Magnetic Resonance Data Research Articles

Predictors of long term tricuspid regurgitation after pulmonary valve replacement: a single center study on the cohort of significant preoperative tricuspid regurgitation

Abstract Background Almost one-third of repaired tetralogy of Fallot (TOF) and pulmonary stenosis (PS) patients referred for pulmonary valve replacement (PVR) have at least moderate tricuspid regurgitation (TR). Predictors of long term TR in this population are not well defined and the role of Tricuspid Annuloplasty (TA) in addition to PVR in this setting is controversial. Purpose Patients with preoperative severe TR or moderate TR with dilated tricuspid annulus (>40mm) undergo TA at the time of PVR as per protocol in our instititution. The aim of this observational study was to evaluate the long term results of this approach and to identify predictors of significant TR at the end of follow-up. Material and methods We retrospectively reviewed 35 repaired TOF and PS patients who underwent surgical PVR with (n=17, group 1) or without (n=18, group 2) TA in a single tertiary hospital between June-2009 and June-2021. Pre- and postoperative echocardiographic and cardiac magnetic resonance data were assessed for TR severity and right ventricle size and systolic function. Baseline and clinical follow up data were collected. Uni- and multivariable tests were used to analyze predictors of at least moderate TR after PVR. Results Mean age at PVR and baseline image parameters were comparable between groups, except for TR grade (p 0.006), tricuspid annulus size (p 0.018) and right ventricle outflow tract diameter (p 0.04) which were greater in group 1. TA did not confer and increased risk of surgical and peroperative complications. Intensive care unit (p 0.94) and total hospital admission days (p 0.59) did not differ among groups. At one year, TR grade significantly improved regardless of TA. At the end of follow-up (5.29±2.9 years), the degree of TR increased in both groups with no differences between groups (p 0.38) (see table 1). In univariable analysis, two independent predictors of at least moderate TR at end of follow-up were identified; mixed TR mechanism (OR 12.5, p 0.006) and severe preoperative TR grade (OR 10.21, p 0.003). Mixed TR mechanism (OR 15.78, p 0.01) and a right ventricle ejection fraction below 45% (OR 1.47, p 0.01) were identified as risk factors of significant TR in multivariable analysis (see Table 2). Conclusions TA seems a reasonable approach at the time of PVR in patients with severe TR or moderate TR with dilated annulus. Mixed TR mechanism and a worse right ventricular function have been identified as independent predictors factors of long term significant postoperative TR in our study cohort. Funding Acknowledgement Type of funding sources: None.

Ventricular Arrhythmia Substrate Distribution and Its Relation to Sympathetic Innervation in Nonischemic Cardiomyopathy Patients.

Nonischemic cardiomyopathy patients referred for catheter ablation of ventricular arrhythmias (VAs) typically have either inferolateral (ILS) or anteroseptal (ASS) VA substrate locations, with poorer outcomes for ASS. Sympathetic denervation is an important determinant of arrhythmogenicity. Its relation to nonischemic fibrosis in general and to the different VA substrates is unknown. This study sought to evaluate the association between VA substrates, myocardial fibrosis, and sympathetic denervation. Thirty-five patients from the Leiden Nonischemic Cardiomyopathy Study, who underwent electroanatomic voltage mapping and iodine-123 metaiodobenzylguanidine imaging between 2011 and 2018 were included. Late gadolinium-enhanced cardiac magnetic resonance data were collected when available. The relation between global cardiac sympathetic innervation and area-weighted unipolar voltage (UV) as a surrogate for diffuse fibrosis was evaluated. For regional analysis, patients were categorized as ASS or ILS. The distribution of low UV, sympathetic denervation, and late gadolinium enhancement (LGE) scar were compared using the 17-segment model. Median area-weighted UV was 12.3mV in patients with normal sympathetic innervation and 8.7mV in patients with sympathetic denervation. Global sympathetic denervation correlated with diffuse myocardial fibrosis (R=0.53; P=0.02). ILS (n=13) matched with low UV, sympathetic denervation, and LGE scar in all patients, whereas ASS (n=11) matched with low UV in all patients, with LGE scar in 63% (P=0.20), but with sympathetic denervation in only 27% of patients (P=0.0002). Global cardiac sympathetic denervation is related to fibrosis in nonischemic cardiomyopathy patients with VA. The mismatch between regional fibrosis and preserved innervation for ASS may contribute to a VA substrate difficult to control by catheter ablation.

Reproducing Patient-Specific 3D-Model of Pulmonary Artery Hemodynamics by Means of In Vitro Benchtop Simulation

Aim: Patient-specific fluid dynamic simulation of pulmonary arteries can be a valuable tool in pre-procedural planning. Materials & methods: For three patients, soft, deformable models of the pulmonary arteries were 3D printed from cardiac magnetic resonance data. In vitro hemodynamics were replicated using a gear flow pump, 40% glycerol solution and a physical Windkessel module. The pulmonary pressures were compared with patient cardiac catheterization pressure. Results: The pulmonary artery pressures and flow volumes had an adequate goodness of fit except for pulmonary pressures in patient 2. Conclusion: Cardiac magnetic resonance angiogram and flow volume data can be leveraged to generate a patient-specific 3D model and reproduce in vivo hemodynamics by means of in vitro simulation.

A coarse-grained approach to NMR-data-assisted modeling of protein structures.

The ESCASA algorithm for analytical estimation of proton positions from coarse-grained geometry developed in our recent work has been implemented in modeling protein structures with the highly coarse-grained UNRES model of polypeptide chains (two sites per residue) and nuclear magnetic resonance (NMR) data. A penalty function with the shape of intersecting gorges was applied to treat ambiguous distance restraints, which automatically selects consistent restraints. Hamiltonian replica exchange molecular dynamics was used to carry out the conformational search. The method was tested with both unambiguous and ambiguous restraints producing good-quality models with GDT_TS from 7.4units higher to 14.4units lower than those obtained with the CYANA or MELD software for protein-structure determination from NMR data at the all-atom resolution. The method can thus be applied in modeling the structures of flexible proteins, for which extensive conformational search enabled by coarse-graining is more important than high modeling accuracy.

Conditional GAN with 3D discriminator for MRI generation of Alzheimer’s disease progression

Many studies aim to predict the degree of deformation on affected brain regions as Alzheimer’s disease (AD) progresses. However, those studies have been often limited since it is difficult to obtain sequential longitudinal MR data of affected patients. Recently, conditional generative adversarial networks (cGANs) have been used to estimate the changes between unpaired images by modeling their differences. However, generating high-quality 3D magnetic resonance (MR) brain images with cGANs requires a large amount of computation. Previous models have been mostly designed to operate in 2D space taking individual slices or down-sampled 3D space, but these approaches often cause spatial artifacts such as discontinuities between slices or unnatural changes in 3D space. To address these limitations, we propose a novel cGAN that can synthesize high-quality 3D MR images at different stages of AD by integrating an additional module that ensures smooth and realistic transitions in 3D space. Specifically, the proposed cGAN model consists of an attention-based 2D generator, a 2D discriminator, and a 3D discriminator that is able to synthesize continuous 2D slices along the axial view resulting in good quality 3D MR volumes. Moreover, we propose an adaptive identity loss so that relevant transformations take place without compromising the features to identify patients. In our experiments, the proposed method showed better image generation performance than previously proposed GAN methods in terms of image quality and image generation suitable for the condition.

Acyltransferase Domain Swapping for the Production of Tenvermectin B Metabolites in Genetically Engineered Strain Streptomyces avermitilis HU02.

Tenvermectins A and B (TVMs A and B) are hybrid natural compounds of avermectins and milbemycins with enhanced insecticidal activity. Aiming at obtaining a strain for the production of the higher activity metabolite-TVM-B as a major constituent, a recombinant strain Streptomyces avermitilis HU02 was constructed by a domain swapping strategy in which milA1-AT0 gene in S. avermitilis MHJ1011 was replaced by eryA1-AT0 gene from Saccharopolyspora erythraea ATCC 40137. Chemical investigation on the culture of S. avermitilis HU02 led to the isolation of a large amount of TVM-B and trace amounts of five new TVM-B analogues. The structures of new metabolites were elucidated by extensive spectroscopic analysis including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data. The bioassay test indicated that five new TVM-B analogues exhibited potent insecticidal activity against Tetranychus cinnabarinus and Bursaphelenchus xylophilus. This study provided a feasible route to the low-cost production of TVM-B and enriched the structural diversity of TVM-B metabolites.

High-Resolution Mass Spectrometry Identification and Characterization of Flavonoids from Fridericia chica Leaves Extract with Anti-Arbovirus Activity.

Plant extracts are complex mixtures that are difficult to characterize, and mass spectrometry is one of the main techniques currently used in dereplication processes. Fridericia chica is a species with medicinal uses in Latin American countries, used in the treatment of inflammatory and infectious diseases. Extracts of this plant species are characterized by the presence of anthocyanidins. In this study, using high-resolution mass spectrometry coupled with liquid chromatography, it was possible to determine the molecular formula of thirty-nine flavonoids. Fragmentation analysis, ultraviolet spectrum and nuclear magnetic resonance data allowed the partial characterization of the structures of these compounds. The spectral dataset allowed the identification of a series of flavones in addition to the desoxyanthocyanidins common in extracts of the species. The occurrence of some of the proposed structures is uncommon in extracts of species of the Bignoniaceae family, and they are reported for the first time in the extract of this species. Quantitative analyses of total flavonoids confirmed the high content of these constituents in the species, with 4.09 ± 0.34 mg/g of dry plant material. The extract under study showed low in vitro cytotoxicity with CC50 ≥ 296.7 ± 1.4 µg/mL for Vero, LLC-MK2 and MRC-5 cell lines. In antiviral activity assays, inhibition of the cytopathic effects of Dengue, Zika and Mayaro viruses was observed, with EC50 values ranging between 30.1 and 40.9 µg/mL. The best result was observed against the Mayaro virus, with an EC50 of 30.1 µg/mL.

Curcuminoids from the Vietnamese Curcuma longa: Phytochemical analysis and biological activities

A phytochemical investigation on the ethanolic (EtOH) extract of the Vietnamese Curcuma longa (C. longa) rhizomes has led to the isolation of four curcuminoids including curcumin (1), demethoxycurcumin (2), bisdemethoxycurcumin (3), and cyclocurcumin (4). The chemical structure of compounds 1-4 was elucidated by Nuclear magnetic resonance (NMR) and Mass spectrometry (MS) spectral data. Based on High-performance liquid chromatography (HPLC) quantitative analysis, the amounts of three major compounds 1-3 in the C. longa extract were calculated and reached 7.215±0.101, 3.927±0.031, and 2.255±0.049 mg/g, respectively. Curcuminoids 1-4 have induced IC50 values of 9.23-14.6 μg/ml in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay as compared with that of the positive control resveratrol (IC50 11.5 μg/ml). Compounds 1-4 with IC50 values ranging between 8.7-15.54 μg/ml were better than the positive control acarbose (IC50 169.14 μg/ml) in α-glucosidase inhibitory examination. In addition, the EtOH extract and compounds 1-4 were also responsible for inhibitions against enzyme acetylcholinesterase and four cancer cell lines including including epidermoid carcinoma (KB), hepatocellular carcinoma (HepG2), lung cancer (SK-LU-1), and breast cancer (MCF7).

DKS Reconstruction and LPA Size

Longitudinal Trends of Vascular Flow and Growth in Patients Undergoing Fontan OperationThe Annals of Thoracic SurgeryPreviewSingle ventricle (SV) patients undergo multiple surgeries with subsequent changes in anatomy and hemodynamics. There are little cardiac magnetic resonance (CMR) data on serial changes in these patients. This study aimed to assess longitudinal changes of SV anatomy and hemodynamics in a large cohort. Full-Text PDF

Clinical Application of Digital 3D Reconstruction and 3D Printing Technology in Endometrial Cancer (EC) Surgery.

Aims We use CTA and magnetic resonance data to use digital three-dimensional reconstruction and 3D printing technology to reproduce the solid replication of the uterus and surrounding tissues in vitro, fully evaluate the adjacency of tumor tissues with surrounding important organs, blood vessels, and lymph nodes, and reduce the impact. The normal organ structure and function of the surgeon can shorten the operation time, reduce the bleeding during the operation, and reduce the perioperative complications of the patient to improve the prognosis of the patient. Materials and Methods Select 40 EC patients and divide them into group A (3D reconstruction data is transmitted to 3D printing equipment according to the results of CTA and MRI examination, and a 3D model is printed out according to the ratio of 1 : 1 for evaluation and judgment before surgery) and group B (according to MRI imaging examination, there were 20 cases each). Different surgical conditions, quality of life, adverse reactions, and clinical efficacy were evaluated in each group. Results The operation time, the time of the first anus exhaust, the hospitalization time after the operation, and the blood loss of the operation in group A were significantly lower than those in group B. Statistics showed that the difference was significant (P < 0.05). The quality of life scores of emotion, cognition, society, and overall health of group A were significantly higher than those of group B, while physical score, fatigue, nausea, vomiting, and pain were lower than those of group B, which were statistically significant (P < 0.05). Both groups of patients had complications after the operation, and they were asked to be followed up at the outpatient clinic 3 months after the operation. All patients recovered well. There were 19 and 18 patients in groups A and B, respectively, complaining of improvement in clinical symptoms, and the difference was not statistically significant (P < 0.05). Conclusion With the support of digital three-dimensional reconstruction and 3D printing technology, complex operations can be accurately performed, improving the efficacy and safety of patients after EC surgery, improving patient outcomes and quality of life, improving EC positioning accuracy, and reducing tumor residue.

A Novel Cryptic Clostridial Peptide That Kills Bacteria by a Cell Membrane Permeabilization Mechanism.

ABSTRACTThis work reports detailed characteristics of the antimicrobial peptide Intestinalin (P30), which is derived from the LysC enzyme of Clostridium intestinale strain URNW. The peptide shows a broader antibacterial spectrum than the parental enzyme, showing potent antimicrobial activity against clinical strains of Gram-positive staphylococci and Gram-negative pathogens and causing between 3.04 ± 0.12 log kill for Pseudomonas aeruginosa PAO1 and 7.10 ± 0.05 log kill for multidrug-resistant Acinetobacter baumannii KPD 581 at a 5 μM concentration. Moreover, Intestinalin (P30) prevents biofilm formation and destroys 24-h and 72-h biofilms formed by Acinetobacter baumannii CRAB KPD 205 (reduction levels of 4.28 and 2.62 log CFU/mL, respectively). The activity of Intestinalin is combined with both no cytotoxicity and little hemolytic effect against mammalian cells. The nuclear magnetic resonance and molecular dynamics (MD) data show a high tendency of Intestinalin to interact with the bacterial phospholipid cell membrane. Although positively charged, Intestinalin resides in the membrane and aggregates into small oligomers. Negatively charged phospholipids stabilize peptide oligomers to form water- and ion-permeable pores, disrupting the integrity of bacterial cell membranes. Experimental data showed that Intestinalin interacts with negatively charged lipoteichoic acid (logK based on isothermal titration calorimetry, 7.45 ± 0.44), causes membrane depolarization, and affects membrane integrity by forming large pores, all of which result in loss of bacterial viability.IMPORTANCE Antibiotic resistance is rising rapidly among pathogenic bacteria, becoming a global public health problem that threatens the effectiveness of therapies for many infectious diseases. In this respect, antimicrobial peptides appear to be an interesting alternative to combat bacterial pathogens. Here, we report the characteristics of an antimicrobial peptide (of 30 amino acids) derived from the clostridial LysC enzyme. The peptide showed killing activity against clinical strains of Gram-positive and Gram-negative pathogens. Experimental data and computational modeling showed that this peptide forms transmembrane pores, directly engaging the negatively charged phospholipids of the bacterial cell membrane. Consequently, dissipation of the electrochemical gradient across cell membranes affects many vital processes, such as ATP synthesis, motility, and transport of nutrients. This kind of dysfunction leads to the loss of bacterial viability. Our firm conviction is that the presented study will be a helpful resource in searching for novel antimicrobial peptides that could have the potential to replace conventional antibiotics.

Modeling for Volume-Fracturing Vertical Wells in Tight Oil Reservoir considering NMR-Based Research on Imbibition

Abstract The lateral broadband fracturing (LBF) technique for vertical well in tight oil reservoir has been proven to provide much larger stimulated reservoir volume (SRV) by widening its width. Although this new fracturing technique has been successfully applied to the development of tight oil reservoirs in Ordos Basin, China, there is still a lack of models and methods to characterize the imbibition of matrix-fracture system, which is heterogeneous permeability distribution. In this paper, a multilinear fractal model considering Nuclear Magnetic Resonance-based research on imbibition (MFMI) is established to characterize the flow characteristics of lateral broadband fracturing vertical wells (LVWs) in tight oil reservoirs by combining the dual-porosity fractal model considering imbibition and the quad-linear flow model. Due to the application of LBF, the nonuniform distribution of fracture system is characterized by fractal porosity and fractal permeability. In addition, the imbibition in SRV of tight oil reservoir is quantitatively characterized by Nuclear Magnetic Resonance (NMR) data. And the production performance of LVWs is quantified by the MFMI. By using the Laplace transformation, Bessel function, iteration, and Stehfest numerical inversion algorithms, the approximate analytic solutions of our established model, including primary hydraulic fractures, SRV, and unstimulated reservoir volume (USRV), are derived. The solutions of pressure and production are used to compare and analyze in order to discuss the influence of parameters related to lateral broadband fracturing (such as fractal parameters, reservoir parameters, and width of SRV) on flow behavior of LVWs in a tight oil reservoir. The modeling results show that the fractal parameters of fracture system have great effect on the fluid flow in LVWs, and LBF contributes to imbibition production.

Paecilins F-P, new dimeric chromanones isolated from the endophytic fungus Xylaria curta E10, and structural revision of paecilin A.

A total of eleven new dimeric chromanones, paecilins F-P (2–12), were isolated from the endophytic fungus Xylaria curta E10, along with four known analogs (1, 13–15). Their structures and absolute configurations were determined by extensive experimental spectroscopic methods, single-crystal X-ray diffraction, and equivalent circulating density (ECD) calculations. In addition, the structure of paecilin A, which was reported to be a symmetric C8-C8′ dimeric pattern, was revised by analysis of the nuclear magnetic resonance (NMR) data, and single-crystal X-ray diffraction. Compound 1 showed antifungal activity against the human pathogenic fungus Candida albicans with a minimum inhibitory concentration of 16 μg/mL, and Compounds 8 and 10 showed antibacterial activity against the gram-negative bacterium Escherichia coli with the same minimum inhibitory concentration of 16 μg/mL.

Identification of Cyclic Dipeptides and a New Compound (6-(5-Hydroxy-6-methylheptyl)-5,6-dihydro-2H-pyran-2-one) Produced by Streptomyces fungicidicus against Alternaria solani.

As an important microbial resource, Actinomycetes, especially Streptomyces, have important application values in medicine and biotechnology. Streptomyces fungicidicus SYH3 was isolated from soil samples in tomato-growing areas and showed good inhibitory effects on Alternaria solani in tomato. To obtain pure active compounds, SYH3 fermentation broth was subjected to XAD-16 macroporous resin and silica gel column chromatography. Combined with the repeated preparation and separation of preparative high-performance liquid chromatography (HPLC), a total of four monomer compounds were obtained after activity tracking. Compound 4 was identified as a new six-membered lactone ring compound named 6-(5-hydroxy-6-methylheptyl)-5,6-dihydro-2H-pyran-2-one by 1D and 2D nuclear magnetic resonance (NMR) data and mass spectrometry (MS). The other three active compounds belong to the cyclodipeptide, and their half maximal inhibitory concentration (IC50) values against A. solani were 43.4, 42.9, and 30.6 μg/mL, respectively. Compound 4 significantly inhibited the spore germination and induced swollen and deformed local hyphae of A. solani with an IC50 value of 24.9 μg/mL. Compound 4 also had broad-spectrum antifungal activity and had a good antifungal effect on the tested plant-pathogenic fungi. The modes of action of new compound (4) still require further investigation, representing a novel and effective anti-fungal agent for future application.

Prediction of pelvic lymph node metastasis in prostate cancer using radiomics based on T2-weighted imaging.

Pelvic lymph node metastasis (PLNM) is an important factor that affects the stage and prognosis of prostate cancer. Invasive extended pelvic lymph node dissection (ePLND) is the most effective method for clinically diagnosing PLNM. Accurate preoperative prediction of PLNM can reduce unnecessary ePLND. This study aims to investigate the clinical value of radiomics nomogram in predicting PLNM of prostate cancer based on T2-weighted imaging (T2WI). Magnetic resonance (MR) data of 71 patients with prostate cancer who underwent ePLND from January 2017 to June 2021 in Peking University First Hospital were collected retrospectively. All patients were assigned into a training set (January 2017 to December 2020, n=56, containing 186 lymph nodes) and a test set (January 2021 to June 2021, n=15, containing 45 lymph nodes) according to the examination time of multiparametric magnetic resonance imaging (mpMRI). Two radiologists matched the dissected lymph nodes on MRI images, and manually annotated the region of interest (ROI). Based on the outlined ROI, 3 metastatic lymph node prediction models were established: Model 1 (only image features of T2WI), Model 2 (radiomics features based on random forest), and Model 3 (combination of the image and radiomics features). A nomogram was also established. The clinicopathologic characteristics of the patients were obtained from the medical records, including age, the Gleason score, the level of prostate-specific antigen (PSA), and clinical and pathological T stage. The preoperative radiological features of the pelvic lymph nodes (LNs) include size of LNs (the short and long diameters) and volume of LNs. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficacy of the 3 models and decision curve analysis (DCA) was used to evaluate the clinical benefits of the models. No significant differences were found between the training set and test set regarding age, Gleason scores, PSA level, and clinical and pathological T stage (all P>0.05). The differences in volume, short diameter and long diameter between metastatic and non-metastatic LNs were statistically significant in both training set and test set (all P<0.05). In multivariate regression analysis, the short diameter and marginal status of LNs were included in Model 1. Eighteen omics features were selected to construct Model 2. The signal distribution of LNs and Rad score were the significant risk factors for predicting metastasis of pelvic LNs in Model 3. The C-index of nomogram based on Model 3 reached 0.964, and the calibration curve showed that the model had high calibration degree. In the test set, the area under the curves of Model 1, 2, and 3 were 0.78, 0.93, and 0.96 respectively, Model 2 and Model 3 showed significantly higher diagnostic efficiency than Model 1 (Model 1 vs Model 2, P=0.019; Model 1 vs Model 3, P=0.020). There was no significant difference in the area under the curve between Model 2 and Model 3 (P=0.649). The DCA results of the 3 models showed that all models obtained higher net benefits than the PLNM-all or PLNM-none protocol in different ranges of threshold probabilities and Model 3 had the highest clinical benefit. The radiomics nomogram based on T2WI shows a good predictive efficacy for preoperative PLNM in patients with prostate cancer, which could be served as an imaging biomarker to optimize decision-making and adjust adjuvant treatments.

Optic nerve sheath diameter measurement: a means of detecting increased intracranial pressure in pseudotumor cerebri patients.

Pseudotumor cerebri (PTC) occurs when the pressure inside the skull increases for no obvious reason. The aim of this study was to investigate three different methods: the optic nerve sheath diameter (ONSD) method, ONSD/eyeball transverse diameter (ETD) index, and ONSD/orbital transverse diameter (OTD) index for the initial detection of elevated intracranial pressure in patients with PTC. A retrospective study of magnetic resonance data from adult PTC patients (n = 42) and control group (n = 40) was performed. ONSD and OTD measurements were made 3 mm and 10 mm posterior to the globe, after intracranial pressure was measured with lumbar puncture. The sensitivity, specificity, and overall accuracy of the findings on magnetic resonance imaging were calculated. The optic nerve sheath was enlarged in the PTC group compared with the control group. It showed 97% sensitivity and 100% specificity and 79% sensitivity and 87.5% specificity for 3 mm and 10 mm, respectively. The ONSD/ETD and ONSD/OTD indices were increased in the PTC group compared with the control group. For 3 mm posterior to the globe, the ONSD/ETD index had 90.5% sensitivity and 92% specificity, and the ONSD/OTD index had 86% sensitivity and 95% specificity. For 10 mm posterior to the globe, the sensitivity and specificity of the ONSD/ETD and ONSD/OTD indices were 86% and 80% and 74% and 82.5%, respectively. According to our study, the ONSD method and the ONSD/ETD and ONSD/OTD indices are reliable diagnostic markers for PTC. These noninvasive techniques may be useful in monitoring the invasive intracranial catheter and have wide potential clinical applications in district hospitals, emergency departments and intensive care units.

Adverse events prediction in nonischemic dilated cardiomyopathy by two machine learning models integrating clinical and cardiovascular magnetic resonance data

Abstract Funding Acknowledgements Type of funding sources: None. Background Risk stratification of patients with nonischemic dilated cardiomyopathy (NIDCM) is challenging. Machine learning (ML) models represent novel technologic tools that promise to improve predictive ability of cardiovascular adverse outcomes. Purpose To implement two ML models to predict the risk of adverse outcome (composite endpoint of all-cause death, heart transplantation, implantation of ventricular assistant device), in patients with NIDCM using clinical and radiological data. Methods We retrospective collected data from patients affected by NIDCM referred to our cardiologic unit between 2002 and 2018. Two ML models, an extreme gradient boosting machine (XGBoost) and an artificial neural network (ANN), were developed using cardiovascular magnetic resonance (CMR) and clinical parameters. Both models were trained on 67% of patients and evaluated based on the other 33% as internal validation. To investigate the contribution of different features in our models, we used Shapley additive explanations (SHAP) analysis. Results The final cohort resulted of 161 patients (mean age 48.9±13.6 years, 71% males), with a mean follow up duration of 79.1 months. During the follow-up 29 adverse event were observed (16 deaths, 12 heart transplantation, 1 implantation of ventricular assistant device). ANN model resulted in an accuracy of 76% with an area under the receiver operating characteristic (ROC) curve of 0.66; SHAP analysis identified male sex, percentage of late gadolinium enhancement (LGE) and LGE distribution in the lateral wall of myocardium as the main markers of adverse outcomes. XGBoost model resulted in an accuracy of 78% with a ROC curve of 0.76; SHAP analysis identified NT-proBNP level, age and serum creatinine mainly related with adverse outcomes. About CMR parameters, left ventricular diameter and ejection fraction better related with adverse outcomes. Conclusions Our models achieved a good performance in prediction of adverse events, suggesting that ML could improve our ability of risk stratification of NIDCM. XGBoost better performed than ANN, and SHAP analysis suggested that both CMR parameters and clinical parameters contribute to the definition of risk. ANN performance and SHAP analysisXGBoost performance and SHAP analysis

Longitudinal Trends of Vascular Flow and Growth in Patients Undergoing Fontan Operation

BackgroundSingle ventricle (SV) patients undergo multiple surgeries with subsequent changes in anatomy and hemodynamics. There are little cardiac magnetic resonance (CMR) data on serial changes in these patients. This study aimed to assess longitudinal changes of SV anatomy and hemodynamics in a large cohort. MethodsAnatomy and flow in SV patients with serial CMRs performed between 2008 and 2019 at a single institution were retrospectively reviewed. Mixed-effects linear regression was used to estimate changes over time at 3 to 9 months, 1 to 5 years, and >5 years after Fontan. ResultsA total of 119 patients were included (51% with hypoplastic left heart syndrome; 77% underwent extracardiac Fontan). A total of 88 patients had 3 serial CMRs. Indexed right superior vena cava, inferior vena cava, neoaortic valve, and descending aorta area decreased over time (beta = -0.19, -0.44, and -0.23, respectively; P < .01), as did indexed right superior vena cava, neoaorta and native aorta, and descending aorta flow (beta = -0.49, -0.53, and -0.59, respectively; P < .0001). Inferior vena cava flow and its contribution to total caval flow increased (beta = 0.33; P < .0001). Indexed right and left pulmonary artery flow did not change; however, indexed left pulmonary artery area decreased (beta = -0.16; P = .0014) with time. Systemic-to-pulmonary collateral flow remained unchanged before and early after Fontan (beta = -0.54; P = .42) but decreased with time from Fontan (beta = -0.22; P < .0001). ConclusionsIn this cohort of longitudinally followed SV patients, there are significant trends in vascular size and flow over time from Fontan. These findings can be used as a framework to interpret serial CMR data in the SV and noninvasively identify deviations from expected patterns before the development of clinical symptoms.

The Variation in the Diastolic Period with Interventricular Septal Displacement and Its Relation to the Right Ventricular Function in Pulmonary Hypertension: A Preliminary Cardiac Magnetic Resonance Study.

Background: Pulmonary hypertension (PH) is known to alter the biventricular shape and temporal phases of the cardiac cycle. The presence of interventricular septal (IVS) displacement has been associated with the severity of PH. There has been limited cardiac magnetic resonance (CMR) data regarding the temporal parameters of the cardiac cycle in PH. This study aimed to quantify the temporal changes in the cardiac cycle derived from CMR in PH patients with and without IVS displacement and sought to understand the mechanism of cardiac dysfunction in the cardiac cycle. Methods: Patients with PH who had CMR and right heart catheterization (RHC) examinations were included retrospectively. Patients were divided into an IVS non-displacement (IVSND) group and an IVS displacement (IVSD) group according to IVS morphology, as observed on short-axis cine CMR images. Additionally, age-matched healthy volunteers were included as the health control (HC). Temporal parameters, IVS displacement, ventricular volume and functional parameters were obtained by CMR, and pulmonary hemodynamics were obtained by RHC. The risk stratification of the PH patients was also graded according to the guidelines. Results: A total of 70 subjects were included, consisting of 33 IVSD patients, 15 IVSND patients, and 22 HC patients. In the IVSND group, only the right ventricle ejection fraction (RVEF) was decreased in the ventricular function, and no temporal change in the cardiac cycle was found. A prolonged isovolumetric relaxation time (IRT) and shortened filling time (FT) in both ventricles, along with biventricular dysfunction, were detected in the IVSD group (p < 0.001). The IRT of the right ventricle (IRTRV) and FT of the right ventricle (FTRV) in the PH patients were associated with pulmonary vascular resistance, right cardiac index, and IVS curvature, and the IRTRV was also associated with the RVEF in a multivariate regression analysis. A total of 90% of the PH patients in the IVSD group were stratified into intermediate- and high-risk categories, and they showed a prolonged IRTRV and a shortened FTRV. The IRTRV was also the predictor of the major cardiovascular events. Conclusions: The temporal changes in the cardiac cycle were related to IVS displacement and mainly impacted the diastolic period of the two ventricles in the PH patients. The IRT and FT changes may provide useful pathophysiological information on the progression of PH.

Experimental Investigation of Pore Characteristics and Permeability in Coal-Measure Sandstones in Jixi Basin, China

The research of pore and permeability characteristics of tight sandstone reservoirs in coal-measure is critical for coal-measure gas development. In this study, the pore systems of tight sandstones were studied based on low-field nuclear magnetic resonance (LF-NMR) data. The permeability of tight sandstones was obtained by the tester based on the pulse transient method. The permeability variation with the effective stress, grains, and pore characteristics was analyzed. The results show that the tight sandstone reservoirs in the coal-measure have low total porosity (2.80–4.14%), low effective porosity (0.51–1.56%), and low permeability (0.351 × 10−6–13.910 × 10−6 um2). LF-NMR T2 spectra of the testing sandstones show that the micropores are the most developed, but most of the micropores are immovable pores. The pore characteristics are significantly affected by the grain size of sandstones. The pore connectivity ranks from good to poor with decreasing sandstone particle size. The total porosity and effective porosity increase with the grain size. There is a near-linear negative relationship between permeability and effective stress when the effective stress is between 405 psi and 808 psi. The greater the number of movable pores and the larger the effective porosity, the bigger the permeability of the sandstone. The effective porosity of sandstones is a sensitive indicator for evaluating the permeability of tight sandstone reservoirs. The stress sensitivity coefficient of permeability (Ss) increases with the increase of the effective stress. The sandstone with lower permeability, smaller effective porosity, and finer grains has a higher Ss. The particle size of sandstone from coal-measure has a great influence on both permeability and Ss. The findings will provide a better understanding of the characterization of pore structure and permeability in the process the coal-measure gas extraction, which is useful for the efficient development of coal-measure gas.