原发性帕金森病的MRS和DTI研究

帕金森病是一种常见于中老年人的慢性进行性中枢神经系统变性性疾病,通常伴有不同程度致残,影响病人及其家人的生活质量。MRS和DTI是无创性影像诊断技术,对帕金森病的早期诊断、鉴别诊断及疗效评价具有重要价值。就MRS和DTI在帕金森病中的应用研究及进展予以综述。     

~1H-MRS在胶质母细胞瘤周围区的应用研究

目的:评价2D多体素磁共振氢质子波谱成像技术(1 H-MRS)在胶质母细胞瘤周围区中的应用价值。方法:对30例胶质母细胞瘤患者行常规MRI及1 H-MRS检查,所有患者均行增强扫描。测量肿瘤周围区(包括水肿区及瘤周显示正常区域)的Cho/Cr、Cho/NAA、NAA/Cr的比值,并且计算瘤周显示正常区域的NAA/nCr的比值,将以上值与对侧正常区域的相应比值进行两样本配对t检验,分析其差异是否有统计学意义。结果:肿瘤周围水肿区及瘤周显示正常区的Cho/Cr、Cho/NAA的比值较对侧明显升高,差异有统计学意义(P<0.05)。肿瘤周围水肿区的NAA/Cr值较对侧降低且差异有统计学意义(P<0.05);肿瘤周围显示正常区的NAA/Cr值较对侧亦有降低,但差异无统计学意义(P>0.05),瘤周显示正常区NAA/nCr值较对侧明显降低,差异有统计学意义(P<0.05)。结论:2D多体素1 H-MRS成像技术对肿瘤周围区代谢物变化的检测可为推断胶质母细胞瘤瘤周区肿瘤细胞的浸润范围提供依据。     

儿童、青少年抑郁症DTI及MRS的研究进展

探索儿童、青少年抑郁症DTI及MRS的研究进展.收集、整理、分析近年来儿童、青少年抑郁症DTI及MRS研究的文献.DTI和MRS可以反映抑郁症患者的神经生化和结构的异常.应用DTI和MRS研究儿童、青少年抑郁症已取得成效,显示出良好的应用前景.     

MRS联合DTI技术在多发性硬化中的初步应用

目的 探讨磁共振波谱(MRS)联合扩散张量成像(DTI)技术在多发性硬化(MS)中的应用价值.资料与方法 26例MS患者和16名性别、年龄相匹配的健康志愿者均进行半卵圆中心层面的多体素MRS扫描和全脑的DTI扫描.分别测量MS患者的额叶病灶区、对侧正常表现的脑白质区(NAWM)以及对照组的双侧额叶对应脑白质区的NAA/Cr、Chow/Cr和表观扩散系数(ADC)、各向异性(FA)值.比较三组之间MRS代谢物比值和DTI的参数之间是否存在相性.结果 NAA/Cr在MS的病灶组(1.617±0.336)、NAWM组(1.809±0.339)中均明显低于正常对照组(2.103±0.245);Chow/Cr在病灶和NAWM内可见轻度升高,但与正常人比较未见明显的统计学差异.在MS病灶内,NAA/Cr与ADC(r=-0.575,P=0.002)和FA(r=0.479,P=0.013)呈明显相.结论 MRS联合DTI技术能同时发现MS病灶的轴索损伤和髓鞘脱失,在反映MS的病理变化和探讨病理机制方面可提供有价值的信息.     

DTI在正常前列腺的应用研究

目的探讨1.5 T MR扩散张量成像(diffusion tensor imaging,DTI)在正常前列腺的参数特点及纤维示踪图像(fiber tracking,FT)表现,为DTI在前列腺癌的应用提供研究基础。资料与方法 21名健康男性志愿者[(24.7±3.59)岁]行前列腺常规MRI及DTI扫描,将DTI扫描数据行后处理分析,测量中央叶和外围叶感兴趣区的表观扩散系数(ADC)和各向异性分数(FA),比较两者的ADC、FA值差异有无统计学意义,并重建前列腺的FT图像。结果 (1)健康男性前列腺DTI左右两侧中央叶和外围叶的ADC、FA值差异均无统计学意义(P>0.05);(2)中央叶和外围叶的ADC、FA值差异有统计学意义,中央叶的ADC值低于外围叶,中央叶的FA值高于外围叶(P<0.05);(3)FT图显示不同颜色的纤维对应不同走行方向,且中央叶的纤维排列比外围叶紧密。结论 1.5 TMR DTI在正常前列腺研究中具有可行性,有助于DTI在前列腺癌中的应用研究。     

BOLD-fMRI联合DTI和MRS在运动皮质受损及功能恢复评估中的研究进展

运动皮质损伤是影响运动功能的主要原因,目前主要通过临床判断结合常规影像学检查,而血氧水平依赖性功能磁共振成像(BOLD-fMRI)则可显示运动功能相关脑区的激活变化情况,用以针对性地评估运动皮质损伤程度且能准确定位病灶,有利于手术治疗和后期恢复性训练的开展.就应用BOLD-fMRI的基础上联合DTI和MRS技术,分别对脑外伤、脑肿瘤和脑卒中所致运动皮质损伤的研究进展及在相关预后分析中的价值进行综述,并提出将来可能联合应用的其他检查方法.     

BOLD-fMRI联合DTI和MRS在运动皮质受损及功能恢复评估中的研究进展

运动皮质损伤是影响运动功能的主要原因,目前主要通过临床判断结合常规影像学检查,而血氧水平依赖性功能磁共振成像（BOLD-fMRI）则可届示运动功能相关脑区的激活变化情况．用以针对性地评估运动皮质损伤程度且能准确定位病灶,有利于手术治疗和后期恢复性训练的开展。就应用BOLD-fMRI的基础上联合DTI和MRS技术,分别对脑外伤、脑肿瘤和脑卒中所致运动皮质损伤的研究进展及在相关预后分析中的价值进行综述．并提出将来可能联合应用的其他检查方法。     

DTI 和 MRS 在 AIDS 相关脑内结核中的临床应用研究

目的：探讨扩散张量成像(DTI)和磁共振波谱成像(MRS)定量指标对获得性免疫缺陷综合征(AIDS)相关机会性感染脑内结核的诊断价值。方法收集17例 AIDS 合并颅内结核患者及16例正常志愿者,行常规 MRI、DTI 及多体素 MRS 扫描,观察病灶形态学表现,测量病例组病灶实质区、水肿区、正常区及对照组相应正常区 ADC、FA、rADC、rFA、NAA/Cho、NAA/Cr 及 Cho/Cr 定量指标,并分析其差异性。结果AIDS 相关脑内结核实质区、水肿区及正常区各指标经方差分析均有统计学意义,两两比较,除水肿区与正常区 NAA/Cr 外,其余均有统计学差异(P<0.05),实质区 ADC 值、FA 值、rADC 值、rFA 值,NAA/Cho、NAA/Cr 均低于水肿区,Cho/Cr 高于水肿区和正常区。受试者工作特征曲线(ROC)分析 rFA 值用于区分实质区及水肿区的效能最高(P <0.05)。2组间正常区比较除 Cho/Cr 外,各指标均有统计学意义(P <0.05)。结论DTI 可以反映 AIDS 脑内结核所引起的脑结构微细改变, MRS 能反映脑内结核的早期病理代谢特点。     

超急性期放射性脑损伤的MRS和DTI研究

目的:探讨MRS和扩散张量成像(DTI)对超急性期放射性脑损伤的诊断价值.方法:18例经病理证实的鼻咽癌初诊患者,在放疗前及放疗后接受总放射剂量分别为20Gy、40Gy和60Gy时,进行颅脑MRI常规扫描、双侧颞叶1H-MRS多体素成像和DTI,将不同时期MRS检查所获得的颞叶Cho/Cr、NAA/Cr和NAA/Cho及DTI检查所测量的表观扩散系数(ADC)和部分各向异性(FA)值进行对比分析.结果:接受放射总剂量60Gy后,所有患者常规MRI扫描均未发现异常信号.MRS检查显示双侧颞叶前部的各代谢物比值在接受放射治疗后降低,并且所测各值的变化与放疗剂量呈负相关改变;DTI结果显示ADC值升高,FA值降低.结论:MRS和DTI能从组织细胞功能代谢水平对放射性脑损伤超急性反应进行评价,为临床对该疾病的病理发展过程进行研究提供客观可行的检测方法.     

~1H-MRS和DTI在脑胶质瘤中的应用

脑胶质瘤是中枢神经系统最常见的恶性肿瘤,磁共振波谱(MRS)和磁共振扩散张量成像(DTI)检查可以获得肿瘤更进一步的功能代谢变化、肿瘤与其周边纤维束三维空间关系的相关信息,有助于胶质瘤定性诊断、术中导航、放射治疗、评价疗效及监测治疗后反应等。     

热射病患者看似正常的小脑扩散张量成像研究

热射病（heat stroke ,HS）是一种常发生于夏季热浪期的致命性急症,以高热（体温常＞40℃）和意识障碍为主要特征［1－2］,可伴发多器官功能受损,并发症包括急性呼吸窘迫综合征、代谢性酸中毒、电解质平衡紊乱、横纹肌溶解症、弥散性血管内凝血等［1］。以往研究表明小脑对热损伤极其敏感［3］,其神经病理学改变主要为小脑 Purkinje细胞的严重丢失［4］。扩散张量成像（diffusion tensor imaging ,DTI）可从微观上探测脑组织的水分子扩散异常［5］。本研究通过研究 HS患者小脑的DTI表现,旨在探讨其应用价值。     

Diffusion tensor imaging of patients with HIV and normal-appearing white matter on MR images of the brain

BACKGROUND AND PURPOSE: HIV enters the CNS early in the course of infection and produces neuropsychiatric impairment throughout the course of illness, which preferentially affects the subcortical white matter. The development of a neuroimaging marker of HIV may allow for the earliest detection of cognitive impairment. The purpose of this study was to determine whether MR diffusion tensor imaging can detect white matter abnormalities in patients who have tested positive for HIV. METHODS: Ten patients with HIV (eight men and two women; mean age, 42 years) underwent MR imaging of the brain with MR diffusion tensor imaging, which included routine fluid-attenuated inversion recovery and fast spin-echo T2-weighted imaging. Diffusion constants and anisotropy indices were calculated from diffusion tensor maps. Peripheral viral load, Centers for Disease Control staging, and cluster of differentiation 4 levels were determined. RESULTS: All patients had normal results of MR imaging of the brain, except for mild atrophy. Four of 10 patients had undetectable viral loads. These patients were receiving highly active antiretroviral therapy. The diffusion constant and anisotropy were normal. Four of 10 patients had viral loads between 10,000 and 200,000. Diffusion anisotropy in the splenium and genu was significantly decreased (P < .02). The diffusion constant of the subcortical white matter was elevated in the frontal and parietooccipital lobes (11%). Two of 10 patients had viral loads >400,000. Anisotropy of the splenium was half normal (P < .0004) and of the genu was decreased 25% (P < .002). The average diffusion constant was diffusely elevated in the subcortical white matter. CONCLUSION: Calculating the diffusion constant and anisotropy in the subcortical white matter and corpus callosum in patients with HIV detected abnormalities despite normal-appearing white matter on MR images and nonfocal neurologic examinations. Patients with the highest diffusion constant elevations and largest anisotropy decreases had the most advanced HIV disease. Patients with the lowest viral load levels, who had normal anisotropy and diffusion constants, were receiving highly active antiretroviral therapy.     

Diffusion tensor MR imaging in pediatric head trauma

PURPOSE: We propose to investigate the fractional anisotropy (FA) values in pediatric patients with closed head trauma and correlate them with the initial Glasgow Coma Scale (GCS). MATERIALS AND METHODS: A retrospective evaluation of 24 pediatric patients (15 men, 9 women; mean age, 13 years; range, 2-18 years) who underwent both unenhanced head computed tomography and cerebral magnetic resonance imaging (MRI), including the tensor diffusion sequence, within 30 days of the incident. Twenty-two atraumatic control patients (9 men, 13 women; mean age, 9 years; range, 4-17 years) were randomly selected from the records of the radiology department within the same period. Fractional anisotropy measurements were taken from each of 6 major white matter volumes. Data extracted from the record of each subject included GCS, initial head computed tomographic results, and length of hospital stay. Kruskal-Wallis and t tests were used for statistical evaluation. RESULTS: The mean acute score on the GCS was 9.7 +/- 5. Mean duration of hospitalization days was 8.7 +/- 10. Statistically significant differences in mean FA values between trauma and control subjects were noted in corpus callosum. Trauma patients with positive findings on MRI and with GCS less than 10 also had lower FA values than patients with GCS greater than 10 and patients who had normal MRI findings. There was a negative correlation between time to discharge and FA values. CONCLUSIONS: In pediatric head trauma, MRI diffusion FA measurements can show abnormalities despite normal-appearing brain MRI findings. Larger investigations are required to verify the stability of correlations.     

Diffusion tensor MR imaging in diffuse axonal injury

BACKGROUND AND PURPOSE: Disruption of the cytoskeletal network and axonal membranes characterizes diffuse axonal injury (DAI) in the first few hours after traumatic brain injury. Histologic abnormalities seen in DAI hypothetically decrease the diffusion along axons and increase the diffusion in directions perpendicular to them. DAI therefore is hypothetically associated in the short term with decreased diffusion anisotropy. We tested this hypothesis by measuring the diffusion characteristics of traumatized brain tissue with use of diffusion tensor MR imaging. METHODS: Five patients with mild traumatic brain injuries and 10 control subjects were studied with CT, conventional MR imaging, and diffusion tensor imaging. All patients were examined within 24 hours of injury. In each participant, diffusion tensor indices from homologous normal-appearing white matter regions of both hemispheres were compared. These indices were also compared between homologous regions of each patient and the control group. In two patients, diffusion tensor images from the immediate post-trauma period were compared with those at 1 month follow-up. RESULTS: Patients displayed significant reduction of diffusion anisotropy in several regions compared with the homologous ones in the contralateral hemisphere. Such differences were not observed in the control subjects. Significant reduction of diffusion anisotropy was also detected when diffusion tensor results from the patients were compared with those of the controls. This reduction was often less evident 1 month after injury. CONCLUSION: White matter regions with reduced anisotropy are detected in the first 24 hours after traumatic brain injury. Therefore, diffusion tensor imaging may be a powerful technique for in vivo detection of DAI.     

Diffusion tensor imaging and MR spectroscopy in hypertension and presumed cerebral small vessel disease.

In patients with cerebral small vessel disease (SVD) diffusion tensor imaging (DTI) is sensitive to white matter damage and correlates better with cognitive function than conventional imaging. It has been proposed as a surrogate marker for treatment trials. However, the pathological changes underlying DTI are not known. The purpose of this study was to use magnetic resonance spectroscopy (MRS) to determine the pathological changes underlying DTI abnormalities in a range of patients from asymptomatic white matter hyperintensities to symptomatic cerebral SVD. 29 SVD patients, 63 hypertensive subjects, and 42 normotensive controls were recruited. The relationship between the DTI and MRS parameters in the centrum semiovale white matter was determined. There was a significant reduction in N-acetylaspartate (NAA; 2.067 +/- 0.042 vs 2.299 +/- 0.029 and 2.315 +/- 0.036, P = 9 x 10(-6)) and increase in mean diffusivity (mm2/s x 10(-3); 0.942 +/- 0.123 vs 0.822 +/- 0.064 and 0.792 +/- 0.057, P = 1 x 10(-8)) in symptomatic SVD patients compared with the other two groups. DTI parameters correlated with NAA in all three groups, in a graded manner depending on severity of disease (r -SVD -0.827, hypertensive subjects -0.457, controls -0.317). NAA is a marker of axonal loss/dysfunction. These findings are consistent with axonal loss/dysfunction being the principal process causing the DTI changes found in cerebral SVD and ageing.     

Diffusion tensor MR imaging of high-grade cerebral gliomas

BACKGROUND AND PURPOSE: Optimizing high-grade glioma treatment requires the delineation of edematous and normal brain from tumor, perhaps by using potential differences in the absolute diffusion parameters of water. Our purpose was to determine whether mean diffusivity and diffusion anisotropic MR imaging data help in this differentiation. METHODS: Nine patients with high-grade cerebral glioblastoma underwent contrast-enhanced structural and diffusion tensor MR imaging before therapy. Tumor, edematous brain, and apparently normal white matter regions were determined on T2-weighted and contrast-enhanced T1-weighted structural images. Fractional anisotropy (FA) and were measured in each tissue type. Differences in these values among the tissue types were assessed with a standard analysis of variance. RESULTS: was highest in the necrotic tumor core (1825.38 +/-404.06) x 10(-6) mm(2)/s, followed by edematous brain (1411.23 +/- 322.31) x 10(-6) mm(2)/s, enhancing tumor core (1308.67 +/- 292.50) x 10(-6) mm(2)/s, enhancing tumor margin (1229.80 +/- 206.80) x 10(-6) mm(2)/s, and normal brain (731.53 +/- 35.21) x 10(-6) mm(2)/s. FA was highest in normal brain (0.47 +/- 0.08) and lowest in the necrotic core (0.09 +/- 0.03). was significantly different in enhancing tumor margins and edematous brain in all patients; FA was significantly different in only seven. These values were significantly different from those of normal brain in all cases in which they were measurable. CONCLUSION: values can be used to differentiate normal white matter, edematous brain, and enhancing tumor margins. Diffusion anisotropic data added no benefit to tissue differentiation. Further studies are required to determine if a value that corresponds to the limit of tumor invasion can be identified.     

Diffusion tensor imaging for target volume definition in glioblastoma multiforme

Introduction

Diffusion tensor imaging (DTI) is an MR-based technique that may better detect the peritumoural region than MRI. Our aim was to explore the feasibility of using DTI for target volume delineation in glioblastoma patients.

Materials and methods

MR tensor tracts and maps of the isotropic (p) and anisotropic (q) components of water diffusion were coregistered with CT in 13 glioblastoma patients. An in-house image processing program was used to analyse water diffusion in each voxel of interest in the region of the tumour. Tumour infiltration was mapped according to validated criteria and contralateral normal brain was used as an internal control. A clinical target volume (CTV) was generated based on the T₁-weighted image obtained using contrast agent (T_1Gd), tractography and the infiltration map. This was compared to a conventional T₂-weighted CTV (T₂-w CTV).

Results

Definition of a diffusion-based CTV that included the adjacent white matter tracts proved highly feasible. A statistically significant difference was detected between the DTI-CTV and T₂-w CTV volumes (p?t?=?3.480). As the DTI-CTVs were smaller than the T₂-w CTVs (tumour plus peritumoural oedema), the pq maps were not simply detecting oedema. Compared to the clinical planning target volume (PTV), the DTI-PTV showed a trend towards volume reduction. These diffusion-based volumes were smaller than conventional volumes, yet still included sites of tumour recurrence.

Conclusion

Extending the CTV along the abnormal tensor tracts in order to preserve coverage of the likely routes of dissemination, whilst sparing uninvolved brain, is a rational approach to individualising radiotherapy planning for glioblastoma patients.     

Multiple sclerosis: diffusion tensor MR imaging for evaluation of normal-appearing white matter

PURPOSE: To determine whether the normal-appearing white matter (NAWM) regions surrounding and remote from multiple sclerosis (MS) plaques have abnormal diffusional anisotropy and to compare anisotropy maps with apparent diffusion coefficient (ADC) maps for sensitivity in the detection of white matter (WM) abnormalities. MATERIALS AND METHODS: Conventional and diffusion tensor magnetic resonance (MR) imaging examinations were performed in 26 patients with MS and in 26 age-matched control subjects. Fractional anisotropy (FA) and ADC maps were generated and coregistered with T2-weighted MR images. Uniform regions of interest were placed on plaques, periplaque white matter (PWM) regions, NAWM regions in the contralateral side of the brain, and WM regions in control subjects to obtain FA and ADC values, which were compared across the WM regions. RESULTS: The mean FA was 0.280 for plaques, 0.383 for PWM, 0.493 for NAWM, and 0.537 for control subject WM. The mean ADC was 1.025 x 10(-3) mm(2)/sec for plaques, 0.786 x 10(-3) mm(2)/sec for PWM, 0.739 x 10(-3) mm(2)/sec for NAWM, and 0.726 x 10(-3) mm(2)/sec for control subject WM. Significant differences in anisotropy and ADC values were observed among all WM regions (P <.001 for all comparisons, except ADC in NAWM vs control subject WM [P =.018]). CONCLUSION: The anisotropy and ADC values were abnormal in all WM regions in the patients with MS and were worse in the periplaque regions than in the distant regions. Diffusion tensor MR imaging may be more accurate than T2-weighted MR imaging for assessment of disease burden.