Improved detection of cortical and subcortical tubers in tuberous sclerosis by fluid-attenuated inversion recovery MRI

We carried out fluid-attenuated inversion recovery (FLAIR) pulse sequences with long repetition and echo times in seven children with tuberous sclerosis, and compared them with conventional spin-echo (SE) sequences. FLAIR images exhibited higher sensitivity than conventional SE images to cortical and subcortical tubers. The low signal intensity of cerebrospinal fluid on FLAIR images allowed more accurate delineation of the cortical and subcortical tubers. However, T1-weighted imaging was still superior for delineation of subependymal nodules. Received: 1 May 1996 Accepted: 12 August 1996     

High signal in cerebrospinal fluid mimicking subarachnoid haemorrhage on FLAIR following acute stroke and intravenous contrast medium

We describe five cases of high signal in the cerebrospinal fluid (CSF) on fast-FLAIR images 24–48 h after onset of stroke. All the patients had undergone perfusion-weighted MRI within 6 h of the onset of the symptoms. The CSF was far brighter than the cortical gyri. The high signal was diffusely around both cerebral hemispheres in two cases and around one hemisphere in two others; it was focal, around the acute ischaemic lesion, in one. CT was normal in all cases. The CSF high signal was transient, decreasing in extent and intensity with time and resolving completely within 3–6 days. It was not associated with worsening of the clinical state or poor outcome. Our explanation of this phenomena is hypothetical: we speculate that it could be due to disruption of the blood-brain barrier resulting in leakage of protein, gadolinium chelates, or both in to the subarachnoid space. It should not be confused with subarachnoid haemorrhage. Received: 23 July 1999 Accepted: 24 September 1999     

Diagnostic use of isotropic diffusion-weighted MRI in patients with ischaemic stroke: detection of the lesion responsible for the clinical deficit

We examined the diagnostic use of isotropic diffusion-weighted (DW) MRI in 140 consecutive patients suspected of or diagnosed as having an ischaemic stroke. Isotropic DW imaging could demonstrate the lesion responsible for the clinical deficit in patients with multiple cerebral infarts at an early stage, even small lesions without a perifocal oedema or mass effect. Accurate diagnosis by DW images may, however, be difficult about 2 weeks after the onset of stroke. Received: 15 November 1998 Accepted: 12 February 1999     

A Phantom for diffusion-weighted imaging of acute stroke

A tissue phantom for diffusion-weighted imaging was developed, basing its contrast between two compartments on different apparent diffusion coefficients, without contrast due to T2 relaxation and proton density. These contrast properties of the phantom simulate the situation found in normal gray matter and areas of acute ischemia. A possible application of the phantom was demonstrated for the investigation of the accuracy of volume measurements based on diffusion-weighted images.     

MR增强后液体衰减反转恢复序列对柔脑膜病变的诊断价值

目的评价MR液体衰减反转恢复（FLAIR）序列对柔脑膜病变的诊断价值。方法分析17例柔脑膜病变的MR平扫FLAIR、增强FLAIR和增强T1WI表现并比较三者对病变高信号的显示。结果柔脑膜病变在MR平扫FLAIR、增强FLAIR和T1WI上均呈沿脑沟、脑池弥漫或局部分布的异常脑回样或线样高信号。增强FLAIR与增强T1WI对病变显示的比较：7例只在增强FLAIR显示病变；7例二者均明显显示病变；2例二者均显示病变，但前者优于后者；另有1例结核性脑膜脑炎的双侧大脑半球脑沟弥漫性病变只在增强FLAIR显示，脑池病变二者均显示但前者优于后者。增强与平扫FLAIR对病变显示的比较：9例只在增强FLAIR显示病变；4例二者均明显显示病变；3例二者均显示病变但前者优于后者；另有1例结核性脑膜脑炎的脑池病变只在增强FLAIR显示，双侧大脑半球脑沟弥漫性病变二者均显示但前者优于后者。结论增强FLAIR显示柔脑膜病变优于平扫FLAIR和增强T1WI，对于平扫FLAIR和（或）增强T1WI怀疑柔脑膜病变时，增强FLAIR是必要的检查序列。     

MRI of the inner ear: use of modified GRASS and fast spin-echo sequences

We report our experience with MRI of the normal and pathological inner ear with fast spin-echo and modified gradient recalled at steady state sequences. Although earlier studies on temporal bone MRI were discouraging, improvements in MR technology combined with the use of paramagnetic contrast media can make MRI a useful diagnostic tool for the assessment of inner ear pathology. Conventional spin-echo imaging seems not to be the modality of choice because of the relatively thick slices and the long acquisition times. Received: 9 March 1994 Accepted: 27 January 1995     

Imaging in acute stroke

Stroke is a syndrome characterized by a sudden neurological deficit caused by intracranial hemorrhage or ischemia. Computed tomography (CT) maintains a primary role in the evaluation of patients with acute stroke. The optimal magnetic resonance imaging (MRI) protocol in acute stroke includes diffusion-weighted imaging (DWI) to show acute ischemic lesion and MR perfusion study to estimate brain perfusion. Careful selection of patients for a thrombolytic therapy is crucial to improve safety and efficacy.     

Assessment of brain perfusion with MRI: methodology and application to acute stroke

We review the methodology of brain perfusion measurements with MRI and their application to acute stroke, with particular emphasis on the work awarded by the 6th Lucien Appel Prize for Neuroradiology. The application of the indicator dilution theory to the dynamic susceptibility-weighted bolus-tracking method is explained, as is the approach to obtaining quantitative measurements of cerebral blood flow (CBF) and volume (CBV). Our contribution to methodological developments, such as CBV measurement with the frequency-shifted burst sequence, development of the PRESTO sequence, comparison of different deconvolution methods and of spin- and gradient-echo sequences, and the validation of MRI measurements against positron emission tomography is summarised. The pathophysiology of brain ischaemia and the role of neuroimaging in the setting of acute stroke are reviewed, with an introduction to the concepts of ischaemic penumbra and diffusion/perfusion mismatch. Our work on the determination of absolute CBF and CBV thresholds for predicting the area of infarct growth, identification of the best perfusion parameters (relative or absolute) for predicting the area of infarct growth and the role of MR angiography is also summarised. We conclude that MRI is a very powerful way to assess brain perfusion and that its use might help in selecting patients who will benefit most from treatment such as thrombolysis.An addendum to this article can be found at     

急性缺血性脑卒中病人FLAIR血管高信号与预后的相关性研究

目的探讨急性缺血性脑卒中病人液体衰减反转恢复(FLAIR)序列血管高信号(FHV)与临床预后是否有关。方法前瞻性纳入北京天坛医院2012年1月—2015年12月的急性缺血性脑卒中绿色通道病人39例,男25例,女14例,平均年龄(59.79±12.99)岁。病人均接受了基线MRI检查,包括扩散加权成像(DWI)、MR血管成像(MRA)和FLAIR,36例病人进行了7 d MRI随访,38例进行了90 d改良Rankin量表(m RS)评估。病人根据7 d MRA表现分为血管再通组与血管未再通组,根据90 d m RS评分分为结局良好组和结局不良组。评价基线FHV的分布范围及7 d复查FHV是否消失,采用Fisher精确检验分析比较7 d血管再通组与血管未再通组之间FHV消失的情况,结局良好组与结局不良组FHV分布范围。结果共评价36例病人7 d随访结果 ,其中血管再通组24例,血管未再通组12例。18例FHV消失,其中17例发生在血管再通组(17/24例,70.83%);1例发生在血管未再通组(1/12例,8.33%),差异有统计学意义(P0.01)。共评价38例病人90 d m RS,其中结局良好组29例,结局不良组9例。2组间FHV分布层面、FHV ASPECTS评分差异均无统计学意义(P0.05)。结论基线FHV的分布范围不能预测90 d临床预后是否良好,但是FHV消失意味着血管再通。     

DTI在涉及皮质脊髓束缺血性脑梗塞中的应用

目的:探讨磁共振弥散张量成像(DTI)在涉及皮质脊髓束的缺血性脑梗塞的应用价值。方法:应用西门子1.5TMR成像系统,对30例累及内囊后肢或放射冠的脑梗塞患者进行检查,均行DTI序列(b值=0,500s/mm2)及颅脑MRI扫描,在Siemens Leonardo工作站应用纤维束跟踪软件(Siemens Standar 12 dirs)进行后处理。结果:梗塞灶FA值较对侧相应部位明显降低,ADC值较对侧相应部位明显升高,皮质脊髓束穿过梗塞灶的患者运动功能恢复较差,皮质脊髓束未穿过梗塞灶的患者运动功能恢复较好。结论:DTI白质纤维束成像可以无创性显示皮质脊髓束与缺血性梗塞灶的空间关系,帮助判断运动功能受损情况与预测预后。     

椎基底动脉延长扩张症的FLAIR影像分析

目的：探讨在椎基底动脉延长扩张症（VBD）患者 FLAIR 序列中血管高信号征（FVH）的特征及其意义。方法：2011年1月－2015年4月本院确诊的49例 VBD 患者,所有患者均行 MRI 常规检查及 TOF-MRA 检查,按照临床表现分为后循环缺血组（18例）及非后循环缺血组（31例）,比较两组临床资料及影像表现的差异,并分析 FVH 征的临床意义。结果：49例 VBD 患者中,36例（73．5％）血管 FVH 征阳性。其中,22例（44．9％）表现为1级,11例表现为2级（22．4％）,3例（6．1％）表现为3级,后循环缺血组 FVH 评分较高者（2或3级）的构成比显著高于非后循环缺血组（55．6％ vs 12．9％,χ2＝11．493,P ＝0．009）。VBD 患者的 FVH 分级与基底动脉（BA）直径、长度及 BA 横向偏移之间具有低度相关性（r＝0．473,P ＝0．001;r＝0．483,P ＜0．001;r＝0．542,P ＜0．001）。结论：VBD 患者 FVH 征阳性率高,其形成机制可能与 BA 血流缓慢有关,且高级别 FVH（2或3级）的出现可以提示 VBD 患者发生后循环缺血的可能性较大。     

Magnetic resonance imaging: Comparison of four pulse sequences in assessing primary bone tumours

A prospective magnetic resonance imaging (MRI) study was carried out in 13 patients (19 examinations) with primary bone tumours to assess the relative value of each of four pulse sequences in showing the extent and nature of the lesion. The four pulse sequences used were a T₁-weighted spin-echo (SE544/44), a T₂-weighted spin echo (SE1500/80), a short TI inversion recovery (STIR) (IR500/100/44), and a partial saturation (PS) (PS500/22) with field echo data collection. For soft tissue disease the combination of PS and STIR gave better definition of the boundary of the tumour than the more conventional T₁ and T₂-weighted spin echo sequences. For the demonstration of bone cortex, periosteal change and calcification, T₁ and T₂-weighted spin echo sequences were better. However, for calcified tissues, plain radiographs were better than either MRI combination. On the assumption that plain films will be available in all cases, PS and STIR sequences could therefore be substituted for T1 and T2-weighted spin echo sequences allowing an increase in soft tissue detectability for lesions in both red and yellow marrow.     

经鼓室注射对比剂内耳增强三维快速液体衰减反转恢复MR检查诊断梅尼埃病

目的 采用经鼓膜穿刺鼓室内注入对比剂钆、内耳三维快速液体衰减反转恢复(3D-FLAIR) MR扫描,探讨3D-FLAIR序列内耳内淋巴显像的可行性及对梅尼埃病的诊断价值.方法 19例经临床确诊的单侧梅尼埃病患者双侧耳均经鼓膜穿刺鼓室内注入Gd-DTPA稀释液,24 h后行3D-FLAIR和三维平衡快速梯度回波(3D-Balance-FFE) MR扫描,观察双侧耳蜗、前庭和(或)半规管外淋巴间隙的增强显影情况,对双侧耳蜗底转鼓阶和前庭阶分别进行评分,对双侧前庭显影范围和前庭及同层面脑干的信号强度比分别进行测量和计算,分别采用Wilcoxon符号秩检验和配对样本t检验进行统计学分析.结果 所有患者内耳3D-FLAIR MRI均显示,对比剂广泛分布于耳蜗、前庭和(或)半规管的外淋巴间隙内,可以清晰对比显示内淋巴间隙.19例患者患侧耳蜗底转前庭阶评2分3例,1分9例,0分7例,健侧耳蜗底转前庭阶评2分15例,1分2例,0分2例,二者比较差异有统计学意义(U=3.090,P＜0.05);患侧与健侧前庭显影范围分别为(5.77±2.33) mm2和(8.11±3.32) mm2,二者比较差异有统计学意义(t =2.638,P＜0.05).结论 运用经鼓膜穿刺鼓室内注入对比剂钆、24 h后行内耳3D-FLAIR MR扫描的方法,基于3D-Balance-FFE MRI,根据外淋巴间隙增强显影情况,可以区分内、外淋巴间隙的边界,推断出膜迷路积水,为梅尼埃病的诊断提供影像依据.     

Perfusion-weighted MRI as a marker of response to treatment in acute and subacute stroke

We carried out baseline and short-term follow-up MRI, including perfusion-weighted imaging (PWI) and tests of neurologic and cognitive function on 15 consecutive patients with large-vessel ischemic stroke who showed a persistent large perfusion-diffusion mismatch at enrollment up to seven days after the onset of symptoms. Of these, ten underwent induced blood pressure elevation with phenylephrine and oral medications (in eight) or intravenous fluids (in two) with the goal of improving perfusion; five had no such treatment. Significant functional improvement was defined by a reduction of 3 or more points on the NIH stroke scale (NIHSS). Significant improvement in perfusion was defined by a reduction in the volume of hypoperfused brain by 30 cc on PWI using time-to-peak (TTP) maps, without enlargement of the infarct. There was a strong, statistically significant association between improved function and improved perfusion: six (75%) of eight patients who improved in function, but none of the seven who did not, showed a reduction in volume of hypoperfused brain. All six patients who met the perfusion goal, and only two (22%) of nine who did not showed significant functional improvement (Fishers exact: P <0.01). There were no differences between patients who improved functionally and those who did not with respect to age, initial volume of abnormality on DWI or PWI, initial NIHSS, or changes on DWI. These findings indicate that reduction in volume of hypoperfused brain on PWI is a marker of response to treatment to improve perfusion even in subacute stroke and that partial reperfusion of regions of salvageable but dysfunctional tissue is a mechanism of improved function associated with induced blood pressure elevation.     

Differentiation of recent and old cerebral infarcts by diffusion-weighted MRI

We performed MRI, including diffusion-weighted imaging, in 15 patients with recurrent strokes with acute ischaemia and at least one old lesion according to the clinical history and/or CT. Routine MRI showed similar signal intensity changes in both situations. Diffusion-weighted images, however, were positive in all acute or subacute infarcts. The high signal of acutely disturbed diffusion due to intracellular oedema could also be identified in small brain stem lesions. Spatial resolution was increased by applying separate gradients in each axis instead of creating anisotropy-independent trace images. Received: 17 September 1997 Accepted: 6 April 1998     

MRI in multiple sclerosis of the spinal cord: evaluation of fast short-tan inversion-recovery and spin-echo sequences

We compared the sensitivity of T2-weighted spin-echo (FSE) and fast short-tau inversion-recovery (fSTIR) sequences in detection of multiple sclerosis of the spinal cord in 100 consecutive patients with clinically confirmed multiple sclerosis (MS); 86 patients underwent also brain MRI. In all, 310 focal lesions were detected on fSTIR and 212 on T2-weighted FSE, spinal cord lesions were seen better on fSTIR images, with a higher contrast between the lesion and the normal spinal cord. In 24 patients in whom cord plaques were shown with both sequences, the cranial study was normal or inconclusive. Assessment of spinal plaques can be particularly important when MRI of the brain is inconclusive, and in there situations fSTIR can be helpful. Received: 20 October 1999 Accepted: 23 February 2000     

Fast FLAIR sequence for detecting major vascular abnormalities during the hyperacute phase of stroke: a comparison with MR angiography

In the hyperacute phase of stroke, occluded vessels can be seen as high signal on fast-FLAIR images or as absence of flow-related enhancement in maximum-intensity projection (MIP) MR angiography (MRA). To compare these techniques, we examined 53 patients within 6 h of a stroke, using a standardised MRI protocol including fast-FLAIR and 3D time-of-flight TOF MR to detect vessel occlusion or reduced flow corresponding to the suspected ischaemic territory. Brain infarcts were confirmed on MRI after 1–5 days in 41 cases (77 %). The overall accuracy of 3D-TOF MRA was 68 % and sensitivity, specificity, positive and negative predictive values were 67 %, 71 %, 87 %, and 43 % respectively. Values for the fast-FLAIR sequence were: 65 %, 85 %, 93 % and 44 %, with an overall accuracy of 70 %. The fast-FLAIR sequence was thus able to show occluded vessels or reduced flow with about the same accuracy as 3D-TOF MRA and enabled better prediction of the ischaemic area. Received: 25 June 1998 Accepted: 3 September 1998     

Bilateral mesial temporal sclerosis: MRI with high-resolution fast spin-echo and fluid-attenuated inversion-recovery sequences

We report a retrospective analysis of MRI in 206 patients with intractable seizures and describe the findings in bilateral mesial temporal sclerosis (MTS) on fast spin-echo (FSE) and fast fluid-attenuated inversion-recovery (fFLAIR) sequences. Criteria for MTS were atrophy, signal change and loss of the digitations of the head of the hippocampus. In patients with bilateral MRI signs of MTS, correlation with clinical electro, volumetric MRI data and neuropsychological tests, when available, was performed. Bilateral MTS was observed in seven patients. Bilateral loss of the digitations and signal change on fFLAIR was seen in all seven. In three, bilateral atrophy was obvious. In two patients, mild bilateral atrophy was observed and in two others, the hippocampi were: asymmetrical, with obvious atrophy on only one side. Volumetric data confirmed bilateral symmetrical atrophy in five patients, and volumes were at the lowest of the normal range in the other two. The EEG showed temporal abnormalities in all patients, unilateral in five and bilateral in two. All patients had memory impairment and neuropsychological data confirmed visual and verbal memory deficits; two patients failed the Wada test on both sides. High-resolution T2-weighted FSE and fFLAIR sequences allow diagnosis of bilateral MTS, which has important therapeutic and prognostic implications. Received: 19 June 1998 Accepted: 7 December 1998     

Diffusion- and perfusion-weighted MRI in a patient with a prolonged reversible ischaemic neurological deficit

We report acute and follow-up diffusion- and perfusion-weighted MRI (DWI, PWI) findings in a patient with a prolonged reversible ischaemic neurological deficit. PWI 12 h after the patient was last seen to be without symptoms revealed a large perfusion deficit in the left posterior MCA territory with a relatively inconspicuous and much smaller abnormality on DWI. Follow-up showed resolution of abnormalities on both DWI and PWI, and conventional MRI was normal, apart from a very slight abnormality, visible only on FLAIR images, at the centre of the initially DWI-positive region. These findings demonstrate the utility of PWI when be used in combination with DWI to investigate the pathophysiology of transient ischemic syndromes. Received: 26 July 1999/Accepted: 20 September 1999