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At least 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Evaluation and calibration of MERRA-2 and CAMS reanalysis for PM 2.5 in a semi-urbanized area in the south of the Amazon

Air pollution has significant implications for the climate and poses irreversible risks to human health. The Amazon region of Brazil is severely affected by biomass burning (BB) emissions, yet air quality monitoring remains highly inadequate. Given the scarcity of surface-based observations, reanalysis models have become essential tools for assessing air pollution. Although MERRA-2 and CAMS PM 2.5 products are widely utilized, their validation and comprehensive evaluation for the Amazon Basin remain limited. Here, this study assesses the performance of these products in a semi-urbanized region in the southern Amazon. The calibrated time series was employed to analyze PM 2.5 concentrations from 2003 to 2023. Our results showed satisfactory performance of both products for the 24-h averages of PM 2.5 , with linear correlations above 0.76. However, it was found that both products overestimate surface concentrations. MERRA-2 performed better, with approximately 30% lower bias than CAMS. Time series analysis showed that the study area is strongly impacted by emissions BB in the dry period, mainly in August and September. Furthermore, our findings indicate a positive trend in increasing PM 2.5 concentrations, with a notable rise observed since 2014. The average PM 2.5 levels frequently exceed the daily air quality guidelines established by the WHO in 2021. It has been estimated that the population of this region is exposed to concentrations above 15 μg.m -3 , on average, more than 30 days per year. Our results contribute to the evaluation of MERRA-2 and CAMS products for Amazon and provide a corrected estimate for surface PM 2.5 . Recent concerns about air quality and the implementation of new surface monitoring networks may improve the evaluation of reanalysis products. In the short term, the need for this information makes our assessments indispensable.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Is There a Need to Revise Goals in the Management of Dyslipidemias?

Purpose of Review: Current guidelines on the management of patients with dyslipidemias recommend specific risk-dependent low-density lipoprotein cholesterol (LDL-C) treatment goals. Recently, several randomized clinical trials have investigated further lowering of LDL-C in addition to statin therapy using novel therapeutic approaches and examined their effects on cardiovascular (CV) risk. This review summarizes newly available data on efficacy and safety of lowering LDL-C beyond statin therapy and below current treatment targets. Recent Findings: In patients at very high risk for CV events, a significant residual risk remains when failing to achieve significant LDL-C reduction on maximally tolerated statin therapy alone. Further lowering of LDL-C, even beyond current treatment targets, has been shown to be safe and was associated with a further reduced CV risk reduction. The relative risk reduction per change in LDL-C levels has been observed to be consistent even in patient populations achieving extremely low levels of LDL-C. Summary: In patients at very high CV risk, further lowering of LDL-C beyond statin therapy and present treatment targets has been observed to further reduce CV risk, which may be foremost relevant for patients at a particular high absolute CV risk, e.g., for patients with progressive and/or very extensive coronary disease.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Emerging Role of Coronary Computed Tomography Angiography in Lipid-Lowering Therapy: a Bridge to Image-Guided Personalized Medicine

Purpose of Review: To summarize the current status of coronary computed tomography angiography (CTA) in the assessment of coronary plaques and discuss the ability of serial coronary CTA to quantitatively measure changes in the plaque burden in response to lipid-lowering therapy. Recent Findings: Recent advances in coronary CTA have allowed identification of high-risk coronary features in acute coronary syndrome and measurement of changes in the coronary plaque burden with good reproducibility. Statin therapy may delay plaque progression and change some plaque features. However, the clinical relevance of quantitative changes in coronary plaques and the optimal methods to reduce the plaque burden remain unclear. Summary: Despite guideline-directed lipid-lowering therapy, adverse events still occur in substantial numbers of patients receiving statins. Coronary CTA is noninvasive and has high diagnostic performance in patients with coronary artery disease, making change in the plaque burden an applicable biomarker for individualized assessment of future risk.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

The Role of Multimodality Imaging in Transcatheter Aortic Valve Replacement

Purpose of Review: Multimodality imaging is integral for diagnosis, procedural guidance, and follow-up of patients undergoing transcatheter aortic valve replacement (TAVR). In this review, we provide an overview of the role of each imaging modality and highlight technical considerations and pitfalls. We also address current controversies and new developments in the field. Recent Findings: Echocardiography remains the primary imaging modality for diagnosis of aortic stenosis and intraprocedural guidance for TAVR, but computed tomography (CT) imaging has supplanted echocardiography for annular sizing and access site evaluation. Magnetic resonance imaging (MRI) shows promise in targeted patient populations. Refined parameters and guidelines for valve sizing and paravalvular regurgitation have sought to standardize these complex assessments. Summary: Multimodality imaging remains critical to the success of TAVR, but its role has evolved over time. Understanding the applications, strengths, and limitations of each imaging modality is a crucial skill for the modern structural imager.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Non-invasive Risk Stratification for Coronary Artery Disease: Is It Time for Subclassifications?

Purpose of Review: Coronary artery disease (CAD) is the leading contributor to cardiovascular disease; it is the most prevalent non-communicable disease globally and has high morbidity, mortality and health care cost. Risk stratification is defined as prevention or containment of disease prior to it occurring or progressing, and non-invasive surrogates include history, examination, biomarkers and non-invasive imaging. This review aims to highlight advancement in current diagnostic strategies and explores gaps for CAD secondary to atherosclerosis and non-obstructive vascular diseases. Recent Findings: Cardiac risk scores have largely proven inadequate in risk stratifying heterogeneous patient populations. Greater emphasis should also be provided to posttest risk stratification. Non-invasive imaging with MRI is the most accurate but least cost efficacious presently due to availability and expertise. Echocardiography and nuclear imaging have good accuracy, but radiation limits the latter. Novel echocardiographic technologies may increase its appeal. Cardiac CT angiography is increasingly promising. Summary: Non-invasive and minimally invasive imaging has significantly influenced the cost-efficacy trajectory of coronary artery disease diagnosis and management. Recent studies suggest that future guidelines will incorporate more subclassifications from the findings of these novel technologies and for more diverse patient demographics.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Can Direct Oral Anticoagulants Be Used for Stroke Prevention Among Patients with Valvular Atrial Fibrillation?

Purpose of Review: To review the clinical evidence underlying the efficacy and safety of the use of direct oral anticoagulants (DOACs) for the treatment of patients with valvular atrial fibrillation (AF). Recent Findings: The recent focused update to the 2014 AHA/ACC/HRS Atrial Fibrillation Guidelines defines valvular AF as AF in the setting of moderate-to-severe mitral stenosis (MS) and/or in the presence of a mechanical heart valve. Landmark clinical trials of DOACs in patients with AF systematically excluded these patient populations. However, there are trial data in both animals and humans regarding the use of DOACs in patients with MS and in those with mechanical heart valves. Summary: Based on sub-analyses and meta-analyses of clinical trial data in patients with AF, the use of DOACs in valvular AF is not recommended. Patients with moderate-to-severe MS or a mechanical heart valve and AF should be anticoagulated with dose-adjusted warfarin. DOACs are reasonable alternatives to warfarin in patients with AF and other types of valvular disease, including mild MS and bioprosthetic valves.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Cardiac Sarcoidosis

Purpose of Review: In this state-of-the-art review, we highlight our current understanding of diagnosis, assessment, and management of cardiac sarcoidosis (CS), focusing on recently published data and expert consensus statement guidelines. Recent Findings: Academic interest in cardiac sarcoidosis research has increased over the past decade along with increased clinical awareness among clinicians. In 2014, the Heart Rhythm Society published the first expert consensus statement on diagnosing and managing arrhythmias associated with CS. Cardiac magnetic resonance has emerged as a valuable tool both for diagnosing CS and predicting risk of life-threatening ventricular arrhythmias based on burden of late gadolinium enhancement. Cardiac fluorodeoxyglucose-positron emission tomography now plays a role in diagnosis, risk stratification, and assessing response to immunosuppressive therapy. Summary: Collaborative, multidisciplinary research efforts are needed to further our understanding of this rare, complex disease. Two large multicenter prospective registries—the international Cardiac Sarcoidosis Consortium and the Canadian Cardiac Sarcoidosis Research Group—are enrolling patients to help provide insights into the natural history of the disease and current treatment strategies. Future research should focus on randomized controlled trials comparing different treatment strategies and identifying and testing novel therapeutic agents.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Bone marrow examination in patients with Ewing sarcoma/peripheral primitive neuroectodermal tumor without metastasis based on {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography

Ewing sarcoma/peripheral primitive neuroectodermal tumor (ES/PNET) is an aggressive bone tumor. Bone marrow aspiration and biopsy (BMAB) has been recognized as the gold standard for assessing bone marrow status. While the latest guideline suggests the need to omit bone marrow aspiration in patients with no findings on {sup 18}F-fluorodeoxyglucose positron emission tomography ({sup 18}F-FDG PET) based on one retrospective report, there is no study using {sup 18}F-FDG PET/computed tomography (CT). We retrospectively reviewed 26 consecutive, previously untreated, ES/PNET patients. We compare the results of bone marrow aspiration and biopsy (BMAB) and those of {sup 18}F-FDG PET/CT in ES/PNET patients. All of the 21 patients without metastases on {sup 18}F-FDG PET/CT had negative BMAB. The sensitivity of bone marrow involvement in bone metastases positive patients on {sup 18}F-FDG PET/CT was 75% (3/4), and the specificity was 100% (22/22). In addition to the metastatic findings on {sup 18}F-FDG PET/CT, tumor diameter, lactate dehydrogenase level at diagnosis, and the presence or absence of bone metastasis were factors related to bone marrow involvement. It may be a reasonable option to omit BMAB in ES/PNET patients with no distant metastasis based on {sup 18}F-FDG PET/CT findings.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Rhabdomyosarcoma in adults: analysis of treatment modalities in a prospective single-center series

Rhabdomyosarcoma (RMS) is rare in adults and it is generally characterized by poor outcome. In a previous retrospective study, we demonstrated a better prognosis in adults treated with multimodality approach resembling pediatric protocols. Thereafter, we developed specific recommendations based on the principles adopted in pediatric oncology. The present analysis reports the results in a subsequent prospective series. The study included 95 consecutive patients (age 18–77 years) treated from 2002 to 2015 for embryonal and alveolar RMS. As in the previous series, patients were stratified by the appropriateness of their treatment according to therapeutic guidelines for childhood RMS. The 5-year event-free survival (EFS) and overall survival (OS) rates were 33.6% and 40.3%, respectively. The 5-year EFS was 40.8% for patients with the highest treatment score, and 15% for those with lower score, while OS was 44.4% and 24.5%, respectively. The developing of specific recommendations enabled an increase in the number of patients treated with intensive multimodal treatment resembling pediatric strategy (69.7% vs. 39.1% in the retrospective series). This study reinforced the idea that adherence to the principles of pediatric protocols, improves adult RMS outcomes. However, treating adults with pediatric-type strategy is not enough to achieve the results obtained in children. Issues in compliance and a more aggressive biology of adult RMS might have a role in the different outcome according to age. Improving the collaboration between pediatric and adult oncologists in promoting specific clinical and biological research is crucial to improve the outcome for this patient population.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Liver graft rejection following immune checkpoint inhibitors treatment: a review

Immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in a variety of solid tumors; nonetheless, they have not been well investigated and are still recognized as a relative contraindication for patients with a liver transplantation (LT) history, since ICIs treatment might potentially lead to graft rejection. The program death-1 (PD-1) and the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) pathways are implicated in the tolerance of transplanted organ, as well as blockade of the pathways, which contribute to eliminating tumors and may inadvertently lead to peripheral transplant rejection. Currently, no guidelines are available regarding the treatment for ICIs patients with a prior LT history. Therefore, this study was carried out to review the recent studies, attempting to introduce the ICIs-related graft rejection after LT from various aspects. We believed that ICIs could be given for the well-informed patients receiving LT and developed recurrence in a controlled setting. Typically, these patients should be treated according to a clinical care path or a prospective clinical trial, so as obtain a persistent anti-tumor immune response in the meantime of avoiding graft rejection, adjust the immunosuppression, reduce the possibility of graft loss following rejection, and have the opportunity to develop biomarkers for tumor response and transplant rejection.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Performance-driven optimization of urban open space configuration in the cold-winter and hot-summer region of China

Urbanization has led to changes in urban morphology and climate, while urban open space has become an important ecological factor for evaluating the performance of urban development. This study presents an optimization approach using computational performance simulation. With a genetic algorithm using the Grasshopper tool, this study analyzed the layout and configuration of urban open space and its impact on the urban micro-climate under summer and winter conditions. The outdoor mean Universal Thermal Climate Index (UTCI) was applied as the performance indicator for evaluating the quality of the urban micro-climate. Two cases—one testbed and one real urban block in Nanjing, China -- were used to validate the computer-aided simulation process. The optimization results in the testbed showed UTCI values varied from 36.5 to 37.3 °C in summer and from -4.9 to -1.9 °C in winter. In the case of the real urban block, optimization results show, for summer, although the average UTCI value increased by 0.6 °C, the average air velocity increased by 0.2 m/s; while in winter, the average UTCI value increased by 1.7 °C and the average air velocity decreased by 0.2 m/s. These results demonstrate that the proposed computer-aided optimization process can improve the thermal comfort conditions of open space in urban blocks. Finally, this study discusses strategies and guidelines for the layout design of urban open space to improve urban environment comfort.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Evaluating the energy impact potential of energy efficiency measures for retrofit applications: A case study with U.S. medium office buildings

Quantifying the energy savings of various energy efficiency measures (EEMs) for an energy retrofit project often necessitates an energy audit and detailed whole building energy modeling to evaluate the EEMs; however, this is often cost-prohibitive for small and medium buildings. In order to provide a defined guideline for projects with assumed common baseline characteristics, this paper applies a sensitivity analysis method to evaluate the impact of individual EEMs and groups these into packages to produce deep energy savings for a sample prototype medium office building across 15 climate zones in the United States. We start with one baseline model for each climate zone and nine candidate EEMs with a range of efficiency levels for each EEM. Three energy performance indicators (EPIs) are defined, which are annual electricity use intensity, annual natural gas use intensity, and annual energy cost. Then, a Standard Regression Coefficient (SRC) sensitivity analysis method is applied to determine the sensitivity of each EEM with respect to the three EPIs, and the relative sensitivity of all EEMs are calculated to evaluate their energy impacts. For the selected range of efficiency levels, the results indicate that the EEMs with higher energy impacts (i.e., higher sensitivity) in most climate zones are high-performance windows, reduced interior lighting power, and reduced interior plug and process loads. However, the sensitivity of the EEMs also vary by climate zone and EPI; for example, improved opaque envelope insulation and efficiency of cooling and heating systems are found to have a high energy impact in cold and hot climates.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Mechanistic modeling of copper corrosions in data center environments

Air-side economizers are increasingly used to take advantage of “free-cooling” in data centers with the intent of reducing the carbon footprint of buildings. However, they can introduce outdoor pollutants to indoor environment of data centers and cause corrosion damage to the information technology equipment. Here, to evaluate the reliability of information technology equipment under various thermal and air-pollution conditions, a mechanistic model based on multi-ion transport and chemical reactions was developed. The model was used to predict Cu corrosion caused by Cl2-containing pollutant mixtures. It also accounted for the effects of temperature (25 °C and 28 °C), relative humidity (50%, 75%, and 95%), and synergism. It also identified higher air temperature as a corrosion barrier and higher relative humidity as a corrosion accelerator, which agreed well with the experimental results. The average root mean square error of the prediction was 13.7 Å. The model can be used to evaluate the thermal guideline for data centers design and operation when Cl2 is present based on pre-established acceptable risk of corrosion in data centers’ environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Myocardial perfusion imaging in women for the evaluation of stable ischemic heart disease—state-of-the-evidence and clinical recommendations

This document from the American Society of Nuclear Cardiology represents an updated consensus statement on the evidence base of stress myocardial perfusion imaging (MPI), emphasizing new developments in single-photon emission tomography (SPECT) and positron emission tomography (PET) in the clinical evaluation of women presenting with symptoms of stable ischemic heart disease (SIHD). The clinical evaluation of symptomatic women is challenging due to their varying clinical presentation, clinical risk factor burden, high degree of comorbidity, and increased risk of major ischemic heart disease events. Evidence is substantial that both SPECT and PET MPI effectively risk stratify women with SIHD. The addition of coronary flow reserve (CFR) with PET improves risk detection, including for women with nonobstructive coronary artery disease and coronary microvascular dysfunction. With the advent of PET with computed tomography (CT), multiparametric imaging approaches may enable integration of MPI and CFR with CT visualization of anatomical atherosclerotic plaque to uniquely identify at-risk women. Radiation dose-reduction strategies, including the use of ultra-low-dose protocols involving stress-only imaging, solid-state detector SPECT, and PET, should be uniformly applied whenever possible to all women undergoing MPI. Appropriate candidate selection for stress MPI and for post-MPI indications for guideline-directed medical therapy and/or invasive coronary angiography are discussed in this statement. The critical need for randomized and comparative trial data in female patients is also emphasized.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Assessment of left ventricular contraction patterns using gated SPECT MPI to predict cardiac resynchronization therapy response

Background: The U-shaped left ventricular (LV) contraction pattern, identified by MRI or echocardiography, is associated with improved CRT response. Gated SPECT MPI can measure both myocardial viability and mechanical dyssynchrony in a single scan. The aim of this study is to examine the relationship of the LV contraction pattern and the response of CRT in patients with left bundle branch block (LBBB). Methods: Fifty-eight patients who met CRT guidelines and who had pre-CRT MPI were enrolled. Myocardial segments with tracer uptake < 50% of maximum were considered as scar. The LV contraction pattern was considered as U-shaped or non-U-shaped (U-shaped has a block line in the direction of contraction propagation). CRT response was defined as an increase in left ventricular ejection fraction ≥ 5% after 6-month follow-up. Results: Twenty-eight patients (48%) had a U-shaped contraction pattern and thirty patients (52%) had a non-U-shaped contraction pattern. The U-shaped group showed a significantly higher response rate than the non-U-shaped group (90% vs. 57%; P = 0.005). By univariate and multivariate logistic regression analysis, the U-shaped pattern was an independent predictor of CRT response. Conclusion: Non-invasive gated SPECT MPI can characterize LV mechanical contraction patterns. A U-shaped contraction pattern identified is associated with improved CRT response. This may prove useful for improved patient selection for CRT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Coronary risk equivalence of diabetes assessed by SPECT-MPI

Background: Several publications and guidelines designate diabetes mellitus (DM) as a coronary artery disease (CAD) risk equivalent. The aim of this investigation was to examine DM cardiac risk equivalence from the perspective of stress SPECT myocardial perfusion imaging (MPI). Methods and Results: We examined cardiovascular outcomes (cardiac death or nonfatal MI) of 17,499 patients referred for stress SPECT-MPI. Patients were stratified into four categories: non-DM without CAD, non-DM with CAD, DM without CAD, and DM with CAD, and normal or abnormal perfusion. Cardiac events occurred in 872 (5%), with event-free survival best among non-DM without CAD, worst in DM with CAD, and intermediate in DM without CAD, and non-DM with CAD. After multivariate adjustment, risk remained comparable between DM without CAD and non-DM with CAD [AHR 1.0 (95% CI 0.84–1.28), P =0.74]. Annualized event rates for normal subjects were 1.4% and 1.6% for non-DM with CAD and DM without CAD, respectively (P = 0.48) and 3.5% (P = 0.95) for both abnormal groups. After multivariate adjustment, outcomes were comparable within normal [AHR 1.4 (95% CI 0.98–1.96) P = 0.06] and abnormal [AHR 1.1 (95% CI 0.83–1.50) P = 0.49] MPI. Conclusions: Diabetic patients without CAD have comparable risk of cardiovascular events as non-diabetic patients with CAD after stratification by MPI results. These findings support diabetes as a CAD equivalent and suggest that MPI provides additional prognostic information in such patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

A need to reduce premature CV mortality in the developing world: How could appropriate use of non-invasive imaging help?

We discuss premature deaths due to coronary heart disease (CHD) in developing countries and the importance of a comprehensive approach, involving clinical judgement, prevention, appropriate use of technology to diagnose and guide CHD treatment. Healthcare policies and levels of knowledge vary tremendously resulting heterogeneous utilization of diagnostic strategies and treatments worldwide. Many countries with high mortality have low utilization of non-invasive cardiac imaging. Appropriate use coupled with guideline-based management could help to improve care in the developing world and potentially result in better life expectancy already experienced by most high-income countries. In a scenario of increasing costs, a rational utilization of resources is imperative for all nations. A stepwise approach to suspected CHD is necessary, starting from good judgement, adding tests only as needed, preferably filtering patients who might benefit from advanced imaging. In stable patients, non-invasive tests should be used as filters to invasive procedure, preventing stable patients from undergoing revascularizations of questionable benefit. In this article, we review the relative role of exercise testing, myocardial perfusion imaging, and coronary computed tomography angiography to evaluate CHD and how these can be utilized as ways to help guide management that could impact premature mortality in developing nations.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Cardiac MRI for the evaluation of oncologic cardiotoxicity

Cancer therapeutics-related cardiac dysfunction (CTRCD) is a well-established adverse effect resulting from a number of cancer therapeutics. Newer immunotherapy has been associated with cardiomyopathy and myocarditis making comprehensive imaging useful for early recognition. Cardiac MRI (CMR) offers a comprehensive evaluation to detect CTRCD. Established guidelines for monitoring left ventricular ejection fraction for potential cardiotoxicity have recently incorporated CMR. We will review the utility of CMR in contemporary evaluation for potential oncologic cardiotoxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗