磁共振扩散张量成像在鉴别胶质瘤不同成分中的应用

目的 评价扩散张量成像(DTI)在区分胶质瘤不同成分方面的价值.方法 对经手术证实的30例颅内胶质瘤行MRI常规序列及DTI扫描,其中低级别胶质瘤16例,高级别14例.并根据扫描结果,计算胶质瘤强化区、非强化区、囊变坏死区、瘤周异常区及对侧正常区的DTI各向异性分数(FA值)和相对各向异性(RA值).结果 低级别胶质瘤中,未强化区与对侧正常区之间的FA值及RA值均有显著性差异(P＜0.05);高级别胶质瘤中,FA值和RA值由高到低的顺序均为:对侧正常区、瘤周异常区、强化区、囊变坏死区;且任2个区域的FA值及RA值差异均有统计学意义(P＜0.05).结论 DTI可为鉴别胶质瘤不同成分提供一定信息,对制定手术计划和放疗方案具有一定的指导作用.     

Differentiation between low-grade and high-grade glioma using combined diffusion tensor imaging metrics

Objective

To ascertain whether diffusion tensor imaging (DTI) metrics including tensor shape measures such as planar and spherical isotropy coefficients (CP and CS) can be used to distinguish high-grade from low-grade gliomas.

Methods

Twenty-five patients with histologically proved brain gliomas (10 low-grade and 15 high-grade) were included in this study. Contrast-enhanced T1-weighted images, non-diffusion weighted b = 0 (b0) images, fractional anisotropy (FA), apparent diffusion coefficient (ADC), CS and CP maps were co-registered and each lesion was divided into two regions of interest (ROI): enhancing and immediate peritumoral edema (edema adjacent to tumor). Univariate and multivariate logistic regression analyses were applied to determine the best classification model.

Results

There was a statistically significant difference in the multivariate logistic regression analysis. The best logistic regression model for classification combined three parameters (CS, FA and CP) from the immediate peritumoral part (p = 0.02), resulting in 86% sensitivity, 80% specificity and area under the curve of 0.81.

Conclusion

Our study revealed that combined DTI metrics can function in effect as a non-invasive measure to distinguish between low-grade and high-grade gliomas.     

弥散张量成像(DTI)对肿瘤脑浸润的量化和应用

目的研究磁共振弥散张量成像对颅内肿瘤脑浸润程度的量化和临床应用。方法颅内肿瘤40例,其中脑胶质瘤20例,脑膜瘤12例,脑转移瘤8例,均经病理证实;建立不同颅内肿瘤的脑浸润病理标准,并以此标准分入各亚组;利用MRI常规成像和弥散张量成像(Diffusion Tensor Imaging,DTI)比较,确定并测量5个兴趣区(肿瘤实体区、瘤周水肿区、水肿外区、相对正常白质区和对侧白质区)的分量各向异性值(fractional anisotropy,FA);比较分析不同肿瘤FA值的差异及其与肿瘤脑浸润程度的相关性。结果脑胶质瘤中有10例的DTI图像超出常规MRI范围,脑膜瘤和脑转移瘤中未见;FA值由瘤体区向外呈递增趋势,其中胶质瘤组内最大增幅出现在瘤周水肿区和水肿外区之间,而脑膜瘤和脑转移瘤亚组出现在肿瘤实体区和瘤周水肿区之间;胶质瘤瘤周水肿区FA值与肿瘤脑浸润程度显著相关;在脑胶质瘤中有脑浸润者的瘤周水肿区FA值显著低于无脑浸润胶质瘤和非胶质来源肿瘤。结论DTI可用于量化比较不同脑肿瘤的脑浸润程度,其瘤周水肿区的FA值可用于指导脑胶质瘤的手术切除范围,对延缓复发、改善预后有较大意义。     

Quantitative analysis of glioma cell invasion by diffusion tensor imaging

We aimed to quantitatively analyze the invasion of glioma cells by diffusion tensor imaging (DTI). Twenty patients with glioma, who required surgical decompression, were included in this study. Peritumoral edematous regional tissues were harvested for tumor cell counting and cell density analysis to establish standards for degrees of tumor infiltration. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of water molecules in brain in five regions of interest (ROI) were measured by DTI: (i) the glioma region; (ii) peritumoral edematous tissue; (iii) surrounding edematous tissue; (iv) white matter; and (v) contralateral white matter. The correlation between FA and ADC values from different ROI, and degree of tumor infiltration was analysed. FA values tended to increase from the glioma region outwards, and the maximum amplification appeared between peritumoral edematous and surrounding edematous regions. FA values from peritumoral edematous regions were negatively correlated with the degree of glioma infiltration. ADC values increased significantly in the peritumoral edematous region, but changes in other regions were variable. FA values from peritumoral edematous regions should be used as an evaluation index for the invasion of glioma cells.     

胶质瘤脑浸润程度与病理级别的相关性研究

目的运用病理和影像学的方法研究胶质瘤脑浸润程度与其病理级别的关系。方法选择需作内减压的脑胶质瘤患者30例,通过手术获取肿瘤区和瘤周水肿区组织标本;肿瘤区组织通过病理检查确定肿瘤分级,瘤周水肿区通过病理检查作肿瘤细胞计数和细胞密度分析,确定肿瘤脑浸润程度,将两者作相关分析;利用磁共振弥散张量成像（DTI）测量5个兴趣区（肿瘤实体区、瘤周水肿区、水肿外区、相对正常白质区和对侧白质区）的分量各向异性（FA）值,将瘤周水肿区的FA值与肿瘤的病理脑浸润程度和病理级别分别作相关分析。结果胶质瘤脑浸润程度和病理级别间无显著相关性;瘤周水肿区的FA值与胶质瘤病理脑浸润程度呈负相关性;瘤周水肿区的FA值与胶质瘤病理级别间无显著相关性。结论从病理和影像学分析的角度来看,传统脑胶质瘤病理分级与肿瘤脑浸润程度无显著相关性,高级别的胶质瘤并不一定具有更高的侵袭性。     

Fractional Anisotropy in Three Variants of Primary Progressive Aphasia

Objective: Our aim was to report diffusion tensor imaging (DTI) patterns in three patients, each with a different primary progressive aphasia (PPA) variant. Design: One agrammatic PPA, one semantic PPA, and one logopenic PPA subject underwent a magnetic resonance imaging examination including DTI sequences. The fractional anisotropy (FA) value was calculated in regions of interest (ROIs) involved in these three variants (perisylvian region, temporal pole, and parietotemporal junction) for each patient. Left-right FA ratios in each ROI were compared between PPA subjects and a group of three amnestic mild cognitive impairment patients with a cerebrospinal fluid biomarker profile of the Alzheimer type. Results: The FA values were lower in the left hemisphere (p = 0.03). The lowest FA values were observed in the left perisylvian region for the non-fluent/agrammatic subtype PPA patient, in the left anterior temporal lobe for the semantic subtype PPA patient, and in the left parietotemporal junction for the logopenic patient (p = 0.028). The left-right FA ratio in these specific ROIs for each PPA variant was significantly lower than in the amnestic mild cognitive impairment group (p = 0.009). Conclusion: DTI patterns could be an effective new tool for diagnosing PPA and classifying the three variants.     

弥散张量成像在颅内环形强化病变中的诊断价值

目的 探讨弥散张量成像(diffusion tensor imaging,DTI)对颅内环形强化病变的诊断价值.方法 53例颅内单发环形强化病例术前行DTI扫描,分别测量病变坏死区、灶周水肿区及对侧正常脑实质的平均弥散系数(MD)值及各向异性分数(FA)值.并通过弥散张量纤维束成像(diffusiontensor tracking,DTT)观察病灶与白质纤维束的关系.结果 脑脓肿坏死区的MD值为(0.60±0.13)×10-3 mm2/s,FA值为0.18±0.03,高级别星形细胞瘤MD值为(2.76±0.26)×10-3mm2/s,FA值为0.07±0.02,脑转移瘤MD为(2.82±0.29)×10-3mm2/s,FA值为0.06±0.02,前者与后两者间差异有统计学意义(P<0.01).高级别星形细胞瘤水肿区的FA值(0.23±0.06)与脑转移瘤(0.17±0.06)和脑脓肿(0.15±0.03)两者水肿区FA值差异有统计学意义(P<0.01).DTT可以较准确地反映病灶与白质纤维束的关系,为手术治疗及评估预后提供依据.结论 坏死区MD值及FA值有助于脑脓肿与环形强化脑肿瘤的鉴别;水肿区FA值有助于脑星形细胞瘤与转移瘤、脑脓肿的鉴别;DTT能够为优化手术方案及评估预后提供一定帮助.     

Progression of microstructural putamen alterations in a case of symptomatic recurrent seizures using diffusion tensor imaging

Microstructural alterations of the putamen were recently reported in patients with partial and generalized epilepsy disorders. However, it is unknown whether these alterations pre-exist or are secondary to recurrent seizures. Here we investigated the progression of putamen fractional anisotropy (FA) alterations in a case of recurrent psychomotor seizures using longitudinal diffusion tensor imaging (DTI) shortly before (DTI-1) and after a psychomotor seizure (DTI-2). We obtained FA values of a hypothesis-guided putamen region-of-interest (ROI) and seven exploratory ROIs. FA values from both DTIs were compared with reference values from 19 controls. Relative to controls, the patient's putamen FA was increased at DTI-1 (13% left putamen, 7% right putamen), an effect that was exacerbated at DTI-2 (24% left putamen (p<0.05), 20% right putamen). In the exploratory ROIs we found FA reductions in the corticospinal tract, temporal lobe, and occipital lobe (p<0.05) relative to controls at DTI-1 and DTI-2. In contrast to the putamen, all exploratory ROIs showed no relevant FA change between DTI-1 and DTI-2. These results suggest that recurrent seizures may lead to progressive microstructural putamen alterations.     

SPECT imaging of gliomas with Thallium-201 and Technetium-99m-HMPAO

Sequential Thallium-201 and Technetium-99m-HMPAO SPECT images were obtained from 7 patients with high-grade gliomas and 5 patients with low-grade gliomas. The histo-pathological tumor-type was verified from either biopsy specimens or resected tissue from surgery. There was an intense uptake of Thallium-201 in all high-grade gliomas. Compared to the contralateral hemisphere the mean uptake was 4.6 times higher. Low-grade gliomas showed only a marginally increased Thallium-201 uptake (1.4 times). No overlap existed between the two groups. There was no correlation between Technetium-99m-HMPAO uptake and tumor type. Thallium-201 appears to be a promising radiopharmaceutical for differentiating high- and low-grade gliomas, whereas Technetium-99m-HMPAO is not.     

Diffusion tensor imaging for preoperative evaluation of tumor grade in gliomas

The relationship between water diffusion parameters measured using diffusion tensor imaging (DTI) and histological malignancy of gliomas was investigated. DTI was performed using a 3.0T MR scanner in 41 consecutive patients with histologically proven gliomas. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated and compared with the WHO classification of the gliomas. The FA values of grade 1 gliomas (0.150 +/- 0.017) were significantly lower than those of grade 3 (0.23 +/- 0.033) or grade 4 gliomas (0.229 +/- 0.033) (P < 0.0001, respectively). The FA values of grade 2 gliomas (0.159 +/- 0.018) were significantly lower than those of grade 3 or grade 4 gliomas (P = 0.0002, P < 0.0001, respectively). The FA threshold between low grade and high grade gliomas was 0.188. The MD values of grade 1 gliomas (1619.1 +/- 157.4 x 10(-6) mm2/s) were significantly higher than those of grade 3 (1084.5 +/- 218.9 x 10(-6) mm2/s) (P = 0.0036) or grade 4 gliomas (1098.0 +/- 291.6 x 10(-6) mm2/s) (P = 0.0002). The MD values were not correlated with the other grades of glioma. FA values can distinguish between high grade and low grade gliomas. This is useful in deciding the surgical strategy or selecting the site of stereotactic biopsy.     

脑胶质瘤的血流改变与其病理生理特点的关系

51例胶质瘤的病人进行~(99m)Tc-HMPAO SPECT和MRI检查.按WHO分类,其中包括21例低级别胶质瘤和30例高级别胶质瘤.使用肿瘤感兴趣区与小脑比值(TCI)半定量~(99m)Tc-HM-PAO的摄取.高、中、低摄取指数在高、低级别胶质瘤中的分布显示了明显的差别(P<0.01),与低级别胶质瘤相比,高级别胶质瘤的血流异常更明显.肿瘤坏死和水肿对~(99m)Tc-HMPAO吸收显示了有意义的影响,是导致局部血流降低的主要因素.     

Diffusion tensor imaging in early relapsing-remitting multiple sclerosis.

Diffusion tensor magnetic resonance imaging (DTI) indices are abnormal in patients with established multiple sclerosis (MS). The objective of this study was to examine the diffusion characteristics of MS lesions, normal appearing white matter (NAWM) and normal appearing grey matter (NAGM) in MS patients with early relapsing-remitting disease. A further objective was to investigate the relationship between three DTI parameters (fractional anisotropy (FA), mean diffusivity (MD) and volume ratio (VR)) and clinical outcome measures (Kurtzke expanded disability status scale (EDSS) and MS Functional Composite Measure) in early disease. DTI was performed in 28 patients and 27 controls. Analysis was carried out using a region of interest (ROI) approach. ROIs were placed in 12 NAWM and nine NAGM regions. Significant differences were found in FA, MD and VR between lesions and NAWM (P< 0.001 for all three DTI parameters). No significant differences were found between patients and controls when examining NAWM or NAGM, although there was a trend for abnormal NAWM FA and VR in some regions. No correlation was found between DTI parameters in lesions, NAWM or NAGM and the clinical outcome measures. The lack of significant DTI abnormality in the NAWM and NAGM may reflect a lack of pathological change or a limited sensitivity of DTI using ROI methodology. Previous studies have shown abnormalities in TI relaxation time, magnetisation transfer ratio (MTR) and N-Acetyl aspartate (NM) in this cohort of patients, and as such, DTI using a region of interest (ROI) approach may not be as sensitive as other MR techniques in detecting subtle changes in normal appearing brain     

颞叶内侧结构弥散张量成像及白质纤维束成像在颞叶癫痫诊断中的应用价值

目的 通过磁共振弥散张量成像(DTI)及白质纤维束示踪(DTT)技术定量分析颞叶癫痫患者双侧颞叶内侧结构弥散参数值及局部纤维束变化特点,评价DTI技术对颞叶癫痫的诊断价值.方法 对广州医学院第二附属医院自2010年12月至2011年2月临床诊断为颞叶癫痫的16例患者和20例健康志愿者进行常规MRI及DTI扫描,测量双侧颞叶杏仁体、海马及颞叶皮质的部分各向异性(FA)、相对各向异性(RA)、表观弥散系数(ADC)等数值并进行统计学分析,同时应用DTT技术观察癫痫患者局部纤维束与正常对照者的差异.结果 正常对照者双侧颞叶内侧各结构FA、RA、ADC值比较差异均无统计学意义(P＞0.05).颞叶癫痫患侧、对侧与正常对照者颞叶内侧各结构FA、RA、ADC值比较差异均有统计学意义(P＜0.05),其中ADC值呈颞叶癫痫患侧＞颞叶癫痫对侧＞正常对照者的变化趋势,以海马尾部变化最为显著;而FA、RA值呈颞叶癫痫患侧＜颞叶癫痫对侧＜正常对照者的变化趋势,并且杏仁体、海马体部变化较海马尾部更显著.结论 DTI技术能充分了解癫痫患者颞叶内侧结构的弥散参数值及纤维束变化特点,有助于癫痫病灶定位的准确诊断,同时加深对颞叶内侧结构整体变化的了解亦有助于术前的整体评估及提高手术疗效.     

Uncinate fasciculus-correlated cognition in Alzheimer's disease: a diffusion tensor imaging study by tractography

Background: Neuroimaging studies show increased diffusivity and decreased anisotropy in Alzheimer's disease (AD) patients by diffusion tensor imaging (DTI). Previous reports have analyzed a correlation with cognitive function and DTI parameters, but their results are inconsistent. A reason for this might be a region of interest (ROI) method, used to calculate parameters for DTI, because this method has various usages of how to place a ROI and includes summations of values for various neuronal fiber tracts, resulting in contamination of unintended fibers. To improve the instability with ROI placement, a tractography‐based method might be useful. Our coworker reported decreased fractional anisotropy (FA) and increased apparent diffusion coefficient (ADC) of uncinate fasciculus (UF) in patients with AD by tractography. To confirm whether DTI parameter values are related to severity of cognitive function in patients with AD, we measured mean diffusion anisotropy and diffusivity of coregistered voxels along the tracking lines (i.e. tract of interest) of UF. Methods: The subjects were 30 patients with probable AD (NINCDS‐ADRDA criteria). Assessment of cognitive function was carried out according to the Mini‐Mental State Examination (MMSE) and the Alzheimer's Disease Assessment Scale‐cognitive component‐Japanese version (ADAS‐Jcog). A 1.5‐T clinical magnetic resonance unit was used to obtain diffusion tensor images. Diffusion tensors were computed and fiber‐tract maps were created using ‘dTV II’ DTI software developed by Masutani et al. We measured mean FA and ADC values along the bilateral UF. Results: FA values were positively correlated with MMSE score (r= 0.67) and were negatively correlated with ADAS‐Jcog score (r=?0.62), while ADC values were negatively correlated with MMSE score (r=?0.58) and were positively correlated with ADAS‐Jcog score (r= 0.59). Conclusion: FA and ADC values might reflect the severity of cognitive dysfunction. The tract‐of‐interest method might be a useful tool for objectively evaluating DTI parameters in AD.     

弥漫性轴索损伤后早期磁共振弥散张量成像与工作记忆障碍的相关性研究

目的探讨磁共振弥散张量成像(DTI)对弥漫性轴索损伤(DAI)导致工作记忆障碍早期诊断及预后评估的价值。方法分别对10例DAI患者(DAI组)和10例健康志愿者(正常对照组)行DTI检查,并对两组DTI图像的钩束、皮质脊髓束、胼胝体和扣带回感兴趣区的部分各向异性(FA)值进行比较分析。DAI后6个月对患者与健康志愿者行认知量表评估,并行对比分析;另外将DAI组FA值与其认知量表评分行直线相关分析。结果与对照组相比,DAI患者4个感兴趣区的FA值显著降低(P<0.05),恢复期总体认知能力略降低,但无统计学意义(P>0.05),而工作记忆功能却显著降低(P<0.05)。DAI患者中的钩束和皮质脊髓束的FA值与工作记忆功能呈正相关(r分别为0.898和0.797,P<0.05);胼胝体和扣带回FA值与工作记忆功能无明显相关性(r分别为0.432和0.387,P>0.05)。结论 DTI技术可为DAI导致的工作记忆障碍早期诊断和预后评估提供依据。     

Cigarette smoking and white matter microstructure in schizophrenia

The majority of patients with schizophrenia smoke cigarettes. Both nicotine use and schizophrenia have been associated with alterations in brain white matter microstructure as measured by diffusion tensor imaging (DTI). The purpose of this study was to examine fractional anisotropy (FA) in smoking and non-smoking patients with schizophrenia and in healthy volunteers. A total of 43 patients (28 smoking and 15 non-smoking) with schizophrenia and 40 healthy, non-smoking participants underwent DTI. Mean FA was calculated in four global regions of interest (ROIs) (whole brain, cerebellum, brainstem, and total cortical) as well as in four regional ROIs (frontal, temporal, parietal and occipital lobes). The non-smoking patient group had a significantly higher intellectual quotient (IQ) compared with the patients who smoked, and our results varied according to whether IQ was included as a covariate. Without IQ correction, significant between-group effects for FA were found in four ROIs: total brain, total cortical, frontal lobe and the occipital lobe. In all cases the FA was lower among the smoking patient group, and highest in the control group. Smoking patients differed significantly from non-smoking patients in the frontal lobe ROI. However, these differences were no longer significant after IQ correction. FA differences between non-smoking patients and controls were not significant. Among smoking and non-smoking patients with schizophrenia but not healthy controls, FA was correlated with IQ. In conclusion, group effects of smoking on FA in schizophrenia might be mediated by IQ. Further, low FA in specific brain areas may be a neural marker for complex pathophysiology and risk for diverse problems such as schizophrenia, low IQ, and nicotine addiction.     

Abnormal frontal white matter tracts in bipolar disorder: a diffusion tensor imaging study

OBJECTIVES: Prefrontal white matter has been hypothesized to be integral to the pathophysiology of bipolar disorder. Recent morphometric studies however, have not observed changes in white matter in bipolar patients. We hypothesized that changes in prefrontal function in bipolar disorder, widely reported in the literature, may be related to a loss of white matter tract integrity with a resultant dysconnectivity syndrome. In this study we utilized diffusion tensor imaging (DTI) to examine prefrontal white matter in patients with bipolar disorder. METHODS: Nine patients with bipolar disorder and nine healthy controls were recruited. DTI and localizing anatomic data were acquired, and regions of interest (ROIs) identified in the prefrontal white matter at 15, 20, 25, and 30 mm superior to the anterior commissure (AC). Fractional anisotropy (FA) and trace apparent diffusion coefficient (TADC) were compared by ROI between study groups. RESULTS: The FA of ROIs 25 and 30 mm above the AC was significantly reduced in patients with bipolar disorder; FA of all ROIs showed high-medium to large effect sizes. No significant group differences were identified in TADC. CONCLUSIONS: Our findings suggest that a loss of bundle coherence is present in prefrontal white matter. This loss of coherence may contribute to prefrontal cortical pathology in patients with bipolar disorder.     

White matter abnormalities and their impact on attentional performance in adult attention-deficit/hyperactivity disorder

Inattention is the most important behavioral feature of adult patients with attention-deficit/hyperactivity disorder (ADHD). Neuroimaging studies in ADHD have demonstrated abnormalities primarily in the frontostriatal circuitry and were mostly conducted in children. We investigated white matter (WM) integrity in adult ADHD patients and the correlation of WM microstructure and neuropsychological parameters in 37 (21 men) never-medicated adult ADHD patients and 34 age- and gender-matched healthy controls. All subjects underwent clinical interviews, rating scales, and neuropsychological tests of attentional performance. Diffusion tensor imaging (DTI) was acquired, and 12 WM regions-of-interest (ROIs) within the attentional network were chosen. Group differences of mean fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for each ROI, and patients' DTI measures were then correlated with measures of attentional performance. FA values in ADHD patients were significantly reduced in the left inferior longitudinal fasciculus (ILF), while MD values were significantly increased in ADHD patients in the frontal portion of the left frontooccipital fasciculus (IFO). In ADHD patients, MD values were negatively correlated with attentional performance in the left ILF. Our findings provide further support for disturbed frontostriatal structural connectivity and also point to an involvement of the left temporal white matter with an impact on attentional performance.     

Analysis of high-voltage electrical spinal cord injury using diffusion tensor imaging

The aim of this study was to investigate spinal cord injury (SCI) on the basis of diffusion tensor imaging (DTI) in patients with high-voltage electrical injury. We recruited eight high-voltage electrical injury patients and eight healthy subjects matched for age and sex. DTI and central motor conduction time were acquired in both the patient and control groups. We obtained DTI indices according to the spinal cord levels (from C2 to C7) and cross-section locations (anterior, lateral, and posterior). Fractional anisotrophy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were compared between the two groups; additionally, they were compared in relation to spinal cord level and cross-section location. In the patient group relative to the control group, the FA value decreased and the MD and RD values increased in all of the regions of interest (ROI) with statistical significance (p < 0.05). In the patient group, particularly in the ROIs of the anterior spinal cord compared with the lateral and posterior spinal cords, the FA value decreased with statistical significance (p < 0.05). The DTI indices did not differ by level. DTI revealed the change of diffusion in the spinal cords of patients with high-voltage electrical injury, and corroborated the pathophysiology, myelinopathy and typical anterior spinal cord location of high-voltage electrical SCI already reported in the literature.