Alzheimer’s disease(AD)is a grave illness that results in cognitive and social issues.A recent study examined the association between neuroimaging results,cognitive dysfunction,atypical cellular immune function,and p...Alzheimer’s disease(AD)is a grave illness that results in cognitive and social issues.A recent study examined the association between neuroimaging results,cognitive dysfunction,atypical cellular immune function,and poor prognostic factors in AD patients who demonstrated poor prognosis.Poor prognosis was associated with abnormal cellular immune function,extrapyramidal symptoms,altered consciousness,abnormal electroencephalogram,modified Rankin scale,increased neutrophil lymphocyte ratio,and severe pneumonia.The impaired cellular immune function characterized by a reduction in the blood T lym-phocytes’proportion predicted poor prognosis as an independent risk factor in AD.Early initiation and maintenance of AD medications is associated with better outcomes.展开更多
Insomnia is one of the most frequently observed sleep disorders, affecting nearly 10% of the general population. It has multiple etiological factors. Recently, it has been reported that EEG abnormalities are associate...Insomnia is one of the most frequently observed sleep disorders, affecting nearly 10% of the general population. It has multiple etiological factors. Recently, it has been reported that EEG abnormalities are associated with insomnia in patients previously diagnosed as idiopathic insomniacs. In addition, transcranial magnetic stimulation (TMS) has shown to be effective in the treatment of disorders characterized by neural hyper-excitability. Method: In the present study, patients with insomnia and EEG abnormalities were submitted to slow repetitive trans-cranial magnetic stimulation, for 15 minutes daily during 10 days. Polysomnographic recordings were performed before and after TMS. Results: The results indicate that the presence of EEG abnormalities significantly decreased after TMS. In addition, most of the sleep parameters showed significant improvement. Conclusions: These data support the notion that TMS is a reliable therapeutic tool for patients affected with abnormalities linked to neuronal hyper-excitability.展开更多
BACKGROUND Alzheimer’s disease(AD)is a serious disease causing human dementia and social problems.The quality of life and prognosis of AD patients have attracted much attention.The role of chronic immune inflammation...BACKGROUND Alzheimer’s disease(AD)is a serious disease causing human dementia and social problems.The quality of life and prognosis of AD patients have attracted much attention.The role of chronic immune inflammation in the pathogenesis of AD is becoming more and more important.AIM To study the relationship among cognitive dysfunction,abnormal cellular immune function,neuroimaging results and poor prognostic factors in patients.METHODS A retrospective analysis of 62 hospitalized patients clinical diagnosed with AD who were admitted to our hospital from November 2015 to November 2020.Collect cognitive dysfunction performance characteristics,laboratory test data and neuroimaging data from medical records within 24 h of admission,including Mini Mental State Examination Scale score,drawing clock test,blood T lymphocyte subsets,and neutrophils and lymphocyte ratio(NLR),disturbance of consciousness,extrapyramidal symptoms,electroencephalogram(EEG)and head nucleus magnetic spectroscopy(MRS)and other data.Multivariate logistic regression analysis was used to determine independent prog-nostic factors.the modified Rankin scale(mRS)was used to determine whether the prognosis was good.The correlation between drug treatment and prognostic mRS score was tested by the rank sum test.RESULTS Univariate analysis showed that abnormal cellular immune function,extrapyramidal symptoms,obvious disturbance of consciousness,abnormal EEG,increased NLR,abnormal MRS,and complicated pneumonia were related to the poor prognosis of AD patients.Multivariate logistic regression analysis showed that the decrease in the proportion of T lym-phocytes in the blood after abnormal cellular immune function(odd ratio:2.078,95%confidence interval:1.156-3.986,P<0.05)was an independent risk factor for predicting the poor prognosis of AD.The number of days of donepezil treatment to improve cognitive function was negatively correlated with mRS score(r=0.578,P<0.05).CONCLUSION The decrease in the proportion of T lymphocytes may have predictive value for the poor prognosis of AD.It is recommended that the proportion of T lymphocytes<55%is used as the cut-off threshold for predicting the poor prog-nosis of AD.The early and continuous drug treatment is associated with a good prognosis.展开更多
By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping (0.00 ≤ x ≤0.30) on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been...By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping (0.00 ≤ x ≤0.30) on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.展开更多
AIM:to study the prevalence and patterns of hepatic abnormal perfusion(HAP)visible by magnetic resonance imaging(MRI)in acute pancreatitis(AP).METHODS:Enhanced abdominal MRI was performed on 51 patients with AP.these ...AIM:to study the prevalence and patterns of hepatic abnormal perfusion(HAP)visible by magnetic resonance imaging(MRI)in acute pancreatitis(AP).METHODS:Enhanced abdominal MRI was performed on 51 patients with AP.these patients were divided into two groups according to the MRI results:those with signs of gallstones,cholecystitis,common bile duct(CBD)stones or dilatation of the CBD on MRI and those without.the prevalence,shape and distribution of HAP in the two groups were analyzed and compared.the severity of AP was graded using the MR severity index(MRSI).the correlation between the MRSI and HAP was then analyzed.RESULTS:Of the 51 patients with AP,32(63%)showed at least one sign of gallbladder and CBD abnormalities on the MR images,while 19(37%)showed no sign of gallbladder or CBD abnormalities.Nineteen patients(37%)had HAP visible in the enhanced images,including strip-,wedge-or patch-shaped HAP distributed in the hepatic tissue adjacent to the gallbladder and left and right liver lobes.there were no significant differences in the prevalence of HAP(χ2=0.305,P=0.581>0.05)or HAP distribution in the liver(χ2=2.181,P=0.536>0.05)between patients with and without gallbladder and CBD abnormalities.there were no significant differences in the MRSI score between patients with and without HAP(t=0.559,P=0.552>0.05).HAP was not correlated with the MRSI score.CONCLUSION:HAP is common in patients with AP and appears strip-,patch-or wedge-shaped on MRI.HAP on MRI cannot be used to indicate the severity of AP.展开更多
Residual stresses in ferromagnetic material affect the direction and structure of domains and generate magnetic field abnormality on the surface. In the formation of stress induced magnetic field, the influence of geo...Residual stresses in ferromagnetic material affect the direction and structure of domains and generate magnetic field abnormality on the surface. In the formation of stress induced magnetic field, the influence of geomagnetic field is unclear. Residual stress specimen was produced by tight matching of a round ring and a peg. The magnetic fields of contrast specimens, which were produced in geomagnetic field or in shielding geomagnetic field, were inspected with 8 mm lift-off. The results show that mean amplitude of magnetic field of the specimen produced in geomagnetic field is 0.85% larger than that of specimen produced in shielding geomagnetic field. So the formation of stress induced magnetic field abnormality above the surface of inspected ferromagnetic material geomagnetic field gives little contribution.展开更多
Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device ...Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device is introduced, and the distribution of mirror magnetic field generated by the loops surrounding the discharge chamber is presented. Both the discharge current-voltage characteristics and the radial distributions of electron density are measured, respectively, with/without the magnetic field. When the discharge occurs in a 99.99% helium with a pressure ranging from 100 Pa to 800 Pa without magnetic field, the voltage, sustaining a certain abnormal glow discharge current, decreases with the increase in gas pressure. With a mirror magnetic field of certain intensity, the discharge voltage increases with the current in a rate slower than that without the magnetic field. Moreover, when the magnetic field intensity increases, the discharge voltage first decreases then increases. Simultaneously, the mirror magnetic field affects the moving characteristics of charged particles, and causes a more inhomogeneous electron density.展开更多
缺血性脑卒中的病因分型对临床治疗决策和预后判断有重要价值。近年来,随着高分辨率磁共振血管壁成像(high-resolution vessel wall magnetic resonance imaging,HR-VW-MRI)在脑卒中临床研究和实践中的应用增加,7 T MRI以其更高信噪比...缺血性脑卒中的病因分型对临床治疗决策和预后判断有重要价值。近年来,随着高分辨率磁共振血管壁成像(high-resolution vessel wall magnetic resonance imaging,HR-VW-MRI)在脑卒中临床研究和实践中的应用增加,7 T MRI以其更高信噪比和更优图像质量,可发现脑血管早期、细微的病理变化,为深入了解各种脑血管疾病的病理机制提供了新思路。然而,超高场强也存在B1场不均、扫描时间长等技术挑战。本文就7 T HR-VW-MRI在缺血性卒中病因分型及临床应用中的进展进行综述,深入分析7 T HR-VW-MRI在提升临床诊断精确性与指导临床治疗中的潜在价值,为临床实践与科研探索提供参考。展开更多
AIM:To determine the merits of magnetic resonance cholangiopancreatography(MRCP) as the primary diagnostic test for choledochal cysts(CC’s).METHODS:Between 2009 and 2012,patients who underwent MRCP for perioperative ...AIM:To determine the merits of magnetic resonance cholangiopancreatography(MRCP) as the primary diagnostic test for choledochal cysts(CC’s).METHODS:Between 2009 and 2012,patients who underwent MRCP for perioperative diagnosis were identified.Demographic information,clinical characteristics,and radiographic findings were recorded.MRCP results were compared with intraoperative findings.A PubMed search identified studies published between 1996-2012,employing MRCP as the primary preoperative imaging and comparing results with either endoscopic retrograde cholangiopancreatography(ERCP) or operative findings.Detection rates for CC’s and abnormal pancreaticobiliary junction(APBJ) were calculated.In addition detection rates for clinically related biliary pathology like choledocholithiasis and cholangiocarcinomas in patients diagnosed with CC’s were also evaluated.RESULTS:Eight patients were identified with CC’s.Six patients out of them had typeⅣCC’s,1 had type I and 1 had a new variant of choledochal cyst with confluent dilatation of the common bile duct(CBD) and cystic duct.Seven patients had an APBJ and 3 of those had a long common-channel.Gallstones were found in 2 patients,1 had a CBD stone,and 1 pancreatic-duct stone was also detected.In all cases,MRCP successfully identified the type of CC’s,as well as APBJ with ductal stones.From analyzing the literature,we found that MRCP has 96%-100% detection rate for CC’s.Additionally,we found that the range for sensitivity,specificity,and diagnostic accuracy was 53%-100%,90%-100% and 56%-100% in diagnosing APBJ.MRCP’s detection rate was 100% for choledocholithiasis and 87% for cholangiocarcinomas with concurrent CC’s.CONCLUSION:After initial ultrasound and computed tomography scan,MRCP should be the next diagnostic test in both adult and pediatric patients.ERCP should be reserved for patients where therapeutic intervention is needed.展开更多
Detecting stress concentration, especially critical stress state leading to structure damage or failure, is one of the most important tasks of equipment diagnosis. Metal magnetic memory technique needs further researc...Detecting stress concentration, especially critical stress state leading to structure damage or failure, is one of the most important tasks of equipment diagnosis. Metal magnetic memory technique needs further research to evaluate stress concentration quantitatively due to ambiguous physical mechanism, though it has potential to detect early defects in ferromagnetic materials. Mild Q235 steel defective specimens in demagnetization state were loaded in tension up to visible necking, with magnetic memory signals measurement made at increasing stress levels. Magnetic signals varied greatly under first several loadings and subsequently tended to stability in the elastic region, which showed that the magnetization always approaches the anhysteretic magnetization curve and was explained by the theory of magnetomechanical effect. In the plastic stage, an abnormal wave occurred in the stress concentration zone and its height value was sensitive to plastic deformation levels and dependent on the distance between the probe and defect, in accordance with the simulation results based on the magnetic dipole model. Different magnetic signal characteristics in the elastic-plastic region indicate that the magnetic memory technique can identify macroyielding and early damage, which is of profound significance for ensuring safe operation of equipment in service.展开更多
Objective To investigate the correlation of magnetic resonance imaging (MRI) with histopathologica changes, and to evaluate T2 mapping in assessing muscle trauma in a rabbit model of muscle injury. Methods We divide...Objective To investigate the correlation of magnetic resonance imaging (MRI) with histopathologica changes, and to evaluate T2 mapping in assessing muscle trauma in a rabbit model of muscle injury. Methods We divided 35 rabbits into seven groups that each represented a different time point after intramuscular hemorrhage and muscle injury. Hemorrhage was created by injecting autologous blood into the left legs, and muscle injury was created by scalpel incision of the biceps femoris of the right legs. At different time points, the rabbits underwent Tl-weighted imaging and T2-weighted imaging (TzWl and T2Wl) and T2 mapping. T2 relaxation times were measured, and the corresponding samples were evaluated for pathological changes. Results After 2 h, the intramuscular hemorrhage model demonstrated an increased signal intensity on both TlWl and T2Wl. Histological examination showed erythrocytes within the muscle bundle. On days 1 and 3, the MRI signals were decreased, and there were no significant changes after day 7. From 2 h to 3 days, the muscle-injury model showed a high signal on both TzWl and T2Wl. Corresponding pathological changes included rupture and edema of muscle fibers, and inflammation. The abnormal signals were reduced on day 7. After day 14, the T2Wl intensity remained high. TlWl showed no abnormal changes, but some models showed a high signal, representing fresh bleeding and fatty tissue. T2 relaxation times were significantly different between the central and marginal regions, and between the marginal and normal regions. Conclusion MRI clearly demonstrates intramuscular hemorrhage and muscle injury, which correlate well with histopathological changes. Tz mapping is useful in assessing the extent of injury.展开更多
AIM: To investigate the accuracy of T2*-weighted magnetic resonance imaging (MRI T2*) in the evaluation of iron overload in beta-thalassemia major patients. METHODS: In this cross-sectional study, 210 patients with be...AIM: To investigate the accuracy of T2*-weighted magnetic resonance imaging (MRI T2*) in the evaluation of iron overload in beta-thalassemia major patients. METHODS: In this cross-sectional study, 210 patients with beta-thalassemia major having regular blood transfusions were consecutively enrolled. Serum ferritin levels were measured, and all patients underwent MRI T2* of the liver. Liver biopsy was performed in 53 patients at an interval of no longer than 3 mo after the MRIT2* in each patient. The amount of iron was assessed in both MRI T2* and liver biopsy specimens of each patient. RESULTS: Patients’ ages ranged from 8 to 54 years with a mean of 24.59 ± 8.5 years. Mean serum ferritin level was 1906 ± 1644 ng/mL. Liver biopsy showed a moderate negative correlation with liver MRI T2* (r = -0.573, P = 0.000) and a low positive correlation with ferritin level (r = 0.350, P = 0.001). Serum ferritin levels showed a moderate negative correlation with liver MRI T2* values (r = -0.586, P = 0.000). CONCLUSION: Our study suggests that MRI T2* is a non-invasive, safe and reliable method for detecting iron load in patients with iron overload.展开更多
Today, the use of cardiovascular magnetic resonance(CMR) is widespread in clinical practice. The increased need to evaluate of subtle myocardial changes, coronary artery anatomy, and hemodynamic assessment has prompte...Today, the use of cardiovascular magnetic resonance(CMR) is widespread in clinical practice. The increased need to evaluate of subtle myocardial changes, coronary artery anatomy, and hemodynamic assessment has prompted the development of novel CMR techniques including T1 and T2 mapping, non-contrast angiography and four dimensional(4D) flow. T1 mapping is suitable for diagnosing pathologies affecting extracellular volume such as myocarditis, diffuse myocardial fibrosis and amyloidosis, and is a promising diagnostic tool for patients with iron overload and Fabry disease. T2 mapping is useful in depicting acute myocardial edema and estimating the amount of salvageable myocardium following an ischemic event. Novel angiography techniques, such as the selfnavigated whole-heart or the quiescent-interval singleshot sequence, enable the visualization of the great vessels and coronary artery anatomy without the use of contrast material. The 4D flow technique overcomes the limitations of standard phase-contrast imaging and allows for the assessment of cardiovascular hemodynamics in the great arteries and flow patterns in the cardiac chambers. In conclusion, the future of CMR is heading toward a more reliable quantitative assessment of the myocardium, an improved non-contrast visualization of the coronary artery anatomy, and a more accurate evaluation of the cardiac hemodynamics.展开更多
Based on analysis of NMR T2 spectral characteristics,a new method for identifying fluid properties by decomposing T2 spectrum through signal analysis has been proposed.Because T2 spectrum satisfies lognormal distribut...Based on analysis of NMR T2 spectral characteristics,a new method for identifying fluid properties by decomposing T2 spectrum through signal analysis has been proposed.Because T2 spectrum satisfies lognormal distribution on transverse relaxation time axis,the T2 spectrum can be decomposed into 2 to 5 independent component spectra by fitting the T2 spectrum with Gauss functions.By analyzing the free relaxation response characteristics of crude oil and formation water,the dynamic response characteristics of the core mutual drive between oil and water,the petrophysical significance of each component spectrum is clarified.T2 spectrum can be decomposed into clay bound water component spectrum,capillary bound fluid component spectrum,micropores fluid component spectrum and macropores fluid component spectrum.According to the nature of crude oil in the target area,the distribution range of T2 component spectral peaks of oil-bearing reservoir is 165-500 ms on T2 time axis.This range can be used to accurately identify fluid properties.This method has high adaptability in identifying complex oil and water layers in low porosity and permeability reservoirs.展开更多
BACKGROUND Non-invasive assessment of non-alcoholic steatohepatitis(NASH)is increasing in desirability due to the invasive nature and costs associated with the current form of assessment;liver biopsy.Quantitative mult...BACKGROUND Non-invasive assessment of non-alcoholic steatohepatitis(NASH)is increasing in desirability due to the invasive nature and costs associated with the current form of assessment;liver biopsy.Quantitative multiparametric magnetic resonance imaging(mpMRI)to measure liver fat(proton density fat fraction)and fibroinflammatory disease[iron-corrected T1(cT1)],as well as elastography techniques[vibration-controlled transient elastography(VCTE)liver stiffness measure],magnetic resonance elastography(MRE)and 2D Shear-Wave elastography(SWE)to measure stiffness and fat(controlled attenuated parameter,CAP)are emerging alternatives which could be utilised as safe surrogates to liver biopsy.AIM To evaluate the agreement of non-invasive imaging modalities with liver biopsy,and their subsequent diagnostic accuracy for identifying NASH patients.METHODS From January 2019 to February 2020,Japanese patients suspected of NASH were recruited onto a prospective,observational study and were screened using noninvasive imaging techniques;mpMRI with LiverMultiScan®,VCTE,MRE and 2DSWE.Patients were subsequently biopsied,and samples were scored by three independent pathologists.The diagnostic performances of the non-invasive imaging modalities were assessed using area under receiver operating characteristic curve(AUC)with the median of the histology scores as the gold standard diagnoses.Concordance between all three independent pathologists was further explored using Krippendorff’s alpha(a)from weighted kappa statistics.RESULTS N=145 patients with mean age of 60(SD:13 years.),39%females,and 40%with body mass index≥30 kg/m2 were included in the analysis.For identifying patients with NASH,MR liver fat and cT1 were the strongest performing individual measures(AUC:0.80 and 0.75 respectively),and the mpMRI metrics combined(cT1 and MR liver fat)were the overall best non-invasive test(AUC:0.83).For identifying fibrosis≥1,MRE performed best(AUC:0.97),compared to VCTE-liver stiffness measure(AUC:0.94)and 2D-SWE(AUC:0.94).For assessment of steatosis≥1,MR liver fat was the best performing non-invasive test(AUC:0.92),compared to controlled attenuated parameter(AUC:0.75).Assessment of the agreement between pathologists showed that concordance was best for steatosis(a=0.58),moderate for ballooning(a=0.40)and fibrosis(a=0.40),and worst for lobular inflammation(a=0.11).CONCLUSION Quantitative mpMRI is an effective alternative to liver biopsy for diagnosing NASH and non-alcoholic fatty liver,and thus may offer clinical utility in patient management.展开更多
文摘Alzheimer’s disease(AD)is a grave illness that results in cognitive and social issues.A recent study examined the association between neuroimaging results,cognitive dysfunction,atypical cellular immune function,and poor prognostic factors in AD patients who demonstrated poor prognosis.Poor prognosis was associated with abnormal cellular immune function,extrapyramidal symptoms,altered consciousness,abnormal electroencephalogram,modified Rankin scale,increased neutrophil lymphocyte ratio,and severe pneumonia.The impaired cellular immune function characterized by a reduction in the blood T lym-phocytes’proportion predicted poor prognosis as an independent risk factor in AD.Early initiation and maintenance of AD medications is associated with better outcomes.
文摘Insomnia is one of the most frequently observed sleep disorders, affecting nearly 10% of the general population. It has multiple etiological factors. Recently, it has been reported that EEG abnormalities are associated with insomnia in patients previously diagnosed as idiopathic insomniacs. In addition, transcranial magnetic stimulation (TMS) has shown to be effective in the treatment of disorders characterized by neural hyper-excitability. Method: In the present study, patients with insomnia and EEG abnormalities were submitted to slow repetitive trans-cranial magnetic stimulation, for 15 minutes daily during 10 days. Polysomnographic recordings were performed before and after TMS. Results: The results indicate that the presence of EEG abnormalities significantly decreased after TMS. In addition, most of the sleep parameters showed significant improvement. Conclusions: These data support the notion that TMS is a reliable therapeutic tool for patients affected with abnormalities linked to neuronal hyper-excitability.
基金Supported by the National Natural Science Foundation of China,No.3206080019 and No.32060182Science and Technology Support Plan of Guizhou Province in China,No.[2020]4Y129Qiannan Prefecture Science and Technology Plan Project,No.[2022]01.
文摘BACKGROUND Alzheimer’s disease(AD)is a serious disease causing human dementia and social problems.The quality of life and prognosis of AD patients have attracted much attention.The role of chronic immune inflammation in the pathogenesis of AD is becoming more and more important.AIM To study the relationship among cognitive dysfunction,abnormal cellular immune function,neuroimaging results and poor prognostic factors in patients.METHODS A retrospective analysis of 62 hospitalized patients clinical diagnosed with AD who were admitted to our hospital from November 2015 to November 2020.Collect cognitive dysfunction performance characteristics,laboratory test data and neuroimaging data from medical records within 24 h of admission,including Mini Mental State Examination Scale score,drawing clock test,blood T lymphocyte subsets,and neutrophils and lymphocyte ratio(NLR),disturbance of consciousness,extrapyramidal symptoms,electroencephalogram(EEG)and head nucleus magnetic spectroscopy(MRS)and other data.Multivariate logistic regression analysis was used to determine independent prog-nostic factors.the modified Rankin scale(mRS)was used to determine whether the prognosis was good.The correlation between drug treatment and prognostic mRS score was tested by the rank sum test.RESULTS Univariate analysis showed that abnormal cellular immune function,extrapyramidal symptoms,obvious disturbance of consciousness,abnormal EEG,increased NLR,abnormal MRS,and complicated pneumonia were related to the poor prognosis of AD patients.Multivariate logistic regression analysis showed that the decrease in the proportion of T lym-phocytes in the blood after abnormal cellular immune function(odd ratio:2.078,95%confidence interval:1.156-3.986,P<0.05)was an independent risk factor for predicting the poor prognosis of AD.The number of days of donepezil treatment to improve cognitive function was negatively correlated with mRS score(r=0.578,P<0.05).CONCLUSION The decrease in the proportion of T lymphocytes may have predictive value for the poor prognosis of AD.It is recommended that the proportion of T lymphocytes<55%is used as the cut-off threshold for predicting the poor prog-nosis of AD.The early and continuous drug treatment is associated with a good prognosis.
基金This work was supported by the National Nature Science Foundation of China (No. 19934003) the State Key Project of Fundamental Research of China (No.001CB610604) the Item of Nature Science Research of Anhui (No. 2001kj244).
文摘By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping (0.00 ≤ x ≤0.30) on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.
文摘AIM:to study the prevalence and patterns of hepatic abnormal perfusion(HAP)visible by magnetic resonance imaging(MRI)in acute pancreatitis(AP).METHODS:Enhanced abdominal MRI was performed on 51 patients with AP.these patients were divided into two groups according to the MRI results:those with signs of gallstones,cholecystitis,common bile duct(CBD)stones or dilatation of the CBD on MRI and those without.the prevalence,shape and distribution of HAP in the two groups were analyzed and compared.the severity of AP was graded using the MR severity index(MRSI).the correlation between the MRSI and HAP was then analyzed.RESULTS:Of the 51 patients with AP,32(63%)showed at least one sign of gallbladder and CBD abnormalities on the MR images,while 19(37%)showed no sign of gallbladder or CBD abnormalities.Nineteen patients(37%)had HAP visible in the enhanced images,including strip-,wedge-or patch-shaped HAP distributed in the hepatic tissue adjacent to the gallbladder and left and right liver lobes.there were no significant differences in the prevalence of HAP(χ2=0.305,P=0.581>0.05)or HAP distribution in the liver(χ2=2.181,P=0.536>0.05)between patients with and without gallbladder and CBD abnormalities.there were no significant differences in the MRSI score between patients with and without HAP(t=0.559,P=0.552>0.05).HAP was not correlated with the MRSI score.CONCLUSION:HAP is common in patients with AP and appears strip-,patch-or wedge-shaped on MRI.HAP on MRI cannot be used to indicate the severity of AP.
文摘Residual stresses in ferromagnetic material affect the direction and structure of domains and generate magnetic field abnormality on the surface. In the formation of stress induced magnetic field, the influence of geomagnetic field is unclear. Residual stress specimen was produced by tight matching of a round ring and a peg. The magnetic fields of contrast specimens, which were produced in geomagnetic field or in shielding geomagnetic field, were inspected with 8 mm lift-off. The results show that mean amplitude of magnetic field of the specimen produced in geomagnetic field is 0.85% larger than that of specimen produced in shielding geomagnetic field. So the formation of stress induced magnetic field abnormality above the surface of inspected ferromagnetic material geomagnetic field gives little contribution.
基金Program for New Century Excellent Talents in University (NCET) of ChinaFundation of the Key Lab of Infrared and Low Temperature Plasma of Anhui Province of China(No.2007A003003U)
文摘Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device is introduced, and the distribution of mirror magnetic field generated by the loops surrounding the discharge chamber is presented. Both the discharge current-voltage characteristics and the radial distributions of electron density are measured, respectively, with/without the magnetic field. When the discharge occurs in a 99.99% helium with a pressure ranging from 100 Pa to 800 Pa without magnetic field, the voltage, sustaining a certain abnormal glow discharge current, decreases with the increase in gas pressure. With a mirror magnetic field of certain intensity, the discharge voltage increases with the current in a rate slower than that without the magnetic field. Moreover, when the magnetic field intensity increases, the discharge voltage first decreases then increases. Simultaneously, the mirror magnetic field affects the moving characteristics of charged particles, and causes a more inhomogeneous electron density.
文摘缺血性脑卒中的病因分型对临床治疗决策和预后判断有重要价值。近年来,随着高分辨率磁共振血管壁成像(high-resolution vessel wall magnetic resonance imaging,HR-VW-MRI)在脑卒中临床研究和实践中的应用增加,7 T MRI以其更高信噪比和更优图像质量,可发现脑血管早期、细微的病理变化,为深入了解各种脑血管疾病的病理机制提供了新思路。然而,超高场强也存在B1场不均、扫描时间长等技术挑战。本文就7 T HR-VW-MRI在缺血性卒中病因分型及临床应用中的进展进行综述,深入分析7 T HR-VW-MRI在提升临床诊断精确性与指导临床治疗中的潜在价值,为临床实践与科研探索提供参考。
文摘AIM:To determine the merits of magnetic resonance cholangiopancreatography(MRCP) as the primary diagnostic test for choledochal cysts(CC’s).METHODS:Between 2009 and 2012,patients who underwent MRCP for perioperative diagnosis were identified.Demographic information,clinical characteristics,and radiographic findings were recorded.MRCP results were compared with intraoperative findings.A PubMed search identified studies published between 1996-2012,employing MRCP as the primary preoperative imaging and comparing results with either endoscopic retrograde cholangiopancreatography(ERCP) or operative findings.Detection rates for CC’s and abnormal pancreaticobiliary junction(APBJ) were calculated.In addition detection rates for clinically related biliary pathology like choledocholithiasis and cholangiocarcinomas in patients diagnosed with CC’s were also evaluated.RESULTS:Eight patients were identified with CC’s.Six patients out of them had typeⅣCC’s,1 had type I and 1 had a new variant of choledochal cyst with confluent dilatation of the common bile duct(CBD) and cystic duct.Seven patients had an APBJ and 3 of those had a long common-channel.Gallstones were found in 2 patients,1 had a CBD stone,and 1 pancreatic-duct stone was also detected.In all cases,MRCP successfully identified the type of CC’s,as well as APBJ with ductal stones.From analyzing the literature,we found that MRCP has 96%-100% detection rate for CC’s.Additionally,we found that the range for sensitivity,specificity,and diagnostic accuracy was 53%-100%,90%-100% and 56%-100% in diagnosing APBJ.MRCP’s detection rate was 100% for choledocholithiasis and 87% for cholangiocarcinomas with concurrent CC’s.CONCLUSION:After initial ultrasound and computed tomography scan,MRCP should be the next diagnostic test in both adult and pediatric patients.ERCP should be reserved for patients where therapeutic intervention is needed.
基金supported by National Natural Science Foundation of China(Grant No. 10772061)Heilongjiang Provincial Natural Science Foundation of China(Grant No. A200907)Specialized Research Fundfor the Doctoral Program of Higher Education of China(Grant No.20092322120001)
文摘Detecting stress concentration, especially critical stress state leading to structure damage or failure, is one of the most important tasks of equipment diagnosis. Metal magnetic memory technique needs further research to evaluate stress concentration quantitatively due to ambiguous physical mechanism, though it has potential to detect early defects in ferromagnetic materials. Mild Q235 steel defective specimens in demagnetization state were loaded in tension up to visible necking, with magnetic memory signals measurement made at increasing stress levels. Magnetic signals varied greatly under first several loadings and subsequently tended to stability in the elastic region, which showed that the magnetization always approaches the anhysteretic magnetization curve and was explained by the theory of magnetomechanical effect. In the plastic stage, an abnormal wave occurred in the stress concentration zone and its height value was sensitive to plastic deformation levels and dependent on the distance between the probe and defect, in accordance with the simulation results based on the magnetic dipole model. Different magnetic signal characteristics in the elastic-plastic region indicate that the magnetic memory technique can identify macroyielding and early damage, which is of profound significance for ensuring safe operation of equipment in service.
基金supported by the National Natural Science Foundation of China (Grant No.81071131)the "215" program (Grant No.2009-2-03)
文摘Objective To investigate the correlation of magnetic resonance imaging (MRI) with histopathologica changes, and to evaluate T2 mapping in assessing muscle trauma in a rabbit model of muscle injury. Methods We divided 35 rabbits into seven groups that each represented a different time point after intramuscular hemorrhage and muscle injury. Hemorrhage was created by injecting autologous blood into the left legs, and muscle injury was created by scalpel incision of the biceps femoris of the right legs. At different time points, the rabbits underwent Tl-weighted imaging and T2-weighted imaging (TzWl and T2Wl) and T2 mapping. T2 relaxation times were measured, and the corresponding samples were evaluated for pathological changes. Results After 2 h, the intramuscular hemorrhage model demonstrated an increased signal intensity on both TlWl and T2Wl. Histological examination showed erythrocytes within the muscle bundle. On days 1 and 3, the MRI signals were decreased, and there were no significant changes after day 7. From 2 h to 3 days, the muscle-injury model showed a high signal on both TzWl and T2Wl. Corresponding pathological changes included rupture and edema of muscle fibers, and inflammation. The abnormal signals were reduced on day 7. After day 14, the T2Wl intensity remained high. TlWl showed no abnormal changes, but some models showed a high signal, representing fresh bleeding and fatty tissue. T2 relaxation times were significantly different between the central and marginal regions, and between the marginal and normal regions. Conclusion MRI clearly demonstrates intramuscular hemorrhage and muscle injury, which correlate well with histopathological changes. Tz mapping is useful in assessing the extent of injury.
基金Supported by The Gastrointestinal and Liver Disease Research Center of Tehran University of Medical Sciences
文摘AIM: To investigate the accuracy of T2*-weighted magnetic resonance imaging (MRI T2*) in the evaluation of iron overload in beta-thalassemia major patients. METHODS: In this cross-sectional study, 210 patients with beta-thalassemia major having regular blood transfusions were consecutively enrolled. Serum ferritin levels were measured, and all patients underwent MRI T2* of the liver. Liver biopsy was performed in 53 patients at an interval of no longer than 3 mo after the MRIT2* in each patient. The amount of iron was assessed in both MRI T2* and liver biopsy specimens of each patient. RESULTS: Patients’ ages ranged from 8 to 54 years with a mean of 24.59 ± 8.5 years. Mean serum ferritin level was 1906 ± 1644 ng/mL. Liver biopsy showed a moderate negative correlation with liver MRI T2* (r = -0.573, P = 0.000) and a low positive correlation with ferritin level (r = 0.350, P = 0.001). Serum ferritin levels showed a moderate negative correlation with liver MRI T2* values (r = -0.586, P = 0.000). CONCLUSION: Our study suggests that MRI T2* is a non-invasive, safe and reliable method for detecting iron load in patients with iron overload.
文摘Today, the use of cardiovascular magnetic resonance(CMR) is widespread in clinical practice. The increased need to evaluate of subtle myocardial changes, coronary artery anatomy, and hemodynamic assessment has prompted the development of novel CMR techniques including T1 and T2 mapping, non-contrast angiography and four dimensional(4D) flow. T1 mapping is suitable for diagnosing pathologies affecting extracellular volume such as myocarditis, diffuse myocardial fibrosis and amyloidosis, and is a promising diagnostic tool for patients with iron overload and Fabry disease. T2 mapping is useful in depicting acute myocardial edema and estimating the amount of salvageable myocardium following an ischemic event. Novel angiography techniques, such as the selfnavigated whole-heart or the quiescent-interval singleshot sequence, enable the visualization of the great vessels and coronary artery anatomy without the use of contrast material. The 4D flow technique overcomes the limitations of standard phase-contrast imaging and allows for the assessment of cardiovascular hemodynamics in the great arteries and flow patterns in the cardiac chambers. In conclusion, the future of CMR is heading toward a more reliable quantitative assessment of the myocardium, an improved non-contrast visualization of the coronary artery anatomy, and a more accurate evaluation of the cardiac hemodynamics.
基金Supported by the China National Science and Technology Major Project(2016ZX05050)
文摘Based on analysis of NMR T2 spectral characteristics,a new method for identifying fluid properties by decomposing T2 spectrum through signal analysis has been proposed.Because T2 spectrum satisfies lognormal distribution on transverse relaxation time axis,the T2 spectrum can be decomposed into 2 to 5 independent component spectra by fitting the T2 spectrum with Gauss functions.By analyzing the free relaxation response characteristics of crude oil and formation water,the dynamic response characteristics of the core mutual drive between oil and water,the petrophysical significance of each component spectrum is clarified.T2 spectrum can be decomposed into clay bound water component spectrum,capillary bound fluid component spectrum,micropores fluid component spectrum and macropores fluid component spectrum.According to the nature of crude oil in the target area,the distribution range of T2 component spectral peaks of oil-bearing reservoir is 165-500 ms on T2 time axis.This range can be used to accurately identify fluid properties.This method has high adaptability in identifying complex oil and water layers in low porosity and permeability reservoirs.
文摘BACKGROUND Non-invasive assessment of non-alcoholic steatohepatitis(NASH)is increasing in desirability due to the invasive nature and costs associated with the current form of assessment;liver biopsy.Quantitative multiparametric magnetic resonance imaging(mpMRI)to measure liver fat(proton density fat fraction)and fibroinflammatory disease[iron-corrected T1(cT1)],as well as elastography techniques[vibration-controlled transient elastography(VCTE)liver stiffness measure],magnetic resonance elastography(MRE)and 2D Shear-Wave elastography(SWE)to measure stiffness and fat(controlled attenuated parameter,CAP)are emerging alternatives which could be utilised as safe surrogates to liver biopsy.AIM To evaluate the agreement of non-invasive imaging modalities with liver biopsy,and their subsequent diagnostic accuracy for identifying NASH patients.METHODS From January 2019 to February 2020,Japanese patients suspected of NASH were recruited onto a prospective,observational study and were screened using noninvasive imaging techniques;mpMRI with LiverMultiScan®,VCTE,MRE and 2DSWE.Patients were subsequently biopsied,and samples were scored by three independent pathologists.The diagnostic performances of the non-invasive imaging modalities were assessed using area under receiver operating characteristic curve(AUC)with the median of the histology scores as the gold standard diagnoses.Concordance between all three independent pathologists was further explored using Krippendorff’s alpha(a)from weighted kappa statistics.RESULTS N=145 patients with mean age of 60(SD:13 years.),39%females,and 40%with body mass index≥30 kg/m2 were included in the analysis.For identifying patients with NASH,MR liver fat and cT1 were the strongest performing individual measures(AUC:0.80 and 0.75 respectively),and the mpMRI metrics combined(cT1 and MR liver fat)were the overall best non-invasive test(AUC:0.83).For identifying fibrosis≥1,MRE performed best(AUC:0.97),compared to VCTE-liver stiffness measure(AUC:0.94)and 2D-SWE(AUC:0.94).For assessment of steatosis≥1,MR liver fat was the best performing non-invasive test(AUC:0.92),compared to controlled attenuated parameter(AUC:0.75).Assessment of the agreement between pathologists showed that concordance was best for steatosis(a=0.58),moderate for ballooning(a=0.40)and fibrosis(a=0.40),and worst for lobular inflammation(a=0.11).CONCLUSION Quantitative mpMRI is an effective alternative to liver biopsy for diagnosing NASH and non-alcoholic fatty liver,and thus may offer clinical utility in patient management.