Dynamic assessment of brain perfusion in a middle cerebral artery occlusion rat model by contrast-enhanced ultrasound imaging: a pilot study.

BACKGROUND: The middle cerebral artery occlusion model (MCAo) is a commonly used animal model for cerebral ischemia studies but lacks accessible imaging techniques for the assessment of hemodynamic changes of the model. PURPOSE: The study aims to explore the value of contrast-enhanced ultrasound (CEUS) in evaluating brain perfusion in the early stages after MCAo surgery. MATERIAL AND METHODS: In total, 18 adult male Sprague-Dawley rats were subjected to right MCAo using an intraluminal filament model, and CEUS was performed at the three following timepoints: before (T0), immediately after (T1), and 6 h after permanent MCAo (T2). Twelve rats successfully completed the study, and their brains were removed and stained using 2, 3, 5-triphenyltetrazolium chloride (TTC). CEUS video images were visualized offline, and the time-intensity curves (TICs) were analyzed. Different cerebrovascular patterns and manifestations of the contrast enhancement in rat ischemic hemispheres were observed. Semi-quantitative parameters of TICs in ischemic areas (ROIi) and the surrounding normal- or hypo-perfused areas (ROIn) were calculated and compared between T0, T1, and T2, and also between ROIi and ROIn. RESULTS: A significant correlation was found between the lesion volume (%) determined by TTC and CEUS parameters (r = -0.691, P = 0.013 for peak intensity; r = -0.742, P = 0.006 for area under the curve) at T2. After the same occlusion, there were differences in contrast perfusion in each group. CONCLUSION: This study suggests that CEUS could be an effective imaging tool for studying cerebral ischemia and perfusion in small animals as long as the transcranial acoustic window allows it.

Imaging methods for surgical revascularization in patients with moyamoya disease: an updated review.

Neuroimaging is crucial in moyamoya disease (MMD) for neurosurgeons, during pre-surgical planning and intraoperative navigation not only to maximize the success rate of surgery, but also to minimize postsurgical neurological deficits in patients. This is a review of recent literatures which updates the clinical use of imaging methods in the morphological and hemodynamic assessment of surgical revascularization in patients with MMD. We aimed to assist surgeons in assessing the status of moyamoya vessels, selecting bypass arteries, and monitoring postoperative cerebral perfusion through the latest imaging technology.

Quantitative Shear Wave Speed Assessment for Muscles With the Diagnosis of Taut Bands and/or Myofascial Trigger Points Using Probe Oscillation Shear Wave Elastography: A Pilot Study.

OBJECTIVE: To use probe oscillation shear wave elastography (PROSE) with two vibration sources to generate two shear waves in the imaging plane to quantitatively assess the shear wave speeds (SWSs) of muscles with and without the diagnosis of taut bands (TB) and/or myofascial trigger points (MTrPs). METHODS: Thirty-three patients were scanned with the PROSE technique. Shear waves were generated through continuous vibration of the ultrasound probe, while the shear wave motions were detected using the same probe. SWSs for the sides with and without TBs and/or MTrPs were computed and compared. The pressure pain thresholds (PPTs) were measured as an indicator of maximum pain tolerance of patients. The statistical differences between the SWSs with and without TBs and/or MTrPs with different PPT values were analyzed using the nonparametric Wilcoxon rank-sum test. RESULTS: The mean SWSs for the sides with TBs and/or MTrPs are faster than that of the contralateral side without TBs and/or MTrPs. A significant difference was observed between mean SWSs with and without TBs and/or MTrPs without any information of PPT, with rank-sum test P < .005. Additionally, with the information of PPT, a significant difference was observed between mean SWSs for the sides with and without TBs and/or MTrPs, for PPT values between 0 and 50 N/cm2 (P < .005), but for PPT values between 50 and 90 N/cm2 , it was difficult to differentiate mean SWSs with and without TBs and/or MTrPs. CONCLUSION: Our preliminary results show that SWSs measured from patients had a significant difference between the mean SWSs with and without TBs and/or MTrPs.

Case 290.

History A 26-year-old man presented with a 1-month history of chest pain, a palpable and painful right inguinal mass, and edema in the right lower extremity. One month earlier, he started to experience left chest pain with no cough. Pulmonary CT angiography (CTA) revealed a left lower lobe segmental pulmonary embolus. The local hospital made a diagnosis of pulmonary embolism (PE). He received anticoagulants, and his chest pain was gradually relieved. At the time of current presentation, the patient was experiencing right lower extremity swelling and pain. Physical examination revealed a 4 × 3 cm palpable right inguinal mass with no redness. His medical history and family history were negative. The results of laboratory work-up were normal, with a D-dimer level of 0.16 mg/L fibrinogen equivalent units (reference range, <0.46 mg/L) and an international normalized ratio of 2.45 (therapeutic range, 2.0-3.0 for a patient taking warfarin), except the prothrombin time was 28.2 seconds (reference range, 9.6-12.8 seconds) and the activated partial thromboplastin time was 52.2 seconds (reference range, 24.8-33.8 seconds). Echocardiography, chest radiography, chest CT, and contrast-enhanced CT revealed no abnormalities. The patient underwent right lower extremity vascular conventional US (Philips IU22; Philips) with an L9-3 probe (3-9 MHz, venous condition) and contrast-enhanced US (1.5-2.0 mL, SonoVue; Bracco) with an intravenous bolus injection at the initial evaluation. Two days later, noncontrast and contrast-enhanced CT images of the lower abdomen (1.5 mL per kilogram of body weight, 300 mg/mL iomeprol, Iomeron; Bracco) were acquired for further evaluation (Figs 1-3).

Case 290: Intravascular Cystic Synovial Sarcoma.

History A 26-year-old man presented with a 1-month history of chest pain, a palpable and painful right inguinal mass, and edema in the right lower extremity. One month earlier, he started to experience left chest pain with no cough. Pulmonary CT angiography (CTA) revealed a left lower lobe segmental pulmonary embolus. The local hospital made a diagnosis of pulmonary embolism. He received anticoagulants, and his chest pain was gradually relieved. At the time of current presentation, the patient was experiencing right lower extremity swelling and pain. Physical examination revealed a 4 × 3 cm palpable right inguinal mass with no redness. His medical history and family history were negative. The results of laboratory work-up were normal, with a d-dimer level of 0.16 mg/L fibrinogen equivalent units (reference range, <0.46 mg/L) and an international normalized ratio of 2.45 (therapeutic range, 2.0-3.0 for a patient taking warfarin), except the prothrombin time was 28.2 seconds (reference range, 9.6-12.8 seconds) and the activated partial thromboplastin time was 52.2 seconds (reference range, 24.8-33.8 seconds). Echocardiography, chest radiography, chest CT, and contrast-enhanced (CE) CT revealed no abnormalities. The patient underwent right lower extremity vascular conventional US (Philips IU22; Philips) with an L9-3 probe (3-9 MHz, venous condition) and contrast-enhanced US (1.5-2.0 mL, SonoVue; Bracco) with an intravenous bolus injection at the initial evaluation. Two days later, noncontrast and contrast-enhanced CT images of the lower abdomen (1.5 mL per kilogram of body weight, 300 mg/mL iomeprol, Iomeron; Bracco) were acquired for further evaluation.

Ultrasonographic features of an intravascular lobular capillary hemangioma originating in the basilic vein: Case report and literature review.

Intravascular lobular capillary hemangioma (ILCH) is a rare variant of pyogenic granuloma, which develops within the lumen of a blood vessel. Here, we report the case of a 38-year-old male presenting with a mobile, incompressible, nonpulsatile nodule in the superficial fascia of the forearm. A first ultrasonographic examination diagnosed the mass as intravascular thrombosis with partial recanalization. Three months later, a second ultrasonographic examination concluded to the existence of an intravascular tumor, which finally turned out at pathological examination to be ILCH. Here, we report the ultrasonographic features of ILCH and the differential diagnosis between ILCH and other intravascular masses like thrombus.

Quantitative Inflammation Assessment for Crohn Disease Using Ultrasensitive Ultrasound Microvessel Imaging: A Pilot Study.

OBJECTIVES: Crohn disease (CD) is a chronic inflammation in the digestive tract that affects millions of Americans. Bowel vascularity has important diagnostic information because inflammation is associated with blood flow changes. We recently developed an ultrasensitive ultrasound microvessel imaging (UMI) technique with high vessel sensitivity. This study aimed to evaluate the feasibility of UMI to assist CD detection and staging. METHODS: Ultrasound microvessel imaging was performed on 76 bowel wall segments from 48 symptomatic patients with CD. Clinically indicated computed tomographic/magnetic resonance enterography was used as the reference standard. The vessel-length ratio (VLR, the number of vessel pixels in the bowel wall segment normalized to the segment length) was derived in both conventional color flow imaging (CFI) and UMI to quantitatively stage disease activity. Receiver operating characteristic curves were then analyzed between different disease groups. RESULTS: The VLR-CFI and VLR-UMI detected similar correlations between vascularization and disease activity: severe inflammation had a higher VLR than normal/mildly inflamed bowels (P < .05). No significant difference was found between quiescent and mild CD due to the small sample size. The VLR-CFI had more difficulties in distinguishing quiescent versus mild CD compared to the VLR-UMI. After combining the VLR-UMI with thickness, in the receiver operating characteristic curve analysis, the areas under the curves (AUCs) improved to AUC1 = 0.996 for active versus quiescent CD, AUC2 = 0.978 for quiescent versus mild CD, and AUC3 = 0.931 for mild versus severe CD, respectively, compared to those using thickness alone (AUC1 = 0.968; P = .04; AUC2 = 0.919; P = .16; AUC3 = 0.857; P = .01). CONCLUSIONS: Ultrasound microvessel imaging offers a safe and cost-effective tool for CD diagnosis and staging, which may potentially assist disease activity classification and therapy efficacy evaluation.

[Contrast-enhanced Ultrasonography and Color Doppler Ultrasonography for Dynamic Assessment of Intracranial Changes in Early MCAO Rats Models].

OBJECTIVE: To assess the value of contrast-enhanced ultrasound (CEUS) and color Doppler ultrasound (DUS) on hemodynamic changes and cerebral perfusion quantitative analyses in Sprague-Dawley (SD) rats with focal permanent ischemic stroke. METHODS: Sixteen SD rats with thin skulls were subjected to establish middle cerebral artery occlusion (MCAO) model. CEUS images were performed before modeling (T 0), immediately after modeling (5-15 min after modeling, T 1), 3 h after modeling (T 2), followed by the measurement of bilateral middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA) using DUS. The peak systolic velocity (PSV), end-diastolic velocity (EDV) and mean velocity (MV) of these arteries were obtained. The brain time-intensity curve was taken as interest region of the whole right brain, and the quantitative parameters of CEUS were obtained, including peak intensity (PI), area under the curve ( AUC), wash in slope (WIS), time to peak (TTP), rise time (RT) and time from peak to one half (TPH). The modified neurological deficit score (mNSS) of the rats was performed 3 h after the modeling, and the data of the rats with a score of 9-11 were statistically analyzed. RESULTS: A total of 12 rats were successfully modeled and completed with mNSS score 9-11. No blood flow signals were observed on the right MCA and ACA in the 12 rats at T 1 and T 2. From T 0 to T 1, PI, AUC and WIS of the right hemisphere decreased sharply with TTP and RT significantly prolonged, and the differences were statistically significant. However, there was no significant difference in hemodynamic parameters at that period of time. From T 1 to T 2, there were no significant changes in CEUS quantitative parameters (except AUCand TPH), while PSV, EDV, MV of LMCA and bilateral PCA showed significant acceleration, and the differences were statistically significant. CONCLUSION: CEUS and DUS can reveal the intracranial hemodynamics and brain tissue perfusion trends of MCAO rats, which could be new methods in assessment of ischemic stroke model at multiple time points.

[Application of Multimodal Transcranial Ultrasound in SD Rats of Cerebral Ischemic Model at Super Early Stage].

OBJECTIVE: To determine the value of applying multimodal ultrasound (mUS) in SD rats of cerebral ischemic model at super early stage (5-15 min after modeling). METHODS: Fifteen focal cerebral ischemic models were established in SD rats with thinning skulls using the suture method. Gray-scale ultrasound, contrast-enhanced ultrasound, and enhanced color Doppler (CECDUS) were performed before and immediately after the modeling to observe the location of the in-cranial suture, perfusion of the right hemisphere, and color flow signal of the middle cerebral artery and the anterior cerebral artery, respectively.A modified neurological deficit score (mNSS) and 2, 3, 5-triphenyltetrazolium chloride (TTC) stains were obtained three hours later to confirm the successful modeling as the gold standard. The positive rate detected by mUS was compared with the gold standard using McNemar tests. RESULTS: One rat died and 14 rats completed the experiment.mUS imaging detected 71% (10/14) positive signals, no significant difference compared with the gold standard (64%, 9/14) ( P>0.05). A hyperechoic double-line at the bottom of the right brain and focal hypoperfused areas in the right hemisphere were observed by gray scale ultrasound and contrast-enhanced ultrasound in the successfully modeled rats, respectively. The CECDUS found no blood flow in the anterior and middle cerebral arteries. Time intensity curve (TIC) analyses indicated significant changes in peak intensity (PI), area under the curve (AUC), wash in slope (WIS), and time to peak (TTP) after successful modeling. CONCLUSION: Multimodal ultrasound can assess modeling success quickly and accurately immediately after the establishment of ischemic model of SD rats.

The value of ultrasound for the preoperative assessment of carotid body tumors.

OBJECTIVES: To evaluate the value of ultrasound (US) examination for the preoperative assessment of carotid body tumors (CBTs) and to predict surgical outcomes. METHODS: A total of 15 CBT lesions in 15 patients were included in this study. CBT measurements determined using US, and included maximal diameter, volume, tumor distance to base of skull (DTBOS), and carotid wall infiltration. A correlation analysis was conducted to determine the correlation between US measurements and surgical outcomes, including estimated blood loss (EBL), cranial nerve injury, surgical time, and hospital length of stay (HLOS). RESULTS: EBL showed a high level of correlation with the maximal dimeter (r = 0.596, p < .05) and the volume of the tumor (r = 0.864, p < .05). Surgical time was positively correlated with tumor volume (r = 0.592, p < .05) and negatively correlated with DTBOS (r = -0.554, p < .05). There was no significant correlation (p > .05) shown between cranial nerve injury and US variables. HLOS showed the high degree of correlation with the maximal dimeter (r = 0.658, p < .05), and was also negatively correlated with DTBOS (r = -0.620, p < .00). CONCLUSIONS: US examination allows for the visualization of features of CBTs, which is a useful and safe tool to be used to predict surgical outcomes. Further research is necessary to validate this exploration method for the preoperative assessment of CBTs.

Reverberation clutter signal suppression in ultrasound attenuation estimation using wavelet-based robust principal component analysis.

Objective. Ultrasound attenuation coefficient estimation (ACE) has diagnostic potential for clinical applications such as quantifying fat content in the liver. Previously, we have proposed a system-independent ACE technique based on spectral normalization of different frequencies, called the reference frequency method (RFM). This technique does not require a well-calibrated reference phantom for normalization. However, this method may be vulnerable to severe reverberation clutter introduced by the body wall. The clutter superimposed on liver echoes may bias the estimation.Approach. We proposed to use robust principal component analysis, combined with wavelet-based sparsity promotion, to suppress the severe reverberation clutters. The capability to mitigate the reverberation clutters was validated through phantom andin vivostudies.Main Results. In the phantom studies with added reverberation clutters, higher normalized cross-correlation and smaller mean absolute errors were attained as compared to RFM results without the proposed method, demonstrating the capability to reconstruct tissue signals from reverberations. In a pilot patient study, the correlation between ACE and proton density fat fraction (PDFF), a measurement of liver fat by MRI as a reference standard, was investigated. The proposed method showed an improvement of the correlation (coefficient of determination,R = 0.82) as compared with the counterpart without the proposed method (R = 0.69).Significance: The proposed method showed the feasibility of suppressing the reverberation clutters, providing an important basis for the development of a robust ACE with large reverberation clutters.

Improved Ultrasound Attenuation Estimation with Non-uniform Structure Detection and Removal.

Accurate detection of liver steatosis is important for liver disease management. Ultrasound attenuation coefficient estimation (ACE) has great potential in quantifying liver fat content. The ACE methods commonly assume uniform tissue characteristics. However, in vivo tissues typically contain non-uniform structures, which may bias the attenuation estimation and lead to large standard deviations. Here we propose a series of non-uniform structure detection and removal (NSDR) methods to reduce the impact from non-uniform structures during ACE analysis. The effectiveness of NSDR was validated through phantom and in vivo studies. In a pilot clinical study, ACE with NSDR provided more robust in vivo performance as compared with ACE without NSDR, indicating its potential for in vivo applications.

Adaptive and Robust Vessel Quantification in Contrast-Free Ultrafast Ultrasound Microvessel Imaging.

The morphological features of vasculature in diseased tissue differ significantly from those in normal tissue. Therefore, vasculature quantification is crucial for disease diagnosis and staging. Ultrasound microvessel imaging (UMI) with ultrafast ultrasound acquisitions has been determined to have potential in clinical applications given its superior sensitivity in blood flow detection. However, the presence of spatial-dependent noise caused by a low imaging signal-to-noise ratio and incoherent clutter artifacts caused by moving hyperechoic scatterers degrades the performance of UMI and the reliability of vascular quantification. To tackle these issues, we proposed an improved UMI technique along with an adaptive vessel segmentation workflow for robust vessel identification and vascular feature quantification. A previously proposed sub-aperture cross-correlation technique and a normalized cross-correlation technique were applied to equalize the spatially dependent noise level and suppress the incoherent clutter artifact. A square operator and non-local means filter were then used to better separate the blood flow signal from residual background noise. On the de-noised ultrasound microvessel image, an automatic and adaptive vessel segmentation method was developed based on the different spatial patterns of blood flow signal and background noise. The proposed workflow was applied to a CIRS phantom, to a Doppler flow phantom and to an inflammatory bowel, kidney and liver, to validate its feasibility. Results revealed that automatic adaptive, and robust vessel identification performance can be achieved using the proposed method without the subjectivity caused by radiologists/operators.

Self-assembly hybridization of COFs and g-C3N4: Decipher the charge transfer channel for enhanced photocatalytic activity.

Organic semiconductors have been recognized as a new generation of photocatalysts for pollutants degradation and energy production. Herein, organic heterojunction (TpMa/CN) consisting of carbon nitride and ß-ketoenamine-based covalent organic framework is fabricated via a controllable self-assembly approach. The as-prepared TpMa/CN heterojunctions show enlarged visible-light absorption. The optimum TpMa/CN-5 photocatalyst achieves the highest photocatalytic activity towards tetracycline degradation, and its photocatalytic degradation rate is improved by 2.3 and 4.3 times than TpMa and CN, respectively. As a multifunctional photocatalyst, TpMa/CN-5 sample also shows remarkable photocatalytic activity for hydrogen peroxide production (880.494 µM h-1), which is 49 times higher than that of CN. Experimental and theoretical investigations indicate that a built-in electric field is formed at the interface of composite, which enables an accelerated charge transfer and separation. This work develops an effective strategy to design difunctional photocatalyst and deciphers the electronic properties and mechanisms of g-C3N4-based organic photocatalysts, which spurs further interests for organic heterojunction photocatalysts in the future.

Long-read assembly of major histocompatibility complex and killer cell immunoglobulin-like receptor genome regions in cynomolgus macaque.

BACKGROUND: The major histocompatibility complex (MHC) and the killer cell immunoglobulin-like receptors (KIR) are key regulators of immune responses. The cynomolgus macaque, an Old World monkey species, can be applied as an important preclinical model for studying human diseases, including coronavirus disease 2019 (COVID-19). Several MHC-KIR combinations have been associated with either a poor or good prognosis. Therefore, macaques with a well-characterized immunogenetic profile may improve drug evaluation and speed up vaccine development. At present, a complete overview of the MHC and KIR haplotype organizations in cynomolgus macaques is lacking, and characterization by conventional techniques is hampered by the extensive expansion of the macaque MHC-B region that complicates the discrimination between genes and alleles. METHODS: We assembled complete MHC and KIR genomic regions of cynomolgus macaque using third-generation long-read sequencing approach. We identified functional Mafa-B loci at the transcriptome level using locus-specific amplification in a cohort of 33 Vietnamese cynomolgus macaques. RESULTS: This is the first physical mapping of complete MHC and KIR gene regions in a Vietnamese cynomolgus macaque. Furthermore, we identified four functional Mafa-B loci (B2, B3, B5, and B6) and showed that alleles of the Mafa-I*01, -B*056, -B*034, and -B*001 functional lineages, respectively, are highly frequent in the Vietnamese cynomolgus macaque population. CONCLUSION: The insights into the MHC and KIR haplotype organizations and the level of diversity may refine the selection of animals with specific genetic markers for future medical research.

Smoked cigarette butts: Unignorable source for environmental microplastic fibers.

The pollution of microplastics and their potential environmental hazards have attracted considerable attention of the public. Cigarette butts, composed of cellulose acetate, are one of the most common plastic pollutants in the environment. Of all the litter that is discarded at will, cigarette butts are the most acceptable. Cigarette butts are dangerous pieces of plastic, but are usually not handled properly and consist of more than 15,000 detachable strands of plastic fiber. Discarded cigarette butts may be carried into rivers and lakes, and finally into the ocean. The plastic fibers will continuously release microplastic fibers into the environment. About 300,000 tons of potential microplastic fibers may enter the aquatic environment from this source per annum. Additionally, toxic substances, such as nicotine, carcinogenic tar, and polycyclic aromatic hydrocarbons, have strong toxic effect, which will cause serious damage to aquatic organisms. However, the mechanism and rate of microplastic fibers release from smoked cigarette butts and the joint toxicity of microplastic fibers and toxic pollutants to aquatic organisms are still in the initial stage. Therefore, it is necessary to understand the mechanism of cigarette butts releasing microplastic fibers, the potential impact on the environment and possible measures to reduce the impacts of cigarette butt litter. The aim of this paper is to evaluate the potential sources of smoked cigarette butts as environmental fiber microplastics and the potential ecological effects of the released microplastic fibers on the ecosystem. In addition, some ways which could help to tackle problem of smoked cigarette butts pollution have also been proposed.

Liraglutide reduces attenuation coefficient as a measure of hepatic steatosis during 16 weeks' treatment in nondiabetic obese patients: A pilot trial.

BACKGROUND AND AIM: Liraglutide, a long-acting GLP-1 analog, is approved for the treatment of obesity with improvements in fasting blood glucose, hemoglobin A1c, and cardiovascular health. Our aim was to measure the impact of liraglutide dose for obesity on hepatic steatosis measured by ultrasound. METHODS: A single-center, randomized, double-blind, placebo-controlled pilot trial was undertaken in nondiabetic obese, otherwise healthy patients aged 18-65 years. Participants were randomly assigned to receive subcutaneous liraglutide (3.0 mg) or placebo over 16 weeks with dose escalation following US Food and Drug Administration guidelines. Both groups received standardized nutritional and behavioral counseling during the 16 weeks. Hepatic fat content was measured by ultrasound at baseline, 8 weeks, and 16 weeks as an attenuation coefficient (ACE). Effects of treatment were assessed using t-test for the entire groups and for patient subgroup with baseline ACE >0.66 (indicating significant steatosis). RESULTS: Among 30 patients (93% female) enrolled, 16 were randomized to placebo and 14 to liraglutide. Baseline body mass indices (BMIs) and average age were similar in the two groups. After 16 weeks, the liraglutide group had a significant improvement in steatosis ACE scores (-0.068 ± 0.02 vs -0.0077 ± 0.02 placebo, P = 0.05). Change in steatosis was positively correlated with change in BMI (R2 = 0.402, P = 0.0007). Within the liraglutide group, patients with baseline ACE >0.66 had improvement in ACE (-0.134 ± 0.03) compared to those without significant steatosis (-0.041 ± 0.02, P = 0.05). CONCLUSIONS: In this pilot trial, liraglutide, 3.0 mg over 16 weeks, reduced hepatic steatosis; a reduction in hepatic steatosis is correlated with BMI reduction, and effects are particularly evident in those with a significant degree of steatosis by ultrasound imaging.

Noise Suppression for Ultrasound Attenuation Coefficient Estimation Based on Spectrum Normalization.

Ultrasound attenuation coefficient estimation (ACE) has great diagnostic potential for fatty liver detection and assessment. In a previous study, we proposed a reference phantom-free ACE method, called reference frequency method (RFM), which does not require a calibrated phantom for normalization. The power of each frequency component can be normalized by the power of an adjacent frequency component in the spectrum to cancel system-dependent effects such as focusing and time gain compensation (TGC). RFM demonstrated accurate ACE in both phantom and in in-vivo liver studies. However, our study also showed that the robustness and penetration of RFM were affected by noise in the ACE signals. Here we propose a noise suppression (NS) and a signal-to-noise ratio (SNR) quality control method to reduce the influence of noise on ACE-RFM performance. The proposed methods were tested in harmonic ACE because harmonic imaging is a more frequently used mode than fundamental imaging for abdominal applications. After applying the NS and SNR control methods, the noise-induced bias for attenuation estimation in harmonic ACE was effectively reduced, leading to significantly improved effective penetration depth. The proposed methods directly measure the noise spectrum of the ultrasound system, which can also be adapted to other spectrum-based ACE methods, such as the reference phantom method and the spectra shift method.

Highly efficient catalytic hydrogenation of nitrophenols by sewage sludge derived biochar.

Finding a low cost and effective alternative to noble metal based catalyst has long been concerned in wastewater treatment and organic transformation. This work developed a highly efficient sewage sludge-based catalyst via a simple one-step pyrolysis method, and for the first time, applied it in the catalytic reduction of nitrophenols. Due to the higher content of graphitic nitrogen, abundant defect sites and low electron transfer resistance, sewage sludge derived biochar obtained at 800 °C (SSBC-800) exhibits the best catalytic performance, with the reaction rate of 0.48 min-1 and turnover frequency for 4-nitrophenol calculated to be 1.25 × 10-4 mmol•mg-1 min-1, which is comparable to or even superior than some reported noble metal-based catalyst. Moreover, SSBC-800 showed good recyclability of 90% 4-nitrophenol removal within 8 min after 4 runs, and maintained high catalytic activity in reduction of other substituent nitrophenols, such as 2-nitrophenol (0.54 min-1), 3-nitrophenol (0.61 min-1) and 2,4-dinitrophenol (0.18 min-1), and in real water samples, indicating its practical applicability. The electron paramagnetic resonance spectra and electrochemical characterization demonstrate that SSBC-800 accelerates the dissociation of BH4- to form active hydrogen, which is the main species responsible for 4-nitrophenol reduction, while electron transfer reaction involving the surface bound hydride derived from the intimate contact between BH4- and SSBC-800 plays an important role in this process. This research not only provides a novel valorization pathway for sewage sludge, but also sheds new light on further designing of carbon-based catalyst for nitrophenol reduction.

In vivo Visualization of Pig Vagus Nerve "Vagotopy" Using Ultrasound.

Background: Placement of the clinical vagus nerve stimulating cuff is a standard surgical procedure based on anatomical landmarks, with limited patient specificity in terms of fascicular organization or vagal anatomy. As such, the therapeutic effects are generally limited by unwanted side effects of neck muscle contractions, demonstrated by previous studies to result from stimulation of (1) motor fibers near the cuff in the superior laryngeal and (2) motor fibers within the cuff projecting to the recurrent laryngeal. Objective: Conventional non-invasive ultrasound, where the transducer is placed on the surface of the skin, has been previously used to visualize the vagus with respect to other landmarks such as the carotid and internal jugular vein. However, it lacks sufficient resolution to provide details about the vagus fascicular organization, or detail about smaller neural structures such as the recurrent and superior laryngeal branch responsible for therapy limiting side effects. Here, we characterize the use of ultrasound with the transducer placed in the surgical pocket to improve resolution without adding significant additional risk to the surgical procedure in the pig model. Methods: Ultrasound images were obtained from a point of known functional organization at the nodose ganglia to the point of placement of stimulating electrodes within the surgical window. Naïve volunteers with minimal training were then asked to use these ultrasound videos to trace afferent groupings of fascicles from the nodose to their location within the surgical window where a stimulating cuff would normally be placed. Volunteers were asked to select a location for epineural electrode placement away from the fascicles containing efferent motor nerves responsible for therapy limiting side effects. 2-D and 3-D reconstructions of the ultrasound were directly compared to post-mortem histology in the same animals. Results: High-resolution ultrasound from the surgical pocket enabled 2-D and 3-D reconstruction of the cervical vagus and surrounding structures that accurately depicted the functional vagotopy of the pig vagus nerve as confirmed via histology. Although resolution was not sufficient to match specific fascicles between ultrasound and histology 1 to 1, it was sufficient to trace fascicle groupings from a point of known functional organization at the nodose ganglia to their locations within the surgical window at stimulating electrode placement. Naïve volunteers were able place an electrode proximal to the sensory afferent grouping of fascicles and away from the motor nerve efferent grouping of fascicles in each subject (n = 3). Conclusion: The surgical pocket itself provides a unique opportunity to obtain higher resolution ultrasound images of neural targets responsible for intended therapeutic effect and limiting off-target effects. We demonstrate the increase in resolution is sufficient to aid patient-specific electrode placement to optimize outcomes. This simple technique could be easily adopted for multiple neuromodulation targets to better understand how patient specific anatomy impacts functional outcomes.