磁共振氢波谱在帕金森病中的应用近况

磁共振波谱（MRS）是一种无创性在活体观察组织代谢的方法。综述了磁共振波谱的原理、检查技术和^1H-MRS在帕金森病（Parkinson disease,PD)的诊断、鉴别诊断以及疗效评价的应用价值。     

脑质子磁共振波谱在早期帕金森病诊断中的价值

目的　探讨质子磁共振波谱 ( 1H -MRS)在早期帕金森病 (Parkinson’sdisease ,PD)诊断中的临床应用价值。方法　对 10例偏侧PD患者 (Hoehn -YahrⅠ级 )和 10例年龄匹配正常对照者双侧基底节区进行 1H -MRS检测 ,对比分析PD患者患侧肢体对侧和同侧以及正常对照者的基底节区N -乙酰基天门冬氨酸 (NAA) /肌酸复合物 (Cr)和胆碱复合物 (Cho) /Cr比值的变化。结果　PD组患者患侧肢体对侧的基底节区NAA/Cr比值显著低于同侧和正常对照组 (P <0 .0 5 ) ,Cho/Cr比值显著高于同侧和正常对照组 (P<0 .0 5 ) ;PD组患者患侧肢体同侧的基底节区NAA/Cr和Cho/Cr比值与正常对照组比较无显著差异 (P >0 .0 5 )。结论　1H -MRS是可以为具有单侧症状的PD患者基底节区的神经细胞病理学改变提供有价值的信息的一种无创技术     

磁共振波谱在帕金森病和帕金森综合征研究中的应用

帕金森病是锥体外系疾病中校常见的一种，主要见于中老年人，是一种慢性、进行性中枢神经变性疾病，严重影响病人的生活质量。MRS临床上可用于评估帕金森综合征病人体内多巴胺受体及纹状体神经元的功能。结合临床就MRS在原发性帕金森病诊断和疗效评估中的价值以及MRS在原发性帕金森病和继发性帕金森综合征中的应用进行综述。     

磁共振扩散加权成像和磁共振波谱在卵巢肿瘤中的应用

磁共振扩散加权成像(DWI)和磁共振波谱(MRS)均属于无创性MRI功能成像技术,分别通过分析组织扩散系数的差异和对组织代谢物的定量分析来描述病变的特征,实现了影像检查技术从形态学到功能学的转变,对卵巢肿瘤的鉴别诊断有重要意义,本文就其原理及其在卵巢肿瘤的临床应用价值做一综述。     

活体肝移植磁共振波谱成像的研究

随着活体肝移植技术的迅速发展,活体供肝及移植术后肝功能的早期准确评价对于提高移植肝的活力和病人生存质量、减少活体肝移植术后各种并发症的发生具有重要意义。磁共振波谱成像能在分子水平反映肝细胞的能量代谢状况,可早期无创客观地评价和监测活体供肝及移植肝的质量及活力,具有重要的临床应用价值。现就磁共振波谱成像的原理及其对活体供肝和肝移植术后移植肝的应用研究予以综述。     

活体肝移植磁共振波谱成像的研究

随着活体肝移植技术的迅速发展,活体供肝及移植术后肝功能的早期准确评价对于提高移植肝的活力和病人生存质量、减少活体肝移植术后各种并发症的发生具有重要意义。磁共振波谱成像能在分子水平反映肝细胞的能量代谢状况,可早期无创客观地评价和监测活体供肝及移植肝的质量及活力,具有重要的临床应用价值。现就磁共振波谱成像的原理及其对活体供肝和肝移植术后移植肝的应用研究予以综述。     

磁共振波谱与脑功能成像

随着磁共振波谱技术及功能性磁共振技术的日臻完善和发展,人们对脑,这个人体内最复杂和最重要的器官的认识,从单纯的影像学研究转而进入了分子水平和超细胞(行为)等各个不同层次上的深入探索。这些对于从本质上揭示脑的结构、功能及行为机制之间的关系无疑提供了巨大的研究前景。本文对磁共振波谱技术的原理及目前在临床和基础科学领域取得的进展作简单回顾,对其在脑功能研究中的地位和价值作出评价。一、磁共振波谱(ｍａｇｎｅｔｉｃｒｅｓｏｎａｎｃｅｓｐｅｃｔｒｏｓｃｏｐｙ,ＭＲＳ)是一种利用核磁共振现象和化学位移作用,进行系列特定…     

磁共振波谱在小儿癫痫中的应用

癫痫在小儿发病率最高,ＭＲＩ及ＭＲＳ对于其病因诊断及指导治疗起重要作用。本文总结了小儿癫痫的ＭＲＩ表现及病理基础,同时指出其与成人癫痫磁共振研究方面的差距;详细阐述了ＭＲＳ技术并分别对＾１Ｈ ＭＲＳ和＾３１Ｐ ＭＲＳ在小儿发育过程中各代谢成份的变化趋势加以总结;分析了小儿癫痫中各代谢成份在癫痫中所起的作用,指出ＭＲＩ与ＭＲＳ联合应用对小儿癫痫病因学的诊断将大有裨益。     

原发性单侧症状帕金森病黑质的DTI研究

目的:研究帕金森病(PD)黑质的DTI 改变状况,探讨PD早期诊断的线索.方法:以原发单侧症状PD患者10例为PD组,年龄和性别相匹配的健康志愿者10名为对照组.两组分别予以磁共振DTI脑检查,测量计算双侧黑质区域的ADC 值和FA 值,并将PD组和对照组进行对比分析.结果:原发单侧症状PD组患者症状对侧的黑质FA值较同侧和健康对照组FA值明显下降(分别为0.254±0.083,0.314±0.022,0.409±0.043;t=-2.424,P=0.038<0.05和t=5.112,P=0.001<0.05).对照组双侧黑质FA值之间差异无显著意义(分别为0.406±0.046,0.419±0.030;t=-1.1871,P=0.301>0.05).PD组症状的同侧黑质FA值与对照组之间差异也有显著意义(分别为0.409±0.043,0.314±0.022;t=6.214,P=0.002<0.05).PD组症状对侧和同侧黑质部位ADC值与对照组之间差异无显著意义(分别为t=0.140,P=0.893>0.05和t=0.334,P=0.748>0.05).结论:单侧症状PD患者的对侧黑质早期就可能存在神经元的缺失或轴突功能受损,提示黑质部位FA值分析可作为PD早期或亚临床诊断的线索之一.     

脑膜瘤的磁共振成像和质子磁共振波谱

探讨磁共振成像（ ＭＲＩ） 和质子磁共振波谱（１ Ｈ ＭＲＳ） 对脑膜瘤的诊断价值。材料和方法：３６４ 例行常规ＭＲＩ 检查, 其中１５ 例加做１ ＨＭＲＳ, 行肿瘤实质与健侧对应部位对照研究。结果： ＭＲＩ 平扫示： Ｔ１ ＷＩ５８ ．０ ％（２１１／３６４） 表现为等信号,３２ ．７ ％ （１１９／３４７） 为略低信号,９ ．３ ％ （３４／３６４） 为混合信号。Ｔ２ ＷＩ４０ ．１ ％ （１３９／３４７） 表现为等信号,４２ ．７ ％ （１４８／３４７） 表现为高信号,９ ．５ ％ （３３／３４７） 为略低信号,７ ．８ ％ （２７／３４７） 为混合信号。注射Ｇｄ － ＤＴＰＡ 后３３７ 例肿瘤实质部分均有不同程度的强化。６５ ．９ ％ （２２２／３３７） 出现“脑膜尾征”。５５ ．５ ％ （２０２／３６４）可见不同程度的水肿。１５ 例１ Ｈ ＭＲＳ 均表现为明显增高的胆碱（Ｃｈｏ） 峰,无氮乙酰门冬氨酸（ＮＡＡ） 峰,Ｃｈｏ／Ｃｒ（ 肌酸） 比值升高,ＮＡＡ／Ｃｒ 及ＮＡＡ／Ｃｈｏ 比值降低。４ 例出现乳酸峰（Ｌａｃ） 。结论：ＭＲＩ 平扫＋ 增强是诊断脑膜瘤的最主要方法,１ Ｈ ＭＲＳ 可作为很重要的补充。     

Topographical alterations of the midbrain and the substantia nigra following unilateral posteroventral pallidotomy in patients with Parkinson's disease using routine and multishot diffusion-weighted magnetic resonance imaging

To determine whether posteroventral pallidotomy (PVP) induces topographical changes of the ipsilateral midbrain and degeneration of the substantia nigra in Parkinson's disease patients, we obtained magnetic resonance (MR) images of 18 patients who had undergone PVP and measured the width of the cerebral peduncle at the mid-point of the inner margin. Then, we assessed MR signal changes in the substantia nigra on T2-weighted images in all patients and on multishot diffusion-weighted images in seven patients. In MR images taken within 1 year of PVP, a comparison between the ratio of the ipsilateral side/contralateral side of the cerebral peduncle of patients after PVP and that of the unaffected side/affected side in the preoperative images revealed no significant difference ( P>0.05). In MR images 1 to 2 years after PVP, there was a significant difference in the ratio of the cerebral peduncle ( P<0.01). A significant difference was still evident in MR images more than 2 years after PVP ( P<0.001). On T2-weighted images obtained within 1 year of PVP, an area of patchy high signal appeared in the posterolateral region of the ipsilateral substantia nigra in six of 13 patients. However, there was no signal change in the substantia nigra in any T2-weighted images more than 1 year after PVP. Multishot diffusion-weighted images obtained from all six patients more than 1 year after PVP revealed an abnormal area of high signal in the posterolateral region of the ipsilateral substantia nigra, however, within 1 year of PVP such a signal change was not seen. PVP would induce degeneration of the ipsilateral substantia nigra and atrophy of the ipsilateral midbrain.     

High resolution magnetic susceptibility mapping of the substantia nigra in Parkinson's disease

Purpose:

To determine if tissue magnetic susceptibility is a more direct marker of tissue iron content than other MR markers of iron. This study presents the first quantitative, in vivo measurements of the susceptibility of the substantia nigra in patients with Parkinson's disease.

Materials and Methods:

Nine patients and 11 controls were studied at 7 Tesla. Susceptibility maps were created by inverting the filtered phase maps associated with T2* weighted images.

Results:

On average, patients showed an increase in susceptibility of the pars compacta compared with controls, which correlates with the predicted increase in brain iron in Parkinson's disease. A rostral–caudal gradient in susceptibility was also observed in controls and patients.

Conclusion:

Susceptibility mapping may provide a new tool for studying the development of Parkinson's disease. J. Magn. Reson. Imaging 2012;35:48‐55. © 2011 Wiley Periodicals, Inc.     

Structural changes of the substantia nigra in Parkinson's disease as revealed by MR imaging

BACKGROUND AND PURPOSE: The possibility of using MR imaging as a sensitive marker of the structural changes in Parkinson's disease has been a long-sought goal. We describe a new method for imaging and quantifying the morphologic changes of the substantia nigra in Parkinson's disease and compare radiologic findings with clinical evaluation. METHODS: Using a combination of two MR imaging inversion-recovery pulse sequences, the substantia nigra was imaged in six patients with Parkinson's disease and six age-related control participants. A radiologic index was defined and used to quantify the signal changes that were observed in the patients. The radiologic index was compared with clinical scores obtained from the Unified Parkinson's Disease Rating Scale. RESULTS: The images showed loss of signal in a lateral-to-medial gradient in cases of Parkinson's disease, corresponding to the known neuropathologic pattern of degeneration. The radiologic index was highly correlated with the Unified Parkinson's Disease Rating Scale score, and there was no overlap in radiologic indices between the patient and the control groups (P < .00005). CONCLUSION: This study suggests that MR imaging is sensitive to structural changes in even the earliest cases of Parkinson's disease, thereby indicating the potential for detecting presymptomatic disease. Furthermore, a radiologic measure has been defined that correlates with the conventional clinical measure of disease severity. Therefore, MR imaging could prove to be a sensitive biological marker for objective staging of the disease.     

Three-dimensional magnetic resonance imaging of congenital heart disease

Three-dimensional surface reconstruction images of the heart and great vessels have been produced from contiguous sequences of EKG-triggered MRI scans in more than 35 patients with congenital heart disease and 5 normal subjects. The scan data was semiautomatically processed to separate the epi- and endocardial surfaces and to define the outlines of the enclosed blood volumes on a slice by slice basis. Surface reconstruction images aid communication with clinicians, establish the size and location of intracardiac defects, and image the pulmonary venous drainage. The method is practical for use in the evaluation of cardiac morphologic abnormalities, especially for planning cardiac surgery.     

Three-dimensional J-resolved H-1 magnetic resonance spectroscopic imaging of volunteers and patients with brain tumors at 3T.

A method that combines two-dimensional (2D) J-resolved spectroscopy with three spatial dimension magnetic resonance spectroscopic imaging (MRSI) is introduced to measure J-coupled metabolites of glutamate (Glu), glutamine (Gln), myo-Inositol (mI), and lactate (Lac) in the brain and to simultaneously obtain T(2) values of choline (Cho), creatine (Cr), and N-acetyl aspartate (NAA). Relatively few points in the t(1) dimension (six echo times) and a flyback echo-planar trajectory were incorporated in the acquisition to speed up the total acquisition time so that it was within a clinically feasible range (23 min). Data obtained using GAMMA software simulations and from phantoms have shown that the (4)CH(2) resonances of Glu can be separated from Gln at 2.35 ppm in TE-averaged spectra. Results from phantoms, six normal volunteers, and four patients demonstrated good signal-to-noise ratio (SNR). The J cross-peaks from the methyl group of Lac were visualized in the 2D spectra from the phantom and the glioma patient, and could be quantified from the spectra at J = +/-4.17 Hz. This technique also enables the evaluation of the changes in metabolite T(2). Compared with the values in normal white matter, the T(2) values of Cho and Cr were statistically significantly increased in regions of glioma.     

Imaging degeneration of the substantia nigra in Parkinson disease with inversion-recovery MR imaging

BACKGROUND AND PURPOSE: Visualizing with MR imaging and obtaining quantitative indexes of degeneration of the substantia nigra in Parkinson disease have been long-sought goals. We investigated the potential role of area and T1 contrast measurements in differentiating patients from controls and their age-related changes. METHODS: Eight patients with Parkinson disease, 8 age-matched controls, and 8 young controls were imaged. We obtained the pixel-wise difference between 2 sets of inversion-recovery images, acquired parallel to the bicommissural plane, with different inversion times. Pixel-intensity ratios between lateral and medial nigral regions, and nigral area and substantia-nigra/midbrain area ratios were computed. RESULTS: Compared with that of controls, loss of substantia nigra was evident in patients, its borders taking a smoother and more irregular appearance. Patients were characterized by a lateral-to-medial gradient, due to reduced hypointensity of the lateral portion of the substantia nigra and relative sparing of its medial portion. The visible nigral area was significantly smaller in patients compared with matched controls (P = .04). The substantia nigra/midbrain area ratio enabled considerably better separation (P = .0001). The lateral/medial pixel-intensity ratio was significantly higher in patients compared with matched controls (P = .01) and in young controls compared with age-matched controls (P = .01). CONCLUSION: Inversion-recovery sequences may provide a convenient way to visualize nigral degeneration. Relative area and pixel-intensity measurements may integrate other techniques (such as diffusion-tensor imaging on nigrostriatal pathways) in the neuroradiologic diagnosis and follow-up of Parkinson disease by quantitatively assessing the degeneration of the substantia nigra.     

Three-dimensional magnetic resonance imaging of the heart

Three-dimensional surface images of the human heart may be produced from magnetic resonance imaging. These examinations are used in the evaluation of congenital heart disease for preoperative planning and postoperative evaluation. Computer graphics software has been adapted to produce three-dimensional images of the beating heart from contiguous two-dimensional serial EKG-triggered magnetic resonance image data sets. The natural boundary between flowing blood and cardiac tissue serves to outline cardiac structures. The techniques for producing these images and pitfalls in the operation of the system as well as examples of their application to the study of patients with congenital heart disease are outlined in this article.     

Long and short echo time proton magnetic resonance spectroscopic imaging of the healthy aging brain

PURPOSE: To investigate the relationship between subject age and white matter brain metabolite concentrations and R(2) relaxation rates in a cross-sectional study of human brain. MATERIALS AND METHODS: Long- and short-echo proton spectroscopic imaging were used to investigate concentrations and R2 relaxation rates of N-acetyl aspartate (NAA) + N-acetyl aspartyl glutamate (NAAG), choline (Cho), creatine (Cr), and myoinositol (mI) in the white matter of the centrum semiovale of 106 healthy volunteers aged 50-90 years; usable data were obtained from 79 subjects. A major aim was to identify which parameters were most sensitive to changes with age. Spectra were analyzed using the LCModel method. RESULTS: The apparent R2 of NAA and the LCModel concentration of Cr at short echo time were significantly correlated with age after multiplicity correction. Large lipid resonances were observed in the brain midline of some subjects, the incidence increasing significantly with age. We believe this to result from lipid deposits in the falx cerebri. CONCLUSION: Since only short-echo spectroscopy showed a robust relationship between Cr and subject age, and detects more metabolites than long echo time, we conclude that short-echo is superior to long-echo for future aging studies. Future studies could usefully determine whether the Cr-age relationship is due to changes in concentration, T1, or both.     

Three-dimensional 31P magnetic resonance spectroscopic imaging of regional high-energy phosphate metabolism in injured rat heart

The purpose of this study was to measure the spatially varying ³¹P MR signals in global and regional ischemic injury in the isolated, perfused rat heart. Chronic myocardial infarcts were induced by occluding the left anterior descending coronary artery eight weeks before the MR examination. The effects of acute global low-flow ischemia were observed by reducing the perfusate flow. Chemical shift imaging (CSI) with three spatial dimensions was used to obtain ³¹P spectra in 54-/μl voxels. Multislice ¹H imaging with magnetization transfer contrast enhancement provided anatomical information. In normal hearts (n = 8), a homogeneous distribution of high-energy phosphate metabolites (HEP) was found. In chronic myocardial infarction (n = 6), scar tissue contained negligible amounts of HEP, but their distribution in residual myocardium was uniform. The size of the infarcted area could be measured from the metabolic images; the correlation of infarct sizes determined by histology and ³¹P MR CSI was excellent (P < 0.006). In global low-flow ischemia (n = 8), changes of HEP showed substantial regional heterogeneity. Three-dimensional ³¹P MR CSI should yield new insights into the regionally distinct metabolic consequences of various forms of myocardial injury.     

Neurite orientation dispersion and density imaging in the substantia nigra in idiopathic Parkinson disease

Objectives

We used neurite orientation dispersion and density imaging (NODDI) to quantify changes in the substantia nigra pars compacta (SNpc) and striatum in Parkinson disease (PD).

Methods

Diffusion-weighted magnetic resonance images were acquired from 58 PD patients and 36 age- and sex-matched controls. The intracellular volume fraction (Vic), orientation dispersion index (OD), and isotropic volume fraction (Viso) of the basal ganglia were compared between groups. Multivariate logistic regression analysis determined which diffusion parameters were independent predictors of PD. Receiver operating characteristic (ROC) analysis compared the diagnostic accuracies of the evaluated indices. Pearson coefficient analysis correlated each diffusional parameter with disease severity.

Results

Vic in the contralateral SNpc and putamen were significantly lower in PD patients than in healthy controls (P?<?0.00058). Vic and OD in the SNpc and putamen showed significant negative correlations (P?<?0.05) with disease severity. Multivariate logistic analysis revealed that Vic (P?=?0.0000046) and mean diffusivity (P?=?0.019) in the contralateral SNpc were the independent predictors of PD. In the ROC analysis, Vic in the contralateral SNpc showed the best diagnostic performance (mean cutoff, 0.62; sensitivity, 0.88; specificity, 0.83).

Conclusion

NODDI is likely to be useful for diagnosing PD and assessing its progression.

Key Points

? Neurite orientation dispersion and density imaging (NODDI) is a new diffusion MRI technique ? NODDI estimates neurite microstructure more specifically than diffusion tensor imaging ? By using NODDI, nigrostriatal alterations in PD can be evaluated in vivo ? NOODI is useful for diagnosing PD and assessing its disease progression