The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging(MRI)magnets requires the careful management of exogenous heat sources.A strongly shielded gradient magnetic f...The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging(MRI)magnets requires the careful management of exogenous heat sources.A strongly shielded gradient magnetic field is important for the optimal operation of cryogen-free MRI systems.In this study,we present an enhanced shielding method incorporating a regionalized stray field constraining strategy.By optimizing the constraint parameters,we could develop engineering-feasible gradient coil schemes without increasing system complexity but with the stray field intensity reduced by half.In real measurement in an integrated MRI system,the developed gradient assembly demonstrated good performance and supported to output images of excellent quality.Our findings suggested that the proposed method could potentially form a useful design paradigm for cryogen-free MRI magnets.展开更多
Magnetic resonance image quality and patient safety have been the focus of engineering and research ever since the invention of equipment in the early 1970s.In high field(or ultrahigh field)MRI systems,the emerging te...Magnetic resonance image quality and patient safety have been the focus of engineering and research ever since the invention of equipment in the early 1970s.In high field(or ultrahigh field)MRI systems,the emerging techniques induced by B1 field challenges have promoted various potential solutions.This paper describes the relationship between RF power and B1þfield performance,and the overall requirements considered in RF subsystem design.The design of the RF in the MR system is systematically summarized,including the entire transmission chain,sequence algorithm and RF pulse design,and the probabilities for improvement and optimization in the system design are indicated.At the same time,the radio frequency related issues of the human whole-body 7 T MR and animal MR systems are discussed,especially the promising future showed by the technologies such as radio frequency parallel transmission technology in the ultrahigh field.展开更多
目的探讨乳腺肿瘤的多参数MRI特征(T_(2)-WI、ADC值和DCE)以及乳腺密度和背景实质增强(BPE)特征在不同乳腺癌(BC)分子亚型中的差异,以期为临床诊断提供重要参考。方法本研究为回顾性研究,纳入344例患者。所有患者均接受了多参数乳房MRI(...目的探讨乳腺肿瘤的多参数MRI特征(T_(2)-WI、ADC值和DCE)以及乳腺密度和背景实质增强(BPE)特征在不同乳腺癌(BC)分子亚型中的差异,以期为临床诊断提供重要参考。方法本研究为回顾性研究,纳入344例患者。所有患者均接受了多参数乳房MRI(T_(2)WI、ADC和DCE序列),并根据最新的BIRADS提取特征,使用ROI之间的类内系数(ICC)来评估读者间协议。结果研究人群分为:luminal A 89例(26%),luminal B HER2阳性39例(11.5%),luminal B HER2阴性168例(48.5%),三阴性(TNBC)41例(12%),HER2富集7例(2%)。Luminal内A肿瘤与特殊的组织学类型、最小的肿瘤大小和持续的动力学曲线相关(P均<0.05)。Luminal B HER2阴性肿瘤与最低ADC值相关(0.77×10^(-3)mm^(2)/s^(2)),其预测BC分子亚型的准确性为0.583。TNBC与不对称和中度/显著BPE,圆形/椭圆形肿块,边缘受限和边缘增强相关(P均<0.05)。HER2富集的BC与最大肿瘤大小相关(平均37.28mm,p值=0.02)。结论BC分子亚型与T_(2)WI、ADC和DCE MRI特征相关,ADC有助于预测luminal B HER2阴性病例。展开更多
目的通过分析膝关节前交叉韧带MRI高信号面积与西安大略和麦克马斯特大学(the Western Ontario and McMaster Universities,WOMAC)评分的相关性,探讨前交叉韧带退行性损伤对膝关节骨关节炎临床病情的影响。方法采用横断面调查研究方法,...目的通过分析膝关节前交叉韧带MRI高信号面积与西安大略和麦克马斯特大学(the Western Ontario and McMaster Universities,WOMAC)评分的相关性,探讨前交叉韧带退行性损伤对膝关节骨关节炎临床病情的影响。方法采用横断面调查研究方法,收集2019年1月至2022年1月中国中医科学院广安门医院收治的80例(84膝)膝关节骨关节炎患者资料,其中男16例,女64例;年龄40~77岁,平均(59.01±9.31)岁。分析前交叉韧带MRI高信号面积与WOMAC评分的相关性。结果84膝前交叉韧带平均MRI高信号面积为(1.89±0.47)cm 2。WOMAC评分总分(44.74±13.09)分,疼痛评分(9.68±3.38)分,僵硬评分(3.19±2.46)分,日常活动困难度评分(31.87±10.38)分。前交叉韧带MRI高信号面积与WOMAC总分、疼痛评分、日常活动困难度评分呈正相关(P<0.01),相关系数分别为0.63、0.47、0.60;与WOMAC僵硬评分无相关性(P=0.09)。结论前交叉韧带的退变和损伤可能会引起或加重膝关节骨关节炎疼痛症状,影响关节功能,带来日常生活不便。展开更多
基金This work is funded by the Magnetic Resonance Union of the Chinese Academy of Sciences(Grant No.2021gzl002)the International Partnership Program of Chinese Academy of Sciences(Grant No.182111KYSB20210014)+1 种基金the National Science Foundation of China(Grant No.52293423,Grant No.52277031)the Research and Development of Key Technologies and Equipment for Major Science and Technology Infrastructure of Development and Reform Commission of Shenzhen Municipality,China(Grant No.ZDKJ20190305002).
文摘The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging(MRI)magnets requires the careful management of exogenous heat sources.A strongly shielded gradient magnetic field is important for the optimal operation of cryogen-free MRI systems.In this study,we present an enhanced shielding method incorporating a regionalized stray field constraining strategy.By optimizing the constraint parameters,we could develop engineering-feasible gradient coil schemes without increasing system complexity but with the stray field intensity reduced by half.In real measurement in an integrated MRI system,the developed gradient assembly demonstrated good performance and supported to output images of excellent quality.Our findings suggested that the proposed method could potentially form a useful design paradigm for cryogen-free MRI magnets.
基金The work is supported by Key-Area Research and Development Program of Guangdong Province(grant no.2018B030333001).
文摘Magnetic resonance image quality and patient safety have been the focus of engineering and research ever since the invention of equipment in the early 1970s.In high field(or ultrahigh field)MRI systems,the emerging techniques induced by B1 field challenges have promoted various potential solutions.This paper describes the relationship between RF power and B1þfield performance,and the overall requirements considered in RF subsystem design.The design of the RF in the MR system is systematically summarized,including the entire transmission chain,sequence algorithm and RF pulse design,and the probabilities for improvement and optimization in the system design are indicated.At the same time,the radio frequency related issues of the human whole-body 7 T MR and animal MR systems are discussed,especially the promising future showed by the technologies such as radio frequency parallel transmission technology in the ultrahigh field.
文摘目的探讨乳腺肿瘤的多参数MRI特征(T_(2)-WI、ADC值和DCE)以及乳腺密度和背景实质增强(BPE)特征在不同乳腺癌(BC)分子亚型中的差异,以期为临床诊断提供重要参考。方法本研究为回顾性研究,纳入344例患者。所有患者均接受了多参数乳房MRI(T_(2)WI、ADC和DCE序列),并根据最新的BIRADS提取特征,使用ROI之间的类内系数(ICC)来评估读者间协议。结果研究人群分为:luminal A 89例(26%),luminal B HER2阳性39例(11.5%),luminal B HER2阴性168例(48.5%),三阴性(TNBC)41例(12%),HER2富集7例(2%)。Luminal内A肿瘤与特殊的组织学类型、最小的肿瘤大小和持续的动力学曲线相关(P均<0.05)。Luminal B HER2阴性肿瘤与最低ADC值相关(0.77×10^(-3)mm^(2)/s^(2)),其预测BC分子亚型的准确性为0.583。TNBC与不对称和中度/显著BPE,圆形/椭圆形肿块,边缘受限和边缘增强相关(P均<0.05)。HER2富集的BC与最大肿瘤大小相关(平均37.28mm,p值=0.02)。结论BC分子亚型与T_(2)WI、ADC和DCE MRI特征相关,ADC有助于预测luminal B HER2阴性病例。
文摘目的通过分析膝关节前交叉韧带MRI高信号面积与西安大略和麦克马斯特大学(the Western Ontario and McMaster Universities,WOMAC)评分的相关性,探讨前交叉韧带退行性损伤对膝关节骨关节炎临床病情的影响。方法采用横断面调查研究方法,收集2019年1月至2022年1月中国中医科学院广安门医院收治的80例(84膝)膝关节骨关节炎患者资料,其中男16例,女64例;年龄40~77岁,平均(59.01±9.31)岁。分析前交叉韧带MRI高信号面积与WOMAC评分的相关性。结果84膝前交叉韧带平均MRI高信号面积为(1.89±0.47)cm 2。WOMAC评分总分(44.74±13.09)分,疼痛评分(9.68±3.38)分,僵硬评分(3.19±2.46)分,日常活动困难度评分(31.87±10.38)分。前交叉韧带MRI高信号面积与WOMAC总分、疼痛评分、日常活动困难度评分呈正相关(P<0.01),相关系数分别为0.63、0.47、0.60;与WOMAC僵硬评分无相关性(P=0.09)。结论前交叉韧带的退变和损伤可能会引起或加重膝关节骨关节炎疼痛症状,影响关节功能,带来日常生活不便。
