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。     

Fluid-attenuated inversion recovery vascular hyperintensities: an important imaging marker for cerebrovascular disease

Vascular hyperintensities have been noted on FLAIR sequences obtained in the setting of acute stroke and intracranial steno-occlusive disease. The presence of FVHs likely represents disordered blood flow, often from collaterals distal to arterial occlusion or stenosis. As opposed to other vessel signs seen in arterial insufficiency, FVH is unique in that it does not represent thrombus, but rather sluggish or disordered blood flow through vessels. This review will discuss the diagnostic and prognostic value of FVH and its impact on clinical decision-making.     

Fluid-attenuated inversion recovery vascular hyperintensities are not visible using 3D CUBE FLAIR sequence

Objective

Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH), initially described on 2D FLAIR images, are a useful imaging marker in patients with acute ischaemic stroke. We aimed to compare the sensitivity of the 3D CUBE FLAIR sequence with 2D FLAIR for the detection of FVH.

Methods

Forty-seven consecutive patients admitted for a suspected stroke were explored by 2D and 3D CUBE FLAIR MR sequences at 1.5 and 3 T. Three blinded readers assessed FVH defined as hyperintensities within cerebral arteries. Location of FVH, acute brain infarct and arterial stenosis were also assessed. 2D images were compared with 3D images for the detection of FVH. Agreement between readers was assessed.

Results

Of the 47 patients, 21 FVHs were observed on 2D FLAIR images of 15 patients (11 with acute brain infarct and 11 with an arterial stenosis). No FVH was visualised on 3D CUBE FLAIR images for either proximal or distal locations. Agreement between readers was excellent.

Conclusion

FVHs are not visible using 3D CUBE FLAIR images. This study suggests that, in suspected acute ischaemic stroke, the assessment of FVH should only be performed on conventional 2D FLAIR images.

Key Points

? Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH) are of neuroradiological importance. ? FVHs are useful imaging markers in patients with an acute ischaemic stroke. ? FVHs are not visible using 3D CUBE FLAIR images. ? Assessment of FVH should be performed on conventional 2D FLAIR images.     

Influential factors and clinical significance of fluid-attenuated inversion recovery vascular hyperintensities in transient ischemic attacks of carotid arterial system

Purpose

Fluid-attenuated inversion recovery vascular hyperintensity (FVH) is often observed in conjunction with acute ischemic stroke (AIS) of the carotid system. Despite its bearing on patient care outcomes, factors influencing FVH and its clinical significance in patients with transient ischemic attacks (TIAs) of the carotid arterial system have yet to be evaluated.

Methods

Consecutive inpatients (N = 154) diagnosed with TIAs of the carotid system in a 2-year period (2012–2014) were enrolled in our study. Each had undergone magnetic resonance imaging (MRI) within 72 h of symptom onset, followed by intracranial and extracranial vascular imaging. We investigated the frequency and nature of factors associated with FVH, also examining its clinical significance in the 30-day prognosis of TIA.

Results

Of the 154 patients enrolled (male, 92; mean age 63.0 ± 11.9), FVH was confirmed in 61 patients (39.6%). In logistic regression analysis, intracranial large-artery disease (LAD) (OR = 2.39, 95% CI 1.16–4.92; p = 0.018) and prior stroke (OR = 3.33, 95% CI 1.48–7.51; p = 0.004) emerged as factors independently associated with FVH positivity. Ultimately, 25 patients (16.2%) progressed to AIS within a 30-day follow-up period. Logistic regression analysis indicated that contralateral FVH positivity (OR = 5.98, 95% CI 1.81–19.76; p = 0.003), atrial fibrillation (OR = 7.05, 95% CI 1.33–37.40; p = 0.022), and extracranial LAD (OR = 4.12, 95% CI 1.26–13.41; p = 0.019) were independently associated with AIS during the 30-day follow-up of TIAs in these patients.

Conclusion

Intracranial LAD and previous stroke are independently associated with FVH in patients experiencing carotid system TIAs. If present, FVH may predict an oncoming AIS in the 30 days following a TIA.

     

Fluid-attenuated inversion recovery intraarterial signal: an early sign of hyperacute cerebral ischemia.

BACKGROUND AND PURPOSE: Early detection of arterial occlusion and perfusion abnormality is necessary for effective therapy of hyperacute cerebral ischemia. We attempted to assess the utility of the fast fluid-attenuated inversion recovery (fast-FLAIR) sequence in detecting occluded arteries as high signal (referred to as intraarterial signal) and to establish the role of fast-FLAIR in detecting ischemic penumbra of hyperacute stroke within 24 hours after ictus. METHODS: We studied 60 patients with hyperacute cerebral ischemia caused by occlusion of intracranial major arteries. We compared intraarterial signal on FLAIR images with time of flight (TOF) on MR angiograms, flow voids on T2-weighted images, hyperintense lesions on diffusion-weighted images, and results of follow-up CT or MR scans. RESULTS: In 58 (96.7%) patients, FLAIR detected intraarterial signals as early as 35 minutes after stroke onset. In 48 (80.0%) patients, intraarterial signal on FLAIR images coincided with lack of TOF on MR angiograms. In 41 (74.5%) of 55 patients, the intraarterial signals of fast T2-weighted imaging depicted occlusion better than did deficient flow void on T2-weighted images. In 25 (41.7%) of 60 patients, the area of intraarterial signal distribution was larger than the hyperintense lesion measured on diffusion-weighted images. Areas of final infarction had sizes between those of intraarterial signal distribution on FLAIR images and lesions measured on diffusion-weighted images. In 35 (87.5%) of 40 patients, areas of intraarterial signal distribution were equal to regions of abnormal perfusion. CONCLUSION: Intraarterial signal on FLAIR images is an early sign of occlusion of major arteries. FLAIR combined with diffusion-weighted imaging can be helpful to predict an area at risk for infarction (ischemic penumbra). FLAIR plays an important role for determining whether a patient should undergo perfusion study.     

脑血管狭窄支架置入术后并发高灌注综合征3例

高灌注综合征(hyperpelfusion syndrome,HS)作为血管成形术后一种少见但严重的并发症值得我们关注.高灌注综合征发生在血管自动调节功能衰退并已适应低灌注压的血管床,通常在同侧出现颅内血管血流量显著增高,毛细血管床灌注压急剧增加而引起血脑屏障破坏,从而导致脑肿胀、颅内出血,严重者可导致死亡[1].     

Fluid-attenuated inversion recovery MR imaging and subarachnoid hemorrhage: not a panacea

BACKGROUND AND PURPOSE: Subarachnoid hemorrhage (SAH) constitutes an important neurologic emergency. Some authors have suggested that fluid-attenuated inversion recovery (FLAIR) MR imaging can detect SAH that may not be apparent on CT scans but may be revealed by lumbar puncture. We sought to determine how often FLAIR MR imaging findings are positive for SAH in cases with negative CT findings and positive lumbar puncture results. METHODS: The CT scans and FLAIR MR images of all patients with suspected SAH during a 3-year interval (2000-2002) were retrospectively reviewed by a blinded reader. Among these cases, we identified 12 with CT findings that were negative for SAH, lumbar puncture results that were positive for SAH, and FLAIR MR imaging findings that were available for review. Eleven of the 12 patients had undergone FLAIR MR imaging within 2 days of CT and lumbar puncture. The 12 patients with negative CT findings were comprised of six male and six female patients with an age range of 7 to 69 years. We evaluated the true and false negative and positive FLAIR MR imaging findings for SAH by using the lumbar puncture results as the gold standard. The FLAIR MR imaging findings of 12 additional patients without SAH (as revealed by lumbar puncture) were used as control data for a blinded reading. RESULTS: For all 12 control cases without SAH, the FLAIR MR imaging findings were interpreted correctly. Of the 12 cases that had positive lumbar puncture results but false-negative CT findings for SAH, FLAIR MR imaging findings were true-positive in only two cases and were false-negative in 10. One of the two true-positive cases had the highest concentration of RBC in the series (365 k/cc), and the other had the second highest value of RBC (65 k/cc). CONCLUSION: FLAIR MR imaging cannot replace lumbar puncture to detect the presence of SAH. FLAIR MR imaging findings are infrequently positive (16.7%) when CT findings are negative for SAH. This is likely because there is a minimum concentration of RBC/cc that must be exceeded for CSF to become hyperintense on FLAIR MR images.     

Fluid-attenuated inversion recovery ring sign as a marker of dysembryoplastic neuroepithelial tumors

PURPOSE: The aim of our study is to describe the hyperintense ring sign on fluid-attenuated inversion recovery (FLAIR) images in patients with dysembryoplastic neuroepithelial tumors (DNET), to discuss the radiopathologic correlation for this appearance, and to determine its role in preoperative diagnosis of DNETs. MATERIALS AND METHODS: We retrospectively analyzed imaging features in 11 patients with pathological diagnosis of DNET. All patients had undergone surgery for refractory seizures. All had FLAIR imaging sequences performed on a 1.5-T magnetic resonance scanner. Clinical and pathological details in all cases were examined. Twenty-one age matched patients with pathologically confirmed low-grade glioma (n = 11), oligodendroglioma (n = 2), and ganglioglioma (n = 8) in similar locations acted as control cases. Ten patients had follow-up imaging. RESULTS: There were 11 patients with DNET (5 girls and 6 boys). The age of presentation varied from 4 to 18 years (average, 9 years 1 month). Tumors were located in the temporal (n = 5), frontal (n = 4), parietal (n = 1), and occipital (n = 1) lobes. In 9 patients (82% sensitivity), the FLAIR images showed a well-defined hyperintense ring around these tumors, either as a complete or incomplete ring. Among the 21 control cases, the hyperintense ring sign was seen in 2 cases (90% specificity): one with low-grade glioma and one with ganglioglioma. Pathological evaluation of the DNETs suggested the hyperintense ring might correspond to the presence of peripheral loose neuroglial elements. Postoperative imaging showed partial residual ring in 3 patients, all of whom had persistent seizures. One patient had recurrent DNET at second surgery. CONCLUSION: Magnetic resonance imaging findings of DNET are well described. We describe an additional imaging sign, the hyperintense ring sign on FLAIR images, which is distinct and is fairly sensitive and specific for DNET. We believe this sign is a helpful adjuvant to preoperatively diagnose these tumors. The presence of this ring on postoperative imaging may indicate residual or recurrent tumor.     

Acute cerebral vascular accident associated with hyperperfusion.

Cerebral radionuclide angiography can demonstrate decreased or normal radioactivity in the affected region during the arterial phase in patients who have sustained a cerebral vascular accident and thus enhances the diagnostic specificity of the static brain image. In an occasional patient, however, a seemingly paradoxical pattern of regional hyperperfusion with a return to normal or subnormal perfusion following the acute phase has been observed. This phenomenon, called "luxury perfusion," has been defined using intra-arterial 133Xe for semiquantitative cerebral blood flow measurements and should be kept in mind as a potentially misleading cerebral imaging pattern.     

Migraine associated cerebral hyperperfusion with arterial spin-labeled MR imaging

We present a case series demonstrating abnormal regional cerebral hyperperfusion associated with migraine headache using arterial spin-labeling (ASL). In 3 of 11 patients, regional cortical hyperperfusion was demonstrated during a headache episode that corresponded to previous aura symptoms.     

Cerebral hyperperfusion syndrome resulting in subarachnoid hemorrhage after carotid artery stenting

A 64-year-old, right-handed man underwent endovascular treatment for internal carotid artery stenosis after experiencing a left-hemispheric transient ischemic attack. ¹⁵O-gas and H ₂ ¹⁵ O positron emission tomography revealed slightly reduced cerebral blood flow (CBF), elevated cerebral blood volume, and severely reduced cerebral vasoreactivity in the ipsilateral hemisphere as determined by an acetazolamide challenge test. The patient underwent left carotid artery stenting (CAS) via a prefemoral approach under local anesthesia without any complications. Follow-up examinations performed 20 h postoperatively showed subarachnoid hemorrhage (SAH) and cerebral hyperperfusion syndrome (CHS) in the left frontal lobe. Although it is a relatively rare phenomenon, SAH resulting from CHS was determined to be specifically caused by CAS. In this case, the causes of SAH may have been related to multiple factors including increased regional CBF, loss of cerebrovascular autoregulation, contrast agent-mediated disruption of major cerebral vessels, and strong antiplatelet therapy.     

Anoxic injury-associated cerebral hyperperfusion identified with arterial spin-labeled MR imaging

BACKGROUND AND PURPOSE: Anoxic brain injury is a devastating result of prolonged hypoxia. The goal of this study was to use arterial spin-labeling (ASL) to characterize the perfusion patterns encountered after anoxic injury to the brain.MATERIALS AND METHODS: Sixteen patients with a history of anoxic or hypoxic-ischemic injury ranging in age from 1.5 to 78.0 years (mean, 50.3 years) were analyzed with conventional MR imaging and pulsed ASL 1.0–13.0 days (mean, 4.6 days) after anoxic insult. The cerebral perfusion in each case was quantified by using pulsed ASL as part of the standard stroke protocol. Correlation was made among perfusion imaging, conventional imaging, clinical history, laboratory values, and outcome.RESULTS: Fifteen of the 16 patients showed marked global hyperperfusion, and 1 patient showed unilateral marked hyperperfusion. Mean gray matter (GM) cerebral blood flow (CBF) in these patients was 142.6 mL/100 g of tissue per minute (ranging from 79.9 to 204.4 mL/100 g of tissue per minute). Global GM CBF was significantly higher in anoxic injury subjects, compared with age-matched control groups with and without infarction (F_2,39 = 63.11; P < .001). Three patients had global hyperperfusion sparing areas of acute infarction. Conventional imaging showed characteristic restricted diffusion in the basal ganglia (n = 10) and cortex (n = 13). Most patients examined died (n = 12), with only 4 patients surviving at the 4-month follow-up.CONCLUSION: Pulsed ASL can dramatically demonstrate and quantify the severity of the cerebral hyperperfusion after a global anoxic injury. The global hyperperfusion probably results from loss of autoregulation of cerebral vascular resistance.

Anoxic injuries resulting from global cessation of oxygenated cerebral blood flow (CBF) have profound effects on cerebral metabolism. Characteristic imaging findings include infarctions in regions with higher metabolic demands, including the basal ganglia and cerebral cortex.^1–3 Arterial spin-labeling (ASL) perfusion imaging generates qualitative and quantitative data. ASL perfusion imaging findings in these patients have not been described in the literature. Xenon CT perfusion has been used to evaluate postresuscitation patients with mixed results.^4–6 Other cerebral perfusion methods, such as nuclear medicine hexamethylpropyleneamine oxime single-photon emission CT and O-15 positron-emission tomography (PET), rely on differences in regional perfusion and may not detect a global symmetric hyperperfusion pattern.⁷ The goal of this study was to use ASL to characterize the perfusion patterns encountered after anoxic injury to the brain. We present a series of 16 patients with a history of anoxic injury who demonstrated marked cerebral hyperperfusion on pulsed ASL perfusion imaging. We propose that this marked hyperperfusion is secondary to the loss of autoregulation of cerebral vascular resistance caused by the anoxic injury.     

症状性颅内动脉狭窄支架置入术围手术期护理

目的：探讨支架置入术治疗症状性颅内动脉狭窄围手术期的护理。方法：回顾性分析21例症状性颅内动脉狭窄患者的术前、术后临床资料并总结护理经验。结果：患者支架全部置放成功。术后有1例患者发生脑梗死，出现一侧肢体偏瘫、失语，经尿激酶溶栓治疗后，症状明显好转。其余患者临床症状均有明显改善，术后随访期间无短暂性脑缺血再发作或卒中。结论：加强症状性颅内动脉狭窄围手术期的护理是手术成功的关键。     

血管内支架成形术治疗颅内动脉狭窄

目的:探讨颅内动脉狭窄血管内球囊支架成形术的可行性、安全性及其疗效。方法:17例患者术前3天给予阿司匹林300mg/天和噻氯吡啶250mg/天,6F(Envoy)导引导管放置到颈内动脉远段或椎动脉近颅底段,造影获得工作位,评价血管狭窄程度:狭窄率=(1-狭窄处管径/狭窄远端管径)×100%,微导丝在路途导引下通过颅内动脉狭窄段,向远端直至P2或M2段,确保足够的支撑力。选择支架大小的依据为狭窄远端正常血管的直径,导丝引导下支架通过狭窄部位,造影确定支架位置正确,充盈球囊至5～6大气压,支架释放后造影确认展开良好,回撤球囊,无并发症,操作完毕。随访3～10月。结果:17例患者颅内动脉狭窄处植入支架,技术成功100%,造影显示狭窄由术前(78.3±12.9)%降至术后(6.8±7.3)%,狭窄的动脉管径恢复,短期随访(3～10个月)显示很好临床效果。术中出现一例蛛网膜下腔少量出血(SAH),对症治疗痊愈。6例随访造影未见血管再狭窄。结论:颅内动脉狭窄支架植入增加血管内径,改善血流量,减轻临床症状,是一种安全、可行有效的治疗方法。     

Fast inversion recovery magnetic resonance angiography of the intracranial arteries

Inversion‐prepared pulse sequences can be used for noncontrast MR angiography (MRA) but suffer from long scan times when acquired using conventional nonaccelerated techniques. This work proposes a subtraction‐based spin‐labeling, three‐dimensional fast inversion recovery MRA (FIR‐MRA) method for imaging the intracranial arteries. FIR‐MRA uses alternating cycles of nonselective and slab‐selective inversions, leading to dark‐blood and bright‐blood images, respectively. The signal difference between these images eliminates static background tissue and generates the angiogram. To reduce scan time, segmented fast gradient recalled echo readout and parallel imaging are applied. The inversion recovery with embedded self‐calibration method used allows for parallel acceleration at factors of 2 and above. An off‐resonance selective inversion provides effective venous suppression, with no detriment to the depiction of arteries. FIR‐MRA was compared against conventional three‐dimensional time‐of‐flight angiography at 3 T in eight normal subjects. Results showed that FIR‐MRA had superior vessel conspicuity in the distal vessels (P < 0.05), and equal or better vessel continuity and venous suppression. However, FIR‐MRA had inferior vessel sharpness (P < 0.05) in four of nine vessel groups. The clinical utility of FIR‐MRA was demonstrated in three MRA patients. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Fluid-attenuated inversion recovery preparation: not an improvement over conventional diffusion-weighted imaging at 3T in acute ischemic stroke

BACKGROUND AND PURPOSE: Change in signal intensity due to acute ischemic stroke can be detected on diffusion-weighted (DW) images soon after symptom onset. Fluid-attenuated inversion recovery (FLAIR) DW imaging suppresses signal intensity from water and has been suggested to be better than conventional DW imaging as a diagnostic imaging technique in acute stroke. We compared the signal intensity-to-noise ratio (SNR) and contrast-to-noise-ratio (CNR) between ischemic and normal tissues by using these two sequences. METHODS: Twenty stroke patients underwent imaging less than 6 hours after stroke onset by using both acquisition methods. The SNR of six regions of interest in normal brain and one region in ischemic brain were compared on both DW imaging and FLAIR DW imaging. We also compared CNR in normal and ischemic tissues. The calculated apparent diffusion coefficient (ADC) maps from each acquisition technique were similarly assessed. RESULTS: The SNR was significantly lower for FLAIR DW imaging than for DW imaging (P < .05). The CNR between normal and ischemic tissue was also lower on FLAIR DW imaging (P < .05). SNR and CNR of the ADC maps were significantly different (P < .05) for all tissues except the putamen and white matter (for SNR and CNR) and globus pallidus (for CNR only). CONCLUSION: Ischemic tissue on FLAIR DW imaging was significantly less conspicuous than on DW imaging and potentially limits the clinical utility of this sequence.