Stress Imaging Research Articles

The interaction between a piezoelectric screw dislocation and collinear rigid lines in one-dimensional hexagonal quasicrystals

The interaction between a piezoelectric screw dislocation and collinear rigid lines in one-dimensional (1D) hexagonal quasicrystals (QCs) under anti-plane mechanical and in-plane electrical loading is analysed. Two idealized electrical assumptions, namely electrically conductive and dielectric, are considered. By using Muskhelishvilid’s complex transformation method, the explicit expressions for the field variables, the singularity of the field variables at the line tip and the force on the dislocation are obtained for a single rigid line. Based on the generalized Peach–Koehler formula, the generalized stress intensity factors and image force on dislocations in piezoelectric quasicrystal (PQC) are obtained. It is evident that the existence of phason field has an effect on image force.

Abstract 4141485: Liver Steatosis in Women with Coronary Microvascular Dysfunction

Introduction: Metabolic dysfunction-associated steatotic liver disease (MASLD) has been previously associated with coronary microvascular dysfunction (CMD) and is closely related to metabolic syndrome among men and women. Data regarding the association of quantitative liver steatosis and CMD in women with ischemia and no obstructive coronary arteries (INOCA) are scarce. Aim: To evaluate the association of liver steatosis with myocardial perfusion in women with CMD and reference controls. Methods: Women with CMD and no obstructive coronary arteries (n=55) from 2 prospective cohort studies (R01HL146158, R01HL153500) and asymptomatic age- and sex-matched reference controls (n=10) underwent stress and rest cardiac magnetic resonance imaging (MRI), with a validated MRI quantification of liver fat by proton density fat fraction (PDFF), at a single center. CMD was confirmed by coronary function testing or prior diagnostic stress tests. Parameters of liver fat and LV structure, function and myocardial perfusion reserve index (MPRI, a measure of CMD) were compared between cases and controls. A threshold of PDFF ≥5.2% was used to define significant liver steatosis. Results: Other than higher prevalence of hypertension in the CMD group, age and cardiometabolic history were not significantly different between the groups, as were the PDFF and prevalence of liver steatosis (Table). PDFF directly correlated with body mass index (r=0.41, p<0.01). There was no correlation between PDFF and MPRI (Figure). Conclusions: In this pilot study, our results suggest similar prevalence of liver steatosis between women with CMD and reference controls. Interestingly, MPRI did not correlate with PDFF, suggesting that mechanisms other than metabolic health may play a significant role in the pathophysiology of CMD among women with INOCA.

Regulating Broadband Near‐Infrared Mechanoluminescence via Energy‐Level Engineering for Potential Biomechanical Imaging

AbstractNear‐infrared mechanoluminescent (NIR ML) materials have attracted attention due to their advantages, such as in situ and real‐time monitoring of biomechanical information in vivo. However, most ML materials are focused on the UV–vis light range, which limits their potential applications in the biological field. In this work, a broadband NIR ML material Ca2YGa3Ge2O12: 0.10Cr3+ (CYGGG: 0.10Cr3+) is successfully prepared by chemical co‐substitution and Cr3+ heavy doping. Density functional theory (DFT) calculations are used to determine the type of defects in the material, and the composite defects formed by interstitial oxygen (iO′′) and antisite defects (CaY′ ‐ YCa°) mostly dominate NIR ML. Cr3+ ions act as electronic bridges to regulate energy levels, becoming the key to turning on the Nd3+ ion's NIR ML. Finally, based on the excellent ML properties of CYGGG: 0.10Cr3+ and CYGGG: 0.10Cr3+, 0.01Nd3+, the ML composites can penetrate pork tissues of different compositions/thicknesses under stress loads. Potentially, this work tries to realize biological tissue stress imaging, providing a new way for the biological application of NIR ML materials.

Cocaine-associated Chest Pain: Our Experience with Myocardial Markers and Stress Lexiscans

Abstract Background: Cocaine is a commonly abused recreational drug, leading to frequent emergency room visits. The aim of this study was to check the effect of cocaine on myocardial markers of injury and the stress myocardial imaging patterns. Materials and Methods: All patients with anginal chest pain or equivalents who tested positive for cocaine on urine drug screen with reversible myocardial ischemia on regadenoson stress myocardial perfusion imaging called lexiscans were included and their corresponding myocardial markers of injury and stress imaging were reviewed. Results: Thirty-four patients had tested positive for cocaine in urine, out of the 192 patients with reversible myocardial ischemia on stress testing. The percentage of cocaine-associated myocardial ischemia was up to 17.70% in our study. Creatine kinase-MB levels were above the normal reference value of 5 ng/mL in 72.7% of patients and the combined cardiac troponins by fourth-generation assays were above the detection levels (≥0.02 ng/mL for cardiac troponin I [cTnI] and ≥0.010 ng/mL for cardiac troponin T [cTnT]) in 50% of patients. None of our patients had severe reversible myocardial ischemia on lexicans, but rather minimal-to-mild reversible myocardial ischemia was seen in the majority (76.5%) of patients. cTnI elevation was significantly associated with minimal reversible myocardial ischemia on one-way analysis of variance (P < 0.05). Conclusion: Cocaine was associated with minimal-to-mild reversible myocardial ischemia on stress testing with significant elevation of cTnI.

Use of chatgpt-4 to explain kawasaki disease to parents and paediatric trainees

Abstract Background Paediatric trainees and parents of Kawasaki disease (KD) patients may face challenges when managing the disease due to insufficient accessibility to KD information. Chat Generative Pre-Trained Transformer (ChatGPT) based on large language models may help explain KD information to paediatric trainees and patient parents. Purpose This study aims to determine the usefulness of Chat Generative Pre- Trained Transformer -4 (ChatGPT-4) in explaining Kawasaki Disease (KD) and its management to parents and paediatric trainees managing KD patients. Methods We created 2 sets of clinical scenarios. In the first set, ChatGPT-4 was instructed to respond to 10 questions based on enquiries from parents of KD patients. Responses were scored in terms of "factual accuracy", "coherence", "comprehensiveness", and "humaneness" by 3 paediatric cardiologists using Likert scale of 0-10. Readability were calculated using Flesch reading-ease test. In the second set, ChatGPT-4 was instructed to respond to 8 KD-related questions based on enquiries from paediatric trainees. Responses are graded based on "relevance", "reliability" and "comprehensiveness" using Likert scale of 0-10 by 3 paediatric cardiologists independently. Reviewers would determine whether major advice from chatGPT-4 would be adopted in clinical judgement. Results For parent-targeted responses, ChatGPT-4 achieved the highest scores in ‘humaneness’ (median 9.00, IQR 8.00 to 9.00) and ‘coherence’ (median 8.00, IQR 7.00 to 8.00). Inaccurate information regarding disease prognosis, actions as well as prescription of medications and surgery is found in 80% of scenarios. Missing information regarding long-term coronary complications, antiplatelet management and cardiac assessments is found in all 10 scenarios. Mean readability of parent-targeted responses is 71.70 ± 6.26, a readability level easily understood by 12-year-olds. For paediatrician-targeted responses, ChatGPT-4 achieved the highest scores in ‘relevance’ (median 9.50, IQR 7.25 to 9.0). Inaccurate information regarding coronary interventions, patient education and immunization recommendations is spotted in 37.5% of the scenarios. Missing information regarding patient education and stress imaging is found in 25% of the scenarios. All reviewers would adopt ChatGPT-4’s advice in 87.5% of the scenarios. Conclusions ChatGPT-4 has significant limitations in accuracy and lacks salient information when providing KD recommendations for parents and paediatric trainees.Performance in parent-targeted questionsPerformance in trainee-targeted question

A randomized, double-blind, placebo-controlled, mechanistic trial on the safety, tolerability and pharmacodynamics of ninerafaxstat in patients with angina and chronic coronary syndrome

Abstract Background/Introduction Symptoms of angina resulting from reversible myocardial ischemia in chronic coronary syndromes have a negative impact on quality of life. Metabolic alterations are a key feature of ischemia, including reduced ATP generation by mitochondrial oxidative phosphorylation, NAD+ depletion, anaerobic glycolysis, proton & lactate accumulation leading to contractile dysfunction. Ninerafaxstat is a novel cardiac mitotrope that shifts metabolism from fatty acids towards glucose utilization, optimizing myocardial energy production during ischemia. Purpose We aimed to investigate the safety, tolerability, impact on myocardial glucose utilization and preliminary anti-ischemic efficacy of ninerafaxstat administered for 8 weeks to patients with symptomatic chronic stable angina who were on anti-anginal therapy and had evidence of myocardial stress hypoperfusion using 15O-H2O PET imaging. Methods IMPROVE-Ischemia was an international, randomized, double-blind, placebo-controlled mechanistic trial comparing ninerafaxstat vs. placebo in patients with symptomatic chronic coronary syndrome. The primary endpoint was the safety and tolerability of ninerafaxstat. Key efficacy evaluations were undertaken at baseline and end-of-treatment (Week 8) including imaging core laboratory assessments of 15O-H2O PET perfusion rest and stress imaging to quantify absolute myocardial blood flow (MBF), dobutamine stress echo with contrast for evaluation of LV contractile response during demand stress using the wall motion score index (WMSI) and, in a subgroup of subjects, 18F-FDG-PET imaging of myocardial glucose metabolism. Results The study randomized 58 subjects (mean age 68.6±7.1 years) with symptomatic stable angina and inducible hypoperfusion from 4 sites across 3 countries (Denmark, Finland, Sweden). 22% had type 2 diabetes and 50% had undergone percutaneous and/or surgical coronary revascularization. The majority (68%) were on ≥2 (up to 4) regular anti-anginals. Ninerafaxstat was well tolerated without impact on systemic hemodynamics. At Week 8, ninerafaxstat significantly increased myocardial glucose utilization and, in those with dobutamine-induced deterioration in wall motion at baseline assessment (n=25, pre-specified subgroup), resulted in a ~50% improvement in mean and peak stress WMSI, without altering rest or hyperemic stress MBF (Table 1). Conclusion(s) Treatment with ninerafaxstat was well-tolerated and showed a neutral hemodynamic profile. Ninerafaxstat significantly increased myocardial glucose utilization consistent with its mechanism of action and improved myocardial contractile response to dobutamine stress in subjects with baseline stress inducible deterioration of wall motion. These findings support a direct, metabolically-mediated, anti-ischemic effect of ninerafaxstat on top of existing anti-anginal agents, supporting its further development in cardiac pathologies characterised by ischemia.

Functional correlates of ischemic electrocardiographic changes during stress echocardiography. data form stress echo 2030 survey

Abstract Background/Introduction Cardiac stress tests are carried out in populations with a low probability of ischemic heart disease (IHD) much more frequently than in the past. Stress ECG remains a frequently used modality for the diagnosis of IHD in vast areas of the world with limited facilities. Purpose To assess the diagnostic value of stress ECG for diagnosing IHD using inducible regional wall motion abnormalities (RWMA) on stress echocardiography (SE) as the gold standard method of diagnosis. Methods The 12-lead ECG response was retrospectively analyzed in 4317 patients (age 64±13 years, 59.6% males) undergoing SE for chronic coronary syndromes who were prospectively recruited from 39 cardiac centers between March 2021 and February 2024. Exclusion criteria were left bundle branch block or pacemaker rhythm. ECG response was considered ischemic according to standard criteria (if ST-segment deviated >1.0 mm from baseline in ≥2 contiguous leads at 80 ms from J point) during an exercise (n=2980, 69.8%), dobutamine (n = 766, 18.0%), or vasodilator (n=519, 12.2%) SE. All patients underwent a comprehensive SE protocol with an assessment of wall motion score index (WMSI), B-lines (4-site simplified score), left ventricular contractile reserve (LVCR) based on force, coronary flow velocity reserve (CFVR) in the mid-distal left anterior descending artery (LAD), and heart rate reserve (HRR). Results ECG changes occurred in 641 patients (14.8%, Group 1) for the overall studied population. Compared to patients without ECG changes (Group 2, n=3676, 85.2%), patients with ECG changes showed higher values of peak WMSI and lower values of CFVR and LVCR (see table).Amongst patients without inducible RWMA (n=3553), there were 392 (11%) patients with an ischemic ECG at stress (89% specificity). Of 764 patients with inducible RWMA during SE, 249 had an ischemic ECG trace (sensitivity 33%). In patients without inducible RWMA, those with ischemic ECG changes showed similar abnormal stress B-lines (23% vs. 21%, p=0.719), LVCR (61% vs. 63%, p=0.602), CFVR (31% vs 33%, p=0.607) and HRR (37% vs 41%, p=0.097) compared to those without ECG changes. Amongst patients with inducible RWMA and ECG changes, CFVR was significantly lower in patients with ECG changes (39.2% and 60.8%, respectively, p<0.001). Conclusions Simple standard stress ECG diagnostic value in the current era in populations with a low probability of IHD seems to be low. However, during SE, stress-induced ischemic ECG changes are associated with more extensive RWMA and blunted global LVCR, with reduced CFVR in the LAD. Therefore, analysis of ST segment changes during stress imaging studies can offer additional, significant information.

Evaluation of coronary microvascular dysfunction and vasospasm in patients with angina and non-obstructive coronary artery disease

Abstract Background Angina in the absence of obstructive coronary artery disease (CAD) is a growing cause of morbidity and mortality, exceeding the economic burden of CAD. Roughly 50-70% of patients undergoing invasive angiography for anginal symptoms have non-obstructive CAD. Within this category, there are distinct sub-populations including patients with angina without evidence of ischemia on prior stress testing (ANOCA), evidence of ischemia on stress testing (INOCA), or history of obstructive CAD with prior revascularization (ANOCA-HxCAD). Coronary microvascular dysfunction (CMD) and/or epicardial vasospasm are common causes of angina in the absence of epicardial CAD despite optimal medical therapy. Differences between these groups, in terms of risk factors and diagnoses remain relatively unknown. Purpose To compare clinical characteristics, symptoms, and diagnoses between patients with ANOCA, INOCA, and ANOCA-HxCAD. Methods In a prospective registry-based cohort study of 306 patients without obstructive CAD (<50% stenosis in epicardial artery) undergoing coronary functional angiography (CFA), we assessed differences in clinical characteristics, symptoms, and CFA diagnoses: (1) endothelial-independent CMD (coronary flow reserve [CFR] <2.5) to adenosine testing, (2) endothelial-dependent CMD (coronary blood flow [CBF]<50% or no change in vessel diameter to 54 mcg intracoronary acetylcholine [ACH]), (3) epicardial vasospasm to 108 mcg intracoronary ACH in 3 groups of patients (ANOCA, INOCA, and ANOCA-HxCAD). Results Among the 306 patients undergoing CFA, 89% were female with a median age of 58 years (49, 67). Patients with ANOCA-HxCAD had a significantly higher prevalence of hypertension, diabetes, heart failure with preserved ejection fraction, and experienced worse dyspnea on exertion as measured by University of San Diego Shortness of Breath (UCSD SOB) in comparison to ANOCA or INOCA patients. However, there were no differences between the groups in terms of anginal severity, functional capacity, or quality of life. In terms of CFA diagnoses, vasospasm was more prevalent in ANOCA-HxCAD (p<0.001) and CMD was more prevalent in ANOCA and INOCA patients (p=0.034) (Table 1). Conclusions Despite differences in clinical characteristics, patients without obstructive CAD have similar anginal severity, functional capacity, and quality of life regardless of evidence of ischemia on prior stress imaging or history of revascularization. There are differences in CFA diagnoses with higher prevalence of CMD in ANOCA and INOCA patients and higher prevalence of vasospasm in ANOCA-HxCAD patients. Determining the underlying diagnoses changes clinical management; therefore, CFA should be considered in all patients without obstructive CAD.

A dual-channel convolutional neural network with attention mechanism DC_EcaNet-6 for creep life prediction of notched components

Machine learning models offer novel possibilities for creep life prediction of materials and components at elevated temperatures. Present studies primarily focus on material-level creep life prediction, with limited reports on component-level analysis due to the complex stress states around structural discontinuities. Based on this, a dual-channel convolutional neural network with attention mechanism, DC_EcaNet-6, is proposed for creep life prediction of notched components, where the images of Mises stress and stress tri-axiality are employed as the input. The prediction results by the DC_EcaNet-6 model are compared with that by some deep learning models and the simplified method. Creep reliability assessment of notched components using the DC_EcaNet-6 model is conducted. The results indicate that the proposed model provides a more superior creep life prediction accuracy of notched components than other models mentioned. This model provides a potential tool for creep life prediction and reliability assessment of notched components.

Study on the rockburst risk of alternate exterior entry under island coal pillar

The extraction of extremely thick coal seams through slicing mining requires leaving behind several island coal pillars in the top slicing, which could lead to rockburst in the bottom slicing. This article proposed a method of alternate exterior entry (AEE) for rockburst prevention based on the stress distribution of bottom slicing. The influences of coal pillar width [Formula: see text] and stress concentration factor [Formula: see text] on stress distribution were explored using two-dimensional stress imaging. The results indicated that K value had a greater effect on stress distribution comparing with B value. Both stress relaxed and stress rate angles increased linearly with an increase in K value. In order to get the optimized location of AEE in the coal mine stress rate angle was chosen as the stress extension angle, which was further verified by field data from 1210 coal faces. Finally, numerical simulation was used to explore the optimized location of special tail entry under dip island coal pillars for rockburst prevention. It was revealed that plan first was found to be most effective due to its presence in a stress-relaxed area, thus verifying the effectiveness of the AEE method for rockburst prevention.

Feasibility and Safety of Post-Transcatheter Aortic Valve Replacement Coronary Revascularization Guided by Stress Cardiac Imaging

Background: Systematic revascularization of asymptomatic coronary artery stenosis before transcatheter aortic valve replacement (TAVR) is controversial. Purpose: The purpose of this study was to evaluate the feasibility and safety of functional evaluation of coronary artery disease (CAD) followed by selective ischemia-guided percutaneous coronary revascularization following TAVR. Methods: This prospective, bi-centric, single-arm, open-label trial included all patients with severe aortic stenosis (AS) eligible for TAVR and with significant CAD defined as ≥1 coronary stenosis ≥ 70%. Patients with left main stenosis ≥ 50%, proximal left anterior descending artery (LAD) stenosis ≥ 90% or > class 2 Canadian Classification Society (CCS) angina were excluded. Myocardial ischemia was evaluated by stress cardiac imaging one month after TAVR. The primary endpoint was a composite of all-cause death, stroke, major bleeding (Bleeding Academic Research Consotium ≥ 3), major vascular complication (Valve Academic Research Consortium 3 criteria), acute coronary syndrome (ACS) and hospitalization for cardiac causes within 6 months of receiving TAVR. Results: Between June 2020 and June 2022, 64 patients were included in this study. The mean age was 84 ± 5.2 years. CAD mostly involved LAD (n = 27, 42%) with frequent multivessel disease (n = 30, 47%) and calcified lesions (n = 39, 61%). Stress cardiac imaging could be achieved in 70% (n = 46) of the patients, while 30% (n = 18) did not attend the stress test. Significant myocardial ischemia was observed in only three patients (4.5%). At 6-month follow-up, fifteen patients (23%) reached the primary endpoint, including death in six patients (9%), stroke in three patients (5%) and major bleeding in three patients (5%). ACS was observed in only two patients (3%) but both had severe coronary stenosis (≥90%) and did not refer for stress imaging for personal reasons. Hospital readmission (n = 27, 41%) was mostly related to non-cardiac causes (n = 17, 27%). Conclusions: In patients with asymptomatic CAD scheduled to undergo TAVR, a selective ischemia-guided coronary revascularization after TAVR seems to be safe, with a very low rate of ACS and few cases of myocardial ischemia requiring revascularization, despite low adherence to medical follow-up in this elderly population. This strategy could be evaluated in a randomized study.

Simultaneous In Vivo Imaging of Neutrophil Elastase and Oxidative Stress in Atherosclerotic Plaques Using a Unimolecular Photoacoustic Probe.

Atherosclerosis, a major global health concern with high morbidity and mortality rates, involves complex interactions of chronic inflammation, oxidative stress, and proteolytic enzymes. Conventional imaging methods struggle to capture the dynamic biochemical processes in atherosclerotic plaques. Here, we introduce a novel unimolecular photoacoustic probe (UMAPP) designed with specific binding sites for neutrophil elastase (NE) and the redox pair O2⋅-/GSH, enabling real-time monitoring of oxidative stress and activated neutrophils in plaques. UMAPP, comprising a boron-dipyrromethene (BODIPY) core linked to a hydrophilic NE-cleavable tetrapeptide and dual oxidative stress-responsive catechol moieties, facilitates NE-mediated modulation of photoinduced electron transfer impacting photoacoustic intensity at 685 nm (PA685). Furthermore, oxidation and reduction of catechol groups by O2⋅- and GSH induce reversible, ratiometric changes in the photoacoustic spectrum (PA745/PA685 ratio). Initial UMAPP applications successfully distinguished atherosclerotic and healthy mice, evaluated pneumonia's effect on plaque composition and verified the probe's effectiveness in drug-treatment studies by detecting molecular alterations before visible histopathological changes. The integrated molecular imaging capabilities of UMAPP offer promising advancements in atherosclerosis diagnosis and management, enabling early and accurate identification of vulnerable plaques.

Simultaneous In Vivo Imaging of Neutrophil Elastase and Oxidative Stress in Atherosclerotic Plaques Using a Unimolecular Photoacoustic Probe

AbstractAtherosclerosis, a major global health concern with high morbidity and mortality rates, involves complex interactions of chronic inflammation, oxidative stress, and proteolytic enzymes. Conventional imaging methods struggle to capture the dynamic biochemical processes in atherosclerotic plaques. Here, we introduce a novel unimolecular photoacoustic probe (UMAPP) designed with specific binding sites for neutrophil elastase (NE) and the redox pair O2⋅−/GSH, enabling real‐time monitoring of oxidative stress and activated neutrophils in plaques. UMAPP, comprising a boron‐dipyrromethene (BODIPY) core linked to a hydrophilic NE‐cleavable tetrapeptide and dual oxidative stress‐responsive catechol moieties, facilitates NE‐mediated modulation of photoinduced electron transfer impacting photoacoustic intensity at 685 nm (PA685). Furthermore, oxidation and reduction of catechol groups by O2⋅− and GSH induce reversible, ratiometric changes in the photoacoustic spectrum (PA745/PA685 ratio). Initial UMAPP applications successfully distinguished atherosclerotic and healthy mice, evaluated pneumonia‘s effect on plaque composition and verified the probe‘s effectiveness in drug‐treatment studies by detecting molecular alterations before visible histopathological changes. The integrated molecular imaging capabilities of UMAPP offer promising advancements in atherosclerosis diagnosis and management, enabling early and accurate identification of vulnerable plaques.

Rationale and design of the multicentric randomized EVAOLD trial: evaluation of a strategy guided by imaging versus routine invasive strategy in elderly patients with ischemia

BackgroundThe management of myocardial infarction without ST segment elevation (NSTEMI) in elderly patients remains challenging, in particular the benefit/risk balance of routine revascularization remains uncertain. Study designEVAOLD is s a multicenter, prospective, open-label trial with 2 parallel arms in NSTEMI patients ≥ 80 years of age. The aim of the trial is to test whether a strategy of selective invasive management guided by ischemia stress imaging (IMG group) will be non-inferior in preventing Major Adverse Cardiac and Cerebrovascular Events (MACCE, ie all-cause death, non-fatal myocardial infarction, non-fatal stroke) rates at 1 year compared with a routine invasive strategy (INV Group). Geriatric assessment and cost- effectiveness analysis will also be performed. A sample size of 1756 patients (assuming a 10% rate of patients lost to follow-up) is needed to show non-inferiority with 80% power. Non-inferiority based on exponential survival curves will be declared if the upper limit of the one-sided 97.5% confidence interval for the hazard ratio is lower than 1.24, corresponding to a non-inferiority margin of 7% in absolute difference and an event rate of 40% in the INV group. ConclusionEVAOLD is a nationwide, prospective, open-label trial testing the non-inferiority of a strategy of selective invasive management guided by ischemia stress imaging versus routine invasive strategy in elderly NSTEMI patients. ClinicalTrials.gov Identifier: NCT03289728

An efficient pseudoelastic pure P‐mode wave equation and the implementation of the free surface boundary condition

AbstractBased on the elastic wave equation, a pseudoelastic pure P‐mode wave equation has been recently derived by projecting the wavefield along the wavefront normal direction. This pseudoelastic pure P‐mode wave equation offers an accurate simulation of P‐wave fields with accurate elastic phase and amplitude characteristics. Moreover, considering no S‐waves are involved, it is computationally more efficient than the elastic wave equation, making it an excellent choice as a forward simulation engine for P‐wave exploration. Here, we propose a new pseudoelastic pure P‐mode wave equation and apply the stress image method to it to implement the free surface boundary condition. The new pseudoelastic wave equation offers significantly improved computational efficiency compared to the previous pseudoelastic wave equation. Additionally, the wavefields simulated by this new pseudoelastic wave equation exhibit clear physical interpretations. We evaluate the accuracy of the new wave equation in simulating elastic P‐waves by employing a model with high‐velocity contrasts. We find that this new equation, which purely admits P‐waves, though having exact amplitude and phase behaviour as the elastic waves for transmission components, the amplitudes slightly suffer in the scattering scenario. The difference in amplitude between the elastic and our pseudoelastic increases as the contrast in velocity at the interface (interlayer velocity ratio) increases, especially the S‐wave velocities. This has negative implications on scattering from the free surface boundary condition or the sea bottom interface, especially if the shear wave velocity below the surface or the sea bottom is high. However, in cases where, like for land data in the Middle East, the transition to a free surface is smoother, the accuracy of the pseudoelastic equation is high. In all cases, regardless of the interlayer velocity ratio, the accuracy of the pseudoelastic wave equation in simulating the elastic case, for scattered waves, exceeds that of the acoustic wave equation in phase and amplitude.

Lateral Compression Fragility Fractures of the Pelvis: Diagnosis, Classifications, and Modern Management.

To describe the diagnosis, classification, and modern management of lateral compression fragility fractures of the pelvis. Practice patterns are shifting toward early operative treatment of fragility fractures of the pelvis among patients who are unable to mobilize or whose injuries demonstrate occult instability on stress imaging. Early internal fixation appears to decrease pain, facilitate mobilization, accelerate hospital discharge, and minimize morbidity in this population. Lateral compression pelvic ring injuries are the most common type of fragility fracture of the pelvis. Similar to fragility fractures of the hip, lateral compression fragility fractures of the pelvis are typically sustained in a ground level fall. These injuries are associated with long acute hospital and post-acute facility admissions, loss of physical function, loss of independence, mortality, anxiety, sleep disturbance, and caregiver burnout. Unlike hip fractures, for which urgent operative treatment and early mobilization reduce mortality, lateral compression fragility fractures of the pelvis are commonly treated without surgery. Recommendations for nonoperative management of these injuries in older adults may be inappropriately generalized from studies of younger patient populations with high-energy mechanisms of pelvis fracture. However, strong evidence to support early internal fixation of these injuries practice is lacking. High quality investigations of early surgical intervention for lateral compression fragility fractures of the pelvis are needed to guide care for these patients.

Hyperspectral Imaging for Phenotyping Plant Drought Stress and Nitrogen Interactions Using Multivariate Modeling and Machine Learning Techniques in Wheat

Accurate detection of drought stress in plants is essential for water use efficiency and agricultural output. Hyperspectral imaging (HSI) provides a non-invasive method in plant phenotyping, allowing the long-term monitoring of plant health due to sensitivity to subtle changes in leaf constituents. The broad spectral range of HSI enables the development of different vegetation indices (VIs) to analyze plant trait responses to multiple stresses, such as the combination of nutrient and drought stresses. However, known VIs may underperform when subjected to multiple stresses. This study presents new VIs in tandem with machine learning models to identify drought stress in wheat plants under varying nitrogen (N) levels. A pot wheat experiment was set up in the glasshouse with four treatments: well-watered high-N (WWHN), well-watered low-N (WWLN), drought-stress high-N (DSHN) and drought-stress low-N (DSLN). In addition to ensuring that plants were watered according to the experiment design, photosynthetic rate (Pn) and stomatal conductance (gs) (which are used to assess plant drought stress) were taken regularly, serving as the ground truth data for this study. The proposed VIs, together with known VIs, were used to train three classification models: support vector machines (SVM), random forest (RF), and deep neural networks (DNN) to classify plants based on their drought status. The proposed VIs achieved more than 0.94 accuracy across all models, and their performance further increased when combined with known VIs. The combined VIs were used to train three regression models to predict the stomatal conductance and photosynthetic rates of plants. The random forest regression model performed best, suggesting that it could be used as a stand-alone tool to forecast gs and Pn and track drought stress in wheat. This study shows that combining hyperspectral data with machine learning can effectively monitor and predict drought stress in crops, especially in varying nitrogen conditions.

Factors affecting adherence to recommendations on pre-operative cardiac testing: A cohort study.

Cardiac risk evaluation prior to noncardiac surgery is fundamental to tailor peri-operative management to patient's estimated risk. Data on the degree of adherence to guidelines in patients at cardiovascular risk in Europe and factors influencing adherence are underexplored. The aim of this analysis was to describe the degree of adherence to [2014 European Society of Cardiology (ESC)/European Society of Anaesthesiology (ESA) guidelines] recommendations on rest echocardiography [transthoracic echocardiography (TTE)] and to stress imaging prior to noncardiac surgery in a large European sample and to assess factors potentially affecting adherence. Secondary analysis of a multicentre, international, prospective cohort study (MET-REPAIR). Twenty-five European centres of all levels of care that enrolled patients between 2017 and 2020. With elevated cardiovascular risk undergoing in-hospital elective, noncardiac surgery. (Non)adherence to each pre-operative TTE and stress imaging recommendations classified as guideline-adherent, overuse and underuse. We performed descriptive analysis. To explore the impact of patients' sex, age, geographical region, and hospital teaching status, we conducted multivariate multinominal regression analysis. Out of 15 983 patients, 15 529 were analysed (61% men, mean age 72 ± 8 years). Overuse (conduction in spite of class III) and underuse (nonconduction in spite of class I recommendation) for pre-operative TTE amounted to 16.6% (2542/15 344) and 6.6% (1015/15 344), respectively. Stress imaging overuse and underuse amounted to 1.7% (241/14 202) and 0.4% (52/14 202) respectively. Male sex, some age categories and some geographical regions were significantly associated with TTE overuse. Male sex and some regions were also associated with TTE underuse. Age and regions were associated with overuse of stress imaging. Male sex, age, and some regions were associated with stress imaging underuse. Adherence to pre-operative stress imaging recommendation was high. In contrast, adherence to TTE recommendations was moderate. Both patients' and geographical factors affected adherence to joint ESC/ESA guidelines. NCT03016936.

Use of downstream stress imaging tests for risk stratification of patients presenting to the emergency department with chest pain and low HEART score

BackgroundPatients with low HEART (History, Electrocardiogram, Age, Risk factors, and Troponin level) risk scores who are discharged from the emergency department (ED) may present clinical challenges and diagnostic dilemmas. The...

Combined Supine-Prone Myocardial Perfusion Imaging: Enhancing Diagnostic Accuracy.

The combined supine-prone imaging protocol for SPECT myocardial perfusion imaging offers significant advantages over supine imaging alone. By comparing supine and prone images, one can distinguish attenuation artifacts in the inferior and anterior walls from true perfusion defects, thus improving specificity and diagnostic accuracy. The recommended protocol is to perform prone imaging after supine stress imaging when perfusion defects are noted. The additional prone imaging time is 20%-40% less than the standard supine imaging time. Implementing prone imaging can optimize patient care and provide substantial benefits for nuclear cardiology labs, especially those without attenuation correction.