm) scanning on tissue surface and synchronized a 2D camera for capturing boundary diffuse laser speckle contrasts. New algorithms were developed to address deformations of line-shaped scanning, thus minimizing CBF reconstruction artifacts. The PS-DSCI was examined in head-simulating phantoms and adult mice. The PS-DSCI enables resolving intralipid particle flow contrasts at different tissue depths. In vivo experiments in adult mice demonstrated the capability of PS-DSCI to image global/regional CBF variations induced by 8% inhalation and transient carotid artery ligations. Compared with conventional point scanning, line scanning in PS-DSCI significantly increases spatiotemporal resolution. The high sampling rate of PS-DSCI is crucial for capturing rapid CBF changes while high spatial resolution is important for visualizing brain vasculature.

Validation of UniverSeg for Interventional Abdominal Angiographic Segmentation.

Automatic segmentation of angiographic structures can aid in assessing vascular disease. While recent deep learning models promise automation, they lack validation on interventional angiographic data. This study investigates the feasibility of angiographic segmentation using in-context learning with the UniverSeg model, which is a cross-learning segmentation model that lacks inherent angiographic training. A retrospective review, after IRB approval, identified 234 patients who underwent interventional fluoroscopy of the celiac axis with iodinated contrast from January 1, 2019, to December 31, 2022. From 261 acquisitions, 303 maximum contrast images were selected, each generating a 128 × 128 pixel partition for arterial detail analysis and binary mask creation. Image-mask pairs were divided into three classes of 101 pairs each, based on arterial diameter and bifurcation number. UniverSeg was tested class independently in a fivefold nested cross-validation. Performance analysis for in-context learning determined average model convergence for class sizes from 1 to 81 pairs. The model was further validated by repeating the tests on the inverse segmentation task. Dice similarity coefficients for decreasing diameters were 78.7%, 72.5%, and 59.9% (σ = 5.96, 7.99, 14.29). Balanced average Hausdorff distances were 0.86, 0.71, and 1.16 (σ = 0.37, 0.52, 0.68) pixels, respectively. Inverted mask testing aligned with UniverSeg expectations for out-of-context problem sets. Performance improved with support class size, vessel diameter, and reduced bifurcations, plateauing to within ± 1.34 Dice score at N = 51. This study validates UniverSeg for arterial segmentation in interventional fluoroscopic procedures, supporting vascular disease modeling and imaging research.

Terahertz Multicolor Imaging of Opaque Objects Using Self-Mixing Interferometry with Quantum-Cascade Lasers

Self-mixing interference in a terahertz quantum-cascade laser has been demonstrated to be suitable for the detection of weak signals scattered or reflected by the target. This technology has achieved the high-sensitivity detection of complex refractive indices, surface/interface morphologies and molecular feature spectra. Here, a set of terahertz quantum-cascade lasers with different lasing frequencies is used to inspect a tiny amount of powder concealed inside a polytetrafluoroethylene tablet by using self-mixing interferometry combined with the penetration properties of terahertz waves. Multicolor spectral images were acquired, which were synthesized by absorption contrast images obtained at different lasing frequencies. They enable the detection of the spatial distribution of hidden objects which are totally opaque in visual light and allow for them to be identified with spectral absorption characteristics. Self-mixing interference technology can also obtain phase information when a terahertz wave interacts with a tablet, showing the difference between the hidden object and surroundings from another dimension. Our research may provide a strategy for the development of terahertz multispectral imaging technology for the inspection of hidden trace residues.

Evaluation value of contrast enhanced ultrasound quantitative parameters in ischemic-type biliary lesions after liver transplantation-a prospectively study.

To explore the evaluation value of contrast enhanced ultrasound (CEUS) quantitative parameters in ischemic-type biliary lesions after liver transplantation to assist its early-diagnosis. Patients who underwent liver transplantation and intravenous CEUS at Beijing Friendship Hospital, Capital Medical University from June 25, 2020 to December 28, 2022 and were diagnosed with Ischemic-type biliary lesions (ITBLs) by Magnetic Resonance Cholangiopancreatography (MRCP) or Endoscopic Retrograde Cholangiopancreatography (ERCP) or Percutaneous Transhepatic Cholangiography (PTC) were prospectively enrolled. SonoLiver software was used to quantitatively analyze the contrast images, transplanted livers with normal biliary tracts as the control group. SPSS 25.0 software was used to analyze the data. There was a total of 35 patients enrolled in the study, and 15 ITBLs and 30 normal biliary tract of transplanted livers, respectively. The dynamic vascular patterns (DVP) curve of the ITBLs group was negative wave, while the DVP curve of the normal biliary tract group was positive wave. Compared with the patients with normal biliary tract, the Maximum intensity (IMAX), Rise slope 50% (Rs50), Area under curve (AUC), Area under curve in Wash-in phase (WinAUC), Wash in Rate (WinR), Rise slope 10-90% (Rs1090), and Wash out Rate (WouR) of the ITBLs group were lower, while the Fall slope (Fs50) was higher. There was no significant difference in Rise time (RT), Time to Peak (TTP), Fall half time (FHT), Mean transit time (mTT), Fall time (FT), WioAUC ((WioAUC = WinAUC + WouAUC)), and Area under curve in Wash-out phase (WouAUC) between the two groups (P > 0.05). The ROC curve results showed that Fs50 > -2.64 was the cutoff value for predicting ITBLs, with an area under the curve of 0.816 (95%CI: 0.683-0.949), and a sensitivity and specificity of 0.846 and 0.607; Rs50 < 7.08, AUC < 39761.7050, WinR < 101.7 and WouR < 474.52 were the cutoff values ​​for predicting ITBLs, with areas under the curve of 0.853 (95%CI: 0.728-0.979), 0.911 (95%CI: 0.783-1.000), 0.756 (95%CI: 0.615-0.896) and 0.700 (95%CI: 0.536-0.864). The quantitative parameters of CEUS imaging, such as IMAX, Rs50, AUC, WinAUC, WinR, Rs1090, WouR, and Fs50, are helpful in predicting ITBLs and improving the reproducibility of diagnosis. The threshold of these quantitative parameters will aid in the early diagnosis of ischemic-type biliary lesions after liver transplantation.

Efficient X-ray dark field contrast simulations using a condensed history approach.

Due to the growing interest in X-ray phase contrast imaging (XPCI), the development of XPCI simulators has become an active field of research. Efficient computer simulations are a prime tool for optimizing the XPCI setup and acquisition process. In addition to phase contrast, modern XPCI setups provide insight into the unresolvable sample micro structure distribution through the dark field signal. However, to accurately simulate XPCI dark field signals, the virtual sample model should contain many fine structures, considerably increasing the simulation time. Moreover, accurately modeling micro structure distributions is challenging and the micro structure distribution of one virtual sample cannot be easily transferred to another. In this work, we apply a condensed history approach to dark field simulations, removing the need to explicitly model the micro structures in the virtual sample. Instead, a tunable dark field material parameter, representing a measure of the material micro structure distribution, is attached to the sample. The condensed history simulation model offers a substantial increase in simulation speed and the dark field material parameter is easily transferable between samples. The implementation is validated using the edge illumination XPCI setup. Condensed history simulations are compared to real data, showing good agreement, and the simulation speed increase is presented for increasing sample thickness and field of view. The simulation model is shown to remain valid even for thick samples. Simulated computed tomography data sets, with and without explicit micro structure, are favorably compared to each other.

Automatic visual detection of activated sludge microorganisms based on microscopic phase contrast image optimisation and deep learning.

The types and quantities of microorganisms in activated sludge are directly related to the stability and efficiency of sewage treatment systems. This paper proposes a sludge microorganism detection method based on microscopic phase contrast image optimisation and deep learning. Firstly, a dataset containing eight types of microorganisms is constructed, and an augmentation strategy based on single and multisamples processing is designed to address the issues of sample deficiency and uneven distribution. Secondly, a phase contrast image quality optimisation algorithm based on fused variance is proposed, which can effectively improve the standard deviation, entropy, and detection performance. Thirdly, a lightweight YOLOv8n-SimAM model is designed, which introduces a SimAM attention module to suppress the complex background interference and enhance attentions to the target objects. The lightweight of the network is realised using a detection head based on multiscale information fusion convolutional module. In addition, a new loss function IW-IoU is proposed to improve the generalisation ability and overall performance. Comparative and ablative experiments are conducted, demonstrating the great application potential for rapid and accurate detection of microbial targets. Compared to the baseline model, the proposed method improves the detection accuracy by 12.35% and hastens the running speed by 37.9 frames per second while evidently reducing the model size.

A Systematic Review of Indocyanine Green Lymphography (ICGL) Imaging for the Diagnosis of Primary Lymphoedema.

This systematic review aims to evaluate the use of Indocyanine Green Lymphography (ICGL) for the investigation of the lymphatics in the lower limbs of primary lymphoedema patients. MEDLINE and EMBASE articles from 01/01/2000 to 01/09/2023 were searched for. A total of 11 studies were included in the review after a two-stage screening process. Data on patient demographics, ICG contrast injection technique, imaging protocols and imaging outcomes were summarised and reviewed in detail. The review highlights the lack of commonality in protocols used. Factors important for good imaging are highly variable, particularly the number of injections, their location and whether they are delivered intradermally or subcutaneously. ICGL has strong potential to become a diagnostic tool to diagnose lymphoedema, due to its non-ionising nature and cost-effectiveness. However due to the lack of thorough phenotyping and genotyping of patients included in the studies, uncertainty still exists as to the value of the described imaging features such as splash, starburst and diffuse dermal rerouting patterns. Future studies, therefore, should aim to explore the diagnostic utility of ICGL for lymphoedema further through the imaging of primary lymphoedema patients with a confirmed genetic diagnosis and using standardised imaging protocols. ICGL is a strong candidate for advancing the diagnosis and understanding of primary lymphoedema, and monitoring response to treatment, but protocol heterogeneity and a lack of consistency in reporting imaging details and patient phenotyping currently hold it back.

Mapping Sentinel Vessels in Uveal Melanomas Using Laser Speckle Contrast Imaging

Introduction: Sentinel vessels provide an important early indication of underlying ocular neoplasm. To date, there is no non-invasive technique available for imaging and mapping of their vascular supply, which remains largely unstudied. We aimed to map sentinel vessels in uveal melanomas non-invasively by laser speckle contrast imaging (LSCI). Case presentations: This report describes a case series of four patients undergoing enucleation due to uveal melanoma. Perfusion was imaged using LSCI during the successive detachment of the four rectus muscles, with their ciliary arteries, and the optic nerve with its ophthalmic artery. Tumor location and possible extrascleral growth were analyzed histopathologically. Results: Sentinel vessels in uveal melanoma could be visualized non-invasively using LSCI, appearing broader and tortuous compared to surrounding vessels. The perfusion in the sentinel vessels was 24-94% higher than in the episcleral vessels. The origin of the sentinel vessel could be determined by perfusion monitoring during the successive detachment of the rectus muscles and the optic nerve. In three patients the sentinel vessel was supplied by the anterior ciliary arteries, and in one patient by the ophthalmic artery. In one of the cases, the sentinel vessel was not visible upon visual inspection. Conclusion: This is the first study of its kind demonstrating detailed mapping of sentinel vessels in uveal melanoma using LSCI. LSCI shows potential for the detection of sentinel vessels before they are visible in slit lamp examination. Vascular changes are a hallmark of tumor growth, and non-invasive imaging with LSCI may be a useful diagnostic tool for the detection of uveal melanoma.

Log subtracted inversion recovery.

Magnetic resonance imaging (MRI) techniques have recently been developed for obtaining high T1 contrast images using inversion recovery (IR) images at two inversion times (TIs) rather than a single TI. They use simple mathematical operations - multiplication, addition, subtraction, division - to create images not attainable by conventional IR. The present study describes a novel two-point IR technique formed by the subtraction of log images. Results show it has a near-linear response to T1 between the nullpoints that peaks sharply at the nullpoints. This produces a bright isoT1 contour at interfaces between tissues where partial volume mixing generates specific T1s. This can provide anatomical information in areas where the signal is not well-differentiated on conventional images.

Neuroprotective effects of hypidone hydrochloride (YL-0919) after traumatic brain injury in mice.

Neurological dysfunction is a common complication of traumatic brain injury (TBI), and early treatments are critical for the long-term prognosis. This study aimed to investigate whether hypidone hydrochloride (YL-0919) improves neurological function impairment in mice with TBI. TBI was induced in adult male C57BL/6J mice using the controlled cortical impact (CCI) method. First, the modified neurological severity score (mNSS), rotarod test, and Morris water maze (MWM) test were conducted to assess the impact of YL-0919 on neurological function in mice with TBI. Next, immunofluorescence and laser speckle contrast imaging were utilized to measure the number and activation of microglia and cerebral blood flow (CBF) after TBI. Enzyme-linked immunosorbent assays (ELISAs) were employed to assess the inflammatory factors. Finally, Western blotting was performed to measure the expression of proteins. Golgi-Cox staining was utilized to investigate the structure of pyramidal neurons. YL-0919significantly alleviated neurological dysfunction in TBI+YL-0919mice compared with TBI+Vehicle mice, increased the time spent on the rotarod (F=1.297, P <0.05), and partially relieved cognitive dysfunction in TBI mice (for mNSS, F=5.540, P <0.01; for MWM test, F=30.78, P <0.05). Additionally, YL-0919 effectively inhibited the proliferation and activation of microglia (both P<0.01), promoted the recovery of CBF around the brain injury site and inhibited the expression of tumor necrosis factor-α (F=9.142, P <0.05) and IL-1β (F=4.662, P <0.05), and increased the concentration of IL-4 (F=5.172, P <0.05). Furthermore, continuous gavage of YL-0919 (2.5mg/kg) for seven days effectively increased the protein expression of brain-derived neurotrophic factor (BDNF), promoted the phosphorylation of mammalian target of rapamycin (mTOR), increased postsynaptic density protein 95 (PSD95) and synapsin1 levels, and increased the neuronal dendritic complexity and the dendritic spine density around the brain injury site (all P <0.05). Our findings indicated that YL-0919 can ameliorate neurological dysfunction in mice after TBI through the suppression of inflammation and the stimulation of the BDNF-mTOR signaling pathway. These findings provide an insightful perspective on the potential pharmacological mechanism involved in the neuroprotective effect of YL-0919.

Estimation of Dislocation Densities With Nondestructive Scanning Electron Microscope Techniques: Application to Gallium Nitride.

Characterizing threading dislocations (TDs) in gallium nitride (GaN) semiconductors is crucial for ensuring the reliability of semiconductor devices. The current research addresses this issue by combining two techniques using a scanning electron microscope, namely electron channeling contrast imaging (ECCI) and high-resolution electron backscattered diffraction (HR-EBSD). It is a comparative study of these techniques to underscore how they perform in the evaluation of TD densities in GaN epitaxial layers. Experiments reveal that the dislocation line vectors mostly deviate from the growth direction of the film, i.e., ∦ [0001], followed by edge-type dislocations (dislocation lines || [0001]) with insignificant screw character. Furthermore, TDs from the dislocation clusters are characterized as edge- and (edge + mixed)-type TDs. By combining ECCI counting of dislocations and HR-EBSD description of geometrically necessary dislocation density type, it is possible to measure the total TD density and provide the proportion of pure (edge and screw) and mixed TDs. It has also been observed from the analyses of residual elastic strain fields and lattice rotations that it is not possible to identify individual dislocations for the spatial resolution of 50 nm in HR-EBSD. Nevertheless, ECCI and HR-EBSD can be complementarily used to count and characterize the TDs.

Information merging and reconstruction of single-shot dual-mode wide-field imaging with high spatial resolution

In many scenarios, it is really desirable but challenging for wide-field imaging to gather both the clear morphologies and fine details of the target. This paper realizes this imaging by a dual-mode imaging on optical parametric amplification (OPA) with a vortex laser pump. This design includes signal imaging and idler imaging, which have complementary point spread functions with each other. The signal acts as bright-field imaging to record morphologic information, whereas the idler does so for spiral phase contrast imaging to capture the featured details with high brightness and contrast, which has been experimentally confirmed with a target of herb tissue. By utilizing the coupling relation among the pump, signal, and idler, the information from the recorded signal and idler images can be merged, which allows us to reconstruct the target picture owning both high-contrast morphologies and high-brightness fine details. Due to high OPA gain, our imaging can work with weak illumination. Its field-of-view covers an area of 0.33 × 0.33 mm2 with a spatial resolution up to 228 lp/mm. This OPA imaging also provides an effective way for the imaging required nonlinear frequency conversion.

Rnd3 Ameliorates Diabetic Cardiac Microvascular Injury via Facilitating Trim40-mediated Rock1 Ubiquitination.

Diabetic microvascular dysfunction is evidenced by disrupted endothelial cell junctions and increased microvascular permeability. However, effective strategies against these injuries remain scarce. In this study, the type 2 diabetes mouse model was established by high-fat diet combined with streptozotocin injection in Rnd3 endothelial- specific transgenic and knockout mice. Echocardiography was employed to evaluate cardiac function. Microvascular corrosion casts, lanthanum nitrate perfusion, trans- endothelial electrical resistance, FITC-dextran permeability assay and laser speckle contrast imaging were performed to evaluate the integrity of endothelial cell junctions and microvascular function. RNA sequencing, mass spectrometry, co-immunoprecipitation, immunofluorescence and molecular docking were used to explore the downstream regulators of Rnd3. Evidence from gain/loss-of-function studies denoted a protective role for Rnd3 against microvascular dysfunction in diabetic heart. Endothelial-specific deletion of Rnd3 significantly exacerbated coronary microvascular barrier dysfunction under diabetic conditions, while Rnd3 overexpression effectively prevented these effects. Furthermore, Rnd3 overexpression also attenuated cardiac dysfunction in diabetic mice, as indicated by increased LVEF, LVFS, and E/A ratio. Rnd3 overexpression inhibited CMECs apoptosis and increased CMECs migration in response to HG-PA challenge. Rnd3 overexpression inhibited Rock1 activity and MLC phosphorylation in CMECs treated with HG-PA stimulus. Mechanically, Rnd3 recruited and interacted with the E3 ubiquitin ligase Trim40 which further facilitated the degradation of Rock1, thus inhibiting endothelial barrier hyperpermeability in HG-PA-stimulated CMECs. However, the cardioprotective effects of Rnd3 were largely abrogated by Trim40 deficiency in diabetic conditions. Collectively, Rnd3 alleviates microvascular hyperpermeability, maintains endothelial barrier integrity, and mitigates cardiac dysfunction by regulating the Rock1/MLC signaling pathway in the state of DCM.

Prediction of post-contrast acute kidney injury by bedside ultrasonography

BackgroundThe incidence of contrast-induced acute kidney injury (CI-AKI) in the general population ranges from 0.6 to 2.3%, whereas for specific high-risk patients, the incidence can reach more than 30–40%. Ultrasound measurements of the development of CI-AKI after contrast-enhanced imaging for diagnosis in the emergency department (ED) have yet to be adequately studied. Accordingly, we aimed to evaluate the usefulness of Doppler ultrasound measurements for predicting CI-AKI in patients with normal renal function.MethodsThis prospective, observational, single-center study was conducted in the ED of a tertiary teaching and research hospital between 1 January and 1 July 2024. All patients who presented to the tertiary training and research hospital ED, who were admitted to the hospital with a decision to undergo contrast-enhanced tomography for diagnosis, and who did not meet any exclusion criteria were included in the study. Patients included in the study were evaluated by ultrasonographic measurements (interlobar renal artery peak systolic velocity (PSV), interlobar renal artery end-diastolic velocity (EDV), inferior vena cava (IVC) collapsibility index, and renal resistive index (RRI)).ResultsThe postcontrast RRI cutoff values were calculated to predict CI-AKI. The area under the curve (AUC) for the postcontrast RRI was 0.914, and the cutoff value for the postcontrast RRI was 0.70 (≥), exhibiting 72.7% sensitivity and 95.6% specificity.ConclusionPostcontrast RRI ultrasound measurements performed after diagnostic contrast imaging in the ED show high specificity in predicting CI-AKI development. Postcontrast ultrasound measurements may predict CI-AKI development, allowing further measures to be taken. Further studies are needed to confirm these findings.Trial registrationClinical trial number: not applicable.

Targeting mutant p53: Evaluation of novel anti-p53R175H monoclonal antibodies as diagnostic tools.

About 50% of all cancers carry a mutation in p53 that impairs its tumor suppressor function. The p53 missense mutation p53R175H (p53R172H in mice) is a hotspot mutation in various cancer types. Therefore, monoclonal antibodies selectively targeting clinically relevant mutations like p53R175H could prove immensely value. We aimed to evaluate the in vitro and in vivo binding properties of two novel anti-p53R175H monoclonal antibodies and to assess their performance as agents for molecular imaging. In vitro, 125I-4H5 and 125I-7B9 demonstrated long shelf life and antigen-specific binding. Our in vivo study design allowed head-to-head comparison of the antibodies in a double tumor model using repeated SPECT/CT imaging, followed by biodistribution and autoradiography. Both tracers performed similarly, with marginally faster blood clearance for 125I-7B9. Repeated molecular imaging demonstrated suitable imaging characteristics for both antibodies, with the best contrast images occurring at 48h post-injection. Significantly higher uptake was detected in the mut-p53-expressing tumors, confirmed by ex vivo autoradiography. We conclude that molecular imaging with an anti-p53R175H tracer could be a promising approach for cancer diagnostics and could be further applied for patient stratification and treatment response monitoring of mutant p53-targeted therapeutics.

Emergence of a contrast-invariant representation of naturalistic texture in macaque visual cortex.

Single neurons in visual cortex respond selectively to multiple stimulus dimensions, so signals from single neurons cannot distinguish changes in one dimension from changes in another. We measured responses from simultaneously recorded neural populations in three hierarchically linked visual areas - V1, V2, and V4 - using texture stimuli that varied in two dimensions, contrast and naturalistic image structure. We used linear decoding methods to extract information about each dimension. In all three areas, contrast could be decoded independently of image structure. Only in V4, however, could image structure be decoded independently of contrast. The reason is that selectivity for texture and contrast in V4 was much more diverse than in V1 or V2. This heterogeneity allows V4 to faithfully represent naturalistic image structure independent of contrast.

Simulation Study of Low-Dose 4D-STEM Phase Contrast Techniques at the Nanoscale in SEM.

Phase contrast imaging is well-suited for studying weakly scattering samples. Its strength lies in its ability to measure how the phase of the electron beam is affected by the sample, even when other imaging techniques yield low contrast. In this study, we explore via simulations two phase contrast techniques: integrated center of mass (iCOM) and ptychography, specifically using the extended ptychographical iterative engine (ePIE). We simulate the four-dimensional scanning transmission electron microscopy (4D-STEM) datasets for specific parameters corresponding to a scanning electron microscope (SEM) with an immersive objective and a given pixelated detector. The performance of these phase contrast techniques is analyzed using a contrast transfer function. Simulated datasets from a sample consisting of graphene sheets and carbon nanotubes are used for iCOM and ePIE reconstructions for two aperture sizes and two electron doses. We highlight the influence of aperture size, showing that for a smaller aperture, the radiation dose is spent mostly on larger sample features, which may aid in imaging sensitive samples while minimizing radiation damage.