Monostatic and Bistatic Low Frequency Ultrawideband SAR Imaging Experiment

Low frequency ultrawideband (LF UWB) synthetic aperture radar (SAR) has lately become of a particular interest to SAR community. Monostatic and bistatic LF UWB SAR system has the well foliage penetrating capability, high-resolution imaging and providing the increased information. In 2015, a monostatic and bistatic LF UWB SAR imaging experiment was conducted. In this experiment, the monostatic and bistatic data were collected simultaneously by operating a moving vehicle-based radar in the SAR mode, in conjunction with a stationary ground-based receiver. The aim was to investigate the imaging property of the bistatic LF UWB SAR system. The one pulse per second (1 PPS) signal in combination with the global position system (GPS) disciplined 100 MHz oscillator from the GPS receivers was used to implement the time and frequency synchronization in this SAR system. The bistatic SAR image was obtained by the subaperture spectrum-equilibrium method integrated with the fast factorized back projection (FFBP) algorithm. Bistatic experiment results are show to prove the validity of the bistatic LF UWB SAR imaging experiment.

Design of synthetic aperture radar low-intercept radio frequency stealth

Not confined to a certain point,such as waveform,this paper systematically studies the low-intercept radio frequency(RF)stealth design of synthetic aperture radar(SAR)from the system level.The study is carried out from two levels.In the first level,the maximum low-intercept range equation of the conventional SAR system is deduced firstly,and then the maximum low-intercept range equation of the multiple-input multiple-output SAR system is deduced.In the second level,the waveform design and imaging method of the low-intercept RF SAR system are given and verified by simulation.Finally,the main technical characteristics of the lowintercept RF stealth SAR system are given to guide the design of low-intercept RF stealth SAR system.

A NOVEL ALGORITHM OF MULTI-SENSOR IMAGE FUSION BASED ON WAVELET PACKET TRANSFORM

In order to enhance the image information from multi-sensor and to improve the abilities of the information analysis and the feature extraction, this letter proposed a new fusion approach in pixel level by means of the Wavelet Packet Transform (WPT). The WPT is able to decompose an image into low frequency band and high frequency band in higher scale. It offers a more precise method for image analysis than Wavelet Transform (WT). Firstly, the proposed approach employs HIS (Hue, Intensity, Saturation) transform to obtain the intensity component of CBERS (China-Brazil Earth Resource Satellite) multi-spectral image. Then WPT transform is employed to decompose the intensity component and SPOT (Systeme Pour I'Observation de la Therre ) image into low frequency band and high frequency band in three levels. Next, two high frequency coefficients and low frequency coefficients of the images are combined by linear weighting strategies. Finally, the fused image is obtained with inverse WPT and inverse HIS. The results show the new approach can fuse details of input image successfully, and thereby can obtain a more satisfactory result than that of HM (Histogram Matched)-based fusion algorithm and WT-based fusion approach.

基于边界元逆问题法的超低场磁共振大鼠脑部成像双通道射频线圈优化设计

目前超低场磁共振成像(MRI)质量较差,为提升图像信噪比,射频线圈需尽可能贴近成像区域从而提升信噪比。该文采用间接边界元法并从逆问题角度求出线圈流函数分布,再利用线性规划寻找最优线圈结构。为验证超低场MRI诊断颅脑疾病的有效性,采用上述方法,在54 mT下针对大鼠头-脑几何形状设计了双通道射频接收线圈,并对大鼠脑卒中及脑外伤模型进行成像试验研究。试验结果表明,54mTMRI能够检出水肿和血肿病变,且与病理切片或临床3T MRI图像结果相符。同时,通过脑外伤模型7天的追踪观察,54 mT图像中病变的信号演变规律与高场影像一致。针对特定成像对象和非规则布线曲面,该文利用间接边界元逆问题法设计高信噪比射频接收线圈,大鼠模型试验证明超低场磁共振成像技术具有脑卒中与脑外份早期诊断与床旁影像监护潜力与价值。

失眠障碍神经影像学特征及重复经颅磁刺激治疗效果

目的基于静息态功能MRI(rs-fMRI)观察失眠障碍(ID)患者脑功能改变,以及重复经颅磁刺激(rTMS)治疗效果。方法前瞻性纳入37例ID患者(ID组)及20名健康受试者(对照组),比较组间及ID组内rTMS治疗前后睡眠状况及心理状态量表评分;基于颅脑rs-fMRI观察组间低频振幅(ALFF)、局部一致性(ReHo)存在差异脑区,并对其与预设脑区进行体素水平静息态功能连接(FC)分析。结果治疗前ID组匹兹堡睡眠质量指数(PSQI)、失眠严重程度指数(ISI)、爱普沃斯嗜睡量表(ESS)评分、贝克忧郁量表(BDI)评分及贝克焦虑量表(BAI)评分均高于对照组(P均<0.05);ID组右侧正中扣带回和扣带旁回(Cingulum_Mid_R)ALFF值及ReHo均低于对照组(FWE校正P均<0.05),Cingulum_Mid_R与左侧前扣带回和扣带旁回(Cingulum_Ant_L)、左侧海马(Hippocampus_L)与右侧额中回(Frontal_Mid_R)间FC降低(FWE校正P均<0.05)。rTMS治疗后ID患者PSQI、ISI及ESS评分均较治疗前减低(P均<0.05),但上述神经影像学指标均无显著改变(FWE校正P均>0.05)。结论ID导致Cingulum_Mid_R ALFF值和ReHo同步减低,额叶-扣带回、额叶和边缘系统之间FC减弱。rTMS可改善ID患者睡眠及精神状态,但其对神经影像学的影响尚需进一步观察。

年轻糖尿病前期、2型糖尿病患者静息态脑功能磁共振成像多指标的对比分析

目的通过多种静息态脑功能磁共振指标探索年轻糖尿病前期(pre-diabetes mellitus,PDM)、2型糖尿病(type 2diabetes mellitus,T2DM)患者的自发神经活动改变,并探讨这种变化是否与临床指标及认知水平相关。材料与方法前瞻性纳入34名T2DM患者和35名PDM患者以及34名正常对照(normal control,NC),年龄均小于40岁。所有被试者进行详细的实验室检查并行3.0 T静息态功能磁共振扫描。图像数据经预处理后,分别计算低频振幅指数、局部一致性指数、度中心性指标。采用两样本t检验比较组间差异,并将性别、年龄和受教育年限作为协变量进行控制。并分析静息态指标与临床指标及认知评分之间的关系。结果与NC组相比,PDM组在多个脑区的自发神经活动增强,例如左侧额叶下回(t=4.710,GRF校正,体素水平P<0.005,簇水平P<0.05),同时也在多个脑区的自发神经活动减弱,例如右侧下顶小叶(t=-4.097,GRF校正,体素水平P<0.005,簇水平P<0.05);T2DM组在多个脑区的自发神经活动增强,例如左侧额叶下回(t=6.348,GRF校正,体素水平P<0.005,簇水平P<0.05),同时也在多个脑区的自发神经活动减弱,例如右侧下顶小叶(t=-5.141,GRF校正,体素水平P<0.005,簇水平P<0.05)。此外,部分静息态指标与临床指标及认知评分存在显著相关性,例如在PDM组中,右侧额叶中回的ALFF值与MoCA评分呈显著负相关(r=-0.410,P=0.014)。结论年轻的PDM、T2DM患者的脑功能指标与临床指标如血糖特征指标、甘油三酯-血糖指数及认知水平相关。本研究增强了我们对糖尿病性脑损伤病理生理学的理解,并为其早期诊断提供了一些潜在的生物学证据。

基于功能影像学探讨百会治疗失眠的中枢机制

百会为治疗失眠的效穴,临床使用频率高。功能影像学,广义上包括多种成像技术,狭义主要指功能性磁共振成像(fMRI),数据分析方法分为功能分离和功能整合两类,试验设计方案包括任务态(Tb-fMRI)与静息态(Rs-fMRI),静息态因操作简便且能直观反映针刺持续和累积效应而被广泛应用。多项fMRI研究表明,失眠患者在视觉区、感觉运动区、情绪相关脑区等存在局部功能异常,针刺百会单穴或组穴可引起特定脑区如顶叶、额叶、颞叶等的改变,从而改善睡眠。针刺单穴百会主要集中在Rs-fMRI局部一致性(ReHo)、比率低频振幅(fALFF)研究,而针刺百会组穴研究从Rs-fMRI局部一致性(ReHo)、度中心度(DC)、种子连接(FC),以及Tb-fMRI比率低频振幅(fALFF)等方面展开,研究发现不同研究方法和穴位组合下的脑区激活改变存在差异,且针刺百会组穴所调控脑区多于单穴针刺,体现了百会对失眠、认知和情绪的调节作用以及腧穴间的协同作用。然而,针刺百会引起的中枢信号改变复杂,功能影像作为评估失眠的中枢指标虽有潜力,但仍需更规范、深入的研究。

Analysis of the differences in brain function response after acupuncture and moxibustion at Zusanli(足三里ST36)in the patients with functional dyspepsia based on fractional amplitude of low frequency fluctuation of rest functional magnetic resonance imaging

Objective:To explore the differences in the central response after acupuncture and moxibusbution at Zusanli(足三里ST36) in treatment of functional dyspepsia(FD) based on the analysis of fractional amplitude of low frequency fluctuation(fALFF) of resting-state functional magnetic resonance imaging(rfMRI).Methods:A total of 60 patients with FD were randomized into an acupuncture group and a moxibustion group,30 cases in each one.In the acupuncture group,acupuncture was applied to bilateral ST36.In the moxibustion group,moxibustion was exerted at bilateral ST36.The treatment was given once a day,5 times a week,totally for 4 weeks in each group,including 20 treatments with acupuncture or moxibustion.Separately,before and at the end of treatment,rfMRI scanning was conducted in two groups.Using data processing assistant for resting-state fMRI(DPARSF) software and MATLAB data platform,rfMRI data were collected for preprocessing and fALFF analysis.Results:Compared with the data before treatment,after treated with acupuncture at ST36 in FD patients,fALFF value was reduced in the right superior frontal gyrus,left superior frontal gyrus,left inferior frontal gyrus,right cuneus,left precuneus,right middle occipital gyrus,left middle occipital gyrus,etc.,and it was increased in the left parahippocampus,right parahippocampus,left cerebellum,etc(all P <0.01).After treated with moxibustion,the remarkable increase of fALFF was not discovered in brain areas,but fALFF decreased significantly in the left superior parietal gyrus(P <0.01).Compared with moxibustion at ST36,after acupuncture at ST36 in FD patients,the increase of fALFF appeared in the right putamen and the decrease of it occurred in the middle occipital gyrus,indicating the statistical significance(both P <0.05).Conclusion:The differences in central function responses are induced in treamtent with acupuncture and moxibustion,which is probably related to the resting-state default network associated with targeted regulation and ventral attention of brain areas in functional dyspepsia.

Correlations between hippocampal functional connectivity,structural changes,and clinical data in patients with relapsing-remitting multiple sclerosis:a case-control study using multimodal magnetic resonance imaging

Multiple sclerosis is associated with structural and functional brain alterations leading to cognitive impairments across multiple domains including attention,memory,and the speed of information processing.The hippocampus,which is a brain important structure involved in memory,undergoes microstructural changes in the early stage of multiple sclerosis.In this study,we analyzed hippocampal function and structure in patients with relapsing-remitting multiple sclerosis and explored correlations between the functional connectivity of the hippocampus to the whole brain,changes in local brain function and microstructure,and cognitive function at rest.We retrospectively analyzed data from 20 relapsing-remitting multiple sclerosis patients admitted to the Department of Neurology at the China-Japan Union Hospital of Jilin University,China,from April 2015 to November 2019.Sixteen healthy volunteers were recruited as the healthy control group.All participants were evaluated using a scale of extended disability status and the Montreal cognitive assessment within 1 week before and after head diffusion tensor imaging and functional magnetic resonance imaging.Compared with the healthy control group,the patients with relapsing-remitting multiple sclerosis had lower Montreal cognitive assessment scores and regions of simultaneously enhanced and attenuated whole-brain functional connectivity and local functional connectivity in the bilateral hippocampus.Hippocampal diffusion tensor imaging data showed that,compared with the healthy control group,patients with relapsing-remitting multiple sclerosis had lower hippocampal fractional anisotropy values and higher mean diffusivity values,suggesting abnormal hippocampal structure.The left hippocampus whole-brain functional connectivity was negatively correlated with the Montreal cognitive assessment score(r=-0.698,P=0.025),and whole-brain functional connectivity of the right hippocampus was negatively correlated with extended disability status scale score(r=-0.649,P=0.042).The mean diffusivity value of the left hippocampus was negatively correlated with the Montreal cognitive assessment score(r=-0.729,P=0.017)and positively correlated with the extended disability status scale score(r=0.653,P=0.041).The right hippocampal mean diffusivity value was positively correlated with the extended disability status scale score(r=0.684,P=0.029).These data suggest that the functional connectivity and presence of structural abnormalities in the hippocampus in patients with relapse-remission multiple sclerosis are correlated with the degree of cognitive function and extent of disability.This study was approved by the Ethics Committee of China-Japan Union Hospital of Jilin University,China(approval No.201702202)on February 22,2017.

Abnormal intrinsic brain activity in amnestic mild cognitive impairment revealed by amplitude of low-frequency fluctuation： a resting-state functional magnetic resonance imaging study

Background Previous studies have shown that brain functional activity in the resting state is impaired in Alzheimer＇s disease （AD） patients. However, alterations in intrinsic brain activity patterns in mild cognitive impairment （MCI） patients are poorly understood. This study aimed to explore the differences in regional intrinsic activities throughout the whole brain between aMCI patients and controls. Methods In the present study, resting-state functional magnetic resonance imaging （fMRI） was performed on 18 amnestic MCI （aMCI） patients, 18 mild AD patients and 20 healthy elderly subjects. And amplitude of low-frequency fluctuation （ALFF） method was used. Results Compared with healthy elderly subjects, aMCI patients showed decreased ALFF in the right hippocampus and parahippocampal cortex, left lateral temporal cortex, and right ventral medial prefrontal cortex （vMPFC） and increased ALFF in the left temporal-parietal junction （TPJ） and inferior parietal Iobule （IPL）. Mild AD patients showed decreased ALFF in the left TPJ, posterior IPL （plPL）, and dorsolateral prefrontal cortex compared with aMCI patients. Mild AD patients also had decreased ALFF in the right posterior cingulate cortex, right vMPFC and bilateral dorsal MPFC （dMPFC） compared with healthy elderly subjects. Conclusions Decreased intrinsic activities in brain regions closely related to episodic memory were found in aMCI and AD patients. Increased TPJ and IPL activity may indicate compensatory mechanisms for loss of memory function in aMCI patients. These findings suggest that the fMRI based on ALFF analysis may provide a useful tool in the study of aMCI patients.

Abnormal brain activity in adolescents with Internet addiction who attempt suicide: an assessment using functional magnetic resonance imaging

Internet addiction is associated with an increased risk of suicidal behavior and can lead to brain dysfunction among adolescents.However,whether brain dysfunction occurs in adolescents with Internet addiction who attempt suicide remains unknown.This observational cross-sectional study enrolled 41 young Internet addicts,aged from 15 to 20 years,from the Department of Psychiatry,the First Affiliated Hospital of Chongqing Medical University,China from January to May 2018.The participants included 21 individuals who attempted suicide and 20 individuals with Internet addiction without a suicidal attempt history.Brain images in the resting state were obtained by a 3.0 T magnetic resonance imaging scanner.The results showed that activity in the gyrus frontalis inferior of the right pars triangularis and the right pars opercularis was significantly increased in the suicidal attempt group compared with the non-suicidal attempt group.In the resting state,the prefrontal lobe of adolescents who had attempted suicide because of Internet addiction exhibited functional abnormalities,which may provide a new basis for studying suicide pathogenesis in Internet addicts.The study was authorized by the Ethics Committee of Chongqing Medical University,China(approval No.2017 Scientific Research Ethics(2017-157))on December 11,2017.

Reverse time migration based on normalized wavefield decomposition imaging condition

With the increasing complexity of prospecting objectives,reverse time migration( RTM) has attracted more and more attention due to its outstanding imaging quality. RTM is based on two-way wave equation,so it can avoid the limits of angle in traditional one-way wave equation migration,image reverse branch,prism waves and multi-reflected wave precisely and obtain accurate dynamic information. However,the huge demands for storage and computation as well as low frequency noises restrict its wide application. The normalized cross-correlation imaging conditions based on wave field decomposition are derived from traditional cross-correlation imaging condition,and it can eliminate the low-frequency noises effectively and improve the imaging resolution. The practical procedure includes separating source and receiver wave field into one-way components respectively,and conducting cross-correlation imaging condition to the post-separated wave field. In this way,the resolution and precision of the imaging result will be promoted greatly.

Brain activation and inhibition after acupuncture at Taichong and Taixi: resting-state functional magnetic resonance imaging

Acupuncture can induce changes in the brain. However, the majority of studies to date have focused on a single acupoint at a time. In the present study, we observed activity changes in the brains of healthy volunteers before and after acupuncture atTaichong （LR3） andTaixi （KI3） using resting-state functional magnetic resonance imaging. Fifteen healthy volunteers underwent resting-state functional magnetic resonance imaging of the brain 15 minutes before acupuncture, then received acupuncture atTaichong andTaixi using the nail-pressing needle insertion method, after which the needle was retained in place for 30 minutes. Fifteen minutes after withdrawal of the needle, the volunteers underwent a further session of resting-state functional magnetic res-onance imaging, which revealed that the amplitude of low-frequency lfuctuation, a measure of spontaneous neuronal activity, increased mainly in the cerebral occipital lobe and middle occipital gyrus （Brodmann area 18/19）, inferior occipital gyrus （Brodmann area 18） and cuneus （Brodmann area 18）, but decreased mainly in the gyrus rectus of the frontal lobe （Brodmann area 11）, inferi-or frontal gyrus （Brodmann area 44） and the center of the posterior lobe of the cerebellum. The present ifndings indicate that acupuncture atTaichong andTaixi speciifcally promote blood lfow and activation in the brain areas related to vision, emotion and cognition, and inhibit brain areas related to emotion, attention, phonological and semantic processing, and memory.

Pixel for Passive Terahertz Imaging System （PTIS） at the Base of Josephson Junction in Self-Pumping Regime

The use of Josephson junctions （JJ） in self-pumping mode as one of the heterodyne detection method can stay the new trend for design modern passive terahertz imaging system （PT1S）. Combination superconductive and semiconductor technologies on the one substrate in any case will born principal trend of the critical electronic technologies, including the realization superconductive JJ near the gate of a semiconductor transistor. Further development will allow to realize the PTIS system with electronic tuning of the receiving frequency. At the same time there exists yet additional new possibility to measure the frequency of the receiving signals （very briefly） on JJ.

首发与复发急性期精神分裂症患者静息态低频振幅与分数低频振幅分析

目的:分析首发和复发急性期精神分裂症患者静息态低频振幅与分数低频振幅改变情况。方法:纳入2014年6月至2020年05月在武汉大学人民医院精神卫生中心60例首发、60例复发急性期精神分裂症患者及60名健康对照者进行静息态功能磁共振扫描,采用基于体素水平的低频振幅(ALFF)及分数低频振幅(fALFF)指标分析3组间局部脑功能活动情况。结果:协方差分析显示三组间ALFF值存在显著差异的脑区位于双侧纹状体(左侧F=23.06,P<0.001;右侧F=19.31,P<0.001),而fALFF值存在显著差异的脑区位于双侧纹状体(左侧F=19.71,P<0.001;右侧F=13.53,P<0.001)和前额叶内侧皮质(F=5.46,P<0.001);事后检验显示与对照组相比,首发组和复发组双侧纹状体ALFF及fALFF值均显著升高、内侧前额叶皮质fALFF值降低;复发组内侧前额叶皮质fALFF值降低较首发组更为明显。结论:首发和复发急性期精神分裂症患者均存在双侧纹状体、内侧前额叶皮质的局部功能活动异常,而复发精神分裂症患者内侧前额叶皮质局部脑功能损害更显著。

原发性失眠相关情绪障碍的低频振幅静息态fMRI研究

目的:探讨原发性失眠相关情绪障碍患者的脑内神经活动异常改变。方法:纳入18~60岁原发性失眠相关情绪障碍患者(失眠组)和正常受试者(对照组)各20例,对比2组低频振幅(ALFF)差异,并分析ALFF值与临床评估量表的相关性。结果:2组匹兹堡睡眠质量指数(PSQI)、焦虑自评量表(SAS)评分、抑郁自评量表(SDS)评分差异均有统计学意义(均P<0.05)。与对照组相比,失眠组ALFF值升高的脑区有左侧颞下回、右侧眶额皮质、右侧前扣带回、右侧颞中回、双侧额上回、右侧枕上回、左侧中央后回,ALFF值降低的脑区有左侧中扣带回、左侧额中回、右侧额上回(AlphaSim校正,P<0.01)。SDS评分与右侧眶额皮质的ALFF值呈正相关(r=0.528,P=0.024),SDS、SAS评分与左侧中扣带回ALFF值均呈正相关(r=0.641,0.494;均P<0.05)。结论:通过ALFF可发现原发性失眠相关情绪障碍患者的脑内异常神经活动,主要是情感、认知相关网络脑区(扣带回、眶额皮质等)存在脑自发活动异常,且部分脑区的自发活动与临床指标存在相关性。异常脑活动改变可能是原发性失眠相关情绪障碍患者的有效神经影像标志物,可为远期疾病严重性评估及疾病治疗提供影像学依据。

脑部静息态功能磁共振低频振幅法检测盆底膀胱过度活动症患者大脑各区功能及结果分析

目的采用脑部静息态功能磁共振(rs-fMRI)低频振幅(ALFF)法检测膀胱过度活动症(OAB)患者脑部各功能区信号图像并对结果进行分析探讨。方法选取2021年3月—2023年3月于3家参与医院就诊并确诊为OAB的患者为OAB组(n=14),收集同期与OAB组患者性别、年龄、受教育年限匹配的健康人群作为对照组(NC组,n=14)。比较两组受试者的膀胱过度活动症状评分表(OABSS)问卷调查、生活质量评分(QoL)、抑郁自评量表(SDS)及焦虑自评量表(SAS)评分。受试者均进行rs-fMRI检测,采集血氧水平依赖磁共振信号图像,采用ALFF技术处理图像数据,对结果进行两样本t检验,获取差异脑区。结果OAB组和NC组的OABSS[(8.07±0.37)分vs.(1.21±0.18)分]、QoL[(4.85±0.21)分vs.(0.64±0.13)分]、SAS[(60.14±1.40)分vs.(37.64±1.57)分]及SDS[(52.50±1.29)分vs.(36.14±0.34)分]评分比较,OAB组高于NC组,差异有统计学意义(P<0.05)。ALFF处理后结果显示,两组受试者ALFF值有明显差异的脑区分别位于左侧补充运动区、左侧额叶内侧额上回及右侧中央前回(P<0.0001)。结论静息状态下大脑的自发活动与相互协调能力异常可能与OAB的相应临床症状有关,涉及的功能异常脑区有左侧补充运动区、左侧额叶内侧额上回及右侧中央前回。

基于高低频特征增强和透射率修正的复杂图像去雾方法

针对复杂图像中存在非均匀散射介质(如大气湍流、烟雾、雾霾等),导致光线在不同区域的传播和散射特性不同,较难准确恢复图像能见度的问题,提出一种基于高低频特征增强和透射率修正的复杂图像去雾方法.首先,基于奇异值分解和Gamma拐点校正,设计低频特征增强方法;其次,基于Shearlet变换分解和非线性变换,得到高频特征增强方法;再次,利用软抠图精化所估计的透射率,构建透射率修正策略;最后,融合上述3种方法,根据大气光值和精化透射率,完成图像去雾,分别增强高、低频特征后,将两者叠加,获得增强的去雾图像.经去雾图像的视觉感观和客观评价指标结果验证表明,该方法的去雾效果较好,能有效恢复复杂图像的细节信息,改善图像的整体视觉质量.

基于ReHo和fALFF的优势半球与非优势半球基底节区脑梗死后运动障碍的静息态脑功能成像研究

目的:采用静息态fMRI技术联合局部一致性(ReHo)和比率低频振幅(fALFF)探讨优势半球与非优势半球基底节区脑梗死后运动障碍患者的脑局部自发活动变化。方法:招募20例基底节区脑梗死后运动障碍患者,按照病灶位置分为优势半球脑梗死组11例和非优势半球脑梗死组9例;招募18例性别、年龄匹配的健康志愿者(对照组)分别行静息态fMRI,利用基于MATLAB的SPM12和DPARSF软件对数据进行分析,采用双样本t检验(体素水平P<0.01,团块水平P<0.05,GRF校正)对3组受试者的ReHo及fALFF脑图行组间两两比较,提取差异脑区的ReHo值及fALFF值。结果:与对照组相比,优势半球脑梗死组左侧三角部额下回的ReHo值显著升高(t=4.97,P<0.05),左侧扣带回白质的fALFF值显著降低(t=-7.57,P<0.05)。与对照组相比,非优势半球脑梗死组左侧额中回的ReHo值显著升高(t=6.01,P<0.05),左侧内侧和旁扣带脑回(t=-6.02,P<0.05)、右侧枕上回(t=-5.25,P<0.05)的ReHo值显著降低,右侧眶部额下回(t=5.01,P<0.05)、左侧枕中回(t=4.74,P<0.05)的fALFF值显著升高,右侧内侧和旁扣带脑回fALFF值显著降低(t=-5.58,P<0.05)。与非优势半球脑梗死组相比,优势半球脑梗死组左侧小脑的ReHo值显著升高(t=4.51,P<0.05),左侧三角部额下回(t=5.29,P<0.05)、左侧舌回(t=5.63,P<0.05)、左侧额中回(t=6.72,P<0.05)的fALFF值显著升高。结论:静息状态下,与对照组相比,优势半球与非优势半球基底节区脑梗死后双侧大脑皮质运动、感觉及认知等多个脑区神经元活动发生变化;与非优势半球脑梗死相比,优势半球脑梗死能更快地出现代偿性激活,增强神经元活动,这一发现可能有助于进一步理解不同半球间基底节区脑梗死后运动障碍患者的大脑局部神经影像学差异。

全色图像引导高光谱图像泛锐化

泛锐化方法通过融合低分辨率高光谱图像和全色图像,从而获取具有高空间、高光谱分辨率的图像。为充分挖掘全色图像空间纹理特征,在VGG19中引入八度卷积,同时关注全色图像不同空间尺度的高低频特征;为增强光谱图像的局部空间特征,添加特征调制模块,将全色图像高频特征注入光谱图像空间细节;为加强光谱图像特征同全色图像低频特征的全局依赖关系、降低网络复杂度,网络深层对多头注意力进行优化,使光谱图像只关注全色图像最相关的图像区域;重建阶段采用Sobel滤波器、GCN图神经网络以及ECA注意力聚合光谱图像边缘细节和显著波段特征,同时,引入VGG感知损失和边缘损失,提高融合后图像的边缘特征比重。在Pavia Center、Botswana和Chikusei这3个数据集与其他泛锐化方法进行验证,其中峰值信噪比(Peak Signal-to-Noise Ratio,PSNR)值分别达到40.80%、45.90%和43.26%,SAM值分别降低到4.15%、1.38%和2.70%。提出泛锐化方法可有效恢复光谱图像空间纹理细节,同时避免光谱失真。