精神分裂症首次发病患者的磁共振弥散张量显像研究

目的探讨从未用过药的精神分裂症首次发病(以下简称首发)患者的重要白质及部分灰质区的磁共振弥散张量显像(DTI)的特点。方法选取9例首发精神分裂症患者(患者组)及9名年龄、性别、受教育程度与患者组相配对的健康者,应用DTI成像技术检测脑额颞交界处、内囊等白质区和颞中回灰质、中央前回、中央后回等灰质区的各向异性(FA)、表观扩散系数(ADC)及双侧海马体积。结果患者组及对照组组内左右两侧兴趣区FA值及ADC值的差异无统计学意义(P>0.05);患者组与对照组各感兴趣区FA值差异无统计学意义(P>0.05),但患者组颞中回灰质(8.655×10-9)、中央前回(7.816×10-9)、中央后回(7.855×10-9)ADC值高于对照组(分别为7.428×10-9,6.921×10-9,7.013×10-9;P=0.049,0.009,0.005);两组内及组间双侧海马体积比较,差异均无统计学意义(P>0.05)。结论首发精神分裂症患者与健康者DTI参数之间没有明显区别。     

Walker-Warburg syndrome: diffusion MR imaging

A 5-month-old boy with Walker-Warburg syndrome is reported. On MR imaging a characteristic pontomesencephalic kink was evident. Collicular fusion, hydrocephalus, callosal dysgenesis, cobblestone lissencephaly, small cerebellar cysts, pontine and cerebellar hypoplasia, and bilateral subretinal hemorrhages were noted. ADC (apparent diffusion coefficient) maps of an echoplanar diffusion MR imaging sequence revealed an elevated diffusion pattern throughout the cerebral white matter, manifested with prominently high ADC values, ranging from 1.82 to 2.45 x 10(-3) mm2/s. This corresponded to prominent hypomyelination. On the other hand, ADC values of the lissencephalic cortex were normal, ranging from 0.95 to 0.97 x 10(-3)mm2/s. In addition, ADC values from the hypoplastic cerebellar hemispheres, and from the hypoplastic pons were normal.     

Diffusion MRI findings in neonatal brain abscess

In neonates and infants, bacterial brain abscess is rare, and the diffusion weighted MR imaging appearance of such abscesses has not been reported. We report the diffusion weighted MR findings of a brain abscess in a 25-day-old boy. The lesion initially had a large cystic component with some high-signal pyogenic material inside on diffusion-weighted (b=1000 sec/mm(2))images. The ADC value of this material was low (0.59 x 10(-3) mm(2)/sec), compared to the value from normal cerebellar parenchyma (0.78 x 10(-3) mm(2)/sec). The unusual initial appearance mimicked a cystic tumor. The lesion markedly decreased in size over 20 days after antibiotic therapy with persistent high-signal pyogenic material. In addition, at the initial presentation b=1000 sec/mm(2) images revealed high-signal changes in the brain parenchyma compressed by markedly dilated ventricles, consistent with ischemia. Also, ADC values of perilesional vasogenic edema (1.74 x 10(-3) mm(2)/sec), and that of transependymal resorption of CSF (1.56 x 10(-3) mm(2)/sec) were noted at the initial stage.     

Multi-modal MRI in normal pressure hydrocephalus identifies pre-operative haemodynamic and diffusion coefficient changes in normal appearing white matter correlating with surgical outcome

Magnetic resonance techniques were used to investigate haemodynamic abnormalities and their consequences in normal pressure hydrocephalus (NPH) and to assess changes in these parameters following surgery. Eleven patients with NPH were studied pre- and post-operatively using perfusion and diffusion weighted imaging and compared with ten age-matched controls. Pre-operative periventricular relative cerebral blood volume (rCBV) was reduced in patients (0.76+/-0.11) compared with control (1.16+/-0.16, P<0.01). There was no difference between outcome groups and no change in haemodynamic parameters following surgery. The periventricular apparent diffusion coefficient (ADC) was elevated in the poor outcome group (1.67+/-0.3 x 10(-3) mm(2) s(-1)) compared with both controls (1.04+/-0.4 x 10(-3) mm(2) s(-1), P<0.05) and the good outcome group (0.99+/-0.3 x 10(-3) mm(2) s(-1), P<0.05) despite appearing normal on conventional imaging. In white matter hyperintensities (WMH), rCBV was reduced (0.70+/-0.12 vs. 1.00+/-0.10, P<0.01), and the ADC was increased (1.98+/-0.6 vs. 1.04+/-0.4 x 10(-3) mm(2) s(-1), P<0.05) compared with the same anatomical location in controls. As low rCBV and high ADC is characteristic of chronic infarction, the findings in WMH regions suggest they are irreversibly damaged. Normal appearing periventricular tissue rCBV was reduced, implying that significant haemodynamic consequences contribute to symptoms in NPH. The elevated pre-operative ADC of the same region, was correlated with poor outcome, and may, therefore, be useful in selecting patients for surgery.     

Lowe syndrome: proton mr spectroscopy, and diffusion mr imaging

A 3-year-old boy with Lowe syndrome had bilateral periatrial hyperintense lesions intermixed with small cyst-like changes in the periatial regions of the deep white matter at MR imaging. Proton MR spectroscopy revealed prominent myoinositol peaks suggesting the presence of gliosis. b = 1000 s/mm2 images of diffusion MR imaging were negative for the periatrial lesions. ADC maps, however, revealed high ADC values (1.76, and 1.66 x 10(-3) mm2/s), compared to the normal brain parenchyma (0.81 x 10(-3) mm2/s). These diffusion MR imaging findings likely represented gliosis.     

Diffusion-weighted image in the study of brain tumors and peritumoral edema

The informative value of the technique of diffusion-weighted images (DWI) and diffusion maps was studied in diagnosing supratentorial tumors of the brain. Sixty four patients were examined. Among them there were 35 patients with glial brain neoplasms of varying malignancy [benign astrocytomas (asc) in 15 patients, anaplastic asc in 10, and glioblastomas in 10)], 15 patients with meningiomas, 5 with hydrocephalus, 9 with cerebral circulatory disorders. To obtain DWI, diffusion-weighted echo-planar impulse sequence was used. ADC was within (1.52 +/- 0.34) x 10(-3) mm2/sec for fibrillary astrocytomes. The anaplastic astrocytoma group showed variations in ADC values: ADC was higher in the contrasted part of the tumor than in the non-contrasted one and averaged (1.23 +/- 0.32) x 10(-3) mm2/sec. Glioblastomas were also noted for a higher variation in ADC that averaged (1.18 +/- 0.29) x 10(-3) mm2/sec. Meningiomas had a greater MR signal in response to DWI and low ADC values [(0.97 +/- 0.17) x 10(-3) mm2/sec]. Particular emphasis is laid on the study of different types of brain edema. ADC in the area of vasogenic (peritumoral), cytotactic (ischemic), and interstitial edema was (1.30 +/- 0.11) x 10(-3), (1.04 +/- 0.05) x 10(-3), and (1.91 +/- 0.1) x 10(-3) mm2/sec, respectively (p < 0.05) and sharply distinct in ADC maps.     

磁共振弥散张量成像在脑膜瘤诊断中的应用

目的探讨磁共振弥散张量成像在脑膜瘤诊断中的应用价值。方法选择60例脑膜瘤患者为研究对象,均接受颅脑MRI平扫及DTI检查,测量并比较肿瘤实质区、瘤周水肿区及瘤周白质区ADC值及FA值。结果1I级脑膜瘤中,上皮细胞型比例最高,为40%,其次为纤维型,比例为28%。各病理亚型ADC值比较,血管瘤型最低,为(7.55±1.17)×10-9 mm2/s,微囊型最高,为(14.24±2.43)×10-9 mm2/s。2良性脑膜瘤中,瘤周水肿ADC值最高,与肿瘤实质及瘤周白质比较,差异具有统计学意义(P0.05)。瘤周白质FA值最高,显著高于肿瘤实质及瘤周水肿,差异具有统计学意义(P0.05)。恶性脑膜瘤中,瘤周水肿ADC值最高,与肿瘤实质及瘤周白质比较,差异具有统计学意义(P0.05)。瘤周白质FA值最高,显著高于肿瘤实质及瘤周水肿,差异具有统计学意义(P0.05)。良恶性脑膜瘤比较,恶性脑膜瘤肿瘤实质ADC值及瘤周白质FA值均显著低于良性脑膜瘤,差异具有统计学意义(P0.05)。结论 DTI能够显示脑膜瘤实质及瘤周组织特征,可以为其诊断和治疗提高有价值的信息。     

Pelizaeus-Merzbacher disease: diffusion MR imaging and proton MR spectroscopy findings

A 5-Year-old boy is reported with genetically confirmed Pelizaeus-Merzbacher disease. On chemical-shift spectroscopic imaging choline (Cho) peaks were prominently decreased in the white matter resulting in markedly high NAA/Cho ratios, and low Cho/Cr ratios, compared to five control cases. Low Cho levels could be indicative of the dysmyelinating disorder in the disease. On b=1000 s/mm(2) images of diffusion MRI, a tigroid pattern was evident, and there was no apparent signal abnormality. However, on ADC maps high signal and high ADC values were evident in the white matter ranging from 1.16 to 1.52 X 10(-3) mm(2)/s, compared to the ADC values of nine control cases, consistent with some disintegration of the white matter secondary to lack of myelination. On the other hand, the ADC values of the cortex were normal (0.79-0.95 X 10(- 3) mm(2)/s). These findings on spectroscopy and diffusion MRI likely represented deficient myelination in the disease.     

Pixel-by-pixel spatiotemporal progression of focal ischemia derived using quantitative perfusion and diffusion imaging.

Pixel-by-pixel spatiotemporal progression of focal ischemia (permanent occlusion) in rats was investigated using quantitative perfusion and diffusion magnetic resonance imaging every 30 minutes for 3 hours. The normal left-hemisphere apparent diffusion coefficient (ADC) was 0.76 +/- 0.03 x 10(-3) mm(2)/s and CBF was 0.7 +/- 0.3 mL x g(-1) x min(-1) (mean +/- SD, n=5). The ADC and CBF viability thresholds yielding the lesion volumes (LV) at 3 hours that best approximated the 2,3,5-triphenyltetrazolium chloride (TTC) infarct volumes (200 +/- 30 mm(3)) at 24 hours were 0.53 +/- 0.02 x 10(-3) mm(2)/s (30% +/- 2% reduction) and 0.30 +/- 0.09 mL x g(-1) x min(-1) (57% +/- 11% reduction), respectively. Temporal evolution of the ADC- and CBF-defined LV showed a significant "perfusion-diffusion mismatch" up to 2 hours (P < 0.05, n = 11), a potential therapeutic window. Based on the viability thresholds, three pixel clusters were identified on the CBF-ADC scatterplots: (1) a "normal" cluster with normal CBF and ADC, (2) an "ischemic core" cluster with markedly reduced CBF and ADC, and (3) a "mismatch" cluster with reduced CBF but slightly reduced ADC. These clusters were color-coded and mapped onto the image and CBF-ADC spaces. Lesions grew peripheral and medial to the initial ADC abnormality. In contrast to the CBF distribution, the ADC distribution in the ischemic hemisphere was bimodal; the relatively time-invariant bimodal-ADC minima were 0.57 +/- 0.02 x 10(-3) mm(2)/s (corresponding CBF 0.35 +/- 0.04 mL x g(-1) x min(-1)), surprisingly similar to the TTC-derived thresholds. Together, these results illustrate an analysis approach to systemically track the pixel-by-pixel spatiotemporal progression of acute ischemic brain injury.     

反社会人格障碍男性青年大脑白质异常改变： 证据来自于基于体素脑形态测量学的DARTEL分析

SPM8 DARTEL工具包对3D脑结构成像数据对男性青年反社会人格障碍者和正常组的大脑白质结构进行基于体素的形态学分析（VBM）。结果显示,与正常对照者比较,反社会人格障碍者主要表现为双侧前额叶、右岛叶、中央前回,左右颞上回、右中央后回、右侧顶下小叶、右侧楔前叶、右枕中叶、右海马旁回及双侧扣带回等多个脑区白质体积密度增加,左颞中叶、右小脑的白质体积密度减小。相关分析显示,额内侧回的白质体积密度增加与反社会行为的评分(PDQ)有正相关。提示反社会人格障碍者存在多个脑区的白质形态学明显异常,这些异常可能与其反社会行为有关。     

Diffusion-weighted magnetic resonance imaging of white matter in bipolar disorder: a pilot study

OBJECTIVE: Diffusion-weighted magnetic resonance imaging (MRI) has shown increased sensitivity in detecting brain white matter disease compared to traditional T2-weighted MRI. Diffusion-weighted imaging (DWI) can quantitatively assess the microstructural integrity of white matter using the average apparent diffusion coefficient (ADC(av)), a measure of the extent to which water molecules move freely within tissue. On the basis of numerous studies suggesting white matter disease in bipolar patients, particularly patients with more severe illness, this study aimed to test the utility of DWI in assessing the white matter integrity of bipolar patients with severe illness. METHODS: The existing MRI scans of eight bipolar patients and eight age-matched controls with neurological illness were examined retrospectively. ADC(av) values for pixels within white matter regions of interest (ROIs) were calculated and used to plot ADC(av) frequency histograms for each ROI. Mean ADC(av) values for the two groups were then compared by ANCOVA. RESULTS: The bipolar mean ADC(av) (0.855 +/- 0.051 x 10(-3) mm2/s) for combined white matter ROIs significantly exceeded that of controls (0.799 +/- 0.046 x 10(-3) mm2/s), while covarying for age (F = 4.47, df = 3, p = 0.025). CONCLUSIONS: This is the first report of an elevated ADC(av) in the white matter of a group of patients with bipolar disorder. In this group of patients with severe illness, increased white matter ADC(av) suggests microstructural changes consistent with decreased white matter integrity. DWI may be an additional, useful tool to assess white matter abnormalities in bipolar disorder.     

Dynamic tracking of acute ischemic tissue fates using improved unsupervised ISODATA analysis of high-resolution quantitative perfusion and diffusion data.

High-resolution (200 x 200 x 1,500 microm3) imaging was performed to derive quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) maps in stroke rats (permanent occlusion) every 30 minutes up to 3 hours after occlusion onset, followed by histology at 24 hours. An improved automated iterative-self-organizing-data-analysis-algorithm (ISODATA) was developed to dynamically track ischemic tissue fate on a pixel-by-pixel basis during the acute phase. ISODATA-resolved clusters were overlaid on the CBF-ADC scatterplots and image spaces. Tissue volume ADC, and CBF of each ISODATA cluster were derived. In contrast to the single-cluster normal left hemisphere (ADC = 0.74 +/- 0.02 x 10(-3) mm2/s, CBF = 1.36 +/- 0.22 mL g(-1)min(-1), mean +/- SD, n = 8), the right ischemic hemisphere exhibited three ISODATA clusters, namely: "normal" (normal ADC and CBF), "ischemic core" (low CBF and ADC), and at-risk "perfusion-diffusion mismatch" (low CBF but normal ADC). At 180 minutes, the mismatch disappeared in five rats (Group I, 180-minute "core" lesion volume = 255 +/- 62 mm3 and 24-hour infarct volume = 253 +/- 55 mm3, P > 0.05), while a substantial mismatch persisted in three rats (Group II, 180-minute CBF-abnormal volume = 198 +/- 7 mm3 and 24-hour infarct volume 148 +/- 18 mm3, P < 0.05). The CBF (0.3 +/- 0.09 mL g(-1)min(-1)) of the "persistent mismatch" (Group II, 0.3 +/- 0.09 mL g(-1)min(-1)) was above the CBF viability threshold (0.2 to 0.3 mL g(-1)min(-1)) throughout and its ADC (0.70 +/- 0.03 x 10(-3) mm2/s) did not decrease as ischemia progressed. In contrast, the CBF (0.08 +/- 0.03 mL g(-1)min(-1)) of the analogous brain region in Group I was below the CBF viability threshold, and its ADC gradually decreased from 0.63 +/- 0.05 to 0.43 +/- 0.03 x 10(-3) mm2/s (ADC viability threshold = 0.53 +/- 0.02 x 10(-3) mm2/s). The modified ISODATA analysis of the ADC and CBF tissue characteristics during the acute phase could provide a useful and unbiased means to characterize and predict tissue fates in ischemic brain injury and to monitor therapeutic intervention.     

Serial diffusion-weighted MR Imaging in delayed postanoxic encephalopathy. A case study

We report a case of delayed postanoxic encephalopathy (DPE) studied with serial diffusion weighted imaging five times in a one-year period along with apparent diffusion coefficient (ADC) map as well as ADC values of periventricular white matter. Compared to the normal value, the ADC values of the white matter were initially low on the three (0.68 +/- 0.08 x 10(-3) mm(2)/s) and seven-week images (0.67 +/- 0.08 x 10(-3) mm(2)/s) but gradually recovered to the normal range on the four, six, and twelve-month images (0.78 +/- 0.05, 0.80 +/- 0.05 and 0.87 +/- 0.11 x 10(-3) mm(2)/s, respectively). Among the several pathogenetic mechanisms associated with DPE, these serial changes may be consistent with cytotoxic edema, from apoptosis, triggered by hypoxia.     

Voxel-based morphometry study on brain structure in children with high-functioning autism

Earlier studies have suggested abnormal brain volumes in autism, but inconsistencies exist. Using voxel-based morphometry, we compared global and regional brain volumes in 17 high-functioning autistic children with 15 matched controls. We identified significant reduction in left white matter volume and white/gray matter ratio in autism. Regional brain volume reductions were detected for right anterior cingulate, left superior parietal lobule white matter volumes, and right parahippocampal gyrus gray matter volume, whereas enlargements in bilateral supramarginal gyrus, right postcentral gyrus, right medial frontal gyrus, and right posterior lobe of cerebellum gray matter in autism. Our findings showed global and regional brain volumes abnormality in high-functioning autism.     

Neuroradiological study of a possible progressive multifocal leukoencephalopathy using diffusion tensor imaging and proton magnetic resonance spectroscopy]

We report a possible case of progressive multifocal leukoencephalopathy (PML) that was attempted to evaluate the pathogenesis by a novel brain MRI techniques. A 72-year-old woman had developed subacute visual disturbance, right hemiparesis and sensory disturbance. Laboratory examinations revealed liver dysfunction and pancytopenia due to liver cirrhosis (type C) and preclinical status of multiple myeloma. Thus, this patient had these two underlying diseases, while anti-HIV antibody was negative. She was suspected with PML by detection of JCV-DNA in cerebrospinal fluid using with PCR. MRI showed multifocal T2-high signals in the bilateral parieto-occipital deep white matter, basal ganglia and right cerebellar hemisphere. No gadolinium enhancement was found. On FLAIR and diffusion weighted images (DWI), the lesion showed hyperintensity. The hyperintense areas on DWI showed various pattern on apparent diffusion coefficient (ADC) and fractional anisotropy (FA). In particular white matter changes, the course of FA reflected the clinical course more than ADC. Proton magnetic resonance spectroscopy (1H-MRS) in deep brain white matter showed ratios of reduced N-acetyl aspartate (NAA) and increased choline (Cho) to creatine. 1H-MRS by chemical shift imaging were undergone three times between 4 and 6 months after the onset. The change of these chemical markers correlated with her clinical course. We conclude that the approach of diffusion tensor imaging (DTI) and 1H-MRS are useful for evaluating neuropathologic observations and clinical course.     

Diffusion-Weighted Magnetic Resonance Imaging in Superior Sagittal Sinus Thrombosis

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) has shown high sensitivity in the diagnosis of acute arterial strokes. The pathophysiology of cerebral venous thrombosis with associated venous stroke appears to differ from that of arterial strokes. The purpose of this study was to describe DWI findings in venous strokes. METHODS: The authors reviewed 3 adults with superior sagittal sinus thrombosis who underwent DWI and magnetic resonance imaging within 24 hours of symptom onset. DWI was obtained at 1.5 T using the multishot echo planar technique (TR = 8000, TE = 97, field of view = 30 x 19 cm, slice thickness = 6.0 mm, interslice gap = 0.5 mm, matrix 128 x 128, NEX = 1). The diffusion gradients were applied in 3 orthogonal directions with 3 increasing b values (0-1000 s/mm2) to create average (trace) DWI images. Apparent diffusion coefficient (ADC) values were calculated on a pixel-by-pixel basis and displayed as ADC maps. RESULTS: DWI showed hyperintensities in patients 1 and 2 and hypointensity in patient 3 in corresponding to parenchymal lesions on conventional images. As compared to the homologous uninvolved location in the contralateral hemisphere, ADC values were decreased (0.53 x 10(-3) mm2/s [patient 1] and 0.68 x 10(-3) mm2/s [patient 2]) and increased (1.1 x 10(-3) mm2/s [patient 3]). The ADC ratio of the lesion in the involved to uninvolved side was 88% (patient 1), 81% (patient 2), and 120% (patient 3). CONCLUSION: Acute cerebral venous strokes may contain cytotoxic edema and/or vasogenic edema on DWI scans. DWI may be helpful in diagnosing cerebral venous thrombosis in cases with cryptic presentations.     

Diffusion-Weighted Imaging With Calculated Apparent Diffusion Coefficient of Enhancing Extra-Axial Masses

BACKGROUND AND PURPOSE: Sometimes intracranial contrast-enhancing tumors like meningiomas, metastases, lymphomas, and schwannomas can mimic each other. It was the aim of the present study to investigate if intracranial contrast-enhancing lesions can be reliably differentiated with the help of diffusion-weighted imaging with calculated apparent diffusion coefficients (ADCs). METHODS: 29 patients (ages ranging from 22 to 82 years, mean age of 58.6 years) were included. Nine meningiomas, 7 metastases, 6 lymphomas, and 7 schwannomas were investigated. The ADC value in the lesions and in the perifocal edema was analyzed. RESULTS: For the lymphomas, the authors measured the lowest ADC values in the contrast-enhancing part (0.59 +/- 0.09 . 10(-3) mm2/sec). The meningiomas showed a mean ADC value of 0.98 +/- 0.18 . 10(-3) mm2/sec. The schwannomas and metastases showed higher ADC values of 1.33 +/- 0.28 . 10(-3) mm2/sec and 1.05 +/- 0.20 . 10(-3) mm2/sec. The authors saw a statistically significant difference between lymphomas, meningiomas, and metastases concerning the ADC values in the contrast-enhancing part. CONCLUSIONS: In spite of a small sample size and partly a wide range of values, the authors found statistically significant differences between meningiomas, metastases, and lymphomas concerning ADC values. Nevertheless, a differentiation of these lesions only with the help of ADC values seems questionable.     

高功能孤独症患儿全脑白质纤维的弥散张量成像研究

目的 分析高功能孤独症患儿的全脑白质纤维的完整性.方法 对18例高功能孤独症患儿(病例组)以及10名年龄、性别、智商与病例组相匹配的健康儿童(对照组)进行全脑弥散张量成像(DTI)测量;应用基于体素的分析方法,比较两组全脑各向异性分数(FA)的差异.使用Spearman相关分析,分析病例组各感兴趣区FA值与儿章期孤独症评定表(CARS)总分及各项目之间的关系.结果 与对照组相比,病例组右侧额下回、左侧额中回及右侧颞下回邻近白质的FA值低(分别为0.67±0.10、0.57±0.09、0.50 ±0.12),左顶上小叶邻近白质的FA值高(0.55±0.15;P<0.001).病例组左额中回邻近白质的FA值与CARS中的与非生命物体的关系的得分呈负相关(r=-0.63,P=0.005).结论 高功能孤独症患儿多个部位的脑白质纤维的完整性受到破坏.     

Diffusion MRI in the postmortem brain: case report

Postmortem brain of a ten-month-old child was examined by MR imaging, and diffusion MR imaging at the 12th hour after death in order to disclose the cause of death. There were basal ganglion lesions indicating a mitochondrial disorder. There was a prominent difference between the ADC values of the white matter (0.28+/-0.04 x 10(-3) mm2/s) and cortex (0.42+/-0.04 x 10(-3) mm2/s), and this was statistically significant (p< 0.0001). This difference suggested that in the postmortem brain the conditions in the white matter leading to restriction of movement of water molecules are more severe than that in the cortex.