Multinuclear MR and MRI study of lithium-ion cells using a variable field magnet and a fixed frequency RF probe

An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(RF)probe was employed in the study.The magnetic field was changed to set the resonance frequency of each nucleus to the fixed RF probe frequency of 33.7 MHz.Two cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were interrogated.One cell was pristine,and one was charged to a cell voltage of 4.2 V.The results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion batteries.These methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.

膝关节隐匿性骨折临床诊断中多层螺旋CT与高场强MRI的作用

目的分析膝关节隐匿性骨折临床诊断中多层螺旋计算机体层成像(multislice spiral computed tomography,MSCT)与高场强磁共振成像(magnetic resonance imaging,MRI)的作用。方法随机选取2022年1月—2023年1月江苏省盱眙县人民医院收治的80例疑似膝关节隐匿性骨折患者为研究对象,以手术病理结果为金标准,分析MSCT与高场强MRI两种检查方式的诊断效能。结果手术病理检查显示,80例患者中膝关节隐匿性骨折确诊62例(77.50%),非膝关节隐匿性骨折18例(22.50%);高场强MRI诊断确诊61例(76.25%),MSCT诊断确诊59例(73.75%)。高场强MRI诊断的灵敏度与特异度分别为96.77%、94.44%,高于MSCT诊断的85.48%、66.67%,差异有统计学意义(P均<0.05)。结论膝关节隐匿性骨折临床诊断中MSCT与高场强MRI检查均有一定的价值,且高场强MRI诊断效能高于MSCT,临床价值显著。

双下肢多发骨梗死MRI类CT及能谱CT钙抑制成像应用一例

骨梗死临床发病率较低,多发生于长骨干骺端及骨干,骨梗死影像新技术报道也较为罕见。本文报道1例双下肢多发骨梗死MRI基于受限回波间距的快速梯度回波类CT成像及能谱CT钙抑制技术的影像表现,为临床提供诊断经验。

64排MSCT、高场强MRI血管成像应用于急性主动脉综合征患者中的临床价值对比

目的 对比64排MSCT、高场强MRI血管成像应用于急性主动脉综合征患者中的临床价值。方法 回顾性分析本院2017年3月至2019年7月收治的90例急性主动脉综合征患者的临床资料,观察MRI检查及MSCT检查的诊断结果进行讨论和分析;对比经MRI检查、MSCT检查对急性主动脉综合征的诊断准确性、敏感性和特异性及两种检查相关指标。结果 经MRI检查对急性主动脉综合征的诊断灵敏性、特异性和准确性分别为92.22%、81.11%、97.78%,MSCT检查对急性主动脉综合征的诊断灵敏性、特异性和准确性分别为88.87%、76.67%、95.56%,MRI检查对急性主动脉综合征的诊断灵敏性、特异性和准确性高于MSCT检查,但两者比较差异无统计学意义(P>0.05);MRI血管成像的图像质量评分高于MSCT血管成像,信噪比低于MSCT血管成像,差异具有统计学意义(P<0.05)。结论 MSCT、高场强MRI血管成像均可有效显示急性主动脉综合征的影像学特点,均可作为辅助诊断急性主动脉综合征的有效手段,临床可结合患者自身情况进行选择。

低场MRI对子宫肌壁间妊娠的诊断应用(附5例报道)

目的 探讨子宫肌壁间妊娠的低场MRI表现及诊断价值,为病变早期诊断及定位提供指导。方法 收集本院经手术及病理诊断的5例子宫肌壁间妊娠的临床及MRI资料,分析其MRI影像学特点。结果 5例子宫肌壁间妊娠患者中4例有多次宫腔操作史,1例合并有盆腔软组织粘连。3例病灶位于后壁,1例位于侧壁,1例位于宫角。病灶均呈圆形或类圆形,大小(2.2×1.4×1.4)cm~(2.7×2.7×2.1)cm,病灶内信号不均匀,表现为混杂T_(1)WI低、T_(2)WI等-高信号影,内均可见囊泡状T_(1)WI低、T_(2)WI高信号,2例周围见斑片状T_(1)WI高信号提示出血。病灶主体位于子宫壁内,子宫内膜高信号及联合带低信号连续,子宫肌层中高信号中断,呈膨胀性生长,未突破浆膜层。结论 低场MRI检查能对子宫肌壁间妊娠进行早期诊断及准确定位,对于临床及超声检查难以确诊的病例可进一步行MRI检查。

高场强MRI联合128层CT三维重建技术在诊断膝关节外伤中的应用效果

目的探究高场强MRI联合128层CT三维重建技术诊断膝关节外伤的效果。方法选取我院77例膝关节外伤患者,均行高场强MRI和128层CT三维重建检查,以关节镜检查或手术结果作为“金标准”,比较高场强MRI、128层CT三维重建单独及联合诊断膝关节外伤类型的准确度,并比较两种检查方法单独及联合诊断膝关节骨折类型、骨折部位、韧带损伤分级、半月板损伤分级的准确度。结果高场强MRI与128层CT三维重建联合诊断膝关节外伤类型的准确度高于二者单独诊断(P<0.05);高场强MRI与128层CT三维重建联合诊断膝关节骨折类型、半月板损伤分级、骨折部位、韧带损伤分级的准确度均高于二者单独诊断(P<0.05)。结论高场强MRI和128层CT三维重建技术均为诊断膝关节外伤的可靠方法,二者联合能有效提高对膝关节外伤类型的诊断准确度,且在膝关节骨折类型、骨折部位、韧带损伤分级、半月板损伤分级的判断方面具有较高的准确性。

High Field MRI in Human African Trypanosomiasis (HAT)

Human African Trypanosomiasis (HAT) or sleeping thickness is a forest and rural disease;where agriculture is the main activity. It is a chronic and lethal disease without treatment. HAT is caused by two parasites;Trypanosoma Brucei Gambiense (gTB) and Trypanosoma Brucei Rhodesiense (rTB) transmitted to humans by the tsetse fly. It is endemic condition in Africa between the 15&deg north latitude and the 20° south latitude. It is reported outside this area in travelers who stayed in endemic zone. Infection by gTB is wider and more frequent (98%) than that by rTB (2%). The Democratic Republic of Congo is the most affected country with more than 75% of reported cases. The geographical distribution is not homogeneous. There are more affected regions in a zone called “foci” which represents areas favorable to the development of the vector. Its diagnosis and treatment are very important because of its social and economic impact at both the individual and community levels. Promising molecules including fexinidazole are currently undergoing testing. Nowadays populations move more and more easily but the discovery of this disease in daily neuroradiological practice is exceptional. We propose in this paper through two observations, reminders on epidemiological, clinical and MRI features of HAT. It typically performs the edematous, bilateral and diffuse encephalitis. It is important to distinguish these aspects from the arsenic-induced encephalitis that may occur during treatment. Only vector control allows eradicating this disease. WHO has set targets elimination of HAT as a public health problem for 2020 deadline.

DCE-MRI全域直方图分析在子宫内膜癌鉴别诊断和浸润分级中的应用

目的:探究DCE-MRI全域直方图分析在子宫内膜癌(EC)鉴别诊断和浸润分级中的应用价值。方法:选取2019年9月-2022年3月本院收治的EC患者51例,采用1.5T MR核磁共振扫描仪检查,使用扩展的Tofts(ET)和分布参数(DP)模型分析DCE-MRI数据。使用Mann-Whitney检验比较高风险和低风险EC间的DCE参数,包括血流(F)、平均通过时间、血容量(Vp)、血管外细胞外体积(Ve)、渗透表面积积(PS)、提取分数、转移常数(Ktrans)和流出速率(Kep)。Bland-Altman分析比较参数一致性,Spearman检验评估参数相关性。通过受试者工作特征曲线(ROC)分析DCE参数的诊断性能,并与传统MRI评估比较。结果:51例患者中高危EC患者的Ktrans、Kep、F、Vp和PS显著降低(P<0.001),ET模式的Ktrans和DP模式的F的曲线下面积(AUC)分别为0.92和0.91。Bland-Altman分析表明,两个模型间Ve或Vp的一致性较低(P<0.001),而Spearman检验显示出很强的相关性(r=0.719、0.871)。Ktrans和F在预测EC风险类型准确性优于传统MRI评估。结论:两种不同模式的DCE-MRI全域直方图分析诊断EC效能均优于传统MRI,DCE-MRI在EC鉴别诊断和浸润分级中具有重要应用价值。

Effects of gradient high-field static magnetic fields on diabetic mice

Although 9.4 T magnetic resonance imaging(MRI) has been tested in healthy volunteers,its safety in diabetic patients is unclear.Furthermore,the effects of high static magnetic fields(SMFs),especially gradient vs.uniform fields,have not been investigated in diabetics.Here,we investigated the consequences of exposure to 1.0-9.4 T high SMFs of different gradients(>10 T/m vs.0-10 T/m)on type 1 diabetic(T1D) and type 2 diabetic(T2D) mice.We found that 14 h of prolonged treatment of gradient(as high as 55.5 T/m) high SMFs(1.0-8.6 T) had negative effects on T1D and T2D mice,including spleen,hepatic,and renal tissue impairment and elevated glycosylated serum protein,blood glucose,inflammation,and anxiety,while 9.4 T quasi-uniform SMFs at 0-10 T/m did not induce the same effects.In regular T1D mice(blood glucose>16.7 mmol/L),the>10 T/m gradient high SMFs increased malondialdehyde(P<0.01) and decreased superoxide dismutase(P<0.05).However,in the severe T1D mice(blood glucose≥30.0 mmol/L),the>10 T/m gradient high SMFs significantly increased tissue damage and reduced survival rate.In vitro cellular studies showed that gradient high SMFs increased cellular reactive oxygen species and apoptosis and reduced MS-1 cell number and proliferation.Therefore,this study showed that prolonged exposure to high-field(1.0-8.6 T)>10 T/m gradient SMFs(35-1 380 times higher than that of current clinical MRI)can have negative effects on diabetic mice,especially mice with severe T1D,whereas 9.4 T high SMFs at 0-10T/m did not produce the same effects,providing important information for the future development and clinical application of SMFs,especially high-field MRI.

High-Field MRI Contribution in Tolosa-Hunt Syndrome (THS). Report of Two Cases and Review of Literature

Background: Tolosa Hunt Syndrome is an inflammatory condition of unknown etiology of the cavernous sinus and superior orbital fissure. Because of the difficulty in establishing histological evidence, his diagnosis is based on a set of arguments established by the International Headache Society. MRI allows indirect visualization of the granuloma and plays a key role in diagnosis and follow-up. Aim: To illustrate High-field MRI contribution in Tolosa-Hunt Syndrome (THS). Cases Presentation: Two patients, a 25-year-old female and a 40-year-old male were recruited in this retrospective case report study at the Radiology service of Fann University Hospital (Dakar Senegal). The first patient has been suffering from a right retro-orbital pain and diplopia for 2 months and the second from a painful oculomotor nerve palsy for 3 months. Blood tests, lumbar puncture, thyroid hormone levels and an infectious screen were done. Screening for converting enzymes, and serum antibodies were also done. They underwent a high field MRI (Siemens 1.5T) with T1, T2, FLAIR, T2*, diffusion B1000, TOF polygon, CISS 3D and T1 gadolinium sequences in the 3 planes space. No significant abnormality was detected in blood tests or CSF analysis. Screening for converting enzymes and serum antibodies screen were also negative. For each patient, MRI examinations showed a non tumoral thickening of the right cavernous sinus, suggesting a granulomatous involvement. Tolosa Hunt Syndrome was evoked firstly. They were put on corticotherapy at high doses with a spectacular regression of symptoms. The Criteria of the International Headache Society of THS were met in both patients. Conclusion: High-field MRI is a significant diagnostic tool in the assessment of painful ophthalmoplegia. It allows a direct visualization of the granuloma of the cavernous sinus and assesses its course throughout the disease.

Analysis of Conservative and Magnetically Induced Electric Fields in a Low-Frequency Birdcage Coil

Numerical methods are used to evaluate variations of the electromagnetic fields generated by a head-sized birdcage coil as a function of load (“loading effect”). The loading effect was analyzed for the cases of a coil loaded with a conductive cylindrical sample, a dielectric cylindrical sample, and an anatomically precise head model. Maxwell equations were solved by means of finite difference time domain (FDTD) method conducted at 12.8, 64, and 128 MHz. Simulation results indicate that at 12.8 MHz the conservative electric field (Ec) caused by the scalar electric potentials between the coil and the load or within the load was significantly higher than the magnetically-induced electric field (Ei) and was the major component of the total electric field (Etotal). The amplitudes of Ec and Etotal are seen to be lower within a sample than at a corresponding location in an empty coil, but approximately 65% higher in the space between coil and sample than at a corresponding location in an empty coil. This is due to polarization effects generating an additional scalar potential parallel to the original field. The increased electric field between coil and sample may cause increased power deposition at the surface of the sample and may affect the RF-induced currents in external leads used for physiological recording, i.e. ECG, during MRI scanning.

Preliminary examination of early neuroconnectivity features in the R6/1 mouse model of Huntington's disease by ultra-high field diffusion MRI

During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness.However,events related to early neuropathological events,neuroinflammation,deterioration of neuronal connectivity and compensatory mechanisms still remain vastly unknown.Ultra-high field diffusion MRI(UHFD-MRI)techniques can contribute to a more comprehensive analysis of the early microstructural changes observed in HD.In addition,it is possible to evaluate if early imaging microstructural parameters might be linked to histological biomarkers.Moreover,qualitative studies analyzing histological complexity in brain areas susceptible to neurodegeneration could provide information on inflammatory events,compensatory increase of neuroconnectivity and mechanisms of brain repair and regeneration.The application of ultra-high field diffusion-MRI technology in animal models,particularly the R6/1 mice(a common preclinical mammalian model of HD),provide the opportunity to analyze alterations in a physiologically intact model of the disease.Although some disparities in volumetric changes across different brain structures between preclinical and clinical models has been documented,further application of different diffusion MRI techniques used in combination like diffusion tensor imaging,and neurite orientation dispersion and density imaging have proved effective in characterizing early parameters associated to alteration in water diffusion exchange within intracellular and extracellular compartments in brain white and grey matter.Thus,the combination of diffusion MRI imaging techniques and more complex neuropathological analysis could accelerate the discovery of new imaging biomarkers and the early diagnosis and neuromonitoring of patients affected with HD.

Assessing neuraxial microstructural changes in a transgenic mouse model of early stage Amyotrophic Lateral Sclerosis by ultra-high field MRI and diffusion tensor metrics

Objective: Cell structural changes are one of the main features observed during the development of amyotrophic lateral sclerosis(ALS). In this work, we propose the use of diffusion tensor imaging(DTI) metrics to assess specific ultrastructural changes in the central nervous system during the early neurodegenerative stages of ALS.Methods: Ultra-high field MRI and DTI data at 17.6 T were obtained from fixed, excised mouse brains, and spinal cords from ALS(G93 A-SOD1) mice.Results: Changes in fractional anisotropy(FA) and linear, planar, and spherical anisotropy ratios(C_L, C_P, and C_S, respectively) of the diffusion eigenvalues were measured in white matter(WM) and gray matter(GM) areas associated with early axonal degenerative processes(in both the brain and the spinal cord). Specifically, in WM structures(corpus callosum, corticospinal tract, and spinal cord funiculi) as the disease progressed, FA, C_L, and C_P values decreased, whereas C_S values increased. In GM structures(prefrontal cortex, hippocampus, and central spinal cord) FA and C_P decreased, whereas the C_L and C_S values were unchanged or slightly smaller. Histological studies of a fluorescent mice model(YFP, G93 A-SOD1 mouse) corroborated the early alterations in neuronal morphology and axonal connectivity measured by DTI.Conclusions: Changes in diffusion tensor shape were observed in this animal model at the early, nonsymptomatic stages of ALS. Further studies of C_L, C_P, and C_S as imaging biomarkers should be undertaken to refine this neuroimaging tool for future clinical use in the detection of the early stages of ALS.

低场脉冲磁共振成像(P-MRI)技术在食品加工中的应用

介绍核磁共振及其成像原理,以及低场脉冲磁共振成像(P-MRI)仪的主要构成。综述了低场P-MRI在食品加工中较有吸引力的几个应用方向:评价果蔬类食品的品质、研究食品中的油脂和水分、测量玻璃态转化温度Tg和研究欧姆加热食品内部的温度分布。说明了低场P-MRI应用在食品科学领域的意义和前景。

低场强MRI的表观弥散系数鉴别急性脑出血与脑梗死的应用价值

目的探讨低场强MRI的表观弥散系数(ADC)在鉴别急性脑出血与脑梗死的诊断价值。方法分别对25例急性脑出血和脑梗死患者进行低场强MRI常规、弥散加权成像(DWI),ADC扫描。观察分析其影像学表现及ADC值,并进行比较。结果脑出血灶的ADC信号从低到高信号不同;脑梗死灶则为低信号。脑出血组ADC值≤0.8×10-3mm2/s的比率(36%)显著低于脑梗死组(84%);ADC值>0.8×10-3mm2/s的比率(64%)显著高于脑梗死组(16%)(均P=0.001)。结论低场强MRI的ADC对鉴别急性脑出血与脑梗死有一定的应用价值。

正常膝关节半月板及关节软骨的低磁场MRI表现

目的:研究正常膝关节半月板及关节软骨的低场MRI表现。材料和方法:选择膝关节无外伤史、无任何临床症状的志愿者28例,按照不同的年龄分为3组。MRI显示正常半月板及关节软骨的外形、信号强度。冠状位T1WI,最厚层面,测量半月板体部厚度;矢状位T1WI,最厚层面,测量半月板前、后角及关节软骨厚度。结果:MRI显示半月板外形均为三角形,厚度随年龄和位置的不同有差异,半月板SET1WI均见不到达关节面的条状高信号。关节软骨的厚度随年龄发生变化,但信号均匀,边缘光整。结论:正常膝关节半月板及关节软骨的厚度随年龄而发生变化,低场MRI半月板内可见线条状高信号,应避免对半月板损伤的误诊。

低磁场MRI对合并椎体内裂样变骨质疏松压缩骨折的诊断价值

目的:探讨低磁场MRI对合并椎体内裂样变骨质疏松压缩骨折的诊断价值。方法:回顾性分析56例行经皮椎体成形术治疗合并椎体内裂样变骨质疏松压缩骨折患者的临床资料、X线平片及MRI资料,评价低磁场MRI对椎体内裂样变的敏感性和特异性。结果:低磁场MRI平扫及增强扫描均对骨质疏松压缩骨折并发椎体内裂样变诊断具有较高的敏感性和特异性,其中增强MRI对合并椎体内裂样变骨质疏松压缩骨折的诊断具有高的敏感性,而非增强MRI对合并椎体内裂样变骨质疏松压缩骨折的诊断具有高的特异性。结论:低磁场MRI对经皮椎体成形术前的合并椎体内裂样变骨质疏松压缩骨折诊断具有重要价值。

巧克力囊肿与囊性畸胎瘤的低场MRI鉴别诊断

目的探讨巧克力囊肿与囊性畸胎瘤的低场MRI鉴别诊断。方法收集10例巧克力囊肿与6例囊性畸胎瘤的低场MRI资料,进行回顾性分析,所有病例均经手术病理证实。结果 10例巧克力囊肿共13个病灶中有9个病灶在短时反转恢复(STIR)脂肪抑制序列出现信号抑制征象。与6例囊性畸胎瘤内脂肪成分在STIR脂肪抑制序列上表现类似。结论在低场MRI上盆腔囊性占位中观察到短T1、长T2信号,STIR出现信号抑制现象时,就存在巧克力囊肿与囊性畸胎瘤的鉴别问题。综合分析病灶内部结构、增强扫描表现以及临床特点,可以作出鉴别诊断。

低场MRI评估高强度聚焦超声对子宫肌瘤治疗价值的研究

目的探讨低场磁共振成像(MRI)评估高强度聚焦超声(HIFU)治疗子宫肌瘤疗效的价值。方法 48例经临床诊断为子宫肌瘤的63个病灶,于治疗前后行MRI检查,分析治疗前后病灶大小、信号特征,计算肌瘤消融率及体积缩小率。结果术前,术后24 h、6月及12月的肿瘤体积分别为(102.6±100.7)cm3、(76.2±76.0)cm3、(43.7±50.0)cm3和(46.7±65.2)cm3,差异显著。肿瘤体积缩小率分别为(25.2%±18.8%)、(56.8%±21.5%)及(60.8%±41.3%),差异显著。肿瘤平均消融率为(74.8%±18.8%),与12个月的体积缩小率有直线相关性。结论低场MRI能够反映子宫肌瘤HIFU治疗后形态、信号及血供的改变,能够用于疗效评估。

低场MRI平扫在高强度聚焦超声治疗子宫肌瘤的早期疗效评价

目的探讨低场MRI在高强度聚焦超声治疗子宫肌瘤的早期疗效价值。方法 29例(35个肌瘤)子宫肌瘤行高强多聚焦超声(HIFU)治疗。分别于治疗前1～7天、治疗后1～3天行核磁共振(MRI)检查,分析治疗前后MRI信号变化。结果子宫肌瘤HIFU治疗术后1～3天,34个病灶主体不同程度T1WI信号增高,外周等低信号,T2WI病灶呈中央低信号内散在斑片状高信号,外周高信号环,与治疗前比较:外周高信号环较前明显增宽,病灶内高信号减少;病灶大小无明显变化。结论 MRI平扫是评价子宫肌瘤HIFU治疗早期疗效的方便、经济、有效方法。