弥散峰度成像对高级别脑胶质瘤和单发脑转移瘤的鉴别价值研究

目的 探讨弥散峰度成像(DKI)对鉴别高级别脑胶质瘤和单发脑转移瘤的临床应用价值.方法 搜集经病理或临床证实的33例脑肿瘤患者纳入研究,其中高级别胶质瘤18例,单发脑转移瘤15例,分别行常规磁共振平扫、DKI及常规增强扫描.经后处理分别得到DKI相关参量图,分别测量在肿瘤实性部分、瘤周水肿区域的各参数值.采用两样本t检验,分析高级别脑胶质瘤与单发脑转移瘤实质部分和瘤周水肿区域的各相对参数值平均弥散峰度(MK)、部分各向异性(FA)、平均扩散系数(MD),分析差异有无统计学意义.结果 在肿瘤实质部分,高级别脑胶质瘤和单发脑转移瘤MK、FA、MD各相对参数值比较,差异均无统计学意义(P值分别为0.529、0.645、0.84).在瘤周水肿区域,高级别胶质瘤和单发脑转移瘤MK、FA、MD各相对参数值比较,差异均有统计学意义(P值分别为0.002、0.003、0.04).结论 (1)DKI各相对参数MK、FA、MD在肿瘤实质部分对鉴别高级别脑胶质瘤和单发脑转移瘤没有明显价值.(2) DKI各相对参数MK、FA、MD在瘤周水肿区域对高级别脑胶质瘤和单发脑转移瘤有鉴别诊断价值.     

正常肝脏扩散峰度成像的可行性及可重复性研究

目的 研究正常肝脏扩散峰度成像(DKI)的可行性及参数测量的可重复性.方法 使用飞利浦1.5TMR扫描仪和相同的序列及参数,对35名年轻志愿者进行2次肝脏DKI扫描,生成平均扩散系数(MD)图和平均峰度系数(MK)图.在左、右肝内分别选取上、中、下3个代表性层面的左、中、右9个测量位置,每个位置放置大小相同的感兴趣区(ROI),分别测量并比较各ROI的MD值和MK值及左、右肝各9个ROI的平均参数值,并评估各参数测量的可重复性.结果 前后2次DKI扫描b=800 s/mm2图像上肝脏的信噪比(SNR)较好,差异无统计学意义(P＞0.05).2次扫描左、右肝内不同测量部位的MD、MK值差异均无统计学意义(P＞0.05),其中右肝中层及左肝下层的MD、MK值可重复性较好.左肝的平均MD值、MK值较右肝高(t=-5.665 ～8.095,P＜0.001),但左肝的平均MD、MK值可重复性均较右肝差;MD值、MK值的可重复性相近.结论 初步研究结果表明,正常肝脏DKI是可行的,右肝中层和左肝下层的MD、MK值的可重复性较好;左肝的平均MD、MK值较右肝高,但可重复性较右肝差,MD、MK值的可重复性相似.     

Fast quantitative diffusion-tensor imaging of cerebral white matter from the neonatal period to adolescence

We investigated the isotropic diffusion coefficient (D) and fractional anisotropy (FA) in white matter (WM) during brain development, using an optimised diffusion-tensor imaging (DTI) method with whole brain coverage in a clinically acceptable time. We images 52 children with no evident neurological abnormality (30 boys, 22 girls aged 1 day–16 years) using high-angle DTI with optimised temporal gradient performance. D and FA were calculated in 10 regions of interest in white matter. We saw that the age-related reduction in D and increase in FA follow a mono- or biexponential model in white matter, probably depending on the compactness and myelination rate of the fibre tracts. In contrast to other areas, in which adult values were reached during the third year, there is a trend to continuous increase in FA in all deep white-matter areas, suggesting continuing maturation and organisation of deep tracts not detected on conventional MRI.     

磁共振扩散峰度成像诊断亚急性脑梗死进展性的价值

目的利用MR扩散峰度成像(DKI)研究亚急性期进展性脑梗死责任病灶,并结合NIHSS评分探讨其影像征象与临床相关性。方法前瞻性研究发病时间>72 h且在本影像中心行MRI扫描的亚急性期脑梗死病人79例,其中男45例,女34例,年龄43~88岁,平均(64.75±11.05)岁。根据NIHSS评分和病灶数目将其分为4组:单发脑梗死进展阴性组、多发脑梗死进展阴性组、单发脑梗死进展阳性组、多发脑梗死进展阳性组。对所有病人进行颅脑DKI及常规MRI扫描,获取MD和MK参数图,并于相应的参数图测量相应的参数值及病灶面积。多发性脑梗死病例在MD和MK图同一层面选取同一供血区内的2个独立病灶,分别将兴趣区设置于该缺血区的核心区(ROI 1)和周边区(ROI 2)。采用配对样本Wilcoxon符号秩检验比较MD图和MK图中病灶面积和信号的差异,采用散点图和信号变化百分比描述缺血灶的时间-信号变化。结果 (1)病灶面积。进展阴性组病人MD图与MK图中不同梗死灶的面积大小均相仿,其差异均无统计学意义(均P>0.05);进展阳性组MD图中不同梗死灶的面积均大于MK图(均P<0.05)。进展阴性组和阳性组的MD/MK不匹配区面积(显著的MD/MK不匹配区)百分比分别为0.2%和9.7%。(2)时间-信号散点图。a单发脑梗死组:与正常脑区相比,不同进展程度的单发脑梗死病人的病灶区均表现为MD值显著下降、MK值显著上升。进展阳性组病灶的信号恢复延迟,且MD、MK值偏离正常值的幅度大于进展阴性组。两组的MK值偏离正常值的幅度均大于MD值的变化幅度。b多发脑梗死组:多发性脑梗死进展阴性组病灶的MD和MK的时间-信号散点图与单发脑梗死进展阴性组相仿,ROI 1和ROI 2的时间-信号变化趋向一致性良好。多发性脑梗死进展阳性组ROI 1的MD和MK的时间-信号散点图与单发脑梗死进展阳性组相仿,而ROI 2的MD和MK的时间-信号散点图则呈无规律的杂乱曲线,表现出多病灶的异质性。结论脑梗死灶MK值恢复的延迟或多病灶的异质性均提示原发脑梗死病灶扩大及新发脑梗死,是亚急性脑梗死进展性诊断的重要征象。     

Diffusion tensor imaging of partial intractable epilepsy

Our aim was to assess the value of diffusion tensor imaging (DTI) in patients with partial intractable epilepsy. We used DTI (25 non-collinear directions) in 15 patients with a cortical lesion on conventional MRI. Fractional anisotropy (FA) was measured in the internal capsule, and in the normal-appearing white matter (WM), adjacent to the lesion, and away from the lesion, at a set distance of 2–3 cm. In each patient, increased or decreased FA measurements were those that varied from mirror values using an arbitrary 10% threshold. Over the whole population, ipsi- and contralateral FA measurements were also compared using a Wilcoxon test (p<0.05). Over the whole population, FA was significantly reduced in the WM adjacent to and away from the lesion, whilst being normal in the internal capsule. FA was reduced by more than 10% in the WM adjacent to and distant from the lesion in 13 and 12 patients respectively. For nine of the ten patients for whom the surgical resection encompassed the limits of the lesion on conventional MRI, histological data showed WM alterations (gliosis, axonal loss, abnormal cells). DTI often reveals WM abnormalities that are undetected on conventional MRI in patients with partial intractable epilepsy.     

扩散峰度成像对特发性全身性癫痫白质改变的研究

目的:探讨扩散峰度成像(DKI)对特发性全身性癫痫(IGE)患者脑白质细微结构的改变特征,并分析其与癫痫患者生活质量评分(QOLIE-31)的相关性。方法:招募20例IGE患者作为IGE组,19名性别、年龄及教育程度与IGE组相匹配的志愿者作为健康对照(HC)组,分别采集其全脑结构像3D T₁WI、T₂WI FLAIR和DKI数据,计算DKI各参数值:各向异性分数(FA)、平均扩散系数(MD)、轴向扩散系数(AD)、径向扩散系数(RD)、平均扩散峰度(MK)、轴向扩散峰度(AK)、径向扩散峰度(RK)、扩散峰度各向异性(FAK),采用两样本t检验比较组间DKI各参数差异。采用Pearson相关分析对差异有统计学意义的脑白质DKI参数与QOLIE-31评分进行相关性分析。结果:与HC组相比,IGE组左侧下纵束FAK升高(t=-2.31,P=0.032);左侧上辐射冠(t=-2.69,P=0.010)、左侧上额枕束(t=-2.85,P=0.007)、右侧上额枕束(t=-2.77,P=0.008)MD升高;右侧下纵束(t=2.04,P=0.048)...     

Magnetic resonance imaging assessment of brain maturation in preterm neonates with punctate white matter lesions

Introduction Early white matter (WM) injury affects brain maturation in preterm infants as revealed by diffusion tensor imaging and volumetric magnetic resonance (MR) imaging at term postmenstrual age (PMA). The aim of the study was to assess quantitatively brain maturation in preterm infants with and without milder forms of WM damage (punctate WM lesions, PWML) using conventional MRI. Methods Brain development was quantitatively assessed using a previously validated scoring system (total maturation score, TMS) which utilizes four parameters (progressive myelination and cortical infolding, progressive involution of glial cell migration bands and germinal matrix tissue). PWML were defined as foci of increased signal on T1-weighted images and decreased signal on T2-weighted images with no evidence of cystic degeneration. A group of 22 preterm infants with PWML at term PMA (PWML group) were compared with 22 matched controls with a normal MR appearance. Results The two groups were comparable concerning gestational age, birth weight and PMA. TMS was significantly lower in the PWML group than in the control group (mean TMS 12.44 ± 2.31 vs 14.00 ± 1.44; P = 0.011). Myelination (mean 2.76 ± 0.42 PWML group vs 3.32 ± 0.55 control group, P = 0.003) and cortical folding (3.64 ± 0.79 vs 4.09 ± 0.43, P = 0.027) appeared to be significantly delayed in babies with PWML. Conclusion Conventional MRI appears able to quantify morphological changes in brain maturation of preterm babies with PWML; delayed myelination and reduced cortical infolding seem to be the most significant aspects.     

额顶叶占位性病变对脑运动功能影响的DTI研究

目的:利用DTI脑白质束的FA图和白质束纤维追踪图,评估额顶叶占位病变影响下脑对指运动功能区形态及功能改变的特征.方法:病变组为20例连续搜集观察的神经外科术前检查的额顶叶占位病变患者,另选20例健康自愿者为正常对照组.采用Siemens 1.5T超导磁共振仪进行扫描,包括常规MRI和DTI.数据后处理运用美国约翰霍普金斯大学编写的DTI-Studio Version 2.02软件处理DTI数据.结果:病变组20例中最后诊断为肿瘤的15例,炎症4例,血管畸形1例.在DTI的FA图中测量两组实验对象颅内相关脑组织区域的平均FA值,显示15例肿瘤病灶区域的FA值与对照组及其自身对侧比较有降低,1例血管畸形伴化脓性感染患者FA值升高.在DTI三维白质束纤维示踪图中显示额顶叶肿瘤患者皮质脊髓束受病灶压迫而移位、中断或破坏.结论:扩散张量成像技术可以实现对活体复杂的白质纤维束结构的显示,在临床应用中DTI技术可以用于评价肿瘤与邻近白质纤维的空间解剖关系、白质纤维的受累情况,为临床病情评估和外科手术入路计划提供有效帮助,对评价术后的功能恢复潜力也有较大意义.     

Unspecific white matter lesions: prevalence,number and distribution in cranial MRI

To establish data about prevalence, number and topography of unspecific white matter lesions as seen on MRI, the T2-weighted MRI scans of 83 patients with hyperintense focal white matter changes were reviewed. Patients with known inflammatory central nervous system disease were excluded. There was an approximately linear increase in prevalence and number of lesions with age. Prevalence ranged from 18% in the third decade to over 90% in those over 70 years. We found a close correlation with concomitant periventricular hyperintensity. However, rating of Virchow-Robin spaces did not correlate with the number of white matter lesions. Both hemispheres were involved nearly equally with a minimal non-significant right side preponderance. Lesions showed a strong predilection for the frontal and parietal paraventricular watershed areas. Offprint requests to: Erich Hofmann     

Serial MR imaging in Creutzfeldt-Jakob disease

Summary Serial magnetic resonance (MR) imagings of two autopsied patients with Creutzfeldt-Jakob disease (CJD) are presented. Both patients showed a dramatic progression of brain atrophy. The initial MR imagings were, however, interpreted as normal except for localized mild cortical atrophy in one patient. When a normal MR image is obtained in a demented middle-aged or aged patient, CJD may still need to be ruled out: follow up MR imaging may be useful.     

Partial volume effect modeling for segmentation and tissue classification of brain magnetic resonance images: A review

Quantitative analysis of magnetic resonance (MR) brain images are facilitated by the development of automated segmentation algorithms. A single image voxel may contain of several types of tissues due to the finite spatial resolution of the imaging device. This phenomenon, termed partial volume effect (PVE), complicates the segmentation process, and, due to the complexity of human brain anatomy, the PVE is an important factor for accurate brain structure quantification. Partial volume estimation refers to a generalized segmentation task where the amount of each tissue type within each voxel is solved. This review aims to provide a systematic, tutorial-like overview and categorization of methods for partial volume estimation in brain MRI. The review concentrates on the statistically based approaches for partial volume estimation and also explains differences to other, similar image segmentation approaches.     

高原和平原地区健康成人脑白质扩散张量成像TBSS分析

目的 采用扩散张量成像(DTI)及基于纤维束追踪空间统计分析(TBSS)研究平原与高原健康成人的脑白质微细结构差异.方法 对16名高原健康成人和与之年龄、受教育程度相匹配的20名平原健康成人行DTI检查,应用TBSS方法分析两组受检者脑白质纤维DTI的相关参数:各向异性分数(FA)、轴向扩散系数(AD)、平行扩散系数(RD)、平均扩散系数(MD).对两组各项参数进行比较.结果 与平原组比较,高原组在胼胝体体部、胼胝体压部、胼胝体膝部、两侧上纵束、两侧上放射冠、右侧内囊前肢、内囊豆状核后肢、右侧丘脑辐射线(包括视辐射线)的AD值显著增高(P＜0.05,FWE校正);MD值显著升高的脑区是胼胝体体部、右侧上纵束、右侧上放射冠、右侧内囊前肢(P＜0.05,FWE校正);RD值显著升高的脑区是胼胝体体部、右侧上纵束.结论 通过DTI及TBSS分析,高原健康成人相对于平原健康成人脑白质纤维存在差异.     

MRI at 3 Tesla detects no evidence for ischemic brain damage in intensively treated patients with homozygous familial hypercholesterolemia

Introduction Homozygous familial hypercholesterolemia (FH) is considered a model disease for excessive plasma cholesterol levels. Patients with untreated homozygous FH have a markedly increased risk for premature atherosclerosis. The frequency and extent of ischemic brain damage detectable by high-field magnetic resonance imaging (MRI) after long-term intensive treatment are unknown. Methods In a case control study, five patients with homozygous FH (one male and four females; mean age: 23.6 ± 9.2, range: 12–36 years; mean pre-treatment serum total cholesterol level: 26.9 ± 3.24 mmol/L; all patients with documented atherosclerotic plaques in the carotid arteries) and five age- and sex-matched healthy controls were studied. All patients had been on maximal lipid-lowering medication since early childhood, and four of them were also on treatment with low-density lipoprotein (LDL) apheresis at bi-weekly intervals. Brain MRI was performed at 3 Tesla field strength with fluid-attenuated T2-weighted inversion recovery and T1-weighted spin-echo MR pulse sequences and subsequently evaluated by two independent readers. Results The maximal lipid-lowering treatment reduced the total serum cholesterol by more than 50% in the patients, but their serum concentrations were still 3.6-fold higher than those found in the controls (11.9 ± 4.2 vs. 4.5 ± 0.5 mmol/L;  p < 0.0047). No brain abnormality was observed in any of the patients with homozygous FH. Conclusion Homozygous FH patients on intensive cholesterol-lowering therapy have no evidence of ischemic brain damage at 3 Tesla MRI despite the remaining high cholesterol levels.     

脑白质疏松的扩散张量成像(DTI)研究

目的 应用扩散张量成像（DTI）检查脑白质疏松（LA）病灶的平均扩散系数（DCavg）、各向异性（FA）值与LA严重程度的关系,探讨常规MBI检查正常的脑白质微结构在DTI中的变化及与认知功能的关系。资料与方法 对55例LA患者和22名健康老年人行DTI检查,测量LA病灶和正常白质区域的DCavg、FA值。结果 LA程度越严重,DCavg值越高,呈正相关;FA值越低,呈负相关。神经心理学测试（简易智能精神状态量表,MMSE）与LA患者的正常脑白质区域的DCavg、FA值明显相关,尤其是前角白质、半卵圆中心的正常脑白质。结论 DTI检查LA,其DCavg、FA值显示出特征性的改变,DTI能够发现常规MRI检查正常的脑白质微结构改变,且这种改变与认知功能相关。     

磁共振扩散张量纤维束成像技术在内侧颞叶癫痫中的应用研究

目的采用扩散张量纤维束成像(DTT)技术对内侧颞叶癫痫(mesial temporal lobe epilepsy,mTLE)中特定的脑白质纤维完整性的改变进行研究,探讨其在mTLE中的应用价值。资料与方法 25例单侧mTLE患者(左侧13例,右侧12例)及21名健康自愿者(对照组)纳入本研究。在1.5 T MR扫描仪下行扩散张量成像(DTI)数据采集。采用Trackvis软件对受检者颞叶相关的5对白质纤维束进行追踪显示,测量其整体部分各向异性分数(FA)值。将两组mTLE患者的左、右侧纤维束FA值分别与对照组相应侧纤维束FA值进行两样本t检验。最后将病例组纤维束FA值与临床因素进行相关分析。结果相对于对照组,左侧mTLE组5个患侧纤维束FA值均减低(P<0.05),而对侧仅扣带束(t=2.458,P<0.05)、上纵束(t=2.112,P<0.05)、下纵束(t=2.093,P<0.05)的FA值减低;右侧mTLE组5个患侧纤维束FA值均减低(P<0.05),而对侧仅下纵束FA值减低(t=2.384,P<0.05)。左侧mTLE组左侧钩束FA值与始发年龄呈线性正相关关系(r=0.764,P<0.01),与发病时长呈线性负相关关系(r=-0.678,P<0.05)。结论 DTT可用于颞叶癫痫相关白质纤维束完整性的检测,并有助于mTLE定侧研究,加深对mTLE病理生理机制的进一步理解。     

Transient neonatal hypoglycemia: cranial US and MRI findings

A case of transient neonatal hypoglycemia with patchy hyperechogenic white matter abnormalities in the frontal and parietooccipital lobes on cranial US is presented. An MRI examination revealed T1 and T2 shortening of the lesions in the occipital and frontal white matter. Follow-up cranial US demonstrated recovery of white matter changes in the patient with normal neurological outcome.     

MRI in Cockayne syndrome type I

Summary MRI findings are reported from two patients with Cockayne syndrome (CS) type I, aged 11 and 37 years. Changes were compatible with diffuse white matter hypomyelination. Basal ganglia calcification was present in both, marked cerebellar atrophy in the older patient. MRI may support the diagnosis of CS in the appropriate clinical context. The view that CS is a dysmyelinating disorder is further substantiated.