MD Values Research Articles

Studies on nanoconfinement effect of NiO-SiO2 spin glass within mesoporous Al2O3 template

Nanoconfinement studies in the glass system xNiO-(1-x)SiO2 having x values as 0.2 and 0.4 were carried out by preparing nanocomposites using mesoporous alumina template. These samples were studied using wide and small angle xrd data. BET analysis was conducted to find the surface area and pore size distribution of the virgin and nanocomposite samples. The microstructure and distribution of transition metal ions in the system were delineated using STEM-EDAX mapping. XPS data provide the quantitative analysis of Ni2+/Ni3+ species present in the system. Theoretical modeling using DFT simulations were implemented to understand the nanoconfinement effect which was in corroboration with the experimental findings. The theoretical model was validated using UV-Vis absorption spectrum. The magnetodielectric results were explained considering Catalan’s model having positive magnetoresistance. Nyquist plot studies were employed to visualize the realistic circuit model with contributions from different layers present in the nanocomposites. The temperature dependent resistivity data were explained using small polaron hopping model and the inter-site separation between Ni2+/Ni3+ ions was found to be larger in nano confined system than the corresponding bulk glass. Existence of more conducting species manifest a significant enhancement in percentile change of MD, MR & conductivity values for NC-2 compared to NC-1. Study of ZFC-FC magnetization curves effectively substantiate spin glass characteristics which exhibit freezing temperature at 4.1 K. The existence of spin glass behavior are well interpreted in terms of memory effect and relaxation dynamics study.

Selective Effects of Healthy Cognitive Aging and Catechol-O-Methyl Transferase Polymorphism on Limbic White Matter Tracts.

Introduction: The cingulum bundle and uncinate fasciculus are major limbic white matter tracts involved in emotion, memory, and cognition. The main goal of the present study was to investigate the relationship between age and structural properties of the uncinate fasciculus and the cingulum bundle using diffusion tensor imaging (DTI) tractography in a large cohort of healthy individuals. The second goal was to determine the effects of the catechol-O-methyl transferase (COMT) gene polymorphism on the DTI measurements of these white matter tracts. Methods: We recruited 140 healthy participants (18-85 years old). DTI data sets were acquired on a 1.5T magnetic resonance imaging system. The rostral, dorsal, and parahippocampal cingulum, as well as uncinate fasciculus, were delineated using deterministic tractography. Fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivities, tract volume, linear (Cl), planar (Cp), and spherical (Cs) tensor shapes were calculated. The COMT polymorphism (methionine homozygous vs. valine carriers) was determined using single nucleotide polymorphism. Results: We found that age was negatively associated with FA, but positively associated with MD and RD for the rostral cingulum, dorsal cingulum, and the uncinate fasciculus but not for the parahippocampal cingulum. Furthermore, individuals with the COMT methionine homozygous had higher FA and lower MD, RD, AD, and Cs values in the right rostral cingulum compared with the valine carriers across the entire adult life span. Discussion: This study indicates that limbic tracts might be nonuniformly affected by healthy aging, and the methionine homozygous genotype might be associated with micro/macro white matter properties of the right rostral cingulum.

Application of Diffusion Weighted Imaging Techniques for Differentiating Benign and Malignant Breast Lesions.

To explore the value of apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM), and diffusional kurtosis imaging (DKI) based on diffusion weighted magnetic resonance imaging (DW-MRI) in differentiating benign and malignant breast lesions. A total of 215 patients with breast lesions were prospectively collected for breast MR examination. Single exponential, IVIM, and DKI models were calculated using a series of b values. Parameters including ADC, perfusion fraction (f), tissue diffusion coefficient (D), perfusion-related incoherent microcirculation (D*), average kurtosis (MK), and average diffusivity (MD) were compared between benign and malignant lesions. ROC curves were used to analyze the optimal diagnostic threshold of each parameter, and to evaluate the diagnostic efficacy of single and combined parameters. ADC, D, MK, and MD values were significantly different between benign and malignant breast lesions (P<0.001). Among the single parameters, ADC had the highest diagnostic efficiency (sensitivity 91.45%, specificity 82.54%, accuracy 88.84%, AUC 0.915) and the best diagnostic threshold (0.983 μm2/ms). The combination of ADC and MK offered high diagnostic performance (sensitivity 90.79%, specificity 85.71%, accuracy 89.30%, AUC 0.923), but no statistically significant difference in diagnostic performance as compared with single-parameter ADC (P=0.268). The ADC, D, MK, and MD parameters have high diagnostic value in differentiating benign and malignant breast lesions, and of these individual parameters the ADC has the best diagnostic performance. Therefore, our study revealed that the use of ADC alone should be useful for differentiating between benign and malignant breast lesions, whereas the combination of MK and ADC might improve the diagnostic performance to some extent.

The diagnostic accuracy of intravoxel incoherent motion and diffusion kurtosis imaging in the differentiation of malignant and benign soft-tissue masses: which is better?

It is difficult for conventional magnetic resonance imaging (MRI) to distinguish benign soft-tissue masses (STMs) from malignant masses. To quantitatively compare the diagnostic value of intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) in STMs. The data from 58 patients with STMs were retrospectively analyzed. The GE Discovery 3.0-T MRI scanner was used to acquire conventional MRI sequences, IVIM, and DKI images. The chi-square test, independent sample t-test, and Mann-Whitney U tests were used to compare the differences between conventional MRI features, IVIM, and DKI parameters (Dslow, Dfast, f, mean kurtosis [MK], and mean diffusivity [MD]) between the benign and malignant groups. Receiver-operating characteristic (ROC) curve analysis was also performed. Tumor size and depth are statistically different in STTs. Dslow, MK, and MD values in the malignant groups are significantly lower than the benign groups (P < 0.05). However, Dfast and f values are not statistically different between the two groups. The area under the curve (AUC) of Dslow value (0.859) is higher than MD (0.765) and MK (0.676) values for identifying benign and malignant STMs. The Dslow value showed the best specificity (82.93%). The sensitivity and specificity of IVIM and DKI parameters are higher than that of conventional MRI sequences. IVIM and DKI can be used to distinguish between benign and malignant STMs, with Dslow as the most meaningful parameter.

East Asian monsoon during the past 10,000 years recorded by grain size of Yangtze River delta

Abstract Paleoenvironmental research is critical for understanding delta evolution processes and managing delta sustainability, particularly for delta experiencing significant recent fluvial sediment discharge. Based on other previously reported optically stimulated luminescence (OSL) data, Holocene environmental changes of the Yangtze River delta in response to climate fluctuations and human activities were reviewed on the basis of grain-size analyses of core YZ07. The results of grain-size and end-member analysis (EMA) provide a detailed history of East Asian monsoon variability and environmental changes since ∼10,000 cal year B.P. The lower median values (Md) and sand content reflect relatively cool and dry climate conditions between 10,000 and 9,570 cal year B.P. During the early Holocene (9,570–7,630 cal year B.P.), the highest Md values and sand contents and the lowest end member 2 (EM2) contents suggest the Holocene transgression. The increased Md values and sand contents indicate that the climate conditions were warm and wet during the mid-Holocene thermal optimum. From 4,690 to 4,150 cal year B.P., the climate was cool and dry, corresponding to the cool event, as indicated by the finer grain size. Subsequently, between 4,150 and 2,850 cal year B.P., the grain size derived from the Md value and sand content increased, which reflect a wet and warm episode. The climate, which shifted from warm and wet to cool and dry between 2,850 and 1,020 cal year B.P., may have caused a reduction in the sand contents and Md values. After 1,020 cal year B.P., the lowest values of Md and Standard deviation (Sd) and the highest contents of EM2 and clay suggest that the Yangtze River delta has been severely affected by anthropogenic activity. The variability of the East Asian monsoon intensity in the Yangtze River delta strongly correlates with other East Asian monsoon paleoclimate records in China. These results are important for investigations into the interactions between regional systems and global change in monsoonal climatic regions and can provide an example of the evolution of a large scale geomorphic feature resulting from river-sea interaction.

Perioküler Yaşlanma İçin Yapilan Kombine Cerrahinin Kozmetik Ve Fonksiyonel Sonuçlari; Görme Alani Ve Kornea Topografisindeki Değişiklikler

Purpose: To evaluate the visual field and corneal topographic findings which occur with combined surgeries in patients who have other involutional periocular changes in association with dermatochalasis. &#x0D; Material and Method: Eighty eyelids of 40 patients were included in the study and the subjects were divided into 2 groups as additional eyelid pathology (Group 1) and additional eyebrow ptosis (Group 2). In the preoperative and postoperative 3rd month, Margin Reflex Distance-1 (MRD-1), corneal parameters obtained by high base topography device and visual field findings obtained by a visual field device were recorded and detailed ophtalmologic examination was performed. &#x0D; Results: A mean elevation of 0.5 mm was observed in the MRD-1 values in both groups. Postoperatively, a marked reduction was observed in the rate of observing scotoma in the visual field and in MD and PSD values (p

Fusion of crown and trunk detections from airborne UAS based laser scanning for small area forest inventories

High density point clouds from unmanned airborne laser scanning (UALS) systems have great potential for small area forest inventories. We propose an UALS-based tree level inventory method that takes advantage of both the segmented crowns and segmented trunks: hybrid tree detection (HTD). The method is tested at twenty 30 m × 30 m validation plots of varying maturity, tree species distribution and stocking density. With the traditional individual tree crown delineation (ITC) approach, tree attributes are only predicted for crown segmented trees. Here, we assume that a segmented crown can contain more than one tree. Our idea is to identify segmented crowns that contain more than one segmented trunk. One of the trunks is linked to a segmented crown (upper most tree) and the remainders are treated as understory trunks. Heights of the crown segmented trees and the diameters of the understory trunks are used as predictor variables in nonlinear mixed-effects models of tree volume. The %RMSE and %MD values of volume predictions at the 30 m × 30 m validation plot level were 22.2%, −13.3% and 18.8%, −8.3% for ITC and HTD, respectively. We conclude that the proposed HTD approach improves the accuracy of ITC in managed boreal forests when using UALS data.

Diffuse Tract Damage Correlates With Global Cognitive Impairment in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy: A Tract-Based Spatial Statistics Study.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common familial arteriopathy characterized by recurrent lacunar stroke, migraine, and depression. The mechanism of cognitive dysfunction in CADASIL is still uncertain. The aim of this study was to use tract-based spatial statistics (TBSS) to map voxelwise the spatial distribution of brain microstructural change revealed by DTI-derived indices in patients with CADASIL to further study the underlying neuropsychopathological mechanism of CADASIL. Twelve patients with CADASIL and 11 age-, sex-matched healthy controls underwent magnetic resonance imaging at 3 T. Then we evaluated DTI-derived indices (fractional anisotropy [FA], mode of anisotropy [MO], mean diffusivity [MD], axial diffusivity [AD] and radial diffusivity [RD]) of brain white matter (WM) between CADASIL patients and healthy subjects through TBSS. Compared with healthy controls, patients with CADASIL showed extensive decreased FA, MO and increased RD, AD, and MD throughout the entire brain (mainly the WM of the temporal poles, inferior and superior longitudinal fasciculus, inferior fronto-occipital fasciculus, corpus callosum, uncinate fasciculus, internal capsule, external capsule, corona radiata, thalamic radiation, and cingulum). Furthermore, these WM microstructural alterations were significantly correlated with cognitive scores and Scheltens scores. Decreased FA values and MO values were positively correlated with Montreal Cognitive Assessment scores in CADASIL patients. Increased AD, RD, and MD values were significantly negatively correlated with Montreal Cognitive Assessment scores. Widespread WM abnormalities were clearly shown in CADASIL by using TBSS. Severity of microstructural changes correlates significantly with extension of T2 hyperintensity. Moreover, WM microstructural damage and cognitive impairment were significantly correlated. This study indicated that WM tract damage plays an important role in cognitive impairment in CADASIL.

Abstract P56: Diffusion Tensor Imaging at the Time of Stroke is Associated With Cognitive Performance 4 Months Later

Introduction: Cognitive impairment after stroke is associated with stroke severity and baseline brain health. We hypothesized that acute diffusion tensor imaging (DTI) metrics would identify patients at risk for post-stroke cognitive impairment. Methods: Patients were enrolled prospectively in an observational study that involves serial MRI and cognitive testing in patients with recent stroke and moderate white matter disease on MRI but without dementia. DTI was performed at the time of stroke; cognitive testing with the MOCA and the Telephone Interview for Cognitive Status (TICS) were performed 3 months later. DTI was used to calculate Peak Skeletonized Mean Diffusivity (PSMD), a measure of global white matter microstructural integrity previously validated in cerebral small vessel disease. Fractional anisotropy maps were skeletonized (figure panel A) and a histogram of the corresponding MD values was used to calculate the peak width in the non-stroke hemisphere (panel B). Linear regression was used to test whether acute PSMD in the non-stroke hemisphere, acute stroke volume, or baseline NIHSS predicted cognitive performance 3 months later. Results: Fourteen patients followed-up at a median of 123 days. Patients had a median age of 73 years, mean baseline NIHSS of 1.2 (IQR 0-1.75), mean infarct volume of 4cc (range 0-16cc), mean MOCA of 25 (range 19-30), mean TICS of 33 (range 23-41), and 50% were women. Using multivariable linear regression, only acute PSMD predicted follow-up MOCA (std beta= -0.64, adj R 2 = 0.37, p= 0.013) while compared to baseline NIHSS, PSMD showed a stronger association with follow-up TICS score (std beta= -0.57 vs -0.44, p= 0.017; model adj R 2 = 0.476, p= 0.011)(Panel C). Conclusions: In this cohort of patients with small strokes we found that acute contralateral PSMD provided a measure of brain health that appears to predict cognitive performance at 3 months better than stroke size or severity. These are preliminary findings from an ongoing study.

Long-Term Follow-Up After Successful Trabeculectomy: A Case Report of Reversal of Cupping and Recovery of Visual Field Progression

Glaucoma is one of the leading causes of blindness worldwide, and reduction of intraocular pressure (IOP) is the only available evidence-based treatment that reduces visual field deterioration in glaucoma. We present a representative case of structural recovery and recovery of visual field progression after successful trabeculectomy (TLE) with long-term follow-up. A 35-year-old woman with glaucoma visited our hospital in 2008. The IOP in her right eye was 11 mmHg at the first visit, and subsequently increased to values in the high teens to 20 mmHg despite treatment with anti-glaucoma eye drops. During this period, the progression of this eye’s visual field deterioration was fast (mean deviation [MD] slope = −0.63 dB/year) and the optic disc cupping was advanced. In the seven-year period after successful TLE in 2014, the IOP declined to between 8 and 12 mmHg without any anti-glaucoma medication. During the first two years after TLE, the MD values were poorer than those before TLE. However, by 2020, MD values improved gradually to a state better than that before the surgery (MD slope during this period was +0.75 dB/year). The appearance of the optic disc was monitored using fundus photography, which showed optic disc morphological changes during topical glaucoma medication before and after TLE. In particular, a remarkable reversal of optic disc cupping enlargement started at two weeks after TLE, and the optic disc shape in 2021 was similar to that in 2008.Minimally invasive glaucoma surgeries are often preferred; however, our findings suggest that successful TLE followed by long-term rigorous IOP control can result in structural recoveries. Additionally, despite the deterioration in visual field in the early years after TLE, in the long term, it may settle down to the same level before the surgery with recovery of visual field progression, which may be a part of functional recovery.

Diffusion kurtosis imaging to evaluate the effect and mechanism of tetramethylpyrazine on cognitive impairment induced by lipopolysaccharide in rats.

Using diffusion kurtosis imaging (DKI) to evaluate the brain changes, the therapeutic effect and mechanism of tetramethylpyrazine in rats with dementia induced by lipopolysaccharide.Thirty-six male Sprague-Dawley rats were randomly divided into control group and five groups pretreated with sham operation, lipopolysaccharide(150ug) and three doses of tetramethylpyrazine(5, 10, and 20mg/mL respectively). The Morris water maze test was used to evaluate cognitive ability. DKI and histology were performed.Low-dose of tetramethylpyrazine pretreated rats showed lower escape latency(6th day: 15.92seconds(s) vs. 5.11s, P = 0.001), spent more time in the target quadrant(15.67s vs. 29.83s, P = 0.009) and crossed the platform area more frequently(3.50 vs. 9.17, P = 0.001) than rats in the LPS-treated group. Compared to sham group, the fractional anisotropy (FA), axial diffusion (Da), mean kurtosis (MK), and axial kurtosis (Ka) values in the cortex of lipopolysaccharide group were lower (P = 0.021,0.003,0.003,0.001,respectively).The MK, Ka, Kr, and FA values in the hippocampus of the lipopolysaccharide group were higher (P = 0.01, 0.026,0.007,0.003,respectively),while MD and Da values were lower (P = 0.045,0.044, respectively). Tetramethylpyrazine-pretreated rats showed higher values of FA, MD, Da, MK, and Ka in the cortex, lower MK, Ka, Kr, and FA values and higher MD,Da values in the hippocampus than the lipopolysaccharide group. Histologically, prominent inflammatory cells infiltration in the brain parenchyma of lipopolysaccharide group were observed, while groups pretreated using tetramethylpyrazine were alleviated.Tetramethylpyrazine can improve cognitive dysfunction induced by lipopolysaccharide. DKI can sensitively detect microstructure integrity of brain parenchyma in a non-invasive manner.

Use of speckle-tracking echocardiography to stratify risk of atrial fibrillation-related stroke: comparison of left atrial and atrial appendage mechanics

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): the National Natural Science Foundation of China onbehalf Sir Run Run Shaw Hospital,Zhejiang University,School of Medicine Background Left atrial (LA) and appendage (LAA) dysfunction were associated with increased risk of stroke in atrial fibrillation. However, usefulness of LA and LAA mechanics has not been fully compared. Methods:201 AF patients were prospectively enrolled. 42(20.8%) had previous stroke/TIA. Speckle tracking was used to measure LA and LAA peak postive strain. LA and LAA MD was defined as the SD of time to peak positive strain corrected by the R-R interval. Results:LA MD and LAA MD were independently associated with stroke/TIA. The model based on CHA2DS2-VASc score for discrimination of stroke was significantly improved by adding LA MD or LAA MD (P &amp;lt; 0.01). Diagnostic value of LA MD was better than LAA MD in patients with normal LA volumes, while LAA MD was more useful in patients with LA enlargement.Conclusion:Both LA and LAA mechanics had incremental value over CHA2DS2VASc score. However, priorities of strain assessment depend on patients’ LA volume. Variables Univariate analysis Multivariate analysis Model 1 Model 2 Model 3 OR (95% CI) P value OR (95% CI) P value OR (95% CI) p value OR (95% CI) P value Clinical parameters Age 1.09(1.04-1.14) &amp;lt;0.001 1.11(1.04-1.17) 0.001 1.11(1.05-1.17) 0.001 1.11(1.04-1.17) 0.001 BMI 0.988(0.89-1.10) 0.84 1.07(0.92-1.25) 0.40 1.07(0.91-1.25) 0.40 CHA2DS2-VASc score 1.52(1.15-2.00) 0.003 1.08(0.67-1.74) 0.76 1.08(0.65-1.80) 0.77 1.10(0.69-1.76) 0.69 Persistent AF 1.88(0.94-3.74) 0.07 0.75(0.23-2.40) 0.63 0.87(0.27-2.81) 0.82 Therapeutic anticoagulation 0.56(0.28-1.11) 0.10 0.22(0.09-0.57) 0.002 0.23(0.09-0.59) 0.002 0.22(0.09-0.57) 0.002 LA parameters LAEF 0.96(0.94-0.99) 0.002 0.982(0.953-1.01) 0.26 iLAVmin 1.03(1.01-1.05) 0.006 0.98(0.94-1.02) 0.27 LA MD 1.22(1.10-1.36) &amp;lt;0.001 1.16(1.02-1.32) 0.02 1.18(1.03-1.34) 0.02 1.16(1.02-1.32) 0.02 LA GLS 0.935(0.893-0.98) 0.005 1.0(0.953-1.14) 0.36 1.02(0.94-1.12) 0.59 1.02(0.94-1.10) 0.72 LAA parameters LAAEV 0.12(0.02-0.74) 0.02 3.34(0.31-36.06) 0.32 LAA EF 0.98(0.96-1.00) 0.06 1.01(0.98-1.04) 0.65 LAA GLS 0.85(0.77-0.94) 0.001 0.96(0.86-1.07) 0.46 0.97(0.87-1.08) 0.59 0.96(0.87-1.06) 0.44 LAA dense SEC/thrombus 3.12(1.39-6.99) 0.006 2.02(0.75-5.45) 0.167 LAA MD 1.19(1.09-1.29) &amp;lt;0.001 1.19(1.08-1.31) 0.001 1.19(1.08-1.31) 0.001 1.19(1.08-1.31) 0.001 Univariable and multivariable logistic regression analyses of associations between clinical and echocardiographic covariates with stroke Abstract Figure.

Clinical and Histological Differences between Guided Tissue Regeneration with Acellular Dermal Matrix of Porcine Origin and Autologous Connective Tissue: An Animal Study.

This research aims to evaluate the clinical and histological parametric differences concerning keratinized tissue that result from two regeneration techniques, the subepithelial autologous connective tissue graft (ACTG) and the acellular dermal matrix (MD) of porcine origin, performed on surgical beds on edentulous spaces in an animal model. The parameters of the MD and ACTG groups were compared with samples of the control group (CG) after 15, 45, and 90 days. Nine female white pigs (Sus scrofa domestica) were used, and each animal provided 20 study areas (12 MD and 8 ACTG). At 15 days, the keratin layer thickness in the MD group was greater than those of the ACTG (25.27 vs. 19.95 μm) and the CG (21.2 μm). After 45 days, the MD and ACTG thickness values decreased but were higher than the CG. At 90 days, MD (19.46 μm) obtained a value close to that of CG, and the ACTG decreased to CG (15.53 μm, p < 0.001). The use of an MD may be a viable alternative to the ACTG because of its ability to provide increased keratinized tissue in comparison to the ACTG.

Efeitos dos treinamentos de alta e de baixa intensidade da musculatura inspiratória na qualidade de vida de indivíduos com doença pulmonar obstrutiva crônica (DPOC) grave e desnutridos

OBJETIVO: Analisar efeitos do treinamento da musculatura inspiratória (TMI) na qualidade de vida (QV) de indivíduos com doença pulmonar obstrutiva crônica (DPOC) grave e desnutridos.MÉTODOS: Trata-se de um estudo clínico randomizado, cego, controlado e longitudinal. Foram avaliados 32 homens, divididos igualmente em dois grupos: G1, submetido ao TMI de alta intensidade e, G2, submetido ao de baixa intensidade, ambos durante 12 semanas. Avaliações do grau de dispneia, prova de função pulmonar, pressão inspiratória máxima (PImáx), distância percorrida (DP), Saint George Respiratory Questionnaire (SGRQ) e mobilidade diafragmática (MD) foram realizadas no pré-TMI, na 12ª semana de treinamento e na 24ª semana pós-TMI.RESULTADOS: Após 12 semanas de TMI, G1 apresentou aumentos significativos de ventilação voluntária máxima (VVM), PImáx, DP e MD, além de diminuição na escala Medical Research Council modificada (MRCm) e das porcentagens do SGRQ, que se mantiveram após 12 semanas do encerramento do treinamento. G2 apresentou o mesmo comportamento do G1 em 12 semanas de treinamento, porém, na 24ª semana pós-TMI, os valores de VVM, MRCm e MD voltaram aos iniciais, de PImáx e DP apresentaram abaixo da avaliação inicial e das porcentagens do SGRQ aumentaram significantemente. Na análise intergrupo da 12ª semana, G1 apresentou valores maiores de VVM, PImáx, DP e MD e valores menores nas porcentagens do SGRQ do que G2. Na 24ª semana, G2 apresentou valores menores de VVM, PImáx, DP e MD e maiores de MRCm e das porcentagens do SGRQ do que G1.CONCLUSÕES: Tanto TMI de alta, quanto de baixa intensidade proporcionaram melhora da QV dos indivíduos com DPOC grave e desnutridos, mas somente o treinamento de alta intensidade apresentou efeitos benéficos a longo prazo.

The value of intravoxel incoherent motion and diffusion kurtosis imaging in the assessment of tumor regression grade and T stages after neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer

PurposeTo evaluate the role of IVIM and diffusion kurtosis imaging (DKI) in identifying pathologic complete response (pCR) and T stages after neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC). MethodForty-two patients with biopsy-proven rectal adenocarcinoma, who underwent both pre-and post-CRT MRI with IVIM and DKI sequences on a 3 T scanner, were enrolled prospectively. According to the pathologic ypTNM stages and tumor regression grade (TRG), patients were grouped into pCR (TRG0) and non-pCR (TRG1−3) groups and low T stage (ypT0−2) and high T stage (ypT3−4) groups. IVIM parameters (the slow diffusion coefficient [D], fast diffusion coefficient [D*], perfusion fraction [f]), DKI parameters (mean diffusivity [MD] and mean kurtosis [MK]), and mono-exponential ADC were calculated and analyzed between groups. ResultsThe pCR group had significantly higher post-CRT ADC, D*, f, and MD values than non-pCR group, and higher percent changes in the ADC, f, and MD values (all P < 0.05). The post-CRT MD values yielded the highest AUC (0.788) with higher sensitivity than post-ADC values (82.9 % vs. 77.1 %, respectively). Post-CRT ADC and MD values and the percent changes in the ADC and MD values were also negatively correlated with TRG (all P < 0.05). Besides, negative correlations were found among the pre-CRT MD, post-CRT ADC, D, f, and MD values and the ypT stages (all P < 0.05). ConclusionsBoth IVIM and DKI parameters could provide more information when evaluating pCR and T stages after nCRT. In particular, the diagnostic performance of the MD values was more valuable than ADC values in being able to determine pCR.

Microstructural alterations of regional white matter tracts predict tau deposition in the Alzheimer’s disease signature regions

AbstractBackgroundWe first aimed to investigate the association between regional white matter (WM) microstructural alterations with tau deposition in Alzheimer’s disease (AD) signature cortical regions. We also tried to develop models to predict pathological tau deposition positivity with regional WM microstructural alterations.MethodOne‐hundred nine older adults with normal cognition or mild cognitive impairment recruited from the Korean Brain Aging Study for the Early diagnosis and prediction of Alzheimer’s disease (KBASE) cohort were included in the analyses. All Participants underwent structural MRI (T1), diffusion tensor imaging, PiB‐PET and Tau‐PET (AV‐1451) scans. AD signature cortical regions for tau deposition included the angular gyrus, posterior cingulate, and inferior temporal cortical regions (Jack et al. 2017). Pathological tau positivity was determined by the presence of significantly high deposition in the Braak regions III‐VI according to the ADNI cutoff (Baker et al. 2017).ResultMean diffusivity (MD) of the posterior corona radiata, fornix, and posterior thalamic radiation were significantly associated with tau deposition in AD signature regions (F(1,107) = 13.48, p &lt; 0.005; F(1,107) = 17.38, p &lt; 0.001; F(1,107) = 15.92, p &lt; 0.001, respectively) (Fig 1). Fractional anisotropy (FA) of the bilateral posterior thalamic radiation was also significantly associated with tau deposition in AD signature regions (F(1,107) = 17.14, p &lt; 0.005) (Fig 1). Pathological tau positivity prediction model based on FA value of the posterior thalamic radiation, MD values of the posterior corona radiata and fornix had area under the curve (AUC) of receiver operating characteristics curve of 0.73 [0.62‐0.84] (Fig. 2a). With additional information on amyloid beta positivity, the AUC increased to 0.86 [0.78‐0.95] (Fig. 2b).ConclusionThe findings indicate that microstructural alterations of the specific regional WM tracts closely linked to AD‐signature cortical regions are strongly correlated with tau deposition in the same cortical regions. Moreover, the findings also support propagation of tauopathy through WM tracts. The information on regional WM alteration may be used for the prediction of pathological tau deposition.

A New Criterion for Prediction of Phase Stability in Al‐Containing High Entropy Alloys

The reliable phase formation rule is demanded for high entropy alloys’ (HEAs) design and property regulation. Previous studies reveal the significant roles of thermodynamic and geometrical parameters in predicting phase structures of HEAs, whereas an accurate criterion is still not available. Herein, taking the most extensively studied Al‐containing HEAs as research object, two alloying parameters, i.e., d‐orbital energy level (Md) and bond order (Bo), combining with valence electron concentration (VEC) and atomic size difference (δ), are introduced to explore the phase stability of Al‐containing HEAs. The results indicate that single FCC solid solution tends to form in the range of δ below 4.5%, ordered phases (such as B2 and intermetallics) are more likely to be produced when the Md value of the alloy is beyond 1.06, and the FCC + BCC dual‐phase structures are mainly concentrated in the region of δ &gt; 4.5% and Md &lt; 1.06. The Md–δ criterion provides a reliable criterion of phase stability and a good guidance in alloy design for Al‐containing HEAs.

Cerebral Micro-Structural Changes in COVID-19 Patients: An MRI-Based Preliminary Study

Background: Increasing evidence supported the possible neuro-invasion potential of SARS-CoV-2. However, no studies were conducted to explore the existence of the structural changes in the neurological system after infection. We aimed to identify the existence of potential brain structural changes related to SARS-CoV-2. Methods: In this prospective study, diffusion tensor imaging (DTI) and 3D high-resolution T1WI sequences were acquired in 48 recovered COVID-19 patients (60.42% male; mean age=47.81 ± 19.51) and 31 age-matched healthy controls (29.03% male; age=43.45 ± 13.6). Registered fractional anisotropy (FA), mean (MD), axial (AD), and radial diffusivity (RD) were quantified for DTI, and a brain score system was introduced. Voxel-based Morphometry (VBM) and DTI metrics were compared using ANCOVA. Independent t-test and Spearman correlation were conducted to assess the relationships among imaging indices, brain scores and clinical information. Findings: COVID-19 patients had higher gray matter volumes (GMV) in hippocampus and Heschl’s gyrus, and higher white matter volumes (WMV) in corona radiata and tapetum. The left paracentral lobule was found to have significantly lower FA, higher MD, AD and RD values when compared with healthy controls. COVID-19 patients also had lower global MD and RD values, as well as lower brain scores of FA-GM, MD-GM, and MD-WM. MD values in the right corona radiata and external capsule were positively related to LDH level (r = 0.428, 0.417). Interpretation: Study findings reveal possible disruption to micro-structural and functional brain integrity in the recovery stages of COVID-19, suggesting neuro-invasion potential of SARS-CoV-2. Funding: This project was supported by Shanghai Natural Science Foundation (Grant No. 18ZR1405700), Youth Program of National Natural Science Foundation of China (Fund No. 81901697), Shanghai Sailing Program (Grant No. 18YF1403000), Shanghai Science and Technology Development (Fund No. 19511121204), Shanghai Municipal Science and Technology Major Project (No. 2018SHZDZX01) and ZJ Lab.Declaration of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Ethics Approval Statement: This was a prospective study, which was approved by the local ethics committee (No.20200616017) and written informed consent was obtained from each participant.

Diffusion-Weighted MRI and Diffusion Kurtosis Imaging to Detect RAS Mutation in Colorectal Liver Metastasis.

To detect RAS mutation in colorectal liver metastasis by Diffusion-Weighted Magnetic Resonance Imaging (DWI-MRI) - and Diffusion Kurtosis imaging (DKI)-derived parameters. In total, 106 liver metastasis (60 metastases with RAS mutation) in 52 patients were included in this retrospective study. Diffusion and perfusion parameters were derived by DWI (apparent diffusion coefficient (ADC), basal signal (S0), pseudo-diffusion coefficient (DP), perfusion fraction (FP) and tissue diffusivity (DT)) and DKI data (mean of diffusion coefficient (MD) and mean of diffusional Kurtosis (MK)). Wilcoxon-Mann-Whitney U tests for non-parametric variables and receiver operating characteristic (ROC) analyses were calculated with area under ROC curve (AUC). Moreover, pattern recognition approaches (linear classifier, support vector machine, k-nearest neighbours, decision tree), with features selection methods and a leave-one-out cross validation approach, were considered. A significant discrimination between the group with RAS mutation and the group without RAS mutation was obtained by the standard deviation value of MK (MK STD), by the mean value of MD, and by that of FP. The best results were reached by MK STD with an AUC of 0.80 (sensitivity of 72%, specificity of 85%, accuracy of 79%) using a cut-off of 203.90 × 10-3, and by the mean value of MD with AUC of 0.80 (sensitivity of 84%, specificity of 73%, accuracy of 77%) using a cut-off of 1694.30 mm2/s × 10-6. Considering all extracted features or the predictors obtained by the features selection method (the mean value of S0, the standard deviation value of MK, FP and of DT), the tested pattern recognition approaches did not determine an increase in diagnostic accuracy to detect RAS mutation (AUC of 0.73 and 0.69, respectively). Diffusion-Weighted imaging and Diffusion Kurtosis imaging could be used to detect the RAS mutation in liver metastasis. The standard deviation value of MK and the mean value of MD were the more accurate parameters in the RAS mutation detection, with an AUC of 0.80.

Effects of nanocomposite polymer flooding on Egyptian crude oil recovery

In this work, a laboratory study of enhanced oil recovery (EOR) was carried out using Egyptian crude oil of 37°API extracted from a reservoir in the Western Desert to identify the optimum conditions for the application of locally prepared nanocomposite polymer flooding under harsh reservoir condition. In contrary to the other studies, we tested the ability of nanocomposite polymer where nanoparticles are involved in the polymer matrix during polymerization process. Measurements of viscosity and shear rate of several solutions were taken. Displacement runs were conducted at different conditions of nanocomposite polymer salinities (10,000, 20,000, 30,000, 40,000, 50,000, 60,000 and 65,000 ppm), concentrations (1, 1.5, 2, 2.5, 3, 3.5 and 4 g/L) and slug sizes (0.2, 0.4, 0.6 and 0.8 PV). A linear sandpack (length of 62.5 cm and diameter of 2″) was prepared and wrapped with thermal jacket to simulate several reservoir temperatures. It was filled by selected sand size to produce linear sandpack model with reasonable porosity (22%) and permeability (129–157 mD) values. The model was used to perform several displacements runs for waterflooding and nanocomposite polymer flooding. The results of the flood runs are analyzed using the water–oil relative permeability curves. The measurements of the solutions properties showed that the critical concentration of the used nanocomposite polymer in the solution is 2 g/L. Also, it was observed that the used nanocomposite polymer solution could withstand a salinity of 60,000 ppm. As a result of the flooding, it was found that the optimum economical slug size of the used nanocomposite polymer is 0.4 PV at reservoir temperature of 40 °C. The results indicated also that the used nanocomposite polymer could withstand a reservoir temperature of 90 °C. The water–oil relative permeability curves showed an enhancement of oil relative permeability and a decrease in the water relative permeability using nanocomposite polymer over waterflooding. The cost of the used nanocomposite polymer with a concentration of 2 g/L and slug size of 0.4 PV is 0.626 $ for each barrel of the incremental oil recovery. Based on the results of this work, it is clear that involving nanoparticles such as silica in the polymer matrix composition improves its properties, thermal and salinity resistivity. Such study is an original contribution to carry out successful nanocomposite polymer EOR projects.