bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast Cyclostationary Feature Detection Method Based on CUDA
Authors: Zhang Hongyuan , Guo Bin , Zhang Yiheng , Hu Yanfei
Published: July 2021

Aiming at the problem of poor real-time performance of cyclostationary feature detection, a fast cyclostationary feature detection algorithm based on the Unified Computing Device Architecture (CUDA) is proposed. This method moves the data processing part to the GPU, and uses the advantages of a large number of GPU stream processors and powerful multi-threaded concurrent execution functions to accelerate the FAM algorithm in parallel, thereby realizing fast signal processing. Experimental results show that compared with traditional serial algorithms, this method reduces the time overhead of the algorithm and improves the real-time performance of the algorithm.
Network intrusion detection method based on deep learning
Authors: Zou Shuai , Zhong Fangwei , Han Bing , Sun Hao , Qian Tao , Yu Changjiang , Jia Jia
Published: July 2021

With the rapid development of the network, network transmission encryption technologies such as SSL and SSH have emerged. Network traffic has grown exponentially, and transmission encryption has become an important means of protecting data security and privacy. However, encrypted data also brings hidden dangers that are not easily detectable to network security. Identifying the encrypted network traffic can effectively solve this problem. However, the current recognition probability is not high enough and the time delay caused by the recognition together makes it impossible to accurately detect and warn the network traffic. An encrypted network traffic recognition method based on deep learning is proposed. Experimental verification shows that the method is applied in the network. The accuracy of encrypted network traffic identification is 97.02%, which can meet actual needs.
Fault diagnosis method for scintillation detector based on BP neural network
Authors: Xie Y.X. , Yan Y.J. , Li X. , Ding T.S. , Ma C.
Published: July 2021

This article gives a scintillation detector fault diagnosis method based on BP neural network. From the aspect of output signals of scintillation detectors, the wavelet packet transform is used to extract the energy characteristic vectors which are treated as the input of BP neural network, and a training database is established as well as BP neural network parameters are optimized. Then the method is employed to establish a fault recognition model and fault types can be concluded. Finally, the simulation data are compared with those of two other methods (the statistical diagnosis method and an method based on multi-classification support vector machine). The experimental results illustrate that the application of proposed method can improve the fault diagnosis accuracy of scintillation detectors effectively.
Does conserving roadless wildland increase wildfire activity in western US national forests?
Authors: Johnston James D , Kilbride John B , Meigs Garrett W , Dunn Christopher J , Kennedy Robert E
Published: July 2021

National forests in the western United States are divided roughly in half between lands without roads managed for wilderness characteristics and lands with an extensive road system managed for multiple uses including resource extraction. We investigated the influence of these land use designations on fire ignitions, fire extent, and fire severity over the last three decades. Although roadless areas experienced fewer fire ignitions and are generally cooler, moister, and higher elevation landscapes less conducive to fire, wildfire extent was far greater in these areas than in roaded areas. An area equivalent to approximately one-third of roadless areas burned in the last three decades, while an area equivalent to less than one-fifth of roaded areas experienced fire. Most of the largest fires that have burned on national forest land in recent years began in roadless areas. Despite greater fire extent in roadless areas, there was no significant difference in fire severity between roadless areas and roaded areas after accounting for biophysical differences between these management regimes. Although fire patterns in roadless areas may pose challenges to land managers, the available evidence suggests that the greater extent of fire in roadless areas may confer resilience to these landscapes in the face of climate change.
Lost Circulation Control for Pump-Injected Reverse Circulation Drilling: Experimental Optimization and Theoretical Analyses
Authors: Okere Chinedu J. , Su Guandong , Zhou Jinhui , Li Gongsheng , Tan Chengwei
Published: July 2021

The reverse circulation drilling method is now widely accepted as an effective way of exploration and grade control. However, the performance of reverse circulation drilling operations is greatly affected by the filtration effect (lost circulation) and no research has critically addressed this issue. In this study, a simulation experiment was conducted, the filtration effect was quantified as the mass of water loss measured at a flow rate of 4.00 m3/h to 8.00 m3/h for reverse and forward circulation drilling. Then the dynamic filtration effect was analyzed in three ways; first, a filtration versus circulation flow rate curve was obtained for both the forward and reverse circulation process. Second, the positive and negative effect of hydrodynamics on filtration was analyzed through a computational fluid dynamic approach, and finally, via qualitative analyses. The results showed that: (1) An optimal flow rate occurred when the filtration effect was minimum, (2) There is a point where the positive and negative effect of the increase in flow rate on filtration is the same, and (3) filtration monotonously increases with flow rate. This study provides a better understanding of the effect of filtration during the reverse circulation drilling process, a guide to field experts, and a theoretical framework for future research.
Study on Stability of Support for Tunnel Damaged by Blasting
Authors: Lai J , Liu Y , Wang Y C
Published: July 2021

Blasting excavation will induce damage of surrounding rock of tunnel, and bolt-mesh-shotcrete support is often used for damaged tunnel. This paper learns force characteristics of bolt, location of fracture surface of tunnel and corresponding stability coefficient through analysis on stability of supported tunnel based on strength reduction method. The study indicates that: it’s easy to induce damage of local rock mass of surrounding rock when the bolt spacing is too big, while tunnel support has limited stability and poor economy when the bolt spacing is too small. The reasonable spacing and length of supporting bolts are 1.0m and 3.5m respectively. Results of the study have certain guiding significance for tunnel engineering construction.
Blind oracular quantum computation
Authors: Gustiani Cica , DiVincenzo David P
Published: July 2021

In the standard oracle model, an oracle efficiently evaluates an unknown classical function independent of the quantum algorithm itself. Quantum algorithms have a complex interrelationship to their oracles; for example the possibility of quantum speedup is affected by the manner by which oracles are implemented. Therefore, it is physically meaningful to separate oracles from their quantum algorithms, and we introduce one such separation here. We define the blind oracular quantum computation (BOQC) scheme, in which the oracle is a distinct node in a quantum network. Our work augments the client–server setting of quantum computing, in which a powerful quantum computer server is available on the network for discreet use by clients on the network with low quantum power. In BOQC, an oracle is another client that cooperates with the main client so that an oracular quantum algorithm is run on the server. The cooperation between the main client and the oracle takes place (almost) without communication. We prove BOQC to be blind: the server cannot learn anything about the clients’ computation. This proof is performed within the composable security definitions provided by the formalism of abstract cryptography. We enhance the BOQC scheme to be runnable with minimal physical qubits when run on a solid-state quantum network; we prove that this scheme, which we refer to as BOQCo (BOQC-optimized), possesses the same security as BOQC.
Invited Commentary: Demystifying Statistical Inference When Using Machine Learning in Causal Research
Authors: Balzer Laura B , Westling Ted
Published: July 2021

In this issue, Naimi et al. (Am J Epidemiol. 2023;192(9):1536–1544) discuss a critical topic in public health and beyond: obtaining valid statistical inference when using machine learning in causal research. In doing so, the authors review recent prominent methodological work and recommend: 1) doubly robust estimators, such as targeted maximum likelihood estimation (TMLE); 2) ensemble methods, such as Super Learner, to combine predictions from a diverse library of algorithms; and 3) sample splitting to reduce bias and improve inference. We largely agree with these recommendations. In this commentary, we highlight the critical importance of the Super Learner library. Specifically, in both simulation settings considered by the authors, we demonstrate that reductions in bias and improvements in confidence-interval coverage can be achieved using TMLE without sample splitting and with a Super Learner library that excludes tree-based methods but includes regression splines. Whether extremely data-adaptive algorithms and sample splitting are needed depends on the specific problem and should be informed by simulations reflecting the specific application. More research is needed on practical recommendations for selecting among these options in common situations arising in epidemiology.
Hepatocellular uptake index obtained with gadoxetate disodium-enhanced magnetic resonance imaging in the assessment future liver remnant function after major hepatectomy for biliary malignancy
Authors: Notake T , Shimizu A , Kubota K , Ikehara T , Hayashi H , Yasukawa K , Kobayashi A , Yamada A , Fujinaga Y , Soejima Y
Published: July 2021

Background

Functional assessment of the future liver remnant (FLR) after major hepatectomy is essential but often difficult in patients with biliary malignancy, owing to obstructive jaundice and portal vein embolization. This study evaluated whether a novel index using gadoxetate disodium-enhanced MRI (EOB-MRI) could predict posthepatectomy liver failure (PHLF) after major hepatectomy for biliary malignancy.

Methods

The remnant hepatocellular uptake index (rHUI) was calculated in patients undergoing EOB-MRI before major hepatectomy for biliary malignancy. Receiver operating characteristic (ROC) curve analyses were used to evaluate the accuracy of rHUI for predicting PHLF grade B or C, according to International Study Group of Liver Surgery criteria. Multivariable logistic regression analyses comprised stepwise selection of parameters, including rHUI and other conventional indices.

Results

This study included 67 patients. The rHUI accurately predicted PHLF (area under the curve (AUC) 0.896). A cut-off value for rHUI of less than 0.410 predicted all patients who developed grade B or C PHLF. In multivariable analysis, only rHUI was an independent risk factor for grade B or C PHLF (odds ratio 2.0 × 103, 95 per cent c.i. 19.6 to 3.8 × 107; P < 0.001). In patients who underwent preoperative portal vein embolization, rHUI accurately predicted PHLF (AUC 0.885), whereas other conventional indices, such as the plasma disappearance rate of indocyanine green of the FLR and FLR volume, did not.

Conclusion

The rHUI is potentially a useful predictor of PHLF after major hepatectomy for biliary malignancy.
Provision of a local anaesthetic minor procedures service by surgical advanced clinical practitioners: 5-year study
Authors: Taib A , Hammill C , Abraham A , Fakim B , Garstang P , Carney J , Natarajan V , Subar D
Published: July 2021

Background

Surgical advanced clinical practitioners (SACPs) form part of the extended surgical workforce drawn from a variety of allied healthcare backgrounds. The primary aim of this study was to determine whether there was a financial benefit in having minor surgical procedures undertaken by dedicated SACPs compared with operating lists assigned to consultant surgeons.

Methods

This was a retrospective cohort study including all patients who had minor ‘lumps and bumps’ procedures undertaken between April 2014 and August 2019 at East Lancashire Hospitals NHS Trust under local anaesthetic by the general surgery team. Clinical patient information, including lesion type, was collected along with operating room staffing levels and duration of operation. The cost of the procedure was calculated as operating time multiplied by cost of staff per minute according to local banding.

Results

A total of 1399 patients had a lesion excised; 907 procedures were carried out by a doctor, and the rest independently by a SACP. The majority of lesions excised were lipomas and cysts. There was no difference in the median surgical time taken between SACPs and doctors (20 (i.q.r. 14–28) min). Minor procedures carried out on consultant surgeon lists cost 62.3 per cent (€25.33) more on average than those on SACP lists (median €65.96 versus 40.63 respectively; P < 0.001).

Conclusion

A dedicated and independent SACP ‘lumps and bumps’ list was financially beneficial. Operating times were similar to those of doctors. These lists safely free trainee and consultant surgeons to undertake more complex work.
Decision Making by Practitioners in the Social Professions Involved in Compulsory Admission to Mental Health Hospital: A Scoping Review
Authors: Abbott Simon
Published: July 2021

This scoping review examined the literature on decision making by practitioners in the social professions involved in compulsory admission to mental health hospital in the UK. This aimed to find out(i) what processes shape social profession decision making about compulsory admission to mental health hospitals in practice? and (ii) what methods have informed studies in this area, and how have these shaped the current state of knowledge?

Three main themes emerged are: professional positioning; characteristics of the person assessed; and organisational factors. The literature has approached answering this question by focusing on social professional jurisdictional perspectives, emphasising concern whether a social perspective is privileged in decision making. Lack of realistic options to avoid in-patient care underpins decisions to detain. The process involves a logistical challenge for the social profession. The social milieu of those assessed is associated with social vulnerability and social deprivation, highlighting the relevance for social work. Concerns about risk and a citizen’s lack of mental capacity to make decisions about care are associated with decisions to detain. Implications for social work include a need for research that explores the institutional and social context of decision making. Finally, implementing supported decision making in social work practice is proposed as an imperative for future research.
Integrative analyses ofCrepidium(Orchidaceae, Epidendroideae, Malaxideae) shed more light on its relationships withDienia,LiparisandMalaxisand justify reinstatement of narrow endemicC. allanii
Authors: Kumar Pankaj , Li Jihong , Gale Stephan W
Published: July 2021

Malaxidinae are a cosmopolitan higher Epidendroid subtribe of > 1250 species that exhibit wide morphological and ecological diversity. Despite almost two centuries of taxonomic deliberation, controversy persists regarding the delimitation of practically all Malaxidinae genera, the most important of which are Crepidium, Dienia, Liparis and Malaxis. Previous attempts to classify these genera using a molecular phylogenetic approach showed Liparis and Malaxis to be polyphyletic and the floral characters traditionally used to define them as homoplastic. Emphasis has instead shifted to vegetative and ecological traits. Here, we conduct an expanded analysis of nuclear (ITS) and plastid (matK) sequences focused on terrestrial taxa, with the resulting phylogram largely corroborating the emerging picture, and we test the efficacy of four previously highlighted traits to recover the same relationships. Although growth habit is underscored as important for resolving a natural distinction between epiphytic Liparis and terrestrial ‘Crepidium clade’ plus ‘Malaxis clade’ taxa, leaf shape and venation and habitat preference are shown to be poor predictors of phylogenetic affiliation. Instead, perennating organ structure (heteroblastic or homoblastic) and placement (predominantly above- or below-ground) – are incisive, with leaf number and texture apparently correlated. These findings are discussed in the context of an inferred evolutionary history of the subtribe. Although homoplastic at the subtribe level, some floral characters are shown to be useful for resolving identities at the species level. Accordingly, the status of four long-confused species (Crepidium acuminatum, C. allanii, C. purpureum and Microstylis biloba) is resolved.
An orderly curriculum for a messy field? Classroom-field tensions in community organization in India
Authors: Vyas Mouleshri
Published: July 2021

The large-scale reverse migration from cities to villages at the start of the COVID-19 pandemic in 2020 and again during the second wave in 2021 highlighted the persistence of poverty in India. Civil society responses pointed to the pressure that it was under in the absence of adequate outreach by the state for meeting food, livelihood, and other insecurities of urban and rural populations. Against this backdrop, the article outlines some of the challenges facing Social Work and Community Development in addressing poverty and marginalization. An examination of the relationship between Social Work with the state, and the contemporary complex neoliberal context for practice, highlights classroom-field tensions in community organization. In preparing graduates for what appears to be a messy field, an orderly curriculum, irrespective of how well thought out it may be, struggles to retain convergence between principles of CD and certain elements of contemporary practice. It emerges that education for CD needs to build systematically on critical community practice and align with an anti- oppressive framework, in order to contribute substantively to addressing poverty and marginalization.
Congenital Human Cytomegalovirus Infection Is Associated With Decreased Transplacental IgG Transfer Efficiency Due to Maternal Hypergammaglobulinemia
Authors: Semmes Eleanor C , Li Shuk Hang , Hurst Jillian H , Yang Zidanyue , Niedzwiecki Donna , Fouda Genevieve G , Kurtzberg Joanne , Walsh Kyle M , Permar Sallie R
Published: July 2021

Background

Placentally transferred maternal immunoglobulin G (IgG) protects against pathogens in early life, yet vertically transmitted infections can interfere with transplacental IgG transfer. Although human cytomegalovirus (HCMV) is the most common placentally-transmitted viral infection worldwide, the impact of congenital HCMV (cCMV) infection on transplacental IgG transfer has been underexplored.

Methods

We evaluated total and antigen-specific maternal and cord blood IgG levels and transplacental IgG transfer efficiency in a US-based cohort of 93 mother-infant pairs including 27 cCMV-infected and 66 cCMV-uninfected pairs, of which 29 infants were born to HCMV-seropositive nontransmitting mothers and 37 to HCMV-seronegative mothers. Controls were matched on sex, race/ethnicity, maternal age, and delivery year.

Results

Transplacental IgG transfer efficiency was decreased by 23% (95% confidence interval [CI] 10–36%, P = .0079) in cCMV-infected pairs and 75% of this effect (95% CI 28–174%, P = .0085) was mediated by elevated maternal IgG levels (ie, hypergammaglobulinemia) in HCMV-transmitting women. Despite reduced transfer efficiency, IgG levels were similar in cord blood from infants with and without cCMV infection.

Conclusions

Our results indicate that cCMV infection moderately reduces transplacental IgG transfer efficiency due to maternal hypergammaglobulinemia; however, infants with and without cCMV infection had similar antigen-specific IgG levels, suggesting comparable protection from maternal IgG acquired via transplacental transfer.
Deliberation, Dissent, and Distrust: Understanding Distinct Drivers of Coronavirus Disease 2019 Vaccine Hesitancy in the United States
Authors: Tram Khai Hoan , Saeed Sahar , Bradley Cory , Fox Branson , Eshun-Wilson Ingrid , Mody Aaloke , Geng Elvin
Published: July 2021

Background

Despite the availability of safe and efficacious coronavirus disease 2019 vaccines, a significant proportion of the American public remains unvaccinated and does not appear to be immediately interested in receiving the vaccine.

Methods

In this study, we analyzed data from the US Census Bureau’s Household Pulse Survey, a biweekly cross-sectional survey of US households. We estimated the prevalence of vaccine hesitancy across states and nationally and assessed the predictors of vaccine hesitancy and vaccine rejection. In addition, we examined the underlying reasons for vaccine hesitancy, grouped into thematic categories.

Results

A total of 459 235 participants were surveyed from 6 January to 29 March 2021. While vaccine uptake increased from 7.7% to 47%, vaccine hesitancy rates remained relatively fixed: overall, 10.2% reported that they would probably not get a vaccine and 8.2% that they would definitely not get a vaccine. Income, education, and state political leaning strongly predicted vaccine hesitancy. However, while both female sex and black race were factors predicting hesitancy, among those who were hesitant, these same characteristics predicted vaccine reluctance rather than rejection. Those who expressed reluctance invoked mostly “deliberative” reasons, while those who rejected the vaccine were also likely to invoke reasons of “dissent” or “distrust.”

Conclusions

Vaccine hesitancy comprises a sizable proportion of the population and is large enough to threaten achieving herd immunity. Distinct subgroups of hesitancy have distinctive sociodemographic associations as well as cognitive and affective predilections. Segmented public health solutions are needed to target interventions and optimize vaccine uptake.
Multi-year progesterone profiles during pregnancy in baleen of humpback whales (Megaptera novaeangliae)
Authors: Lowe Carley L , Hunt Kathleen E , Rogers Matthew C , Neilson Janet L , Robbins Jooke , Gabriele Christine M , Teerlink Suzie S , Seton Rosemary , Buck C Loren
Published: July 2021

Understanding calving rates of wild whale populations is critically important for management and conservation. Reproduction of humpback whales (Megaptera novaeangliae) is difficult to monitor and, even with long-term sighting studies, basic physiological information such as pregnancy rates and calving intervals remain poorly understood in many populations. We hypothesized that pregnant whales have sustained elevations in baleen progesterone that temporally correlate with gestation. To test this hypothesis, baleen progesterone profiles from two adult female North Pacific humpbacks, both with extensive sighting records and documented pregnancies, were compared to those of a nulliparous female (adult female never seen with a calf) and a juvenile male. Baleen specimens recovered during necropsy were subsampled every 2 cm from the base to the tip of the plate, with each interval representing 30–45 days of growth. Homogenized baleen powder was assayed for progesterone using enzyme immunoassays. The date of growth of each sampling location on the baleen plate was estimated based on stable isotope analysis of annual δ15N cycles. Progesterone profiles from both pregnant whales showed sustained high progesterone content (>350 ng/g) in areas corresponding to known pregnancies, inferred from calf sightings and post-mortem data. The younger female, estimated to be 13 years old, had higher progesterone during pregnancy than the 44.5 year old, but levels during non-pregnancy were similar. The nulliparous female and the male had low progesterone throughout their baleen plates. Baleen hormone analysis can determine how progesterone concentrations change throughout gestation and has potential for estimating age at first reproduction, pregnancy intervals, failed pregnancies and early calf mortality. Understanding rates of calving and current and historic reproductive patterns in humpbacks is vital to continuing conservation measures in this species.
Functionathon: a manual data mining workflow to generate functional hypotheses for uncharacterized human proteins and its application by undergraduate students
Authors: Duek Paula , Mary Camille , Zahn-Zabal Monique , Bairoch Amos , Lane Lydie
Published: July 2021

About 10% of human proteins have no annotated function in protein knowledge bases. A workflow to generate hypotheses for the function of these uncharacterized proteins has been developed, based on predicted and experimental information on protein properties, interactions, tissular expression, subcellular localization, conservation in other organisms, as well as phenotypic data in mutant model organisms. This workflow has been applied to seven uncharacterized human proteins (C6orf118, C7orf25, CXorf58, RSRP1, SMLR1, TMEM53 and TMEM232) in the frame of a course-based undergraduate research experience named Functionathon organized at the University of Geneva to teach undergraduate students how to use biological databases and bioinformatics tools and interpret the results. C6orf118, CXorf58 and TMEM232 were proposed to be involved in cilia-related functions; TMEM53 and SMLR1 were proposed to be involved in lipid metabolism and C7orf25 and RSRP1 were proposed to be involved in RNA metabolism and gene expression. Experimental strategies to test these hypotheses were also discussed. The results of this manual data mining study may contribute to the project recently launched by the Human Proteome Organization (HUPO) Human Proteome Project aiming to fill gaps in the functional annotation of human proteins.

Database URL: http://www.nextprot.org
3D cardiac magnetic resonance stress-perfusion in elderly patients
Authors: Karolyi M , Gotschy A , Plein S , Paetsch I , Jahnke C , Frick M , Gebker R , Alkadhi H , Manka R
Published: July 2021

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Swiss National Science Foundation

Introduction

Age related comorbidities and reduced compliance often limit ischaemia testing in elderly patients.

Purpose

To assessed the accuracy of 3D cardiac magnetic resonance (CMR) stress perfusion in the elderly population.

Methods

56 patients aged ≥75 years underwent 3D CMR stress-perfusion and invasive coronary angiography with quantitative coronary angiography (QCA) and fractional flow reserve (FFR) as part of a multicenter study. The accuracy of 3D CMR stress-perfusion was compared to patients aged <75 years old (n = 360) using qualitative and quantitative imaging parameters.

Results

Sensitivity, specificity, positive and negative predictive values of qualitative 3D perfusion CMR were similar for both age groups in the detection of high-grade (≥50%) coronary stenosis on QCA and hemodynamically relevant (<0.8) stenosis on FFR, p > 0.05 all. Quantitative myocardial ischemia burden was larger in elderly patients (15% ± 17% vs. 9% ± 13%) with similarly high diagnostic accuracy of quantitative 3D CMR perfusion in both age groups to predict pathological FFR (AUC ≥75: 0.906; AUC <75: 0.866).

Conclusions

3D CMR perfusion is well suited for myocardial ischaemia testing in the elderly patients with similarly high diagnostic accuracy as in younger individuals.
Dark blood ischemic LGE segmentation using a deep learning approach
Authors: Torlasco C , Papetti D , Mene R , Artico J , Seraphim A , Badano LP , Moon JC , Parati G , Xue H , Kellman P , Nobile M
Published: July 2021

Funding Acknowledgements

Type of funding sources: None.

Introduction

The extent of ischemic scar detected by Cardiac Magnetic Resonance (CMR) with late gadolinium enhancement (LGE) is linked with long-term prognosis, but scar quantification is time-consuming. Deep Learning (DL) approaches appear promising in CMR segmentation.  Purpose: To train and apply a deep learning approach to dark blood (DB) CMR-LGE for ischemic scar segmentation, comparing results to 4-Standard Deviation (4-SD) semi-automated method. Methods: We trained and validated a dual neural network infrastructure on a dataset of DB-LGE short-axis stacks, acquired at 1.5T from 33 patients with ischemic scar. The DL architectures were an evolution of the U-Net Convolutional Neural Network (CNN), using data augmentation to increase generalization. The CNNs worked together to identify and segment 1) the myocardium and 2) areas of LGE. The first CNN simultaneously cropped the region of interest (RoI) according to the bounding box of the heart and calculated the area of myocardium. The cropped RoI was then processed by the second CNN, which identified the overall LGE area. The extent of scar was calculated as the ratio of the two areas. For comparison, endo- and epi-cardial borders were manually contoured and scars segmented by a 4-SD technique with a validated software. Results: The two U-Net networks were implemented with two free and open-source software library for machine learning. We performed 5-fold cross-validation over a dataset of 108 and 385 labelled CMR images of the myocardium and scar, respectively. We obtained high performance (> ∼0.85) as measured by the Intersection over Union metric (IoU) on the training sets, in the case of scar segmentation. With regards to heart recognition, the performance was lower (> ∼0.7), although improved (∼ 0.75) by detecting the cardiac area instead of heart boundaries. On the validation set, performances oscillated between 0.8 and 0.85 for scar tissue recognition, and dropped to ∼0.7 for myocardium segmentation. We believe that underrepresented samples and noise might be affecting the overall performances, so that additional data might be beneficial. Figure1: examples of heart segmentation (upper left panel: training; upper right panel: validation) and of scar segmentation (lower left panel: training; lower right panel: validation). Conclusion: Our CNNs show promising results in automatically segmenting LV and quantify ischemic scars on DB-LGE-CMR images. The performances of our method can further improve by expanding the data set used for the training. If implemented in a clinical routine, this process can speed up the CMR analysis process and aid in the clinical decision-making. Abstract Figure.
Reduction of extracellular volume and reverse cardiac remodeling during sacubitril/valsartan therapy assessed by cardiac magnetic resonance in patients with heart failure (REMODELING CMR-HF)
Authors: Plata Mosquera CA , Herrera-Escandon A , Vernaza-Pizarro A , Tamayo-Artunduaga N , Rodriguez-Casanova A , Vivas-Mayor M , Fajardo D
Published: July 2021

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

REMODELING HF

Background/Introduction: Extracellular volume (ECV) expansion is a major determinant of cardiac remodeling in heart failure. Cardiac magnetic resonance (CMR) T1 mapping has been developed as a noninvasive technique to estimate ECV.

Purpose

The objective of this study is to assess the response to Sacubitril/Valsartan by measuring changes in myocardial ECV and their association with reverse cardiac remodeling in patients with heart failure with reduced ejection fraction (HFrEF).

Methods

Prospective, single-center, open-label study of two hundred-four HFrEF patients underwent CMR T1 mapping using the modified Look-Locker inversion recovery (MOLLI) sequence for ECV calculation, and initiated with sacubitril-valsartan treatment according to Guideline-Directed Medical Therapy. Absolute change in myocardial ECV, serum levels of procollagen type I amino-terminal peptide (PINP) and procollagen type III amino-terminal peptide (PIIINP), left ventricular end-diastolic volume index, left ventricular end-systolic volume index and left ventricle ejection fraction (LVEF) were analyzed from baseline to 12-month follow-up.

Results

Baseline MOLLI-ECV was 48.2% ± 2.4 in 106 patients with ischemic cardiomyopathy (ICM) and 38.7% ± 2.7 in 98 with idiopathic dilated cardiomyopathy (DCM), decreasing to 34% ± 2.4 for ICM and 29.5% ± 2.7 for DCM (P < 0.001), at 12 months with sacubitril-valsartan therapy. These changes were correlated with a reduction of -36 μg/L for PINP (CI 95% 78-93, P < 0.001), and -3.0 μg/L for PIIINP (CI 95% 73-91, P < 0.001), -20 ml/m² in left ventricle end-diastolic and -18 ml/m² in end-systolic volumes, and an improvement in LVEF from 29% to 36% in both groups (P < 0.001).

Conclusions

For the first time, we observe that changes in extracellular volume induced by sacubitril-valsartan therapy are related to reverse cardiac remodeling in patients with in HFrEF. These findings suggest that there may be an opportunity to decrease adverse remodeling with the use of a CMR-guided therapeutic approach aimed at decreasing fibrogenic activity and modulate the remodeling process.
High interstudy repeatability of automatic deep learnt biventricular CMR measurements
Authors: Alabed S , Karunasaagarar K , Alandejani F , Garg P , Uthoff J , Metherall P , Sharkey M , Lu H , Wild JM , Kiely DG , Van Der Geest RJ , Swift AJ
Published: July 2021

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Wellcome Trust (UK), NIHR (UK)

Introduction

Cardiac magnetic resonance (CMR) measurements have significant diagnostic and prognostic value. Accurate and repeatable measurements are essential to assess disease severity, evaluate therapy response and monitor disease progression. Deep learning approaches have shown promise for automatic left ventricular (LV) segmentation on CMR, however fully automatic right ventricular (RV) segmentation remains challenging. We aimed to develop a biventricular automatic contouring model and evaluate the interstudy repeatability of the model in a prospectively recruited cohort.

Methods

A deep learning CMR contouring model was developed in a retrospective multi-vendor (Siemens and General Electric), multi-pathology cohort of patients, predominantly with heart failure, pulmonary hypertension and lung diseases (n = 400, ASPIRE registry). Biventricular segmentations were made on all CMR studies across cardiac phases. To test the accuracy of the automatic segmentation, 30 ASPIRE CMRs were segmented independently by two CMR experts. Each segmentation was compared to the automatic contouring with agreement assessed using the Dice similarity coefficient (DSC). 

A prospective validation cohort of 46 subjects (10 healthy volunteers and 36 patients with pulmonary hypertension) were recruited to assess interstudy agreement of automatic and manual CMR assessments. Two CMR studies were performed during separate sessions on the same day. Interstudy repeatability was assessed using intraclass correlation coefficient (ICC) and Bland-Altman plots. 

Results

DSC showed high agreement (figure 1) comparing automatic and expert CMR readers, with minimal bias towards either CMR expert. The scan-scan repeatability CMR measurements were higher for all automatic RV measurements (ICC 0.89 to 0.98) compared to manual RV measurements (0.78 to 0.98). LV automatic and manual measurements were similarly repeatable (figure 2). Bland-Altman plots showed strong agreement with small mean differences between the scan-scan measurements (figure 2).

Conclusion

Fully automatic biventricular short-axis segmentations are comparable with expert manual segmentations, and have shown excellent interstudy repeatability.
Assessing access to mri in patients with cardiac implantable electronic devices in australia
Authors: Page N , Chia K , Brazier D , Manisty C , Kozor R
Published: July 2021

Funding Acknowledgements

Type of funding sources: None.

Background

"Legacy" cardiac implantable electronic devices (CIEDs) have historically been considered non-MRI-conditional. However, a number of recent studies indicate that if certain protocols are followed, patients with such devices may undergo MRI without significant adverse outcomes. Nowadays, industry standards dictate that "modern" CIEDs are MRI compatible. Despite these developments, some patients with CIEDs are denied MRI. Paucity of access to this vital service has been shown to increase expense, lead to more invasive imaging and later diagnosis, and poorer patient outcomes. 

This study aims to identify if Australian public hospitals provide MRI services for patients with modern and legacy CIEDs, the characteristics of the services, and the barriers to implementing such a service. 

Methods

This study surveyed all Australian Tertiary Referral Public Hospitals (n = 38), with a mixed qualitative and quantitative questionnaire. 

Results

35 of the 38 sites completed the survey. Figure 1A shows that the majority of hospitals (30/35, 85.7%) offer MRIs for modern MRI-conditional CIEDs. In contrast, Figure 1B shows that only a minority of hospitals (3/35, 8.6%) offer MRIs for legacy CIEDs. 

Protocols governing patient eligibility vary greatly among hospitals that scan modern devices. Locations either allow all CIEDs to be scanned, only non-dependent CIEDs, or only pacemaker CIEDs. 1.5 Tesla is the preferred strength to scan Modern CIEDs (59%), however a sizeable proportion scan at only 3.0 Tesla (10%) or both strengths (31%). A majority (80%) of staff in attendance of the scan were ACLS-trained (Advanced Cardiac Life Support), with no correlation to strength of MRI used. A range of different personnel attend the scan with varied patient monitoring strategies, and a majority (79%) offer thoracic as well as extra-thoracic scanning. 

The few hospitals that scan legacy devices only scan at 1.5 tesla, and follow individualised protocols. These sites offer more personnel in attendance for the scan than for modern CIED scans, with all staff ACLS-trained including a physician who can direct CIED programming of required. These sites have more involved patient monitoring, and all also offer thoracic and extra-thoracic MRI scanning. 

The predominant barrier identified was an absence of National Guidelines, followed by a lack of formal training or logistical device support.

Conclusions

The majority (85.7%) of Australian Tertiary Referral Public Hospitals have a MRI service for patients with modern CIEDs, but only 8.6% offer this service to patients with legacy CIEDs. 

This highlights the need for a national effort to guide the provision of MRI services for patients with CIEDs, and address the identified barriers.
Prognostic value of pulmonary transit time by cardiac magnetic resonance in patients with heart failure with preserved ejection fraction
Authors: Elshibly M , Kanagala P , Budgeon C , Wright R , Jerosch-Herold M , Gulsin GS , Squire IB , Ng LL , Mccann GP , Arnold JR
Published: July 2021

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): National Institute for Health Research Leicester Cardiovascular Biomedical Research Centre

Background

Quantifying pulmonary transit time (PTT) from cardiac magnetic resonance (CMR) first pass perfusion imaging is a novel technique for the evaluation of haemodynamic congestion in heart failure. Previous studies have demonstrated that PTT is prolonged in patients with heart failure with reduced ejection fraction (HFrEF) and that it provides independent prognostic information in this patient group. However, the potential diagnostic and prognostic roles of PTT assessment in patients with heart failure with preserved ejection fraction (HFpEF) remain to be established.

Aim

To compare PTT in healthy controls and in patients with HFpEF, and to determine the prognostic value of PTT in HFpEF.

Methods

In a prospective, observational study, HFpEF and age-matched control subjects underwent multi-parametric CMR at 3-Tesla, comprising quantitative left ventricular volumetric assessment using a standard steady-state free precession (SSFP) pulse sequence, and first-pass perfusion imaging at rest using a T1-weighted segmented inversion recovery gradient echo sequence (following injection of 0.04mmol/kg of contrast). PTT was calculated as the time interval between the peaks of signal intensity curves in the right and left ventricular blood pools (defined on the basal slice of the rest perfusion images). The primary endpoint was the composite of death or hospitalisation with heart failure.

Results

88 HFpEF patients (age 73 ± 9 years, 51% male, EF 56.4 ± 5.6%) and 40 controls (age 73 ± 5 years, 43% male, EF 58.5 ± 4.7%) were studied. PTT was comparable in HFpEF patients (7.7 ± 3.8s) and in healthy controls (7.5 ± 1.8, p = 0.69). Normalised to cardiac cycle lengths, PTT remained comparable in HFpEF patients and healthy controls (8.5 ± 4.0 cardiac cycles versus 7.8 ± 1.6 cardiac cycles, respectively, p = 0.19). In the HFpEF group, during median follow-up of 3.4 years, there were 38 events (25 hospitalisations with heart failure, 13 deaths); a significant relationship between survival and PTT was not demonstrated (HR 1.06 [0.99,1.14] for a one-unit increase, p = 0.098).

Conclusion

In HFpEF, PTT is not prolonged compared with PTT in healthy subjects. Unlike in HFrEF, PTT does not appear to be diagnostically or prognostically significant in HFpEF.

Figure 1: Graph showing signal intensity curves in the right (red) and left (green) ventricular blood pools

Figure 2: Kaplan-Meier plot showing comparable rates of the composite endpoint in patients with PTT greater/less than median PTT (8 cardiac cycles)
Value of cardiac magnetic resonance imaging derived spectral myocardial strain pattern for non-invasive diagnosis of myocarditis
Authors: Laqua FC , Polacin M , Luecke C , Klingel K , Alkadhi H , Manka R , Thiele H , Gutberlet M , Lurz P , Baessler B
Published: July 2021

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Society of Radiology European Institute for Biomedical Imaging Research

Background

Traditionally, cardiac function is quantified by measures of peak excursion, for example ejection fraction. However, myocardial strain estimation from cine- cardiac MRI allows quantification of cardiac motion over the whole heart cycle. We propose a spectral decomposition of the strain curves applying Discrete Fourier transformation (DFT).

Purpose

To evaluate a potential additive diagnostic value of spectral temporal strain curve quantification for non-invasive diagnosis of myocarditis using cardiac MRI.

Methods

In the single-center prospective study patients with suspected myocarditis underwent comprehensive cardiac MRI followed by biventricular endomyocardial biopsy (EMB) between 2012 and 2014. DFT was applied to myocardial strain curves extracted from cine-Images. As reference model, a L1- and L2-penalized logistic regression model using global native T1 time, T2 time and presence of late-gadolinium enhancement was trained to predict EMB results and compared to two models which additionally include three orders of DFT coefficients and ejection fraction, respectively. Predictive performance was evaluated in a tournament-leave-pair-out cross-validation approach with a bootstrap correction for testing of multiple hyperparameter configurations.

Results

Out of 100 patients (28 % female, median age 40 [IQR 32 to 56) years) with acute symptom-onset (<30 days) 65 had pathologically proven myocarditis in EMB. The DFT model showed best discrimination (Area under the receiver-operating-curve [AUC] 0.72 [95% CI 52 to 87]). Addition of ejection fraction (AUC 0.60 [95% CI: 0.43 to 0.74]) did not increase AUC compared to the reference (AUC 0.60 [95% CI: 0.43 to 0.74]). Posterior distribution of the bootstrap-corrected AUC difference between DFT and reference model was gaussian (mean 12%, standard deviation 12%) with a posterior probability of 86%, that DFT has a greater AUC.

Conclusions

Discrimination of myocarditis from similar clinical presentations remains challenging. The results support incremental discriminatory value of DFT-decomposed myocardial strain for non-invasive diagnosis of myocarditis. Future research should address the value of the spectral decomposition of cardiac motion trajectories in larger samples and different disease entities.
Invasive validation of a novel approach to determine aortic valve area with phase-contrast cardiac magnetic resonance imaging
Authors: Troger F , Lechner I , Reindl M , Tiller C , Holzknecht M , Pamminger M , Reinstadler SJ , Bauer A , Gizewski ER , Metzler B , Klug G , Mayr A
Published: July 2021

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Austrian Society of Cardiology

Background. Echocardiography is considered the standard method for screening and diagnosing aortic valve stenosis. However, inaccuracies in the determination of stroke-volumes by the continuity equation might particularly make the evaluation of patients with low-flow states difficult. Phase-contrast cardiac magnetic resonance (PC-CMR) is a promising tool in overcoming these limitations by the simultaneous determination of flow volumes and velocities across the stenotic valve.

Purpose

The aim of this study is to validate a novel approach based on PC-CMR against the invasive determination of the aortic valve area (AVA).

Methods. PC-CMR was performed in 50 patients with moderate or severe AS (n = 52; age 72 years [interquartile range (IQR) 66 - 78], 38% of patients with low-flow states). All of them were referred to invasive evaluation of aortic stenosis by cardiac catheterization. Additionally, transthoracic echocardiography (TTE) was performed. Aortic valve area (AVA) was determined by PC-CMR (AVAPC-CMR) via plotting momentary flow across the valve against momentary flow velocity. AVAPC-CMR at different time points over the entire cardiac cycle was compared to invasively determined AVA, calculated according to the Gorlin-formula. Stroke volumes (SV) were determined by the Fick-principle, pressure gradients according to the modified Bernoulli-equation.

Results. Mean AVA during the whole systolic phase showed a good correlation (r: 0.544, p < 0.001) with invasive AVA with a small bias (AVACMR: 0.78 cm², IQR: [0.60-0.96] versus AVAINVASIVE: 0.70 cm², IQR: [0.52-0.87], bias: 0.08 cm², p = 0.017). Intermethodical correlation and bias of AVA as measured by TTE (AVATTE) and AVAINVASIVE were similar to AVAPC-CMR (AVATTE: 0.81 cm²; IQR: [0.64-0.96] versus AVAINVASIVE: 0.70 cm², IQR: [0.52-0.87] r: 0.580, p < 0.001, bias 0.11 cm², p < 0.001). SV by PC-CMR showed a good correlation with Cine-CMR with no significant bias (r: 0.730, p < 0.001; SVPC-CMR: 86 ± 31 ml; SVCine: 85 ± 19 ml). Maximum gradients determined by PC‑CMR were 65 ± 2 9mmHg and showed a good inverse correlation with AVAPC-CMR (r: ‑0.371; p = 0.008).

Conclusion. PC-CMR with continuous determination of flow volumes and flow velocities is able to determine AVA in patients with severe aortic stenosis with a tendency to overestimate AVA compared to invasively determined AVA.