期刊文献+
共找到2,485篇文章
< 1 2 125 >
每页显示 20 50 100
Magnetic resonance imaging techniques for lithium-ion batteries:Principles and applications
1
作者 Hongxin Lin Yanting Jin +4 位作者 Mingming Tao Yingao Zhou Peizhao Shan Danhui Zhao Yong Yang 《Magnetic Resonance Letters》 2024年第2期22-39,共18页
Operando monitoring of internal and local electrochemical processes within lithium-ion batteries(LIBs)is crucial,necessitating a range of non-invasive,real-time imaging characterization techniques including nuclear ma... Operando monitoring of internal and local electrochemical processes within lithium-ion batteries(LIBs)is crucial,necessitating a range of non-invasive,real-time imaging characterization techniques including nuclear magnetic resonance(NMR)techniques.This review provides a comprehensive overview of the recent applications and advancements of non-invasive magnetic resonance imaging(MRI)techniques in LIBs.It initially introduces the principles and hardware of MRI,followed by a detailed summary and comparison of MRI techniques used for characterizing liquid/solid electrolytes,electrodes and commercial batteries.This encompasses the determination of electrolytes'transport properties,acquisition of ion distribution profile,and diagnosis of battery defects.By focusing on experimental parameters and optimization strategies,our goal is to explore MRI methods suitable to a variety of research subjects,aiming to enhance imaging quality across diverse scenarios and offer critical physical/chemical insights into the ongoing operation processes of LIBs. 展开更多
关键词 Lithium-ion batteries magnetic resonance imaging(mri) Electrolytes ELECTRODES Commercial batteries
下载PDF
Reduced Imaging Time and Improved Image Quality of 3D Isotropic T2-Weighted Magnetic Resonance Imaging with Compressed Sensing for the Female Pelvis
2
作者 Hao Mei Feng Xiao Ming Deng 《Journal of Beijing Institute of Technology》 EI CAS 2023年第5期579-585,共7页
This study is to compare three-dimensional(3D)isotropic T2-weighted magnetic resonance imaging(MRI)with compressed sensing-sampling perfection with application optimized contrast(CS-SPACE)and the conventional image(3D... This study is to compare three-dimensional(3D)isotropic T2-weighted magnetic resonance imaging(MRI)with compressed sensing-sampling perfection with application optimized contrast(CS-SPACE)and the conventional image(3D-SPACE)sequence in terms of image quality,estimated signal-to-noise ratio(SNR),relative contrast-to-noise ratio(CNR),and the lesions’conspicuous of the female pelvis.Thirty-six females(age:51,28-73)with cervical carcinoma(n=20),rectal carcinoma(n=7),or uterine fibroid(n=9)were included.Patients underwent magnetic resonance(MR)imaging at a 3T scanner with the sequences of 3D-SPACE,CS-SPACE,and twodimensional(2D)T2-weighted turbo-spin echo(TSE).Quantitative analyses of estimated SNR and relative CNR between tumors and other tissues,image quality,and tissue conspicuity were performed.Two radiologists assessed the difference in diagnostic findings for carcinoma.Quantitative values and qualitative scores were analyzed,respectively.The estimated SNR and the relative CNR of tumor-to-muscle obturator internus,tumor-to-myometrium,and myometrium-to-muscle obturator internus was comparable between 3D-SPACE and CS-SPACE.The overall image quality and the conspicuity of the lesion scores of the CS-SPACE were higher than that of the 3D-SPACE(P<0.01).The CS-SPACE sequence offers shorter scan time,fewer artifacts,and comparable SNR and CNR to conventional 3D-SPACE,and has the potential to improve the performance of T2-weighted images. 展开更多
关键词 compressed sensing sampling perfection with application-oriented contrasts(SPACE)using variable flip angle evolutions three-dimensional(3D)imaging magnetic resonance imaging(mri) PELVIS
下载PDF
Role of pulmonary perfusion magnetic resonance imaging for the diagnosis of pulmonary hypertension:A review
3
作者 Miriam Lacharie Adriana Villa +3 位作者 Xenios Milidonis Hadeer Hasaneen Amedeo Chiribiri Giulia Benedetti 《World Journal of Radiology》 2023年第9期256-273,共18页
Among five types of pulmonary hypertension,chronic thromboembolic pulmonary hypertension(CTEPH)is the only curable form,but prompt and accurate diagnosis can be challenging.Computed tomography and nuclear medicine-bas... Among five types of pulmonary hypertension,chronic thromboembolic pulmonary hypertension(CTEPH)is the only curable form,but prompt and accurate diagnosis can be challenging.Computed tomography and nuclear medicine-based techniques are standard imaging modalities to non-invasively diagnose CTEPH,however these are limited by radiation exposure,subjective qualitative bias,and lack of cardiac functional assessment.This review aims to assess the methodology,diagnostic accuracy of pulmonary perfusion imaging in the current literature and discuss its advantages,limitations and future research scope. 展开更多
关键词 Pulmonary perfusion mri Pulmonary hypertension Dynamic contrast enhanced magnetic resonance imaging Chronic thromboembolic pulmonary hypertension Computed tomography pulmonary angiography Chronic thromboembolic disease
下载PDF
An Improved Jellyfish Algorithm for Multilevel Thresholding of Magnetic Resonance Brain Image Segmentations 被引量:4
4
作者 Mohamed Abdel-Basset Reda Mohamed +3 位作者 Mohamed Abouhawwash Ripon K.Chakrabortty Michael J.Ryan Yunyoung Nam 《Computers, Materials & Continua》 SCIE EI 2021年第9期2961-2977,共17页
Image segmentation is vital when analyzing medical images,especially magnetic resonance(MR)images of the brain.Recently,several image segmentation techniques based on multilevel thresholding have been proposed for med... Image segmentation is vital when analyzing medical images,especially magnetic resonance(MR)images of the brain.Recently,several image segmentation techniques based on multilevel thresholding have been proposed for medical image segmentation;however,the algorithms become trapped in local minima and have low convergence speeds,particularly as the number of threshold levels increases.Consequently,in this paper,we develop a new multilevel thresholding image segmentation technique based on the jellyfish search algorithm(JSA)(an optimizer).We modify the JSA to prevent descents into local minima,and we accelerate convergence toward optimal solutions.The improvement is achieved by applying two novel strategies:Rankingbased updating and an adaptive method.Ranking-based updating is used to replace undesirable solutions with other solutions generated by a novel updating scheme that improves the qualities of the removed solutions.We develop a new adaptive strategy to exploit the ability of the JSA to find a best-so-far solution;we allow a small amount of exploration to avoid descents into local minima.The two strategies are integrated with the JSA to produce an improved JSA(IJSA)that optimally thresholds brain MR images.To compare the performances of the IJSA and JSA,seven brain MR images were segmented at threshold levels of 3,4,5,6,7,8,10,15,20,25,and 30.IJSA was compared with several other recent image segmentation algorithms,including the improved and standard marine predator algorithms,the modified salp and standard salp swarm algorithms,the equilibrium optimizer,and the standard JSA in terms of fitness,the Structured Similarity Index Metric(SSIM),the peak signal-to-noise ratio(PSNR),the standard deviation(SD),and the Features Similarity Index Metric(FSIM).The experimental outcomes and the Wilcoxon rank-sum test demonstrate the superiority of the proposed algorithm in terms of the FSIM,the PSNR,the objective values,and the SD;in terms of the SSIM,IJSA was competitive with the others. 展开更多
关键词 magnetic resonance imaging brain image segmentation artificial jellyfish search algorithm ranking method local minima Otsu method
下载PDF
Semi-automated segmentation of magnetic resonance images for thigh skeletal muscle and fat using threshold technique after spinal cord injury 被引量:1
5
作者 Mina P.Ghatas Robert M.Lester +1 位作者 M.Rehan Khan Ashraf S.Gorgey 《Neural Regeneration Research》 SCIE CAS CSCD 2018年第10期1787-1795,共9页
Magnetic resonance imaging is considered the "gold standard" technique for quantifying thigh muscle and fat cross-sectional area. We have developed a semi-automated technique to segment seven thigh compartments in p... Magnetic resonance imaging is considered the "gold standard" technique for quantifying thigh muscle and fat cross-sectional area. We have developed a semi-automated technique to segment seven thigh compartments in persons with spinal cord injury. Thigh magnetic resonance images from 18 men(18–50 years old) with traumatic motor-complete spinal cord injury were analyzed in a blinded fashion using the threshold technique. The cross-sectional area values acquired by thresholding were compared to the manual tracing technique. The percentage errors for thigh circumference were(threshold: 170.71 ± 38.67; manual: 169.45 ± 38.27 cm2) 0.74%, subcutaneous adipose tissue(threshold: 65.99±30.79; manual: 62.68 ± 30.22) 5.2%, whole muscle(threshold: 98.18 ± 20.19; manual: 98.20 ± 20.08 cm2) 0.13%, femoral bone(threshold: 6.53 ± 1.09; manual: 6.53 ± 1.09 cm2) 0.64%, bone marrow fat(threshold: 3.12 ± 1.12; manual: 3.1 ± 1.11 cm2) 0.36%, knee extensor(threshold: 43.98 ± 7.66; manual: 44.61 ± 7.81 cm2) 1.78% and % intramuscular fat(threshold: 10.45 ± 4.29; manual: 10.92 ± 8.35%) 0.47%. Collectively, these results suggest that the threshold technique provided a robust accuracy in measuring the seven main thigh compartments, while greatly reducing the analysis time. 展开更多
关键词 spinal cord injury magnetic resonance imaging semi-automated segmentation subcutaneous adipose tissue intramuscular fat
下载PDF
Application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis 被引量:1
6
作者 Yakun He Min Wang +1 位作者 Heping Deng Jin Ren 《Oncology and Translational Medicine》 CAS 2021年第1期31-34,共4页
Objective The aim of the study was to investigate the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis.Methods ... Objective The aim of the study was to investigate the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)combined with magnetic resonance spectroscopy(MRS)in prostate cancer diagnosis.Methods In the outpatient department of our hospital(Sichuan Cancer Hospital,Chengdu,China),60 patients diagnosed with prostate disease were selected randomly and included in a prostate cancer group,60 patients with benign prostatic hyperplasia were included in a proliferation group,and 60 healthy subjects were included in a control group,from January 2013 to January 2017.Using Siemens Avanto 1.5 T high-field superconducting MRI for DCE-MRI and MRS scans,after the MRS scan was completed,we used the workstation spectroscopy tab spectral analysis,and eventually obtained the crest lines of the prostate metabolites choline(Cho),creatine(Cr),citrate(Cit),and the values of Cho/Cit,and(Cho+Cr)/Cit.Results Participants who had undergone 21-s,1-min,and 2-min dynamic contrast-enhanced MR revealed significant variations among the three groups.The spectral analysis of the three groups revealed a significant variation as well.DCE-MRI and MRS combined had a sensitivity of 89.67%,specificity of 95.78%,and accuracy of 94.34%.Conclusion DCE-MRI combined with MRS is of great value in the diagnosis of prostate cancer. 展开更多
关键词 prostate cancer magnetic resonance imaging(mri) dynamic contrast-enhanced(DCE) spectroscopy
下载PDF
Generalized Nonconvex Low-Rank Algorithm for Magnetic Resonance Imaging (MRI) Reconstruction
7
作者 吴新峰 刘且根 +2 位作者 卢红阳 龙承志 王玉皞 《Journal of Donghua University(English Edition)》 EI CAS 2017年第2期316-321,共6页
In recent years,utilizing the low-rank prior information to construct a signal from a small amount of measures has attracted much attention.In this paper,a generalized nonconvex low-rank(GNLR) algorithm for magnetic r... In recent years,utilizing the low-rank prior information to construct a signal from a small amount of measures has attracted much attention.In this paper,a generalized nonconvex low-rank(GNLR) algorithm for magnetic resonance imaging(MRI)reconstruction is proposed,which reconstructs the image from highly under-sampled k-space data.In the algorithm,the nonconvex surrogate function replacing the conventional nuclear norm is utilized to enhance the low-rank property inherent in the reconstructed image.An alternative direction multiplier method(ADMM) is applied to solving the resulting non-convex model.Extensive experimental results have demonstrated that the proposed method can consistently recover MRIs efficiently,and outperforms the current state-of-the-art approaches in terms of higher peak signal-to-noise ratio(PSNR) and lower high-frequency error norm(HFEN) values. 展开更多
关键词 magnetic resonance imaging(mri) low-rank approximation nonconvex optimization alternative direction multiplier method(ADMM)
下载PDF
Obstacles Facing the Implementation of Functional Magnetic Resonance Imaging (fMRI) of Brain in Jeddah City
8
作者 Abrar Mohammed Shafia M. Noor Hanan Mohammed Alzahrani Zuber Ahmed 《Computer Technology and Application》 2013年第2期123-126,共4页
fMRI (Functional Magnetic Resonance Imaging) is a relatively new technique that uses MRI (Magnetic Resonance Imaging) to measure the hemodynamic response (change in blood flow) related to neural activity in the ... fMRI (Functional Magnetic Resonance Imaging) is a relatively new technique that uses MRI (Magnetic Resonance Imaging) to measure the hemodynamic response (change in blood flow) related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training. 展开更多
关键词 fmri (Functional magnetic resonance imaging brain imaging mri magnetic resonance imaging).
下载PDF
Improved neurological diagnoses and treatment strategies via automated human brain tissue segmentation from clinical magnetic resonance imaging
9
作者 Puranam Revanth Kumar Rajesh Kumar Jha +1 位作者 P Akhendra Kumar B Deevena Raju 《Intelligent Medicine》 EI CSCD 2024年第3期161-169,共9页
Objective Segmentation of medical images is a crucial process in various image analysis applications.Automated segmentation methods excel in accuracy when compared to manual segmentation in the context of medical imag... Objective Segmentation of medical images is a crucial process in various image analysis applications.Automated segmentation methods excel in accuracy when compared to manual segmentation in the context of medical image analysis.One of the essential phases in the quantitative analysis of the brain is automated brain tissue segmentation using clinically obtained magnetic resonance imaging(MRI)data.It allows for precise quantitative examination of the brain,which aids in diagnosis,identification,and classification of disorders.Consequently,the efficacy of the segmentation approach is crucial to disease diagnosis and treatment planning.Methods This study presented a hybrid optimization method for segmenting brain tissue in clinical MRI scans us-ing a fractional Henry horse herd gas optimization-based Shepard convolutional neural network(FrHHGO-based ShCNN).To segment the clinical brain MRI images into white matter(WM),grey matter(GM),and cerebrospinal fluid(CSF)tissues,the proposed framework was evaluated on the Lifespan Human Connectome Projects(HCP)database.The hybrid optimization algorithm,FrHHGO,integrates the fractional Henry gas optimization(FHGO)and horse herd optimization(HHO)algorithms.Training required 30 min,whereas testing and segmentation of brain tissues from an unseen image required an average of 12 s.Results Compared to the results obtained with no refinements,the Skull stripping refinement showed significant improvement.As the method included a preprocessing stage,it was flexible enough to enhance image quality,allowing for better results even with low-resolution input.Maximum precision of 93.2%,recall of 91.5%,Dice score of 91.1%,and F1-score of 90.5% were achieved using the proposed FrHHGO-based ShCNN,which was superior to all other approaches. 展开更多
关键词 Brain tissue segmentation Deep learning magnetic resonance imaging Optimization technique Shepard convolutional neural network
原文传递
Two Stages Segmentation Algorithm of Breast Tumor in DCE-MRI Based on Multi-Scale Feature and Boundary Attention Mechanism
10
作者 Bing Li Liangyu Wang +3 位作者 Xia Liu Hongbin Fan Bo Wang Shoudi Tong 《Computers, Materials & Continua》 SCIE EI 2024年第7期1543-1561,共19页
Nuclearmagnetic resonance imaging of breasts often presents complex backgrounds.Breast tumors exhibit varying sizes,uneven intensity,and indistinct boundaries.These characteristics can lead to challenges such as low a... Nuclearmagnetic resonance imaging of breasts often presents complex backgrounds.Breast tumors exhibit varying sizes,uneven intensity,and indistinct boundaries.These characteristics can lead to challenges such as low accuracy and incorrect segmentation during tumor segmentation.Thus,we propose a two-stage breast tumor segmentation method leveraging multi-scale features and boundary attention mechanisms.Initially,the breast region of interest is extracted to isolate the breast area from surrounding tissues and organs.Subsequently,we devise a fusion network incorporatingmulti-scale features and boundary attentionmechanisms for breast tumor segmentation.We incorporate multi-scale parallel dilated convolution modules into the network,enhancing its capability to segment tumors of various sizes through multi-scale convolution and novel fusion techniques.Additionally,attention and boundary detection modules are included to augment the network’s capacity to locate tumors by capturing nonlocal dependencies in both spatial and channel domains.Furthermore,a hybrid loss function with boundary weight is employed to address sample class imbalance issues and enhance the network’s boundary maintenance capability through additional loss.Themethod was evaluated using breast data from 207 patients at RuijinHospital,resulting in a 6.64%increase in Dice similarity coefficient compared to the benchmarkU-Net.Experimental results demonstrate the superiority of the method over other segmentation techniques,with fewer model parameters. 展开更多
关键词 Dynamic contrast-enhanced magnetic resonance imaging(DCE-mri) breast tumor segmentation multi-scale dilated convolution boundary attention the hybrid loss function with boundary weight
下载PDF
Current and future applications of magnetic resonance imaging and spectroscopy of the brain in hepatic encepha-lopathy 被引量:8
11
作者 VP Bob Graver M Alex Dresner +5 位作者 Daniel M Forton Serena Counsell David J Larkman Nayna Patel Howard C Thomas Simon D Taylor-Robinson 《World Journal of Gastroenterology》 SCIE CAS CSCD 2006年第19期2969-2978,共10页
Hepatic encephalopathy (HE) is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting. The manifestat... Hepatic encephalopathy (HE) is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting. The manifestations of HE are widely variable and involve a spectrum from mild subclinical disturbance to deep coma. Research interest has focused on the role of circulating gut-derived toxins, particularly ammonia, the development of brain swelling and changes in cerebral neurotransmitter systems that lead to global CNS depression and disordered function. Until recently the direct investigation of cerebral function has been difficult in man. However, new magnetic resonance imaging (MRI) techniques provide a non-invasive means of assessment of changes in brain volume (coregistered MRI) and impaired brain function (fMRI), while proton magnetic resonance spectroscopy (^1H MRS) detects changes in brain biochemistry, including direct measurement of cerebral osmolytes, such as myoinositol, glutamate and glutamine which govern processes intrinsic to cellular homeostasis, including the accumulation of intracellular water. The concentrations of these intracellular osmolytes alter with hyperammonaemia. MRS-detected metabolite abnormalities correlate with the severity of neuropsychiatric impairment and since MR spectra return towards normal after treatment, the technique may be of use in objective patient monitoring and in assessing the effectiveness of various treatment regimens. 展开更多
关键词 Hepatic encephalopathy magnetic resonance imaging magnetic resonance spectroscopy Diffusion weighted imaging Arterial spin labeling Functional mri
下载PDF
Targeted prostate biopsy: value of multiparametric magnetic resonance imaging in detection of localized cancer 被引量:3
12
作者 Jesse D Le Jiaoti Huang Leonard S Marks 《Asian Journal of Andrology》 SCIE CAS CSCD 2014年第4期522-529,共8页
Prostate cancer is the second most common cancer in men, with 1.1 million new cases worldwide reported by the World Health Organization in one recent year. Transrectal ultrasound (TRUS)-guided biopsy has been used f... Prostate cancer is the second most common cancer in men, with 1.1 million new cases worldwide reported by the World Health Organization in one recent year. Transrectal ultrasound (TRUS)-guided biopsy has been used for the diagnosis of prostate cancer for over 2 decades, but the technique is usually blind to cancer location. Moreover, the false negative rate of TRUS biopsy has been reported to be as high as 47%. Multiparametric magnetic resonance imaging (mp-MRI) includes T1- and T2-weighted imaging as well as dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI). mp-MRI is a major advance in the imaging of prostate cancer, enabling targeted biopsy of suspicious lesions. Evolving targeted biopsy techniquesmincluding direct in-bore biopsy, cognitive fusion and software-based MRI-ultrasound (MRI-US) fusion--have led to a several-fold improvement in cancer detection compared to the earlier method. Importantly, the detection of clinically significant cancers has been greatly facilitated by targeting, compared to systematic biopsy alone. Targeted biopsy via MRI-US fusion may dramatically alter the way prostate cancer is diagnosed and managed. 展开更多
关键词 fusion biopsy magnetic resonance imaging (mri prostate biopsy prostate cancer targeted biopsy ULTRASOUND
下载PDF
Magnetic resonance imaging for prostate cancer clinical application 被引量:2
13
作者 Bing Li Yong Du +3 位作者 Hanfeng Yang Yayong Huang Jun Meng Dongmei Xiao 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2013年第2期240-249,共10页
As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In... As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In clinical practice, magnetic resonance imaging (MRI) is one of the imaging tools for the evaluation of prostate cancer, the fusion of MRI or dynamic contrast-enhanced MRI (DCE-MRI) with magnetic resonance spectroscopic imaging (MRSI) is improving the evaluation of cancer locafon, size, and extent, while providing an indication of tumor aggressiveness. This review summarizes the role of MRI in the application of prostate cancer and describes molecular MRI techniques (including MRSI and DCE-MRI) for aiding prostate cancer management. 展开更多
关键词 Prostate cancer magnetic resonance imaging (mri fimctional mri molecular MR[
下载PDF
Nasopharyngeal adenoid cystic carcinoma: magnetic resonance imaging features in ten cases 被引量:8
14
作者 Xue-Wen Liu Chuan-Miao Xie +7 位作者 Hui Li Rong Zhang Zhi-Jun Geng Yun-Xian Mo Jing Zhao Mu-Yan Cai Yan-Chun Lv Pei-Hong Wu 《Chinese Journal of Cancer》 SCIE CAS CSCD 2012年第1期19-28,共10页
Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with high local invasiveness. To date, there is no consensus on the imaging characteristics of NACC. To address this, we retrospectively reviewed 10 ... Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with high local invasiveness. To date, there is no consensus on the imaging characteristics of NACC. To address this, we retrospectively reviewed 10 cases of NACC and summarized the magnetic resonance imaging (MRI) features. MR images of 10 patients with histologically validated NACC were reviewed by two experienced radiologists. The location, shape, margin, signal intensity, lesion texture, contrast enhancement patterns, local invasion, and cervical lymphadenopathy of all tumors were evaluated. Clinical and pathologic records were also reviewed. No patients were positive for antibodies against Epstein-Barr virus (EBV). The imaging patterns of primary tumors were classified into two types as determined by location, shape, and margin. Of all patients, 7 had tumors with a type 1 imaging pattern and 3 had tumors with a type 2 imaging pattern. The 4 tubular NACCs were all homogeneous tumors, whereas 3 (60%) of 5 cribriform NACCs and the sole solid NACC were heterogeneous tumors with separations or central necrosis on MR images. Five patients had perineural infiltration and intracranial involvement, and only 2 had cervical lymphadenopathy. Based on these results, we conclude that NACC is a local, aggressive neoplasm that is often negative for EBV infection and associated with a low incidence of cervical lymphadenopathy. Furthermore, MRI features of NACC vary in locations and histological subtypes. 展开更多
关键词 磁共振成像 腺样囊性癌 淋巴结肿大 恶性肿瘤 磁共振图像 成像模式 信号强度
下载PDF
Neuromelanin-sensitive magnetic resonance imaging:a promising technique for depicting tissue characteristics containing neuromelanin 被引量:2
15
作者 Ken Nakamura Keizo Sugaya 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第7期759-760,共2页
Idiopathic Parkinson's disease (IPD) is a progressive, neurodegenerative movement disorder characterized by bradykinesia, muscular rigidity, pos- tural instability and tremor. IPD is usually diagnosed based on clin... Idiopathic Parkinson's disease (IPD) is a progressive, neurodegenerative movement disorder characterized by bradykinesia, muscular rigidity, pos- tural instability and tremor. IPD is usually diagnosed based on clinical findings, but diagnoses are only 75-90% accurate when compared with autopsy results. Improving diagnostic accuracy is critical for the early dif- ferentiation of IPD from other Parkinsonism-related disorders because of differences in their prognoses and treatment. Furthermore, IPD is clinically heterogeneous, with variable prognosis. Although the biological function of neuromelanin has not yet been determined, the selective vulnerability of neuromelanin-containing neurons in patients with IPD suggests a role for this pigment in neurodegeneration. Recently developed ultra-high-field magnetic resonance imaging (MRI) systems produce Tl-weighted neuro- melanin-sensitive images with very high spatial resolution, enabling the de- piction of tissue containing neuromelanin. Here we review recent advances in neuromelanin-sensitive MRI in IPD and related conditions suggesting that neuromelanin may be a potential diagnostic biomarker for IPD. 展开更多
关键词 IPD Neuromelanin-sensitive magnetic resonance imaging mri BTP
下载PDF
Recent Advances in ^(19)Fluorine Magnetic Resonance Imaging with Perfluorocarbon Emulsions 被引量:2
16
作者 Anne H.Schmieder Shelton D.Caruthers +2 位作者 Jochen Keupp Samuel A.Wickline Gregory M.Lanza 《Engineering》 SCIE EI 2015年第4期475-489,共15页
The research roots of 19fluorine (19F) magnetic resonance imaging (MRI) date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imagi... The research roots of 19fluorine (19F) magnetic resonance imaging (MRI) date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imaging approaches, making magnetic resonance an indispensable pillar of biomedical diagnostic imaging. For many years during this timeframe, 19F imaging research continued at a slow pace as the various attributes of the technique were explored. However, over the last decade and particularly the last several years, the pace and clinical relevance of 19F imaging has exploded. In part, this is due to advances in MRI instrumentation, ~gF/1H coil designs, and ultrafast pulse sequence development for both preclinical and clinical scanners. These achievements, coupled with interest in the molecular imaging of anatomy and physiology, and combined with a cadre of innovative agents, have brought the concept of ~gF into early clinical evaluation. In this review, we attempt to provide a slice of this rich history of research and development, with a particular focus on liquid perfluorocarbon compound-based agents. 展开更多
关键词 FLUORINE magnetic resonance imaging (mri dual-tuned coil PERFLUOROCARBON ANGIOGENESIS cell labeling
下载PDF
Intravoxel incoherent motion magnetic resonance imaging for diagnosis of cervical cancer and evaluation of response of uterine cervical cancer to radiochemotherapy: A pilot study 被引量:1
17
作者 Yanchun Wang Shan Hu +7 位作者 Xuemei Hu Jianjun Li Yaqi Shen Xiaoyu Liu Zhi Wang Xiaoyan Meng Zhen Li Daoyu Hu 《Oncology and Translational Medicine》 CAS 2015年第4期164-170,共7页
Objective The aim of this study was to investigate the ability of intravoxel incoherent motion(IVIM) diffusion-weighted magnetic resonance imaging(MRI) to diagnose cervical cancer and to evaluate the response of uteri... Objective The aim of this study was to investigate the ability of intravoxel incoherent motion(IVIM) diffusion-weighted magnetic resonance imaging(MRI) to diagnose cervical cancer and to evaluate the response of uterine cervical cancer to radiochemotherapy(CRT).Methods This prospective study was approved by the institutional review board, and informed consent was obtained from all patients. A total of 23 patients with primary cervical cancer who were undergoing CRT and 16 age-matched healthy subjects were prospectively recruited for IVIM(b = 0–800 s/mm2) and standard pelvic MRI. Bi-exponential analysis was performed to derive f(perfusion fraction), D*(pseudo-diffusion coefficient), and D(true molecular diffusion coefficient) in cervical cancer(n = 23) and the normal cervix(n = 16). The apparent diffusion coefficient(standard ADC) was calculated. The independent-samples t-test and paired-samples t-test were used for comparisons.Results Pre-treatment cervical cancer had the lowest standard ADC(1.15 ± 0.13 × 10-3 mm2/s) and D(0.89 ± 0.10 × 10-3 mm2/s) values, and these were significantly different from the normal cervix and posttreatment cervical cancer(P = 0.00). The f(16.67 ± 5.85%) was lowest in pre-treatment cervical cancer and was significantly different from the normal cervix and post-treatment cervical cancer(p = 0.012 and 0.00, respectively). No difference was observed in D*.Conclusion IVIM is potentially promising for differentiating between the normal cervix and cervical cancer because pre-treated cervical cancer has low perfusion and diffusion IVIM characteristics. Further, the standard ADC, D, and f of cervical cancer showed a tendency to normalize after CRT; thus, IVIM may be useful for monitoring the response to CRT in cervical cancer. 展开更多
关键词 diffusion-weighted imaging magnetic resonance imaging (mri investigate the ability of intravoxel incoherent motion (IVIM) cervical cancer RADIOCHEMOTHERAPY
下载PDF
Comparison of computed tomography and magnetic resonance imaging for the detection of mandibular condylar osteochondroma 被引量:1
18
作者 Molun Shen Ling Zhu +2 位作者 Hongbo Yu Lei Zhang Xudong Wang 《Oncology and Translational Medicine》 2018年第3期108-115,共8页
Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients wit... Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients with unilateral condylar osteochondroma were reviewed. The morphology, location, continuity with the parent bone, cartilage cap, perichondrium of tumors, and changes in soft and hard tissues adjacent to the lesions were investigated by two reviewers. Data were analyzed using Mc Nemar test. A P value < 0.05 was considered significant.Results Among the 33 condylar osteochondromas, 11 were of the diffuse type, 10 were of the sessile type, and 12 were of the pedunculated type. Continuity with the cortex and marrow of the host condyle was observed on both CT and MRI. Both modalities had identical detection rates of surface reconstruction of the temporal bone joint, condylar dislocation, and pseudarthrosis formation. However, MRI showed significantly higher detection rates of the cartilage cap and perichondrium than CT(P < 0.05). Furthermore, MRI showed ipsilateral and contralateral temporo-mandibular joint(TMJ) disc displacement in 4 cases and 6 cases, respectively, and ipsilateral and contralateral TMJ effusion in 20 cases and 14 cases, respectively.Conclusion CT can intuitively display the morphology and spatial location of condylar osteochondromas through three-dimensional reconstruction. MRI may be superior to CT in the detection of cartilage cap, perichondrium of the condylar osteochondroma, and changes in the TMJ and adjacent soft tissues. 展开更多
关键词 mandibular condyle OSTEOCHONDROMA computed tomography (CT) magnetic resonance imaging (mri
下载PDF
Prediction of radiosensitivity in primary central nervous system germ cell tumors using dynamic contrast-enhanced magnetic resonance imaging 被引量:3
19
作者 Chenlu Feng Peiyi Gao +4 位作者 Xiaoguang Qiu Tianyi Qian Yan Lin Jian Zhou Binbin Sui 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2015年第3期231-238,共8页
Objective: To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging(DCEMRI) for predicting tumor response to radiotherapy in patients with suspected primary central nervous system(CNS) ... Objective: To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging(DCEMRI) for predicting tumor response to radiotherapy in patients with suspected primary central nervous system(CNS) germ cell tumors(GCTs).Methods: DCE-MRI parameters of 35 patients with suspected primary CNS GCTs were obtained prior to diagnostic radiation, using the Tofts and Kermode model. Radiosensitivity was determined in tumors diagnosed 2 weeks after radiation by observing changes in tumor size and markers as a response to MRI. Taking radiosensitivity as the gold standard, the cut-off value of DCE-MRI parameters was measured by receiver operating characteristic(ROC) curve. Diagnostic accuracy of DCE-MRI parameters for predicting radiosensitivity was evaluated by ROC curve.Results: A significant elevation in transfer constant(K^trans) and extravascular extracellular space(Ve)(P=0.000), as well as a significant reduction in rate constant(Kep)(P=0.000) was observed in tumors. K^trans, relative K^trans, and relative Kep of the responsive group were significantly higher than non-responsive groups. No significant difference was found in Kep, Ve, and relative Ve between the two groups. Relative K^trans showed the best diagnostic value in predicting radiosensitivity with a sensitivity of 100%, specificity of 91.7%, positive predictive value(PPV) of 95.8%, and negative predictive value(NPV) of 100%.Conclusions: Relative K^trans appeared promising in predicting tumor response to radiation therapy(RT). It is implied that DCE-MRI pre-treatment is a requisite step in diagnostic procedures and a novel and reliable approach to guide clinical choice of RT. 展开更多
关键词 Dynamic contrast-enhanced magnetic resonance imaging (DCE-mri) extravascular extracellular space germ cell tumors (GCTs) RADIOSENSITIVITY rate constant transfer constant
下载PDF
Relationships among magnetic resonance imaging, histological findings, and IGF-I in steroid-induced osteonecrosis of the femoral head in rabbits 被引量:7
20
作者 Xing-can CHEN Jian WENG +4 位作者 Xue-qun CHEN Ji-zeng DU Miao-ping ZHU Yong-qing PAN Miao LIU 《浙江中西医结合杂志》 2008年第9期739-746,共8页
Objective: To study the relationships among magnetic resonance imaging (MRI), histological findings, and insu- lin-like growth factor-I (IGF-I) in steroid-induced osteonecrosis of the femoral head in rabbits. Methods:... Objective: To study the relationships among magnetic resonance imaging (MRI), histological findings, and insu- lin-like growth factor-I (IGF-I) in steroid-induced osteonecrosis of the femoral head in rabbits. Methods: Thirty rabbits were randomly divided into experimental Group A (n=15) and control Group B (n=15). The 7.5 mg/kg (2 ml) of dexamethasone (DEX) and physiological saline (2 ml) were injected into the right gluteus medius muscle twice at one-week intervals in animals of Groups A and B, respectively. At 4, 8 and 16 weeks after obtaining an MRI, the rabbits were sacrificed and the femoral head from one side was removed for histological study of lacunae empty of osteocytes, subchondral vessels, and size of fat cells under microscopy, and the femoral head from the other side was removed for enzyme-linked immunoadsorbent assay (ELISA) for IGF-I. Results: At 4, 8 and 16 weeks after treatment, no necrotic lesions were detected in Group B, while they were detected in Group A. Light microscopy revealed that the fat cells of the marrow cavity were enlarged, subchondral vessels were evidently decreased, and empty bone lacunae were clearly increased. The IGF-I levels in Group A were significantly higher than those in Group B. At 8 weeks after the DEX injection, the MRI of all 20 femora showed an inhomogeneous, low signal intensity area in the femoral head, and at 16 weeks, the findings of all 10 femora showed a specific "line-like sign". The MRI findings of all femora in Group B were normal. Conclusion: MRI is a highly sensitive means of diagnosing early experimental osteonecrosis of the femoral head. However, the abnormal marrow tissues appeared later than 4 weeks when the expression of IGF-I increased. This reparative factor has an early and important role in response to steroid-induced osteonecrosis of the femoral head, and provides a theoretical foundation for understanding the pathology and designing new therapies. 展开更多
关键词 大脑 诊断方法 磁共振图象 类固醇 股骨
下载PDF
上一页 1 2 125 下一页 到第
使用帮助 返回顶部