胼胝体变性的扩散加权成像和多体素氢质子波谱分析

目的 探讨扩散加权成像(DWI)和多体素氢质子波谱(1H-MRS)在急性和亚急性胼胝体变性(MBD)中的应用价值. 资料与方法 5例长期酗酒男性MBD 患者均经DWI检查,其中急性型3例经1H-MRS检查,测量DWI不同信号病灶的ADC值,多体素1H-MRS采集胼胝体病灶的胆碱复合物(Cho)、氮-乙酰天门冬胺酸(NAA)、肌酸(Cr)等波峰,计算Cho/Cr、NAA/Cr及Cho/NAA的比值. 结果 大部分病灶在DWI上表现为高和稍高信号,根据液体衰减翻转恢复序列(FLAIR)、DWI、ADC图上病灶信号的不同分为3组,不同病灶区的ADC值表现为不同程度升高或降低.1H-MRS示胼胝体病灶的Cho/Cr升高,NAA/Cr不同程度下降,1例探测到倒置的乳酸(Lac)峰,所有胼胝体病灶的Cho/NAA均明显升高,比值在2.03～2.53之间.结论 DWI和1H-MRS分别可以提供MBD所致脑组织微观结构的改变和局部代谢物变化方面的信息,对于MBD的诊断具有重要价值.     

原发性中枢神经系统淋巴瘤的MRI与~1H-MRS研究

目的:探讨免疫功能正常人原发性中枢神经系统淋巴瘤(PCNSL)的常规MRI及多体素质子磁共振波谱(1H-MRS)表现。方法:对15例经病理证实的PCNSL的MRI和1H-MRS表现进行回顾性分析。结果:15例患者共检出24个病灶,其MRI及1H-MRS表现如下:①PCNSL的MRI表现:病灶T1WI呈低或等信号,T2WI呈等或稍高信号;DWI呈高信号;增强后病灶明显均匀强化,"缺口征"、"尖角征"的出现具有特异性;②PCNSL的1H-MRS表现:肿瘤实质区及瘤周近侧水肿区Cho峰升高及NAA、Cr峰降低,肿瘤实质区可见升高的Lip峰。4例病灶在正常组织区可见异常谱线。结论:传统MRI结合1H-MRS表现能够显著提高PCNSL的诊断与鉴别诊断水平;1H-MRS对于肿瘤浸润及多发病灶的显示优于传统MR检查。     

磁共振扩散加权成像与氢质子波谱联合应用对脑内环形强化病变的鉴别诊断

目的:探讨磁共振扩散加权成像(DWI)与氢质子磁共振波谱(1 H-MRS)联合应用对常见脑内环形强化病变的鉴别诊断价值。方法:回顾性分析经手术病理证实或临床随访证实43例脑内环形强化病变的常规MRI图像、DWI信号特点、ADC值和多体素1 H-MRS波谱信息,比较DWI上信号特点、ADC值及1 H-MRS上AA峰、Cho峰、NAA峰、Cho/Cr、NAA/Cr、Cho/NAA的差别,并做统计学分析。结果:①DWI上12例脑脓肿(BA)患者9例(9/12)呈不同程度的高信号,ADC图呈低信号,1例(1/12)呈低信号,ADC图呈高信号,2例(2/12)呈混杂信号,平均ADC值为(0.521±0.183)×10-3 mm2/s;31例脑内囊性肿瘤(BCT)患者,28例(28/31)DWI上呈低信号,ADC图呈高信号,2例(2/31)呈混杂信号,1例(1/31)呈高信号,平均ADC值为(2.811±0.264)×10-3 mm2/s;BA与BCT的平均ADC值比较差异有统计学意义(P<0.01)。②1 H-MRS上12例BA内部出现特征性AA峰,脓肿壁Cho和NAA低于对侧,差异有统计学意义(P均<0.05),Cho/Cr、NAA/Cr、Cho/NAA差异无显著性意义(P均>0.05);31例BCT内均无AA峰,肿瘤壁Cho、Cho/Cr及Cho/NAA均较对侧正常组织明显升高,Cr及NAA较正常对照处明显减低,差异有显著性(P均<0.01)。结论:在常规MRI检查基础上,综合应用多体素1 H-MRS及DWI能对BA和BCT的鉴别诊断及判断肿瘤对肿瘤周围侵犯情况提供更多有价值的信息,是常规MRI检查序列的重要补充,能进一步提高MRI诊断准确率及临床指导作用。     

脑内原发性淋巴瘤MRI特征

目的探讨脑原发性淋巴瘤的MRI表现特征,以提高对该病诊断的准确性。资料与方法回顾性分析11例经病理证实为脑原发性淋巴瘤的数目、部位、信号、强化方式、水肿、占位效应、扩散加权成像(DWI)及磁共振波谱(MRS)表现。结果单发3例(27%),多发8例(73%)。21个(63%)病灶位于幕上脑深部白质近脑室旁,7个(21%)病灶位于脑表面,5个(16%)位于幕下。24个(73%)病灶在T1WI上呈稍低信号,18个(55%)在T2WI上呈稍高信号;5个(36%)病灶周围轻度水肿及占位效应,9个(64%)病灶周围有中重度水肿及占位效应;团块状、结节状均匀强化15个(46%),不均匀环状强化8个(24%);3例肿瘤在DWI上呈高信号,氢质子磁共振波谱(1H-MRS)表现为氮-乙酰天门冬氨酸(NAA)峰、肌酸(Cr)峰降低,胆碱(Cho)峰显著升高,见乳酸(Lac)峰和高大脂质(Lip)峰。结论脑原发性淋巴瘤有较为特征的MRI表现,结合DWI、MRS有助于鉴别诊断。     

皮质下动脉硬化性脑病的1H-MRS初步研究

目的 应用2D多体素1H质子磁共振波谱成像(1H-MRS)检查皮质下动脉硬化性脑病(BD)患者,分析其代谢产物特点及变化规律.方法 对经临床诊断的20例BD患者和20名健康老年人行常规MRI和二维1 H-MRS检查,测量BD组常规MRI表现阳性病灶区、BD组表现正常脑白质区及对照组正常脑白质3组NAA/Cr、Cho/Cr值,并进行统计学分析;观察Lac峰的变化情况.结果 BD病灶区NAA/Cr值、Cho/Cr值降低,与对照组脑白质差异均有统计学意义(P＜0.05);BD正常脑白质区NAA/Cr值与正常对照组相比有所降低,且差异有统计学意义(P＜0.05),BD正常脑白质区Cho/Cr值较对照组脑白质相比差异没有统计学意义(P＞0.05);BD病灶区全部出现Lac峰,BD正常脑白质区出现Lac峰12例.结论 1H-MRS检查能够反映BD代谢特点及变化规律;1H-MRS中的NAA/Cr可以显示常规MRI检查表现正常的脑白质微代谢改变.     

磁共振常规及其功能成像在原发性颅内淋巴瘤的应用价值

目的：探讨磁共振成像(MRI)、扩散加权成像(DWI)、磁共振灌注成像(PWI)、磁共振波谱成像(MRS)在原发性颅内淋巴瘤诊断及鉴别诊断中的应用价值。方法回顾性分析27例原发性颅内淋巴瘤患者的 MRI、DWI、PWI、MRS 影像资料。结果所有病灶 T1 WI 呈低-等信号,T2 WI 呈等、稍高、高信号,DWI 呈稍高、高信号。增强扫描22例病灶呈明显均匀强化,5例病灶呈不均匀强化。19例病灶可见“蝶翼征”“握拳征”“缺口征”“尖角征”。18例病灶均为低灌注表现。MRS 表现为病灶实质区 NAA 峰明显降低或消失,Cho 峰增高,23例出现高大 Lip 峰,12例出现 Lac 峰。结论磁共振常规及其功能成像在原发性颅内淋巴瘤的诊断及鉴别诊断中具有很高的应用价值,低灌注、肿瘤实质区出现高耸的 Lip 峰是原发性颅内淋巴瘤的特征性表现。     

大鼠肝肿瘤细胞灶性凋亡MRI表现

目的:建立大鼠肝肿瘤细胞凋亡模型并研究其磁共振成像表现.方法:选取45只肝肿瘤大鼠,随机分成放疗组,酒精注射组及对照组,每组15只,分1d、3d、7d共3个时间点观察;每组大鼠每个时间点均采集磁共振MRI、DWI、~1H-MRS图像,分析磁共振图像,并测量ADC值及~1H-MRS各代谢物波峰下面积,进行统计学处理;磁共振检查后取标本送病理学(HE,TUNEL,PCNA)及电镜检查;将病理学检查结果与磁共振图像对照分析.结果:①病理学检查结果证实放疗组肝肿瘤细胞发生凋亡;酒精注射组肝肿瘤细胞以发生坏死为主;②放疗组同未治疗组比较肿瘤体积减小,T_1 WI信号等低,T_2 WI信号稍减低,DWI信号下降,呈等高信号,内见条片状等低信号区,ADC值增加,Lip、Cho、Lae、Glx峰下降,Cr峰变化不大;③酒精治疗组体积缩小,病灶中央信号强度明显减低,旱条片状,T_1 WI等低信号,T_2 WI低信号;DWI信号不均匀片状减低,ADC值介于正常组织与残留肿瘤组织之间;Lip、Cho、Lac、Glx、Cr各峰明显下降.结论:大鼠肝肿瘤放疗可诱导细胞凋亡,凋亡后磁共振检查有特异性表现.特别是T_2WI、DWI、~1H-MRS,活体检测肿瘤细胞凋亡成为可能.     

3．0T磁共振多体素^1H-MRS和DWI对常见脑肿瘤特征分析的价值

目的：探讨3．0T磁共振多体素^1H-MRS及DWI在常见颅内肿瘤特征分析的价值。方法：脑肿瘤患者30例,多体素^1H-MRS感兴趣区包括肿瘤实质区、瘤周水肿区及正常参照区。计算上述各区域的NAA、Cho、Cr等多种代谢物的值;DWI测量肿瘤不同部位信号值,计算ADC值。结果：胶质瘤、转移瘤、脑膜瘤三者之间肿瘤实质区的NAA／Cho、NAA／Cr和Cho／Cr平均值与参照区比较有显著性差异（P〈0．05）;高、低级别胶质瘤间瘤周水肿区的NAA／Cho和Cho／Cr具有统计学差异（P〈0．05）,高级别胶质瘤与转移瘤间瘤周水肿区的NAA／Cho、NAA／Cr和Cho／Cr均有统计学差异（P〈0．05）。DWI示高、低级别胶质瘤间肿瘤实质区及瘤周水肿区的ADC值均有显著性差异（P〈0．05）;高级别胶质瘤与转移瘤间瘤周水肿区的ADC值有统计学差异（P〈0．05）。结论：多体素^1H-MRS与DWI相结合有助于脑肿瘤的特征分析、胶质瘤恶性程度分级、确定病灶浸润范围等。     

~1H-MRS对单发急性脑梗死治疗前与后病灶整体取样的监测价值

目的研究单发急性脑梗死整体病灶区治疗前与后氢质子磁共振波谱(1H-MRS)特征,并探讨其临床应用价值。资料与方法 26例患者分别在急性期和治疗平稳期行常规MRI及1H-MRS检查。1H-MRS检测采用单体素或多体素对病灶区行整体取样。对比分析治疗前与后整体梗死病灶区氮-乙酰天门冬氨酸(NAA)、胆碱类复合物(Cho)和肌酸(Cr)积分值,记录乳酸(Lac)峰次数;同时检测对侧正常脑组织区相应代谢物。运用Barthel指数量表记录患者的神经功能评分。扩散加权成像(DWI)上测量病灶容积并分析治疗前与后容积变化。比较治疗前与后病灶区NAA积分值与梗死病灶容积(V)的比值并分析其与神经功能评分的相关性。结果 26例患者在12～72 h和治疗(20±7.17)天接受了两次MR检查,获得52次1H-MRS结果。治疗前、后病灶区NAA分别与对侧半球相应正常区相比均有下降(P<0.05),梗死病灶区治疗前与后NAA未见明显改变(P>0.05);治疗后梗死病灶容积较治疗前变小(P<0.05);治疗后NAA/V比值及神经功能评分较治疗前值均有升高(P<0.05);NAA/V比值与患者神经功能评分呈正相关(r=0.315,P<0.05)。病灶区治疗前与后Cho及Cr值相比及其分别与对侧相应区相比,无显著性差异(P>0.05),但部分Cho(9/26)及Cr(7/26)治疗前后的值起伏较大。Lac峰出现率为23%(12/52)。结论1H-MRS对单发急性脑梗死治疗前与后病灶整体取样动态监测其单一的NAA水平改变,对于评价临床神经功能康复有局限性;动态监测梗死病灶区NAA水平与梗死病灶容积比值,可能是一项反映临床神经功能恢复的客观指标;Cho与Cr值总体相对平稳;Lac峰的出现有一定的诊断价值。     

MRI常规扫描结合1H-MRS对儿童髓母细胞瘤的诊断价值

目的 评价MRI 常规扫描结合1H-MRS对儿童髓母细胞瘤(CMB)的诊断价值.方法 回顾性分析经手术病理证实的21例CMB,21例均行MRI 常规平扫加增强扫描,其中,6例行1H-MRS检查.结果 CMB 的MRI表现特征为:病变全部位于小脑蚓部.MRI平扫T1WI或T1FLAIR呈低信号15例,等信号6例,T2WI均为高或稍高信号.增强MRI显示肿瘤实性部分有较明显强化,小囊变区未见强化.6例行1H-MRS检查均表现为:Cho峰明显升高,NAA峰明显降低,Cr峰明显降低,其中,3例显示低矮Lac/Lip峰.结论 MRI常规扫描结合1H-MRS 对CMB的诊断和鉴别诊断有重要价值.     

Biomedical implants and devices: assessment of magnetic field interactions with a 3.0-Tesla MR system

PURPOSE: To evaluate magnetic field interactions for 109 different biomedical implants and devices in association with exposure to a 3.0-Tesla magnetic resonance (MR) system. MATERIALS AND METHODS: A total of 109 implants and devices (aneurysm clips, 32; clips, fasteners, and staples, 10; coils and stents, 10; heart valve prostheses and annuloplasty rings, 12; orthopedic implants, five; suture materials, 13; vascular access ports and accessories, 13; miscellaneous implants and devices, 14) were tested for magnetic field interactions at 3.0-Tesla using previously-described, standardized techniques to assess magnetic field translational attraction and torque. RESULTS: The deflection angles and torque measurements ranged, respectively, from 0 to 16 degrees and 0 to +2 for the aneurysm clips; 0 to 90 degrees and 0 to +4 for the clips, fasteners, and staples; 0 to 47 degrees and 0 to +4 for the coils and stents; 0 to 4 degrees and 0 to +1 for the heart valve prostheses and annuloplasty rings; 0 to 12 degrees and 0 to +2 for the orthopedic implants; 0 to 13 degrees and 0 to +2 for the suture materials; 0 to 52 degrees and 0 to +4 for the vascular access ports and accessories; and 0 to 28 degrees and 0 to +3 for the miscellaneous implants and devices. CONCLUSION: Of the 109 implants and devices assessed for magnetic field interactions at 3.0-Tesla, four (4%) are potentially unsafe based on deflection angle criteria. The implications of these results for patients undergoing MR procedures at 3.0-Tesla is discussed. Notably, these results are specific to the 3.0-Tesla MR system used for this evaluation.     

自旋回波及其改良序列在肺实质磁共振成像中的应用

目的　选择肺实质磁共振功能成像合适的序列。方法　选择健康志愿者 8人 ,健康家犬 8条 ,对自旋回波及其改良序列进行调试、组合。结果　选择的序列是单激发快速自旋回波序列和单激发反转快速自旋回波序列。结论　适合肺实质磁共振功能成像的序列是中心相位编码方式的单激发快速自旋回波序列和单激发反转快速自旋回波序列     

Direct comparison of sensitivity encoding (SENSE) accelerated and conventional 3D contrast enhanced magnetic resonance angiography (CE‐MRA) of renal arteries: Effect of increasing spatial resolution

Purpose:

To assess the effect of attaining higher spatial resolution in contrast‐enhanced magnetic resonance angiography (MRA) of renal arteries using parallel imaging, sensitivity encoding (SENSE), by comparing the SENSE contrast‐enhanced (CE) MRA against a conventional CE‐MRA protocol with identical scan times, injection protocol, and other acquisition parameters.

Materials and Methods:

Numerical simulations and a direct comparison of SENSE‐accelerated versus conventional acquisitions were performed. A total of 41 patients (18 male) were imaged using both protocols for a direct comparison. Both protocols used fluoroscopic triggering, centric encoding, breath‐holding, equivalent injection protocol, and lasted ≈30 seconds.

Results:

Simulated point‐spread functions were narrower for the SENSE protocol compared to the conventional protocol. In the patient study, although the SENSE protocol produced images with lower signal‐to‐noise ratio (SNR), image quality was better for all segments of the renal arteries. In addition, ringing of kidney parenchyma and renal artery blurring were significantly reduced in the SENSE protocol. Finally, reader confidence improved with the SENSE protocol.

Conclusion:

Despite a reduction in SNR, the higher‐resolution SENSE CE‐MRA provided improved image quality, reduced artifacts, and increased reader confidence compared to the conventional protocol. J. Magn. Reson. Imaging 2010;31:149–159. © 2009 Wiley‐Liss, Inc.     

Parallel imaging improves the image quality and duct visibility of breathhold two‐dimensional thick‐slab MR cholangiopancreatography

MRI has become a reliable tool in medical imaging for assessing morphological and functional details of the human body in a noninvasive manner. Perfusion is an important parameter to assess status and functionality of tissue and organs. This review summarizes the different approaches to measure perfusion based on MRI. Some basics of the theoretical background are provided as well as measurement techniques with and without contrast media are described. J. Magn. Reson. Imaging 2014;40:269–279 . © 2013 Wiley Periodicals, Inc .     

磁共振Keyhole技术在颈动脉动态增强血管成像中的应用

目的　探讨匙孔 (Keyhole)技术在颈动脉动态增强磁共振血管成像 (dynamiccontrastechancedMRA ,DCE -MRA)中的应用优势。方法　将疑有颈部动脉疾病的 16例患者分为 2组 ,实验组 8例患者使用Keyhole技术 ;对照组 8例未使用Keyhole技术 ,直接行DCE -MRA扫描。结果　对照组 8例患者中 2例扫描在 6～ 8s时 ,只有动脉显示 ,而静脉未显影 ,3例扫描时间 8～ 9s时 ,已有静脉轻微显影。 3例扫描时间 >10s时 ,静脉已完全显影。实验组的 8例患者由于扫描时间缩短了一半 ,8例均获得了清晰、立体的颈动脉血管及分支全貌且无静脉显示的图像。结论　Keyhole技术的使用大大地缩短了扫描时间 ,可使颈动脉图像快速显影 ,不受静脉同时显示的干扰 ,提高了诊断准确性     

Clinical Evaluation of Respiratory-triggered 3D MRCP with Navigator Echoes Compared to Breath-hold Acquisition Using Compressed Sensing and/or Parallel Imaging

Purpose:To compare the image quality of three-dimensional magnetic resonance cholangiopancreatography (MRCP) acquired with respiratory triggering against breath-hold 3D MRCP with compressed sensing (CS) and parallel imaging (PI) in a clinical setting.Methods:This study included 93 patients (45 men, mean age: 69.7 ± 9.3 years), in whom three types of 3D MRCP were performed: 3D breath-hold MRCP with CS and PI reconstruction (BH-CS-MRCP) and PI only reconstruction (BH-PI-MRCP) additionally to 3D respiratory triggered MRCP with navigator echoes (Nav-MRCP). Duct visualization and overall image quality were blindly evaluated on a four-point scale by two independent radiologists. Quantitative analysis was performed by calculating the relative duct-to-periductal contrast (RC) of three main biliary segments. Comparison between the methods was performed using paired t-test.Results:Acquisition time was 23 s for both breath-hold MRCP protocols and 1 min 29 s for Nav-MRCP. Mean grading (Nav/CS/PI) for common bile duct (2.74/2.87/2.94), common hepatic duct (2.82/2.92/3.00), central right hepatic duct (2.75/2.85/2.98), central left hepatic duct (2.75/2.85/2.92) and cystic duct (2.22/2.34/2.42) was higher in BH-CS- and BH-PI-MRCP, whereas Nav-MRCP showed higher grading in the peripheral segments (peripheral right hepatic duct: 2.24/2.01/2.12; peripheral left hepatic duct: 2.23/2.02/2.13). Overall image quality of Nav-MRCP (2.91 ± 0.7) was not different from BH-PI-MRCP (2.92 ± 0.6) (P = 0.163), but higher than BH-CS-MRCP (2.80 ± 0.7) (P = 0.031). Quantitative analysis showed lower RC values for CS- and PI-MRCP than Nav-MRCP (P < 0.001).Conclusion:Breath-hold 3D MRCP were feasible using PI and CS. Visualization of the greater ductal system was even superior in breath-hold MRCP than in Nav-MRCP by considerably reducing acquisition time. Both breath-hold methods are suitable for revised MRI protocols notably in patients with irregular respiratory cycle.     

磁共振脑血管血流分析的临床应用——脑血栓、脑缺血与正常组对比研究

目的：测定脑血栓、脑缺血患者和正常人的颅内动脉血流，为临床提供进一步的诊断资料。材料和方法：应用ＭＲ血流分析技术，对４２例大脑中动脉（ＭＣＡ）、颅内动脉（ＩＣＡ）及基底动脉（ＢＡ）血流进行了测量与分析。结果：（１）ＭＣＡ脑梗塞组血流速度峰值增高而平均血流量值降低；脑缺血组血流速度峰值增高或正常而平均血流量值正常或降低，二者必居其一；正常组之ＭＲ血流分析无异常。（２）ＩＣＡ和ＢＡ二者均未见明显异常。结论：推测ＭＲ脑血流分析技术在预测中风方面可能是有效的检测手段。     

Magnetic resonance imaging of inflammatory bowel disease: evaluation in a rabbit model

PURPOSE: To correlate intestinal contrast enhancement and wall thickening with the degree of inflammation in an experimental model of inflammatory bowel disease. MATERIALS and METHODS: Inflammatory bowel disease was elicited in 39 New Zealand White rabbits by rectal instillation of 2,4,6-trinitrobenzene sulphonic acid (TNBA). Magnetic resonance imaging (MRI) was used to determine bowel wall thickness and intestinal contrast enhancement after the administration of 0.1 mmol/kg of gadodiamide intravenously. MR measurements were compared with the complete histopathologic analysis. RESULTS: MR measurements of bowel wall thickness correlated well with histopathologic measurements in vitro (r = 0.85, P < 0.0001) and with histopathologic evidence of chronic inflammatory bowel disease (P < 0.02). Chronic inflammation was characterized by increased intestinal contrast enhancement (137 +/- 25%) when compared to normal bowel (86 +/- 7%, P = 0.04). CONCLUSION: Contrast-enhanced MRI accurately reflects inflammatory bowel disease in the rabbit model.     

Resistive NMR of intracranial hematomas

Summary Comparison between computed tomography and nuclear magnetic resonance imaging in 17 patients with intracranial hematomas indicates a distinct role for NMR in evaluating the stable patient with hematoma. NMR is useful for delineating the extent of the hematoma, the relationship of the hematoma to brain anatomy, and the presence of hematoma at a time when the hematoma is isodense on CT.