Average Contrast Research Articles

Impact of iodinated contrast shortage on contrast-associated acute kidney injury: a single center experience

Background In March 2022, a COVID-19 outbreak disrupted the global supply of iodine contrast media (ICM). Healthcare systems implemented contrast-saving strategies to maintain their remaining ICM supplies. This study sought to determine the impact of contrast shortage on the incidence of contrast-associated acute kidney injury (CA-AKI). Methods This was a retrospective study of 265 patients undergoing 278 percutaneous coronary interventions (PCI) during 4-month periods prior to (9/1/2021 to 12/31/2021) and during (5/1/2022 to 8/31/2022) contrast shortage at a single center. The primary endpoint was the incidence of CA-AKI between study periods. Results A total of 148 and 130 PCIs were performed before and during contrast shortage, respectively. The incidence of CA-AKI significantly decreased from 11.5% to 4.6% during contrast shortage (P = 0.04). During the shortage, average contrast volume per PCI was significantly lower (123 ± 62 mL vs 88 ± 46 mL, P < 0.001), while coronary imaging was significantly higher (34.3% vs 50%, P = 0.009) compared to preshortage. All-cause mortality at discharge was comparable between study periods (2.8% vs 3.3%, respectively; P = 0.90). Conclusion The scarcity of ICM for PCI procedures in this single-center experience was associated with a significant increase in the utilization of intravascular imaging and a significant reduction in CA-AKI.

An Improved 3D OPC Method for the Fabrication of High-Fidelity Micro Fresnel Lenses.

Based on three-dimensional optical proximity correction (3D OPC), recent advancements in 3D lithography have enabled the high-fidelity customization of 3D micro-optical elements. However, the micron-to-millimeter-scale structures represented by the Fresnel lens design bring more stringent requirements for 3D OPC, which poses significant challenges to the accuracy of models and the efficiency of algorithms. Thus, a lithographic model based on optical imaging and photochemical reaction curves is developed in this paper, and a subdomain division method with a statistics principle is proposed to improve the efficiency and accuracy of 3D OPC. Both the simulation and the experimental results show the superiority of the proposed 3D OPC method in the fabrication of Fresnel lenses. The computation memory requirements of the 3D OPC are reduced to below 1%, and the profile error of the fabricated Fresnel lens is reduced 79.98%. Applying the Fresnel lenses to an imaging system, the average peak signal to noise ratio (PSNR) of the image is increased by 18.92%, and the average contrast of the image is enhanced by 36%. We believe that the proposed 3D OPC method can be extended to the fabrication of vision-correcting ophthalmological lenses.

Interferometric apodization by homothety – II. Experimental validation

ABSTRACT This work presents the results of experimental laboratory tests on the apodization of circular and rectangular apertures using the Interferometric Apodization by Homothety (IAH) technique. The IAH approach involves splitting the amplitude of the instrumental PSF into two equal parts. One of the two produced PSFs undergoes homothety to change its transverse dimensions while its amplitude is properly controlled. The two PSFs are then combined to produce an apodized image. The diffraction wings of the resulting PSF are subsequently reduced by some variable reduction factor, depending on an amplitude parameter γ and a spread parameter η. This apodization approach was implemented in the laboratory using an interferometric set-up based on the Mach–Zehnder Interferometer (MZI). The experimental results exhibit a strong agreement between theory and experiment. For instance, the average experimental contrast obtained at a low angular separation of 2.4λ/D does not exceed 5 × 10−4. This work also allowed us to study the influence on the apodizer’s performance of some parameters, such as the wavelength and the density of the neutral filters.

Fire identification based on improved multi feature fusion of YCbCr and regional growth

Fire is one of the mutable hazards that damage properties and destroy forests. However, fire-like objects easily influence many existing image-based fire detection methods. In order to improve the performance of fire identification, this paper proposes a new fire identification algorithm by merging fire segmentation and multi feature fusion of fire. First, the improved YCbCr models in the reflection and non-reflection environment are constructed according to the color model. Simultaneously, the reflection and non-reflection conditions can be judged according to the segmented area. Second, the seed points are determined according to the weighted average of centroid of each connected region. Simultaneously, the fine segmentation of fire image is implemented according to the entropy of average contrast and uniformity within the connected region. Experiments show that the segmentation is not affected by image noises. Finally, the quantitative indicators of fire identification are given according to the coefficient of variation of area, the dispersion of centroid and the circularity. Cases show that the proposed identification method of fire not only accurately identifies fire, but also has a lower computation complexity than the deep learning method.

DDEL-11. FOCUSED ULTRASOUND-MEDIATED DELIVERY OF ANTI-PROGRAMMED CELL DEATH-LIGAND 1 ANTIBODY TO THE BRAIN OF A PORCINE MODEL

Abstract Focused ultrasound-combined with microbubble-mediated blood-brain barrier opening (FUS-BBBO) has been established as a promising brain drug delivery technology for the treatment of brain tumors. Immune checkpoint inhibitor therapy is a form of cancer immunotherapy that has revolutionized the treatment of cancer and shown remarkable efficacy in a range of cancers. Previous studies reported successful delivery of a checkpoint inhibitor anti-PD-L1 antibody (aPD-L1) by FUS-BBBO in the mouse brain. The objective of this study was to evaluate the feasibility and safety of FUS-BBBO in the delivery of aDP-L1 to the brain of a large animal model. Pigs (4 weeks old, male, n=3) were used as the large animal model. A FUS transducer (frequency of 650 kHz, aperture of 65 mm, and a focal length of 65 mm) was used to sonicate three different brain regions in the presence of systemically injected microbubbles (Definity) for every pig. Near-infrared fluorescent dye-labeled aPD-L1 was injected intravenously to the pig after FUS sonication. Contrast-enhanced MRI was conducted to evaluate the BBB permeability. Pig brains were then harvested and imaged by the Licor Pear imaging system. Successful BBBO was confirmed by in vivo T1-weighted MR imaging. The average MR contrast enhancement volume in the FUS-targeted regions was 4.8× of that in the contralateral non-targeted regions. Ex vivo fluorescence imaging found that FUS sonication enhanced aPD-L1 delivery by 2.1× compared with the non-targeted regions. Histological analysis by hematoxylin and eosin (H&amp;E) staining did not find evidence for tissue damage. These findings suggest that FUS-BBBO can achieve noninvasive, localized, and safe delivery of aPD-L1 to the brain of large animals, providing strong preclinical data to support the clinical translation of this promising technique for brain cancer immunotherapy.

Abstract 18372: Peripheral Intravascular Lithotripsy to Facilitate Transfemoral Transcatheter Aortic Valve Replacement - Updated Outcomes

Background: Transfemoral transcatheter aortic valve replacement (TF-TAVR) approach has proven to be superior to alternative access[1]. However, a subset of patients being evaluated for TF-TAVR are deemed unfit secondary to peripheral arterial disease. Despite reduction of delivery system profiles to 14 - 18 Fr, current systems still pose an increased risk of access vessel injury. For patients anatomically unfit for standard transfemoral access, peripheral intravascular lithotripsy (IVL) has emerged to facilitate femoral access for TAVR. Methods: Single center, retrospective analysis of an institutional patient database, queried from 1/2018 through 12/2022 for all patients undergoing TAVR. All patients undergoing IVL facilitated lithotripsy for transfemoral access were analyzed. Results: A total 2,209 TAVR cases were identified, with 75 (3.78%) having undergone lithotripsy: 14 in 2018, 15 in 2019, 16 in 2020, 13 in 2021, and 17 in 2022. The lithotripsy cohort consisted of 45% female with mean age of 78±9.8 years. Average length of stay was 3 days. Common and external iliac lesions were the most common target (n=41/75), followed by common iliac alone (n=25/75). Majority of IVL was performed with 7-mm lithotripsy catheter (n=55/75). Procedural success was 98.7% (n=74/75). Average fluoroscopy time 31 minutes, and average total contrast infusion 87cc. Average number of pulses per lesion was 260 ±52. Mean target lesion diameter on the right 5.0 ±1.2mm and left 5.3 ±1.3mm. Average aortic valve calcium score was 2405.6 ±1260.4. Total complication rate was 28%. Complications requiring secondary vascular procedure occurred in 5.3% (n=4/75) with femoral stenosis requiring balloon dilation, external iliac pseudoaneurysm and retroperitoneal bleed secondary to common femoral pseudoaneurysm primarily repaired, and CFA occlusion required open endarterectomy. Mortality at 30-days 1.3% (n=1/75). Conclusions: This abstract aims to provide an updated report of a single institution experience for the use of IVL to facilitate transfemoral TAVR. The IVL facilitated TF-TAVR is feasible, safe, and effective at preserving the transfemoral TAVR route in patients with severe peripheral artery disease. [1] Holmes. et al. J Am Coll Cardiol, 2015. 66(25): p. 2813-2823

49 Locus Coeruleus MR Signal Interacts with CSF p-tau/AB42 to Predict Attention, Executive Function, and Verbal Memory

Objective:The locus coeruleus (LC) plays a key role in cognitive processes such as attention, executive function, and memory. The LC has been identified as an early site of tau accumulation in Alzheimer’s disease (AD). LC neurons are thought to survive, albeit with limited functionality, until later stages of the disease, though how exactly this limited functionality impacts cognition through the course of AD is still poorly understood. We investigated the interactive effects of an imaging biomarker of the LC and AD-related cerebrospinal fluid (CSF) biomarkers on attention, executive function, and memory.Participants and Methods:We recruited 67 older adults from the San Diego community (mean age=74.52 years; 38 cognitively normal, 23 with mild cognitive impairment, and 6 with probable AD). Participants had LC-sensitive magnetic resonance imaging (MRI) used to obtain a measure of LC signal relative to surrounding tissue, with lower LC signal possibly indicating limited functionality. Participants also underwent a lumbar puncture to obtain CSF measurements of amyloid-beta 42 (Ab42) and phosphorylated tau (p-tau). We calculated the p-tau/Ab42 ratio, which is positively correlated with AD progression. Finally, participants were administered a comprehensive neuropsychological battery, and cognitive composites were created for attention (Digit Symbol, Digit Span Forward, Trails A), executive function (Digit Span Backward, Trails B, Color-Word Inhibition Switching), and two measures of verbal memory [learning (CVLT List A 1-5, Logical Memory Immediate Recall) and delay (CVLT Long Free Recall, Logical Memory Delayed Recall)]. Four multiple linear regressions modeled the relationship between each composite with age, gender, education, p-tau/Ab42, average LC contrast, and interactions between average LC contrast and p-tau/Ab42. For models that were statistically significant, additional regressions were assessed to determine which segment of the LC (caudal, middle, rostral) contributed to the relationship.Results:Our model predicted attention (p=.001, R2=.298) with main effects of average LC signal, p-tau/Ab42, and LC by p-tau/Ab42 interaction. Follow-up regressions revealed that each LC segment contributes to this relationship. Our model predicted executive function (p=.006, R2=.262) with a main effect of average LC signal and LC by p-tau/Ab42 interaction. Follow-up regressions revealed that this relationship was limited to the caudal and middle LC. Our models predicted both verbal learning (p&lt;.001, R2=.512) and delayed memory (p&lt;.001, R2=.364); both with main effects of gender and education. Follow-up regressions revealed that the rostral LC signal interacts with p-tau/Ab42 to predict both verbal learning and delayed memory. For all interactions, those with low p-tau/Ab42 exhibited a positive relationship between LC signal and cognition, whereas those with higher p-tau/Ab42 showed a negative relationship.Conclusions:MR-assessed LC signal relates to attention, executive function, and verbal learning and memory in a manner that depends on CSF levels of p-tau and Ab42. The relationship between LC signal and cognition is positive at low levels and negative at higher levels of p-tau/Ab42. If lower LC signal indicates reduced integrity, these findings imply that MR-assessed LC signal may be a more meaningful marker of AD progression in earlier stages of the disease. Alternatively, this measure may capture a different underlying mechanism depending on tau and amyloid biomarker status.

The kinetic quantitative characteristics of non-mass breast lesions with contrast-enhanced ultrasound: a prospective study.

To characterize non-mass breast lesions (NML) quantitatively by contrast-enhanced ultrasound (CEUS) and to evaluate its additional diagnostic value based on the Breast Imaging Reporting and Data System (BI-RADS) categories. A prospective study was performed among consecutive patients with NMLs. All lesions were examined by grayscale ultrasound and CEUS and diagnosed on pathology. Standard mammograms were obtained in the patients over 30 years old. Three independent radiologists assessed the features on grayscale ultrasound and mammograms and classified NMLs according to BI-RADS categories. Combined with the quantitative analysis in CEUS, the BI-RADS categories were reassessed, and the sensitivity, specificity, positive-predictive value, negative-predictive value and area under the receiver operating characteristic curve (AUC) were calculated for the evaluation of the diagnostic performance. 30 benign and 24 malignant NMLs were finally enrolled in this study, with ductal carcinoma in situ being the majority of malignant (15/24). Average contrast signal intensity (AI), wash-in rate (WiR) and enhancement intensity at 40 s (I40) were found to be the most efficient kinetic parameters to diagnose malignant NMLs. Combined with the cut-off values of 205.2 for AI, 127.8 for WiR and 136.4 for I40, the diagnostic accuracy was improved (AUC = 0.904), with the sensitivity of 95.8% and the specificity of 70.0%. The results suggested that hyperenhancement and rapid wash-in and wash-out are the characteristics of malignant NMLs. The kinetic analysis using CEUS can reflect hypervascular nature of malignant NMLs, thus improving the diagnostic performance combined with grayscale ultrasound. In this study, we quantified the enhancement characteristics of non-mass breast lesions with CEUS. We revealed that the combination of CEUS and conventional ultrasound provided higher sensitivity for diagnosing malignant NMLs.

Methods and software for capturing three-dimensional digital images using spatial demodulation

The paper proposes the generalized technique of demodulation, which can be applied for capturing digital three-dimensional images in optical microscopes. This technique allows the calculation of the contrast of harmonic spatial modulation with any values of phase angles. The input data is a stack of digital images with harmonic spatial modulation. Three digital images with different phases of modulation captured in the same focus position are processed to get one data set about the contrast distribution. This data makes it possible to compose the three-dimensional images by the selection of the maximal values of the contrast in three-dimensional space. The paper contains the analytical solution of the system with three linear equations that helps to identify the principal parameters of harmonic spatial modulation, including its average value and contrast. As a result, the expression for contrast calculation is present in an analytical form. This expression is valid for any modulation phase angles that do not coincide. The paper contains MathCAD modeling, which illustrates the procedure of composing the three-dimensional images.&#x0D; The modeling confirms the correctness of described calculations and demonstrates the built of the three-dimensional surface image as a composition of the contrast distribution map and the corresponded height map. The advantage of the proposed technique is the possibility to apply the economical units for the formation of a harmonious spatial modulation. These units can be installed on most optical microscopes with digital cameras and motorized focusing drives without purchasing expensive commercial software. It significantly reduces the price of transforming these optical microscopes into instruments for capturing digital three-dimensional images.

Exploring the impact of PVC and PVA microplastics on zebrafish tissue using multi-spectral imaging, Optical Coherence Tomography (OCT) and biospeckle OCT (bOCT)

Plastics are widely used in industry and households, but improper disposal has caused their accumulation in aquatic systems worldwide. As a result, mechanical and photochemical processes break down these plastics into microplastics or nano plastics, posing a severe threat to marine organisms and humans as they enter the food chain. This study investigates the effect of Polyvinyl chloride (PVC) and Polyvinyl alcohol (PVA) microplastics in zebrafish by using multi-spectral imaging (MSI), Optical Coherence Tomography (OCT), and Biospeckle OCT (bOCT). These techniques allow for long-term studies in the fish without invasive procedures in real-time. Zebrafish were exposed to Nile red labeled PVC and PVA for 21 days with 500mg/L concentration. Image acquisition and analysis were performed every five days till the end of the study. MSI images revealed deposition of microplastics in the gills region of the fish; some diffused deposition was seen throughout the body in the PVA group towards the end of the experiment. The effect of these MPs on the structure of the gills and their exact location was determined by capturing OCT images. bOCT was used to determine the average speckle contrast for all the OCT images to determine the change in biological activity within the gills region. An increase in bioscpeckle contrast was observed for the MPs treated groups compared to the control group. PVC appeared to cause a more considerable rise in activity compared to PVA. The results indicated that the MPs exert stress on the gills and increase activity within the gills, possibly due to the blockage of the gills and disruption of the water filtration process, which could be monitored non-invasively only by using bOCT. Overall, our study demonstrates the usefulness of non-invasive, robust techniques like MSI, bOCT, and biospeckle for long-term zebrafish studies and real-time analyses.

Model observer performance in contrast-enhanced lesions in breast CT: The influence of contrast concentration on detectability.

The use of iodine-based contrast agent for better delineation of tumors in breast CT (bCT) has been shown to be compelling, similar to the tumor enhancement in contrast-enhanced breast MRI. Contrast-enhanced bCT (CE-bCT) is a relatively new tool, and a structured evaluation of different imaging parameters at play has yet to be conducted. In this investigation, data sets of acquired bCT images from 253 patients imaged at our institution were used in concert with simulated mathematically inserted spherical contrast-enhanced lesions to study the role of contrast enhancement on detectability. To quantitatively evaluate the improvement in lesion detectability due to contrast enhancement across lesion diameter, section thickness, view plane, and breast density using a pre-whitened matched filter (PWMF) model observer. The relationship between iodine concentration and Hounsfield units (HU) was measured using spectral modeling. The lesion enhancement from clinical CE-bCT images in 22 patients was evaluated, and the average contrast enhancement (ΔHU) was determined. Mathematically generated spherical mass lesions of varying diameters (1, 3, 5, 9, 11, 15mm) and contrast enhancement levels (0, 0.25, 0.50, 0.75, 1) were inserted at random locations in 253 actual patient bCT datasets. Images with varying thicknesses (0.4-19.8mm) were generated by slice averaging, and the role of view plane (coronal and axial planes) was studied. A PWMF was used to generate receiver operating characteristic (ROC) curves across parameters of lesion diameter, contrast enhancement, section thickness, view plane, and breast density. The area under the ROC curve (AUC) was used as the primary performance metric, generated from over 90,000 simulated lesions. An average 20% improvement (ΔAUC=0.1) in lesion detectability due to contrast enhancement was observed across lesion diameter, section thickness, breast density, and view plane. A larger improvement was observed when stratifying patients based on breast density. For patients with VGF≤40%, detection performance improved up to 20% (until AUC →1), and for patients with denser breasts (VGF>40%), detection performance improved more drastically, ranging from 20% to 80% for 1- and 5-mm lesions. For the 1mm lesion, detection performance raised slightly at the 1.2mm section thickness before falling off as thickness increased. For larger lesions, detection performance was generally unaffected as section thickness increased up until it reached 5.8mm, where performance began to decline. Detection performance was higher in the axial plane compared to the coronal plane for smaller lesions and thicker sections. For emerging diagnostic tools like CE-bCT, it is important to optimize imaging protocols for lesion detection. In this study, we found that intravenous contrast can be used to detect small lesions in dense breasts. Optimal section thickness for detectability has dependencies on breast density and lesion size, therefore, display thickness should be adjusted in real-time using display software. These findings may be useful for the development of CE-bCT as well as other x-ray-based breast imaging modalities.

Monitoring martian slope streaks in the northeast of Lycus sulci

Slope streaks are dark features found in low-latitude regions of Mars, formed from rapid-duration events in low thermal inertia terrain. The sudden appearance of low reflectance factor (I/F) patches followed by gradual whitening is a planet-relevant environmental indicator. The present work aims to quantify the variation in the fading of slope streaks using HiRISE/MRO images. We carried that out by analyzing I/F contrast of 31 streaks about their surroundings north of Olympus Mount, arranged in 16 images dated from 2007 to 2021, used as a dataset for measuring the formation and brightening of the streaks in the region. For the contrast calculations, we used I/F data points extracted from within the streaks and their brighter surroundings. We conducted a statistical analysis on the contrast distribution of each slope streak to test for normality and homogeneity of variances. Using Welch's t-Test, we found that the average albedo contrast values of the slope streaks were statistically different across all pairwise comparisons between dates. Our study provides some insight on the contrast variation (due to sediment deposition) of the streaks along time and seasonal correlation. The results point out to a possible dry formation process, such as dust avalanches, but are not sufficient to rule out wet mechanisms.

Accurate OCT-based diffuse adult-type glioma WHO grade 4 tissue classification using comprehensible texture feature analysis

Maximum safe resection of diffuse adult-type glioma WHO grade 4 (glioma °4) is a well-established procedure in order to prolong a patient’s lifetime. However, differentiation between glioma and healthy brain tissue remains a challenge in an intraoperative setting. As shown previously, the attenuation coefficient extracted from OCT images does not provide sufficient discrimination between healthy gray matter and tumor infiltrated tissue. On the other hand, the majority of published approaches based on structural information in OCT images uses sophisticated machine learning approaches as e.g. deep convolutional neural networks which bring the need for large data sets for reasonable modeling. In this work, we propose a method, which is based on comprehensible texture features and provides reasonable classification performance for healthy gray and white matter against glioma °4 samples, while requiring a relatively low number of samples for training. Our sample collective consists of 36 tissue samples from 27 different patients. Texture features based on the average contrast were optimized with respect to best discrimination of the tissue types of interest. Best discrimination could be obtained for the contrast of structure sizes of approximately 100μm. By using a linear discriminant analysis (LDA), we could achieve a sensitivity and specificity of 97.7% and 91.7%, respectively, when classifying white matter and samples with a mixture of white and gray matter against glioma °4 samples. For an extended data set, also including pure gray matter samples, we determined a sensitivity of 86.7% and a specificity of 86.3%.

Outcomes of preloaded toric intraocular lens implantation in eyes undergoing phacoemulsification.

To evaluate the clinical outcomes of preloaded toric intraocular lens (IOLs) implantation in eyes undergoing phacoemulsification. This prospective study included 51 eyes of 51 patients with visually significant cataracts and corneal astigmatism ranging between 0.75 and 5.50 D. All patients underwent phacoemulsification with SupraPhob toric intraocular lens implantation under topical anesthesia. The main outcome measures were uncorrected distance visual acuity (UDVA), residual refractive cylinder, spherical equivalent, and IOL stability at 3 months follow-up. At 3 months, 49% (25/51) of patients had UDVA equal to or better than 20/25 with 100% of eyes achieving better than 20/40. Mean logMAR UDVA improved from 1.02 ± 0.39, preoperatively to 0.11 ± 0.10 at 3 months follow-up (P < 0.001, Wilcoxon signed-rank test). The mean refractive cylinder improved from - 1.56 ± 1.25 D preoperatively to - 0.12 ± 0.31 D at 3 months follow-up (P < 0.001) while the mean spherical equivalent value changed from - 1.93 ± 3.71D preoperatively to - 0.16 ± 0.27D (P = 0.0013). The mean root mean square value for higher order aberrations was 0.30 ± 0.18 μm while the average contrast sensitivity value (Pelli-Robson chart) was 1.56 ± 0.10 log unit, at the final follow-up. The mean IOL rotation at 3 weeks was 1.7 ± 1.61 degrees, which did not change significantly at 3 months (P = 0.988) follow-up. There were no intraoperative or postoperative complications. SupraPhob toric IOL implantation is an effective method for addressing preexisting corneal astigmatism in eyes undergoing phacoemulsification with good rotational stability.

In vivo skin optical clearing efficacy quantification of clinically compatible agents using line-field confocal optical coherence tomography.

The clinical use of optical methods for in vivo skin imaging is limited by skin strong scattering properties, which reduce image contrast and probing depth. The efficiency of optical methods can be improved by optical clearing (OC). However, for the use of OC agents (OCAs) in a clinical setting, compliance with acceptable non-toxic concentrations is required. OC of in vivo human skin, combined with physical and chemical methods to enhance skin permeability to OCAs, was performed to determine the clearing-effectiveness of biocompatible OCAs using line-field confocal optical coherence tomography (LC-OCT) imaging. Nine types of OCAs mixtures were used in association with dermabrasion and sonophoresis for OC protocol on three volunteers hand skin. From 3D images obtained every 5min for 40min, the intensity and contrast parameters were extracted to assess their changes during the clearing process and evaluate each OCAs mixture's clearing efficacy. The LC-OCT images average intensity and contrast increased over the entire skin depth with all OCAs. The best image contrast and intensity improvement was observed using the polyethylene glycol, oleic acid, and propylene glycol mixture. Complex OCAs featuring reduced component concentrations that meet drug regulation-established biocompatibility requirements were developed and proved to induce significant skin tissues clearing. By allowing deeper observations and higher contrast, such OCAs in combination with physical and chemical permeation enhancers may improve LC-OCT diagnostic efficacy.

Performance of Creatinine and Cystatin C-Based Equations to Estimate Kidney Function in Renal Transplant Recipients

Background: Numerous equations are applied in order to estimate the glomerular filtration rate (GFR). Objectives: This study aimed to spot the optimal equation that accurately estimates GFR and, therefore, the chronic kidney disease (CKD) stage in renal transplant patients. Methods: This cross-sectional study was conducted on 58 renal transplant patients. Their venous blood samples were obtained for serum creatinine and cystatin C determination used to calculate estimated GFR (eGFR). The average contrast of GFR in each equation was calculated using the Bland-Altman method. The correlation, bias, imprecision, and 10% and 30% accuracy were compared between the eGFR cystatin C and creatinine. Concordance between both equations for CKD staging was assessed. The classification of patients was also investigated. Results: Bland-Altman plots and bias demonstrated that eGFR by the abbreviated modification of diet in renal disease (Ab-MDRD) was the most accurate compared with chronic kidney disease epidemiology collaboration (CKD-EPI) cystatin C, followed by CKD-EPI eGFR creatinine. With reference to CKD-EPI cystatin C, the imprecision of the equations was approximately similar to Ab-MDRD, and CKD-EPI creatinine is still better than the Cockcroft-gault (CG) formula. They also showed good 30% accuracy. Finally, our finding suggested that Ab-MDRD and CKD-EPI eGFR creatinine might be the best-performing equation in the classification of the CKD stages in a cutoff of 60 mL/min/1.73 m2. Conclusions: Due to the high cost and potential delay in measuring cystatin C, it would be much more appropriate to measure Ab-MDRD; after that, CKD-EPI eGFR creatinine as an alternative approach in order to facilitate rapid clinical decision in renal transplant patients.

Large-Array Deep Abdominal Imaging in Fundamental and Harmonic Mode.

Deep abdominal images suffer from poor diffraction-limited lateral resolution. Extending the aperture size can improve resolution. However, phase distortion and clutter can limit the benefits of larger arrays. Previous studies have explored these effects using numerical simulations, multiple transducers, and mechanically swept arrays. In this work, we used an 8.8-cm linear array transducer to investigate the effects of aperture size when imaging through the abdominal wall. We acquired channel data in fundamental and harmonic modes using five aperture sizes. To avoid motion and increase the parameter sampling, we decoded the full-synthetic aperture data and retrospectively synthesized nine apertures (2.9-8.8 cm). We imaged a wire target and a phantom through ex vivo porcine abdominal samples and scanned the livers of 13 healthy subjects. We applied bulk sound speed correction to the wire target data. Although point resolution improved from 2.12 to 0.74 mm at 10.5 cm depth, contrast resolution often degraded with aperture size. In subjects, larger apertures resulted in an average maximum contrast degradation of 5.5 dB at 9-11 cm depth. However, larger apertures often led to visual detection of vascular targets unseen with conventional apertures. An average 3.7-dB contrast improvement over fundamental mode in subjects showed that the known benefits of tissue-harmonic imaging extend to larger arrays.

Design and synthesis of novel D-A copolymers based on fused thienothiophene for efficient broad absorption electrochromism

Developing conjugated polymers with broad spectrum modulation is highly desirable in electrochromic field. Herein, three novel polymers based on fused thienothiophene derivative (tris(thienothiophene) (TTT) or indacenodithieno[3,2-b]thiophene (IDTT)) and two acceptors (5,8-bis(4-(2-butyloctyl)thiophen-2-yl)-dithieno[3′,2':3,4; 2″,3'':5,6]benzo[1,2-c][1,2,5]thiadiazole (TBT) and 2,1,3-Benzothiadiazole (BT)) are synthesized via direct arylation polymerization (DArP). The neutral copolymers exhibit visibly broadband absorption due to the combination of the π-π* transition and intramolecular charge transfer absorption, which can be tuned by the feed ratio of the donor and acceptor monomers. As a result, the copolymer synthesized by IDTT, TBT and BT with a feed ratio of 3/2/1 presents a black color in the neutral state and high transparency in the oxidized state, which gives an average optical contrast of 34% in the visible band (400 nm–700nm), good stability and high coloration efficiency (370 cm2/C). Additionally, an electrochromic device with excellent electrochromic performance is fabricated based on the synthesized polymers. All of these confirm the synthesized polymers are attractive candidates for broad absorption electrochromism.

Safety and feasibility of a novel bi-directional portal vein access kit during transjugular intrahepatic portosystemic shunt creation

BackgroundTransjugular intrahepatic portosystemic shunt (TIPS) creation remains as one of the more technically challenging endovascular procedures. Portal vein access from the hepatic vein often requires multiple needle passes, which increases procedure times, risk of complications, and radiation exposure. With its bi-directional maneuverability, the Scorpion X access kit may be a promising tool for easier portal vein access. However, the clinical safety and feasibility of this access kit has yet to be determined.Materials and methodsIn this retrospective study, 17 patients (12 male, average age 56.6 ± 9.01) underwent TIPS procedure using Scorpion X portal vein access kits. The primary endpoint was time taken to access the portal vein from the hepatic vein. The most common indications for TIPS were refractory ascites (47.1%) and esophageal varices (17.6%). Radiation exposure, total number of needle passes, and intraoperative complications were recorded. Average MELD Score was 12.6 ± 3.39 (range: 8–20).ResultsPortal vein cannulation was successfully achieved in 100% of patients during intracardiac echocardiography-assisted TIPS creation. Total fluoroscopy time was 39.31 ± 17.97 min; average radiation dose was 1036.76 ± 644.15 mGy, while average contrast dose was 120.59 ± 56.87 mL. The average number of passes from the hepatic vein to the portal vein was 2 (range: 1–6). Average time to access the portal vein once the TIPS cannula was positioned in the hepatic vein was 30.65 ± 18.64 min. There were no intraoperative complications.ConclusionsClinical utilization of the Scorpion X bi-directional portal vein access kit is both safe and feasible. Utilizing this bi-directional access kit resulted in successful portal vein access with minimal intraoperative complications.Level of evidenceRetrospective cohort.

Detection of fault zone head waves and the fault interface imaging in the Xianshuihe–Anninghe Fault zone (Eastern Tibetan Plateau)

SUMMARY Fault zone head waves (FZHWs) are an essential diagnostic signal that provides high-resolution imaging of fault interface properties at seismogenic depth. In this study, we validate the existence of a bi-material interface in the Xianshuihe–Anninghe Fault (XAF) zone around their intersection and determine the cross-fault velocity contrast. We employ a semi-automatic workflow to detect and pick FZHWs and direct P waves. In addition, to improve the identification ability of potential FZHWs in the automatic picking process, we adopt a ‘forward-detecting and backward-picking’ strategy combining the short-term average/long-term average (STA/LTA) algorithm with a kurtosis detector. The polarization and characteristic periods of the waveforms are then used to manually refine the picks and evaluate the quality. The results indicate that the average velocity contrast along the southern Xianshuihe Fault is 3–5 per cent, with the northeast side characterizing a faster P-wave velocity, in agreement with tomographic results. A systematic moveout between FZHWs and the direct P waves over a 100 km long fault segment reveals a single continuous interface in the seismogenic zone. The single bi-material fault structure might be conducive to the preparation of large earthquakes and further influences the corresponding dynamic rupture processes.