Variation Of Signal Intensity Research Articles

Dynamic pulmonary MRI using motion-state weighted motion-compensation (MostMoCo) reconstruction with ultrashort TE: A structural and functional study.

To improve the quality of structural images and the quantification of ventilation in free-breathing dynamic pulmonary MRI. A 3D radial ultrashort TE (UTE) sequence with superior-inferior navigators was used to acquire pulmonary data during free breathing. All acquired data were binned into different motion states according to the respiratory signal extracted from superior-inferior navigators. Motion-resolved images were reconstructed using eXtra-Dimensional (XD) UTE reconstruction. The initial motion fields were generated by registering images at each motion state to other motion states in motion-resolved images. A motion-state weighted motion-compensation (MostMoCo) reconstruction algorithm was proposed to reconstruct the dynamic UTE images. This technique, termed as MostMoCo-UTE, was compared with XD-UTE and iterative motion-compensation (iMoCo) on a porcine lung and 10 subjects. MostMoCo reconstruction provides higher peak SNR (37.0 vs. 35.4 and 34.2) and structural similarity (0.964 vs. 0.931 and 0.947) compared to XD-UTE and iMoCo in the porcine lung experiment. Higher apparent SNR and contrast-to-noise ratio are achieved using MostMoCo in the human experiment. MostMoCo reconstruction better preserves the temporal variations of signal intensity of parenchyma compared to iMoCo, shows reduced random noise and improved sharpness of anatomical structures compared to XD-UTE. In the porcine lung experiment, the quantification of ventilation using MostMoCo images is more accurate than that using XD-UTE and iMoCo images. The proposed MostMoCo-UTE provides improved quality of structural images and quantification of ventilation for free-breathing pulmonary MRI. It has the potential for the detection of structural and functional disorders of the lung in clinical settings.

Dihydrogen phosphate anion boosts the detection of sugars in electrospray ionization mass spectrometry: A combined experimental and computational investigation.

Sugars are key molecules of life but challenging to detect via electrospray ionization mass spectrometry (ESI-MS). Unfortunately, sugars are challenging analytes for mass spectrometric methods due to their high gas-phase deprotonation energies and low gas-phase proton affinities which make them difficult to ionize in high abundance for MS detection. Hydrogen-bond interactions in H2 PO4 - -saccharide anionic systems were studied both experimentally (via electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, ESI-FT-ICR-MS) and computationally by several sophisticated density-functional theoretical methods (DFT and DFT-D3). The H2 PO4 - dopant boosts the detection of sugars up to 51-times in the case of sucrose and up to 263-times for glucose (at 0.1 ppm concentration level). H2 PO4 - binds toward sugar molecules with noticeably more hydrogen bonds than the established dopant chloride Cl- does, with increasing binding energies in the order: Monosaccharides < Trisaccharides < Disaccharides. Analysis of a complex oak plant sample revealed that NH4 H2 PO4 specifically labeled a diverse set of sugar-type plant metabolites in the form of [M + H2 PO4 ]- complexes. We reveal the mechanism of interaction of H2 PO4 - with different sugars and glycosylated organic compounds, which significantly enhances their ionization in mass spectrometry. A computational and experimental investigation is presented. A strong correlation between the MS signal intensities of detected [M + H2 PO4 ]- anions of different saccharides and their calculated dissociation enthalpies was revealed. Thus, the variation in MS signal intensities can be very well described to a large extent by the variation in calculated saccharide affinities toward the H2 PO4 - dopant anion, showing that DFT-D3 can very well describe experimental FT-ICR-MS observations.

Analysis of Physicochemical Natures of Modern Artifacts in MRI

Magnetic resonance imaging (MRI) is very useful in the medical sector as it uses radio waves and robust magnetic fields to produce images of the inside of the human body. MRIs are so helpful in pathologies. However, artifacts in MRI occur due to the complex nature of MRI. Artifacts in MRI may reduce the examination quality and may also be confused with pathology. Failing to identify artifacts in MRI can bring troubles. Hence, it’s very important to reduce or avoid artifacts in MRI. The major reasons behind artifacts in MRI are improper action of the MRI scanner, magnetic susceptibility, motion, chemical shifts, variation in signal intensity, etc. Due to MRI artifacts, patients can suffer from serious problems. Therefore, we have analyzed the physicochemical natures of artifacts in MRI. The research has made attempts to identify various types of artifacts in MRI and find out the causes of these artifacts. There have been samples of various types of artifacts based on which the analyses have been done. Based on these identifications of artifacts, there have also been discussions and analyses on how to avoid artifacts in MRI.

Clinical 7T MRI for epilepsy care: Value, patient selection, technical issues, and outlook.

Ultra-high-field 7.0 Tesla (T) MRI offers substantial gains in signal-to-noise ratio (SNR) over 3T and 1.5T, but for over two decades has remained a research tool, while 3T scanners have achieved widespread clinical use. This much slower translation of 7T relates to daunting technical challenges encountered in ultra-high-field human MR imaging. The recent introduction of United States Food and Drug Administration (FDA)-approved clinical 7T scanners promises to be a watershed for many 7T neuroimaging applications, including epilepsy imaging. The high SNR of 7T allows clinical imaging of fine neuroanatomic detail at unprecedented spatial resolution, helping with detection and differentiation of subtle, potentially treatable lesions undetectable or suboptimally assessed at 3T. The accompanying research paper reports our group's analysis of 7T MRI efficacy in epilepsy treatment planning. Here, we introduce the technical background and clinical approach we currently use, in order to assist clinical epileptologists and neuroimagers contemplating, creating, or referring patients to a clinical 7T epilepsy imaging service. We describe a tiered epilepsy imaging strategy and protocols designed to optimize 7T value and work around signal intensity variation and signal loss artifacts, which remain significant challenges to full exploitation of 7T clinical value. We describe FDA-approved techniques for mitigating these artifacts and briefly outline techniques currently under development, but not yet FDA approved. Finally, we discuss the major issues in 7T patient safety and toleration, outlining their physical causes and effects on workflow, and provide references to more comprehensive technical reviews for readers seeking greater technical detail.

Prognostic Value of Late Enhanced Cardiac Magnetic Resonance Imaging Derived Texture Features in Dilated Cardiomyopathy Patients With Severely Reduced Ejection Fractions.

Background: Late enhanced cardiac magnetic resonance (CMR) images of the left ventricular myocardium contain an enormous amount of information that could provide prognostic value beyond that of late gadolinium enhancements (LGEs). With computational postprocessing and analysis, the heterogeneities and variations of myocardial signal intensities can be interpreted and measured as texture features. This study aimed to evaluate the value of texture features extracted from late enhanced CMR images of the myocardium to predict adverse outcomes in patients with dilated cardiomyopathy (DCM) and severe systolic dysfunction.Methods: This single-center study retrospectively enrolled patients with DCM with severely reduced left ventricular ejection fractions (LVEFs < 35%). Texture features were extracted from enhanced late scanning images, and the presence and extent of LGEs were also measured. Patients were followed-up for clinical endpoints composed of all-cause deaths and cardiac transplantation. Cox proportional hazard regression and Kaplan–Meier analyses were used to evaluate the prognostic value of texture features and conventional CMR parameters with event-free survival.Results: A total of 114 patients (37 women, median age 47.5 years old) with severely impaired systolic function (median LVEF, 14.0%) were followed-up for a median of 504.5 days. Twenty-nine patients experienced endpoint events, 12 died, and 17 underwent cardiac transplantations. Three texture features from a gray-level co-occurrence matrix (GLCM) (GLCM_contrast, GLCM_difference average, and GLCM_difference entropy) showed good prognostic value for adverse events when analyzed using univariable Cox hazard ratio regression (p = 0.007, p = 0.011, and p = 0.007, retrospectively). When each of the three features was analyzed using a multivariable Cox regression model that included the clinical parameter (systolic blood pressure) and LGE extent, they were found to be independently associated with adverse outcomes.Conclusion: Texture features related LGE heterogeneities and variations (GLCM_contrast, GLCM_difference average, and GLCM_difference entropy) are novel markers for risk stratification toward adverse events in DCM patients with severe systolic dysfunction.

SERSNet: Surface-Enhanced Raman Spectroscopy Based Biomolecule Detection Using Deep Neural Network.

Surface-Enhanced Raman Spectroscopy (SERS)-based biomolecule detection has been a challenge due to large variations in signal intensity, spectral profile, and nonlinearity. Recent advances in machine learning offer great opportunities to address these issues. However, well-documented procedures for model development and evaluation, as well as benchmark datasets, are lacking. Towards this end, we provide the SERS spectral benchmark dataset of Rhodamine 6G (R6G) for a molecule detection task and evaluate the classification performance of several machine learning models. We also perform a comparative study to find the best combination between the preprocessing methods and the machine learning models. Our best model, coined as the SERSNet, robustly identifies R6G molecule with excellent independent test performance. In particular, SERSNet shows 95.9% balanced accuracy for the cross-batch testing task.

Surface-enhanced Raman scattering of DNA bases using frozen silver nanoparticle dispersion as a platform.

Raman spectroscopy is a powerful method to characterize molecules in various media. Although surface-enhanced Raman scattering (SERS) is often employed to compensate for the intrinsically poor sensitivity of Raman spectroscopy, there remain serious tasks, such as simple preparations of SERS substrates, sensitivity control, and reproducible measurements. Here, we propose freezing as an efficient way to overcome these problems in SERS measurements using DNA bases as model targets. Solutes are expelled from ice crystals and concentrated in the liquid phase upon freezing. Silver nanoparticles (AgNPs) are also concentrated in the liquid phase to aggregate with Raman target analytes. The SERS signal intensity is maximized when the AgNP concentration exceeds the critical aggregation value. Freezing allows up to 5000 times enhancements of the SERS signal. Thus, an efficient SERS platform is prepared by simple freezing. The simultaneous detection of four DNA bases effectively eliminates variations of signal intensities and allows the reliable determination of concentrationratios.

DETECTION OF OSTEOPOROSIS IN PANORAMIC IMAGE RADIOGRAPH AREA OF MANDIBLE BONE USING HARRIS CORNER DETECTION

Every human will grow older. The aging process in a person is characterized by osteoporosis. Osteoporosis is a person's bone condition becomes porous and fragile. Marked by a decrease in bone tissue that is easily fragile or broken, a bent back and a shorter body. Alternative detection of osteoporosis can be done by X-ray image of the jaw bone from dental panoramik which analyzed the texture using machine learning and image processing techniques. Harris Corner Detection is a corner detection system that is often used because it is able to produce consistent values in images that experience rotation, scaling, variations in lighting and having lots of noise. Angular detection using the Harris method is based on variations in signal intensity. A large variation in intensity indicates the angle of the image. In the process of osteoporosis detection system using image processing, it is started from preprocessing, processing and final results. The data used in the study were 152 data, with 3 stages of classification, namely : 3-20 years old, 20-40 years old and 40-71 years old group. Based on the expert validation calculation that has been done, the percentage of suitability of the 3-20 years old group is 100%, group 20-40 years old is 98.78%, age group 40-71 years old is 76.47%.

Sparse and continuous sampling approaches to fMRI of overt vocalization tasks

Sparse temporal sampling has become the dominant paradigm for functional magnetic resonance imaging studies of auditory stimuli or verbal responses, as it allows the presentation or production of stimuli during the relatively quiet periods when there is no gradient switching and ensures that task-related movements are not occurring during scan acquisitions. To date, however, there has been no direct comparison between sparse and continuous acquisition protocols for overt auditory-verbal studies (i.e., speaking or singing). The aim of this study was to determine whether sparse temporal sampling would reduce movement artefacts and show better network activation for overt singing compared to continuous imaging. Fifteen healthy adults performed the same overt singing task under both sparse and continuous scanning conditions. We noted significant variations in signal intensity between adjacent slices in our sparse acquisition, with (odd-numbered) slices acquired in the second half of each volume acquisition being of lower intensity and showing less reliable task-related activation, and thus requiring the removal of these slices prior to preprocessing. Edge artefacts, presumably due to movement, were observed in both acquisition types at a subthreshold level, although ventricular space artefacts were more apparent in the continuous data. However, statistical comparison revealed no significant differences in functional activation nor in motion correction parameters. Our results show that sparse imaging has the potential to introduce significant image artefacts affecting downstream analyses. While sparse sampling provides benefits that may be essential for certain studies (e.g., periods free from scanner noise), the technical requirements of such sequences should not be overlooked and inspection of raw data is essential. Our data also show that continuous imaging can be used for overt response auditory-verbal studies and may be of wider utility than previously appreciated.

Tuning CO2 sensing properties of HPTS along with newly synthesized coordination polymers (CPs)

Coordination polymers (CPs), new functional hybrid materials, have received important attention due to their structural features and many different applications such as gas storage, catalysis, energy storage, small molecule adsorption, luminescence, and chemical sensors. In this study, two newly synthesized metal-organic frameworks (MOFs); [Mn2(µ4-dmg)-(µ4-dmg)(µ-bipy)]n (CP1) and [Mn2(µ4-dmg)(µ4-dmg)(µ-dpeten)]n (CP2); were used for sensing of gaseous carbon dioxide with a spectrofluorometric method with a dye, 8-hydroxypyrene-1, 3, 6-trisulfonic acid (HPTS) as matrix additive material for the first time. The ion-pair form of the HPTS was used in the polymethyl methacrylate matrix as a thin film form. When the HPTS based sensing slides along with the CPs, resulted in many advances such as high relative signal change and larger linear response range, improved sensor dynamics, and higher sensitivity with respect to the additive-free form. More specifically, in the presence of silver nanoparticles (AgNPs), the variation in relative signal intensities of CP1 and CP2 doped HPTS sensing agents were measured as 60 and 40% for the concentration range of 0–10% pCO2, respectively. The aim of this study is to enhance the CO2 response of HPTS with doped CPs due to their useful attributes and potential applications containing selective gas absorption.

Could we use cardiac MRIfor diagnosis of infective endocarditis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Echocardiography is a reliable imaging tool in diagnosing infective endocarditis (IE) according to "modified Dukes criteria"; however, it lacks tissue characterization of cardiac masses, and transthoracic echocardiography (TTE) has low sensitivity in detection of vegetations. Moreover, transesophageal echo (TEE) is considered semi-invasive and intolerable in some situations .On the other hand, cardiac magnetic resonance (CMR) is a powerful true 3D imaging tool with wide field of view, and superior capability of tissue characterization of cardiac masses; however, modest information is available about utility of CMR in diagnosing IE. Purpose To assess the feasibility of CMR to identify vegetations and complications of IE, and compare obtained findings with those obtained from echocardiography regarding: presence, number, size of vegetations, and detection of cardiac complications (e.g. aortic root abscess, periannular abscess, and shunts). Materials and Methods Eighty consecutive patients with suspected IE were enrolled in the study. All patients underwent TTE; only those with left-sided lesions underwent TEE. When clinical situation allowed, CMR examination using 1.5 Tesla magnet were performed using the following sequences: Steady-state free precession (SSFP), T1W (± fat suppression) and T2W, first-pass perfusion, and delayed hyperenhancement. Moreover, chest and abdominal survey was done. Results Sixty-one patients (45 males and 16 females) were able to undergo and complete CMR study. Affection of tricuspid valve was seen in 39.3%, mitral 31.1%, aortic 24.6%, and pulmonary 4.9% of cases. All vegetations visualized by echocardiography were also clearly detected and confirmed by CMR. The sensitivity, specificity, accuracy and Kappa agreement of CMR with echocardiography in depicting &amp;gt;0.5cm vegetations were all 100%. By tissue characterization, vegetations resemble features of thrombi (with variation in signal intensity according to age of vegetation). However, in some cases, masses have a unique pattern that is different from vegetations of IE, and subsequently other diagnoses were suggested (e.g. fibroelastoma, Libman-Saks endocarditis). In 22 patients, CMR provided more information than echocardiography, and in 6 patients, CMR made a paradigm shift of diagnosis. Conclusion Cardiac MRI is a powerful imaging tool in diagnosis of IE and its complications. In comparison with echocardiography, CMR can identify the presence, numbers, and size of vegetations accurately. Moreover, with its unique ability of tissue characterization, CMR helps distinguish vegetations from other masses; therefore changes the diagnosis of IE and subsequent management in some patients.

Preoperative Magnetic Resonance Cholangiopancreatography for Detecting Difficult Laparoscopic Cholecystectomy in Acute Cholecystitis.

Previous studies have shown that signal intensity variations in the gallbladder wall on magnetic resonance imaging (MRI) are associated with necrosis and fibrosis in the gallbladder of acute cholecystitis (AC). However, the association between MRI findings and operative outcomes remains unclear. We retrospectively identified 321 patients who underwent preoperative magnetic resonance cholangiopancreatography (MRCP) and early laparoscopic cholecystectomy (LC) for AC. Based on the gallbladder wall signal intensity on MRI, these patients were divided into high signal intensity (HSI), intermediate signal intensity (ISI), and low signal intensity (LSI) groups. Comparisons of bailout procedure rates (open conversion and laparoscopic subtotal cholecystectomy) and operating times were performed. The recorded bailout procedure rates were 6.8% (7/103 cases), 26.7% (31/116 cases), and 40.2% (41/102 cases), and the median operating times were 95, 110, and 138 minutes in the HSI, ISI, and LSI groups, respectively (both p < 0.001). During the multivariate analysis, the LSI of the gallbladder wall was an independent predictor of both the bailout procedure (odds ratio [OR] 5.30; 95% CI 2.11–13.30; p < 0.001) and prolonged surgery (≥144 min) (OR 6.10, 95% CI 2.74–13.60, p < 0.001). Preoperative MRCP/MRI assessment could be a novel method for predicting surgical difficulty during LC for AC.

Diffusion-weighted imaging of uterine adenomyosis: Correlation with clinical backgrounds and comparison with malignant uterine tumors.

To elucidate correlation between signal intensity on diffusion-weighted images (SI-DWI) and clinical backgrounds for uterine adenomyosis and to compare SI-DWI of adenomyosis and malignant uterine tumors. This study examined 46 adenomyosis patients diagnosed using magnetic resonance imaging and 25 patients with surgically confirmed malignant uterine myometrial tumor. First, adenomyosis cases were classified visually into high-intensity and low-intensity groups based on the SI-DWI compared with that of normal uterine myometrium. Secondly, correlation was assessed between SI-DWI of adenomyosis and patient clinical background information such as age, menopausal status, menstrual cycle and dysmenorrhea severity. Third, quantitative comparison was made of low-intensity adenomyosis (LIA), high-intensity adenomyosis (HIA) and malignant tumor groups for the signal intensity ratio (SIR) on DWI and the apparent diffusion coefficient (ADC). Their diagnostic performance was evaluated using logistic regression analysis and receiver operating characteristic (ROC) analysis. The 46 adenomyosis cases were classified as 26 low-intensity and 20 high-intensity cases. Significant correlation was found only for menstrual cycle phases. HIA had significantly lower SIR and higher ADC than malignant tumor. The ADC of HIA was significantly higher than that of LIA. The combination of SIR and ADC showed excellent diagnostic performance (area under ROC curve, 0.99). There is a variation in signal intensity on DWI of uterine adenomyosis and it is associated with menstrual cycle phase. Adenomyosis with high signal intensity on DWI can be differentiated from malignant lesions by its lower signal intensity on DWI and higher ADC than that found for malignant uterine tumors, however overlaps exist.

Retracted] Effect of Manganese Ions on Spectroscopic and Insulating Properties of Aluminophosphate Glasses

The melt‐quenching technique was used to produce 39CdO–10Al2O3‐(51‐x) P2O5: xMnO glasses (x = 0, 0.1, 0.2, 0.3, and 0.4 wt.%). Various stability factors were calculated and presented from DTA analysis. The stability of the glass network appears to increase with the increase of MnO concentration, according to the findings. IR spectral analysis of these glasses exhibited several symmetrical and asymmetrical bands due to phosphate groups. The observed change in these band intensities with the rise in MnO concentrations, ranging from 0.1 wt.% to 0.4 wt.%, shows an increase in the stability of the glass network. Optical absorption analyses of these glasses revealed an absorption band that shifted from 500 to 488 nm as the concentration of manganese oxide (MnO) increased from 0.1 wt.% to 0.4 wt.%, indicating that Mn2+ ions were gradually converted into Mn3+ ions. EPR spectra of these glasses were characterized by two signals due to Mn2+ and Mn3+ ions. Observations on these signal intensity variations revealed an increase in stability of the glass network with the increase of MnO concentration from 0.1 wt.% to 0.4 wt.%. Parameters, which describe the insulating characteristics, for example, dielectric constant, ε, dielectric loss, tan δ, and AC conductivity σac, were determined in relation to frequency (103 Hz to 105 Hz) and temperature (20°C to 400°C) and presented in the dielectric analysis of these glasses.

MRI histogram texture analysis of lateral pterygoid muscle in patients with temporomandibular disorders

Objective: To evaluate the functional changes of lateral pterygoid muscle (LPM) in the patients with temporomandibular disorders (TMD) using histogram texture analysis. Methods: A total of 28 TMD patients, including 15 males and 13 females, aged (26.2±12.1) years (15-62 years), were enrolled in the outpatient clinic of Department of Radiology, Hainan Hospital of Chinese PLA General Hospital from May 2016 to April 2020. At the same time, 13 volunteers with normal temporomandibular joint [6 males and 7 females, aged (23.5±3.3) years (20-30) years] were recruited. All participants were performed with temporomandibular joint MRI scan, and the subjects were classified into 3 groups according to the disc displacement: TMD with disc without displacement (TMD-DwoD), TMD with disc displacement without reduction (TMD-DDwoR) and NC with disc displacement without reduction (NC-DwoD) for each temporomandibular joint. The area, signal intensity, coefficient of variation (CV) of mean signal intensity and histogram texture of the superior belly of LPM (SBLPM) and inferior belly of LPM (IBLPM) were measured using regions of interests. Results: The area of SILPM presented significantly smaller in TMD-DwoD [(67.36±30.23) mm2] compared with that in NC-DwoD [(91.42±45.01) mm2] (P<0.05) and in TMD-DDwoR group [(72.27±37.53) mm2] (P>0.05). The mean signal intensity of SBLPM was identified significantly higher in TMD-DwoD (304.20±29.90) and TMD-DDwoR (315.06±40.20) compared with that in NC-DwoD (269.79±25.54) (P<0.05). The CV of mean signal intensity of SBLPM presented significantly higher in TMD-DwoD (8.89±2.60) compared with that in NC-DwoD (6.76±1.82) and TMD-DDwoR (7.63±1.62) (P<0.05). The skew and kurtosis showed no significantly differences among three groups for SBLPM (P>0.05). The mean signal intensity and CV for IBLPM presented significantly higher in TMD-DwoD (286.69±23.48 and 9.96±2.24, respectively) and TMD-DDwoR (275.98±30.55 and 10.25±1.96, respectively) compared with that in NC-DwoD (243.56±17.04 and 8.49±1.94, respectively) (P<0.05). The skewness showed significantly lower in TMD-DwoD (0.90±0.94) and TMD-DDwoR (0.73±0.97) compared with that in NC-DwoD (1.40±1.03) (P<0.05). The area and kurtosis for IBLPM showed no significant differences among three groups (P>0.05). Conclusions: The MR histogram texture analysis could primarily be considered as a tool to evaluate the LPM function in TMD patients.

Threshold assessment, categorical perception, and the evolution of reliable signaling.

Animals often use assessment signals to communicate information about their quality to a variety of receivers, including potential mates, competitors, and predators. But what maintains reliable signaling and prevents signalers from signaling a better quality than they actually have? Previous work has shown that reliable signaling can be maintained if signalers pay fitness costs for signaling at different intensities and these costs are greater for lower quality individuals than higher quality ones. Models supporting this idea typically assume that continuous variation in signal intensity is perceived as such by receivers. In many organisms, however, receivers have threshold responses to signals, in which they respond to a signal if it is above a threshold value and do not respond if the signal is below the threshold value. Here, we use both analytical and individual-based models to investigate how such threshold responses affect the reliability of assessment signals. We show that reliable signaling systems can break down when receivers have an invariant threshold response, but reliable signaling can be rescued if there is variation among receivers in the location of their threshold boundary. Our models provide an important step toward understanding signal evolution when receivers have threshold responses to continuous signal variation.

Variation of some planetary seismic hazard indices on the occasion of Lefkada, Greece, earthquake of 17 November, 2015

In this paper we investigate the variation of the tidal triggering effect efficiency, by means of the tidal seismicity compliance parameter p, and the lower Ionosphere variations, by means of the variation of the High-Frequency limit, fo, of the ionospheric turbulence content with the time and space proximity to the site of the earthquake occurrence as well as by the intensity variations of VLF signals transmitted over the seismic area. It is shown that the “Earth tides-seismicity compliance parameter” p may be used as a medium time earthquake warning while the frequency content of the ionospheric turbulence over the earthquake epicenter, deduced directly from GPS network TEC observations or indirectly through the VLF transmission network, may be used for the short time earthquake forecasting, deserving the special attention of the authorities, the scientists and the society.

Prognostic utility of differential contrast-enhancement patterns on late gadolinium enhancement cardiac MRI (LGE-CMR) in patients with cancer-associated cardiac masses

Abstract Background LGE-CMR tissue characterization is widely used to identify cardiac masses (CMASS) in cancer patients – including neoplasm (NEO) and thrombus (THR). Prognostic utility of their differential LGE patterns is unknown. Purpose To determine incremental prognostic utility of LGE patterns in CMASS Methods The population comprised of cancer patients with CMASS on LGE-CMR, for which etiology was classified based on presence (NEO) or absence (THR) of enhancement, and controls matched for cancer type/stage. LGE-CMR tissue properties of NEO was classified based on extent of contrast enhancement – diffusely enhancing (DE), mixed (ME), and predominantly avascular (PA). Clinical follow up was performed for embolic events within 6 months of CMR and all-cause mortality. Results 330 cancer patients (55% M; 55±16yo) with an array of cancer diagnoses (19% sarcoma, 17% GI, 13% GU) were studied. Among CMASS+ pts (n=190), 66% had NEO and 34% had THR on LGE. All THR were non-enhancing. Among NEO, LGE pattern was variable (46% DE, 41% ME, 13% PA); ME lesions were larger than other groups (Fig. 1A). Quantitative tissue properties were consistent with qualitative groups, as evidenced by stepwise variation in signal intensity and CNR. Cumulative embolic events were 3-fold higher in CMASS+ than controls (All: 20% vs. 7%, p=0.001; PE: 13% vs. 5%, p=0.02; CVA/systemic embolism: 10% vs. 3%, p=0.01). Median time to event was 1.3 months [IQR 0.1–2.3] from CMR. Aggregate events were similar between NEO and THR, reflecting similar rates of PE and CVA (p=NS). Among CMASS pts with embolic events, 56% were on anticoagulation at time of event (59% NEO, 50% THR, p=0.61). Regarding CMASS morphology, emboli were 3-fold higher among intracavitary (IC) or highly mobile (HM) CMASS (IC: 25% vs 7%, p&amp;lt;0.001; HM: 38% vs 12%, p=0.001). Regarding location, right sided CMASS were associated with a 3–5 fold increase in PE (IC: 19% vs 6%; HM: 35% vs 7%, both p&amp;lt;0.001) and similar CVA events among left sided CMASS (IC: 17% vs. 6%, p=0.02; HM: 33% vs 6%, p=0.05). Embolic events were similar when partitioned based on quantitative LGE patterns between patients with and without embolic events. As for all-cause mortality, NEO on CMR conferred increased mortality than THR (HR 3.06 [CI=1.84–5.1], p&amp;lt;0.001) and matched controls (HR 2.08 [CI=1.42–3.04], p&amp;lt;0.001) during a median follow-up of 9.4 months [IQR 3.6–23.2]. Among NEO subgroups (Fig. 1B), survival was lower in patients with heterogeneous LGE patterns vs matched controls: the lowest survival in ME (p=0.002) suggests increased vascularity and tumor hypoxia/necrosis associated with aggressive tumors and hence larger lesions. Conclusions Among cancer patients, CMR-evidenced CMASS confers high short-term embolic risk, which are equivalently common between NEO and THR. Intra-cavitary location and increased mobility augment embolic risk irrespective of CMASS tissue properties whereas differential LGE patterns on CMR strongly impact prognosis. Funding Acknowledgement Type of funding source: None

The use of Cardiac MRI in diagnosis of infective endocarditis: a comparative study with echocardiography

Abstract Introduction Echocardiography is a reliable imaging tool in diagnosing infective endocarditis (IE) according to “modified Dukes criteria”; however, it lacks tissue characterization of cardiac masses, transthoracic echocardiography (TTE) has low sensitivity in detection of vegetations, and moreover, transesophageal echo (TEE) is considered semi-invasive and intolerable in some situations. On the other hand, cardiac magnetic resonance (CMR) is a powerful true 3D imaging tool with wide field of view, and superior capability of tissue characterization of cardiac masses; however, modest information is available about utility of CMR in diagnosing IE. Purpose To assess the feasibility of CMR to identify vegetations and complications of IE, and compare obtained findings obtained with those obtained from echocardiography regarding: number and size of vegetations, detection of cardiac complications (e.g. aortic root abscess, periannular abscess, and shunts). Materials and methods Eighty consecutive patients with suspected IE were enrolled in the study. All patients underwent TTE; only those with left-sided lesions underwent TEE. When clinical situation allowed, CMR examination using 1.5 Tesla magnet were performed: SSFP sequence for mobile masses (SSFP), T1W (± fat suppression) and T2W, first-pass perfusion, and delayed hyperenhancement were used. Moreover, chest and abdominal survey was done. Results Sixty-one patients (45 males and 16 females) were able to undergo and complete CMR study. Affection of tricuspid valve was seen in 39.3%, mitral 31.1%, aortic 24.6%, and pulmonary 4.9% of cases. All vegetations visualized by echocardiography were also clearly detected by CMR. The sensitivity, specificity, accuracy and Kappa agreement of CMR with echocardiography in depicting &amp;gt;0.5cm vegetations were all 100%. By tissue characterization, vegetations resemble features of thrombi (with variation in signal intensity according to age of vegetation). However, in some cases, masses have a unique pattern that is different from vegetations of IE, and subsequently other diagnoses were suggested (e.g. fibroelastoma, Libman-Saks endocarditis). In 22 patients, CMR provided more information than echocardiography, and in 6 patients, CMR changed completely the diagnosis. Conclusion Cardiac MRI is a powerful imaging tool in diagnosis of IE and its complications. In comparison with echocardiography, CMR can identify the presence, numbers, and size of vegetations accurately. Moreover, with its unique ability of tissue characterization, CMR helps distinguish vegetations from other masses; therefore changes the diagnosis of IE and subsequent management in some patients. Funding Acknowledgement Type of funding source: None

Effect of ablation behavior on the matrix effect in nanosecond laser ablation inductively coupled plasma mass spectrometry.

To investigate the effect of ablation behavior on the matrix effect, nanosecond laser ablation inductively coupled plasma mass spectrometry is used to analyze variations in element signal intensities of NIST 610 and GSE-1G standard samples with different laser fluence. Scanning electron microscopy and super depth-of-field microscopy are used to capture the morphology of the ablation crater and obtain depth information, respectively. A pump-probe shadowgraph is used to record the dynamic process of plasma plume evolution during sample ablation. Experimental results show that the proportion of refractory elements to volatile elements in the ablation materials with two different matrices increases with an increase in laser fluence. For the GSE-1G matrix, this range of increase is relatively small, and the signal loss of refractory elements occurs at a higher laser fluence. Combined with the morphology of the ablation crater and evolution of the plasma plume, this potential cause is related to the plasma shielding, which is beneficial to form and deposit large particles, resulting in the loss of refractory elements at high energy fluence.