MR FLAIR序列、DWI序列及CT检查对急性蛛网膜下腔出血的诊断价值

目的探讨MR液体衰减反转恢复(FLAIR)序列、弥散加权成像(DWI)序列及CT对急性蛛网膜下腔出血(SAH)的诊断价值。方法分析69例经腰穿证实的SAH患者的MR检查(包括FLAIR、DWI序列)及CT资料,观察SAH的MR、CT表现,并比较两种方式的诊断价值。结果 69例经腰穿证实的SAH患者中,MR FLAIR序列检查阳性患者66例,3例阴性患者,检出率为95.65%,其中59例局限性SAH,7例广泛性SAH;而MR DWI序列检查阳性患者65例,4例阴性患者,检出率为94.20%,其中43例局限性SAH,22例广泛性SAH。CT扫描阳性患者55例,14例阴性患者,检出率为79.71%,其中44例局限性SAH,图像表现为局限于脑沟或脑池中的条形铸型或片状高密度影,11例广泛性SAH。MR FLAIR、DWI序列与CT三组间诊断SAH的价值比较,差异具有统计学意义(P0.05)。两两组间比较,除MR FLAIR序列与MR DWI序列的差异无统计学意义(P0.05)外,MR FLAIR序列与CT、MR DWI序列与CT比较,差异具有统计学意义(P0.05)。结论 MR FLAIR序列、DWI序列对急性蛛网膜下腔出血的诊断价值高于CT检查。     

液体衰减反转恢复序列MR成像在颅脑创伤诊断中价值的研究

目的评价MR液体衰减反转恢复序列(fluid-attenuated inversion recovery,FLAIR)诊断各种颅脑创伤病变的价值.方法22例颅脑创伤病例均进行了CT和MR T1WI、T2WI及FLAIR序列检查,CT与MR检查的时间间隔为4.6±3.7天.观察CT与三种MR序列上各种病变病灶的显示数,将FLAIR所见的结果分别与CT、T1WI及T2WI结果作统计学分析(t检验).结果22例共有100个颅内创伤病灶,CT检出率为25%,T1WI为49%,T2WI为71%,FLAIR检出率为100%,差异显著(P<0.0005).其中FLAIR对非出血性脑挫伤的显示效果最佳,优于其它三种技术(P<0.0005);对于出血性挫伤,FLAIR优于CT(P<0.0025),但与T1WI及T2WI无明显差别;FLAIR对硬膜下/硬膜外血肿的发现能力与其它三种技术相似,对硬膜下积液的显示优于CT(P<0.0025),与T1WI及T2WI则无显著差异;FLAIR对亚急性期的蛛网膜下腔出血(SAH)的显示能力超过CT和T2WI(P<0.05),但CT与FLAIR对急性SAH的显示能力一致.结论FLAIR序列能明显地改善颅脑创伤性病变的显示,优于CT和常规MRI技术,其中以非出血性挫伤和亚急性期的SAH效果最佳.FLAIR序列可作为颅脑创伤检查的常规手段.     

高场MRIFLAIR及SWI序列在蛛网膜下腔出血诊断中的价值

目的 :探讨高场MRI FLAIR及SWI序列在蛛网膜下腔出血(subarachnoid hemorrhage,SAH)诊断中的价值。方法 :回顾性分析我院47例分别行高场MRI和CT检查的SAH患者的临床和影像资料,比较CT、MRI常规序列、FLAIR和SWI对不同类型病变的显示情况。结果:MRI FLAIR序列显示SAH呈高信号影,而在SWI序列上均呈不同程度的低信号。T1WI、T2WI对于急性SAH检出率较低,对于亚急性SAH和陈旧性SAH检出率更低;CT对急性SAH和亚急性SAH的检出率分别为75.00%和52.94%;SWI、FLAIR对急性SAH的检出率分别为100%和93.75%,对亚急性SAH的检出率分别为94.12%和82.35%,对陈旧性SAH的检出率分别为100%和92.86%,均明显高于CT和T1WI、T2WI序列,SWI、FLAIR联合诊断准确率为100%,差异具有统计学意义(P0.05)。结论:高场MRI FLAIR和SWI对SAH诊断敏感性高,具有较好的诊断价值,应常规应用。     

T2FLAIR与GRE-T2?WI对诊断创伤性颅内脑外出血的比较研究

目的：探讨液体衰减反转恢复(FLAIR)序列与梯度回波 T2?加权(GRE-T2? WI)序列对急性创伤性颅内脑外出血诊断的价值。方法50例 CT 平扫发现的急性创伤性颅内脑外出血患者,于急性期同时行 FLAIR 序列及 GRE-T2? WI 序列检查,分析比较两者对蛛网膜下腔出血(SAH)、硬膜外出血(EDH)及硬膜下出血(SDH)诊断的总体一致性(Kappa)、总体检出率,并利用χ2检验进一步比较 FLAIR、GRE-T2? WI 序列及结合2序列分别诊断8个部位 SAH 的差异。结果48例患者最终入组。48例 SAH患者的 FLAIR 序列及 GRE-T2? WI 序列诊断总体一致性很高(k =1.0),总体检出率均为100%,各部位检出率与结合2序列诊断比较,FLAIR 序列较 GRE-T2? WI 序列与结合2序列更容易误诊中脑周围池 SAH(P 值<0.05);3例 EDH 患者 FLAIR 序列及GRE-T2? WI 序列诊断一致性很高(k =1.0),检出率均为100%;12例 SDH 患者诊断一致性较高(k =0.943),FLAIR 序列检出率为100%,1例 SDH 患者 GRE-T2? WI 序列未能诊断。结论FLAIR 序列与 GRE-T2? WI 序列对诊断急性创伤性颅内脑外出血的检出率均较高,2序列结合能够提高对急性创伤性颅内脑外出血诊断的准确性。     

兔急性少量蛛网膜下腔出血的模型建立及影像学表现

目的 拟通过动物实验,对比分析CT和MR常规序列对急性少量蛛网膜下腔出血(SAH)的诊断敏感度,以期发现更为敏感的检查方法.方法 选用新西兰大耳白兔18只,随机分为实验组(A组、B组)、对照组(C组)采用枕大池穿刺一次注血法建立SAH模型,分别于术后2 h、48 h行CT和MR扫描,记录CT和MR常规序列对SAH的显示.结果 ①实验组A组、B组MR FLAIR序列诊断兔急性少量SAH的敏感度较MR T1WI、T2WI及CT均高;MR FLAIR序列与CT比较,两者差异有统计学意义(P<0.05).②对照组C组未见SAH.结论 ①本研究成功建立了"枕大池一次注血法"兔SAH模型,为后续的影像学研究奠定了基础.②MR FLAIR序列对急性少量SAH的诊断较CT更为敏感,可常规用于急性少量SAH的诊断.     

高场磁共振磁敏感加权成像联合液体衰减恢复序列对蛛网膜下腔出血的诊断价值

目的：评价高场磁共振磁敏感加权成像（SWI）联合液体衰减恢复序列（FLAIR）对蛛网膜下腔出血（SAH）的诊断价值。方法回顾性分析50例经磁共振诊断为蛛网膜下腔出血的患者MR表现,行常规T1WI、T2WI扫描及FLAIR、SWI序列扫描。结果50例蛛网膜下腔出血患者FLAIR及SWI均可显示,FLAIR表现为脑沟裂池内高信号,SWI为低信号,6例患者T1WI可见高信号蛛网膜下腔出血,T2WI无一例显示。结论常规MR序列诊断SAH准确率不高,FLAIR联合SWI对SAH敏感性高,诊断准确率高,可作为诊断SAH的常规序列组合。     

高敏感SWAN序列诊断自发性蛛网膜下腔出血的价值

目的 :探讨SWAN序列对自发性蛛网膜下腔出血(subarachnoid hemorrhage,SAH)及合并脑室内积血(intraventricular hemorrhage,IVH)的诊断价值。方法 :回顾性分析自发性SAH患者32例,均行CT平扫及MRI T1WI、T2WI、FLAIR、SWAN、DWI检查,分析CT平扫与MRI各序列对各期SAH和IVH的检出率。结果:1急性期:CT平扫、FLAIR序列、SWAN对SAH的诊断敏感度均较高,三者差异无统计学意义,但与MRI其他序列相比,差异有统计学意义(P=0.031)。2亚急性期:T1WI、FLAIR、SWAN对SAH的诊断敏感度优于CT和MR其他序列,差异有统计学意义(P0.05)。3慢性期:MRI各序列对于SAH的诊断敏感度均明显优于CT,尤其是SWAN序列(P=0.008)。4对SAH合并IVH的检出,急性期CT与SWAN、DWI(b=0 s/mm~2)的检出能力相当,较MRI其他序列强;且亚急性期和慢性期SWAN、DWI(b=0 s/mm~2)的检出能力明显优于CT。结论:SWAN序列对各期SAH的诊断敏感度较CT及MRI其它序列有优势,SWAN、DWI(b=0 s/mm~2)对于SAH合并IVH的检出也有优势,SWAN是目前检出少量SAH及IVH最好的检查方法。     

快速液体抑制反转恢复脉冲序列在脑挫裂伤中的应用

目的探讨快速液体抑制反转恢复脉冲序列(FastFLAIR)在脑挫裂伤诊断中的应用价值.材料与方法回顾性分析36例脑挫裂伤患者的MR表现,对FastFLAIR、T2W/TSE及T1W/SE三种序列进行比较.结果在36例脑挫裂伤患者中FLAIR显示病灶较T2WI清晰者28例,在经过腰穿或CT检查证实合并有蛛网膜下腔出血的29例患者中,FLAIR序列可100%明确诊断,而T1WI明确诊断的仅11例(占37.9%).结论对脑挫裂伤病灶的显示及蛛网膜下腔出血的诊断FLAIR具有重要价值.     

低场磁共振T_1FLAIR序列在颅脑肿瘤诊断中的应用

目的 :通过T1FLAIR(液体反转恢复 )序列与传统SE(自旋回波 )序列T1加权图像对比分析 ,评价T1FLAIR作为T1成像序列对颅脑肿瘤的诊断价值。方法 :对 2 3例颅脑疾病患者均用两种序列检查。结果 :在 2 3例颅脑肿瘤中 ,T1FLAIR序列对病灶显示的图像清晰度比SE序列高。结论 :在相同病变检出率的情况下 ,T1FLAIR像在显示颅脑中灰白质对比度、病变和背景对比情况及病变的边界、大小、范围方面优于传统SE序列T1加权像 ,具有重要的临床诊断价值。     

磁共振T_2FLAIR与DWI序列在少量自发性蛛网膜下腔出血中的诊断价值

目的探讨磁共振T_2FLAIR与DWI序列在少量自发性蛛网膜下腔出血中的诊断价值。方法回顾性分析21例经腰穿证实的少量自发性蛛网膜下腔出血患者的MRI资料,包括T_2FLAIR与DWI,并与CT对比。结果 21例少量自发性蛛网膜下腔出血中,磁共振T_2FLAIR全部显示阳性,显示率100%,CT仅2例显示阳性,显示率9.5%。21例中DWI检查16例,显示阳性10例,显示率62.5%。结论磁共振T_2FLAIR与DWI序列显示少量自发性蛛网膜下腔出血明显优于CT。     

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.     

磁共振快速液体衰减反转恢复序列对亚急性和慢性蛛网膜下腔出血的诊断价值

目的研究ＭＲ快速液体衰减反转恢复（ｆｌｕｉｄａｔｅｎｕａｔｅｄｉｎｖｅｒｓｉｏｎｒｅｃｏｖｅｒｙ,ＦＬＡＩＲ）序列诊断亚急性和慢性蛛网膜下腔出血（ｓｕｂａｒａｃｈｎｏｉｄｈｅｍｏｒｈａｇｅ,ＳＡＨ）的价值。方法３０例头部健康者和１７例次ＳＡＨ患者在发病后第４～３５天进行头部ＭＲＩ检查。扫描机为０．５Ｔ超导ＭＲ机。观察亚急性和慢性ＳＡＨ在ＦＬＡＩＲ的信号表现,并与同期ＣＴ和常规ＭＲＩ所见比较。再对４６个正常和病变的ＦＬＡＩＲ图像做双盲比较分析,以评价其诊断可靠性。结果ＦＬＡＩＲ成像显示亚急性和慢性ＳＡＨ（９４％）明显优于Ｔ１ＷＩ（４１％,Ｐ＜０．０１）和ＣＴ（２７％,Ｐ＜０．０１）。尤其在亚急性期,ＦＬＡＩＲ成像显示率达１００％,与ＣＴ（３３％,Ｐ＜０．０１）相比差异有非常显著性意义。双盲分析结果,无一例假阳性和假阴性诊断。结论快速ＦＬＡＩＲ序列诊断亚急性和慢性ＳＡＨ明显优于ＣＴ和常规ＭＲＩ,应作为本病检查的常规方法     

MR imaging of hyperacute subarachnoid and intraventricular hemorrhage at 3T: a preliminary report of gradient echo T2*-weighted sequences

We describe MR imaging findings applying gradient echo (GRE) T2*-weighted and fluid-attenuated inversion recovery (FLAIR) MR images at 3T to three patients with hyperacute subarachnoid and intraventricular hemorrhage from ruptured aneurysms. Hyperacute subarachnoid and intraventricular hemorrhages (SAH and IVH) were more clearly visualized as an area of decreased signal intensity on GRE T2*-weighted sequences than on FLAIR sequences in all three patients. These preliminary results suggest that acute SAH and IVH with GRE T2*-weighted imaging can be reliably diagnosed at 3T.     

Imaging of acute subarachnoid hemorrhage with a fluid-attenuated inversion recovery sequence in an animal model: comparison with non-contrast-enhanced CT.

BACKGROUND AND PURPOSE: Fluid-attenuated inversion recovery (FLAIR) MR imaging sequences have been previously described in the evaluation of acute subarachnoid hemorrhage (SAH) in human subjects and have demonstrated good sensitivity. The purpose of this study was to evaluate a FLAIR sequence in an animal model of SAH and to compare the results with those obtained with non-contrast-enhanced CT. METHODS: SAH was experimentally induced in 18 New Zealand rabbits by injecting autologous arterial blood into the subarachnoid space of the foramen magnum. Nine animals had high-volume (1-2 mL) injections, and nine animals had low-volume (0.2-0.5 mL) injections. Four control animals were injected with 0.5 mL of saline. The animals were imaged with a FLAIR sequence and standard CT 2-5 hours after injection. Gross pathologic evaluation of seven of the animals was performed. Four blinded readers independently evaluated the CT and FLAIR images for SAH and graded the probability of SAH on a scale of 1 to 5 (1 = no hemorrhage, 5 = definite hemorrhage). RESULTS: Overall, the sensitivity of FLAIR was 89%, and the sensitivity of CT was 39% (P <.01). In animals with a high volume of SAH, the sensitivity of FLAIR was 100%, and the sensitivity of CT was 56%. In animals with a low volume of SAH, the sensitivity of FLAIR was 78%, and the sensitivity of CT was 22%. The specificity of FLAIR in animals without SAH was 100%, and the specificity of CT was 100%. The average reader score for FLAIR was 3.8, and that for CT was 2.2 (P <.001). Reader scores for FLAIR were higher than those for CT in 94% (P <.01) of animals with SAH and in 25% of animals without SAH (P >.05). Seven animals underwent gross pathologic examination, and all had blood in the subarachnoid space around the brain stem. CONCLUSION: FLAIR was more sensitive than CT in the evaluation of acute SAH in this model, especially when a high volume of SAH was present. This study provides a model for further experimentation with MR imaging in the evaluation of SAH. These findings are consistent with those of current clinical literature, which show FLAIR to be an accurate MR sequence in the diagnosis of SAH.     

Fluid-attenuated inversion-recovery MR imaging in acute and subacute cerebral intraventricular hemorrhage.

BACKGROUND AND PURPOSE: Fluid-attenuated inversion-recovery (FLAIR) MR imaging may show subarachnoid hemorrhage (SAH) with high sensitivity. We hypothesized that the FLAIR technique is effective and reliable in the diagnosis of cerebral intraventricular hemorrhage (IVH). METHODS: Two observers evaluated the 1.5-T MR fast spin-echo FLAIR images, T1- and T2-weighted MR images, and CT scans of 13 patients with IVH and the FLAIR images of 40 control subjects. RESULTS: IVH appeared bright on the FLAIR images obtained during the first 48 hours and was of variable appearance at later stages. FLAIR MR imaging detected 12 of 13 cases of IVH; no control subjects were falsely thought to have IVH (92% sensitivity, 100% specificity). However, IVH could not be fully excluded in the third ventricle (20%, n = 8) or in the fourth ventricle (28%, n = 11) on some control images because of CSF pulsation artifacts. Two cases had CT-negative IVH seen on FLAIR images. One case had FLAIR-negative IVH seen by CT. Although the sensitivities of conventional MR imaging (92%) and CT (85%) were also high, FLAIR imaging showed IVH more conspicuously than did standard MR imaging and CT in 62% of the cases (n = 8). FLAIR was as good as or better than CT in showing IVH in 10 cases (77%). FLAIR images showed all coexisting SAH. CONCLUSION: FLAIR MR imaging identifies acute and subacute IVH in the lateral ventricles with high sensitivity and specificity. In cases of subacute IVH, conventional MR imaging complements FLAIR in detecting IVH. The usefulness of the FLAIR technique for detecting third and fourth ventricular IVH may be compromised by artifacts. Blood hemoglobin degradation most likely causes the variable FLAIR appearance of IVH after the first 48 hours.     

Sulcal hyperintensity on fluid-attenuated inversion recovery imaging in acute ischemic stroke patients treated with intra-arterial thrombolysis: iodinated contrast media as its possible cause and the association with hemorrhagic transformation

OBJECTIVE: To investigate the effect of iodinated contrast medium on sulcal hyperintensity on fluid-attenuated inversion recovery (FLAIR) imaging immediately after intra-arterial thrombolysis in patients with acute ischemic stroke and to determine whether it may be associated with subsequent hemorrhagic transformation (HT). METHODS: Fourteen consecutive patients with acute ischemic stroke who were treated with intra-arterial thrombolysis were enrolled. All patients underwent noncontrast computed tomography (NCT) and diffusion-weighted (DWI), perfusion-weighted, gradient-recalled echo (GRE), and gadolinium-enhanced T1-weighted magnetic resonance imaging (MRI). Immediate follow-up NCT and MRI (T2-weighted, FLAIR, GRE, DWI, perfusion-weighted, T1-weighted, and gadolinium-enhanced T1-weighted) were obtained and evaluated to determine the presence of sulcal hyperintensity or subarachnoid hemorrhage (SAH). The same follow-up images were obtained on days 1, 3, and 7 and evaluated to determine HT. RESULTS: Sulcal hyperintensity was found in 8 (57.1%) of 14 patients and was seen as hyperattenuation on immediate follow-up NCT and as hyperintensity on T1-weighted images in 4 (50%) of 8 patients. It may be suggested that the sulcal hyperattenuation was responsible for the sulcal hyperintensity, considering signal intensity and follow-up imaging. All patients with sulcal hyperintensity showed enhancement in the corresponding gyri on gadolinium-enhanced T1-weighted imaging. Hemorrhagic transformation developed in 5 of 8 patients with sulcal hyperintensity and in 1 of 4 patients without (P = 0.031). CONCLUSIONS: In acute ischemic patients treated with intra-arterial thrombolysis, sulcal hyperintensity on FLAIR imaging may be caused by iodinated contrast medium, which should not be considered SAH. Sulcal hyperintensity is significantly associated with subsequent HT.