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 …

目的 研究ＭＲ快速液体衰减反转恢复（ＦＬＡＩＲ）序列诊断亚急性和慢性蛛网膜下腔出血（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Ｓ     

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。     

蛛网膜下腔出血磁共振成像与CT的对照研究

目的：利用磁敏感加权成像（SWI）、液体衰减反转恢复（FLAIR）、CT诊断蛛网膜下腔出血（SAH）,进一步比较联合磁共振成像（MRI） SWI/FLAIR与CT比较评估MRI是否优于CT。方法25例经临床证实的蛛网膜下腔出血的患者纳入本研究,所有患者均在发病3 d内进行CT、MRI检查。观察CT及MRI图片,将蛛网膜下腔分为8个区进行分析。结果总共145个区域被诊断为SAH,CT诊断了105个区域（72．4％）, FLAIR诊断了125个区域（86．2％）,SWI诊断了137个区域（94.5％）,FLAIR联合SWI诊断了135个区域（93．1％）。结论 FLAIR、SWI对于SAH的显示优于CT,FLAIR对颞枕部病灶的显示具有优势,SWI对中央区域的SAH比较敏感,将FLAIR、SWI两者融合,可以互补,能更准确地诊断SHA。     

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。     

MR FLAIR序列对急性蛛网膜下腔出血的诊断价值

目的评价MR液体衰减反转恢复(fluid attenuated inversion recovery,FLAIR)序列对急性蛛网膜下腔出血(subarachnoid hemorrhage,SAH)的诊断价值。资料与方法30例无颅脑疾病者和65例急性SAH患者在发病3天内行头MRI检查,观察急性SAH在FLAIR序列上的信号表现及CT表现,将两种检查结果进行比较。对颅脑正常者和SAH的FLAIR图像进行双盲分析,以评价FLAIR对SAH的诊断价值。结果MRFLAIR序列对急性SAH的显示率为96.9%(63/65),明显高于CT显示率(80.0%,52/65)。结论MRFLAIR序列对急性SAH的诊断优于CT,应作为常规检查方法。     

急性蛛网膜下腔出血的低场强MRI诊断

目的探讨低场强ＭＲＩ诊断急性蛛网膜下腔出血的价值。材料与方法对８０例临床疑诊急性蛛网膜下腔出血的病人行ＭＲ检查,扫描机为ＡＳＭ—０１５ｐ,采用ＳＥ序列,参数Ｔ２ＷＩ≤ＴＲ２０００／ＴＥ１００ｍｓ,所有病例分别经腰穿、手术或治疗后复查证实,并与化脓性脑膜炎、结核性脑膜炎等脑脊液蛋白量增高的疾病进行了鉴别,与脑出血破入脑室或溢入蛛阿膜下腔者进行对照。结果本组病例在低场强ＭＲＩ条件下于病变区脑沟（裂池）等蛛网膜下腔Ｔ２ＷＩ均出现异常高亮脑脊液信号。探其原因为蛛网膜下腔出血可延长Ｔ２值。脑脊液蛋白含量高的其它疾病不出现异常高亮信号。结论低场强磁共振成像对急性蛛网膜下腔出血有较大的诊断价值。     

蛛网膜下腔出血MRI诊断价值与进展

蛛网膜下腔出血(SAH)是临床最常见的危急病之一,准确及时地诊断十分必要.随着现代医学影像技术的飞速发展,尤其是MRI新技术的临床应用,其对SAH诊断的敏感性不断增加,但对蛛网膜下腔少量出血的早期确诊仍是影像学检查的一个挑战.简述CT与MRI各序列的成像原理,对比了CT和MRI对急性、亚急性、慢性SAH诊断的敏感性,并总结SAH在CT和MRI影像表现上的各种假阳性情况.旨在提高本病的诊断率,为临床确定治疗方案提供依据,探讨最合适的影像学检查方法.     

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。     

外伤性蛛网膜下腔出血诊断

目的:探讨外伤性蛛网膜下腔出血的诊断。方法:对以外伤后头痛头晕症状明显为主诉,3d内症状无明显缓解的患者92例为研究对象,结合体征及头颅CT检查结果行腰穿检查。结果:头颅CT提示脑皮质点片状高密度影及脑池、脑沟高密度影及可疑脑池、脑沟高密度影患者腰穿结果均证实有蛛网膜下腔出血。头痛头晕症状明显头颅CT检查未见异常患者行腰穿90%证实有蛛网膜下腔出血。结论:无论是否伴有恶心呕吐症状或脑膜刺激征,头颅CT提示脑皮质点片状高密度影及脑池、脑沟高密度影及可疑脑池、脑沟高密度影患者均符合蛛网膜下腔出血的诊断。头痛头晕症状明显头颅CT检查未见异常3d内症状无明显缓解的患者要高度怀疑蛛网膜下腔出血的可能。外伤性蛛网膜下腔出血脑膜刺激征表现可不明显。     

颅脑MRI快速液体衰减反转回复技术探讨

目的：探讨快速液体衰减反转回复（ＦＬＡＩＲ）技术原理及其在颅脑的临床应用。材料与方法：对４０例健康志愿者及１２４例颅脑疾患患者前瞻性地进行快速ＦＬＡＩＲ及Ｔ２加权序列ＭＲ检查，并比较了快速ＦＬＡＩＲ上不同ＴＲ、ＴＩ（间隔时间）、ＴＥ组合所得图像质量。结果：ＴＲ／ＴＩ／ＴＥ为８０００／２０００／２００毫秒的组合能较好地抑制脑脊液信号。ＦＬＡＩＲ与快速自旋回波Ｔ２加权序列比较，能增加病灶的对比度，从而     

Pediatric subarachnoid hemorrhage: Pseudotrauma

We report three pediatric patients presenting with acute subarachnoid hemorrhage in a clinical setting of trauma. A berry aneurysm was ultimately diagnosed in each patient as the source of hemorrhage, and we believe that the trauma that these patients sustained was not contributory to their subarachnoid hemorrhage. We now use magnetic resonance imaging and magnetic resonance angiography (MRI/MRA) to evaluate these patients noninvasively. MRI/MRA is useful for the diagnosis and subsequent guidance of treatment planning in pediatric patients with subarachnoid hemorrhage without severe head trauma. The opinions and assertions contained herein are solely those of the aforementioned authors and are not to be construed as official or as representing those of the U.S. Army Medical Department, U.S. Army, or Department of Defense.     

MRI in acute subarachnoid haemorrhage; findings with a standardised stroke protocol

There is doubt as to whether acute haemorrhage is visible on MRI. We carried out MRI within 6 h of symptom onset on five patients with minor (low Hunt and Hess grades 1 or 2) subarachnoid haemorrhage (SAH) diagnosed by CT to search for any specific pattern. We used our standard stroke MRI protocol, including multiecho proton density (PD)- and T2-weighted images, echoplanar (EPI) diffusion- (DWI) and perfusion- (PWI) weighted imaging, and MRA. In all cases SAH was clearly visible on PD-weighted images with a short TE. In four patients it caused a low-signal rim on the T2*-weighted source images of PWI, and DWI revealed high signal in SAH. In the fifth patient SAH was perimesencephalic; susceptibility effects from the skull base made it impossible to detect SAH on EPI DWI and T2*-weighted images. Perfusion maps were normal in all cases. MRA and conventional angiography revealed an aneurysm in only one patient. Stroke MRI within 6 h of SAH thus shows a characteristic pattern.     

Comparative evaluation of magnetization transfer contrast and fluid attenuated inversion recovery sequences in brain tuberculoma

AIM: To compare T1-weighted magnetization transfer (MT) with fluid attenuated inversion recovery (FLAIR) imaging for evaluating conspicuity and number of lesions in individuals with brain tuberculoma. MATERIALS AND METHODS: In all 28 patients with brain tuberculoma underwent MR examination using fast spin-echo (FSE) T2, spin-echo (SE) T1, T1-weighted MT and FLAIR imaging. Post-contrast T1-weighted MT imaging was taken as the gold standard for assessing the number of lesions. Tuberculomas detected both on T1-weighted MT and FLAIR imaging were examined for the wall to be defined, and were divided into two groups on the basis of presence (group 1) or absence (group 2) of perilesional oedema visible on FLAIR imaging. The mean signal intensity of the wall of the lesions and adjacent oedema or brain parenchyma was analyzed qualitatively and quantitatively. RESULTS: The number of lesions detected on T1-weighted MT was higher than on FLAIR imaging (209 versus 163). Conspicuity in both groups was better on T1-weighted MT images qualitatively as well as quantitatively. The difference in the signal intensity of the wall of the lesion and perilesional oedema was statistically significant only on T1-weighted MT images in group 1 (p=0.0003 versus 0.3), whereas in group 2 it was statistically significant both on T1-weighted MT and FLAIR imaging (p=0.009 versus 0.05). CONCLUSION: FLAIR imaging is not helpful in the examination of brain tuberculomas compared with T1-weighted MT imaging, as it neither contributes to the characterization of lesion nor assesses the true disease load.     

Magnetic resonance imaging of subarachnoid hemorrhage

Summary Magnetic resonance (MR) imaging of subarachnoid hemorrhage (SAH) due to a ruptured aneurysm has been evaluated in relation to CT findings on 30 patients. In the acute stage, particularly less than 24 hours after the bleeding episode (25 patients), SAH appeared of high intensity relative to the surrounding brain on a T-2 weighted SE image but isointense where the corresponding CT scan showed blood clot of attenuation value over 60H. A T-2 weighted SE image was able to reveal subtle evidence of SAH not visible on the CT scan. The T-1 weighted IR image was not as sensitive. Blood clot (HU>60) appeared isointense, but mild and moderate SAH (HU<60) was indistinguishable from normal CSF. MR imaging was also sensitive to subacute and chronic SAH (5 patients). Three out of four SAH appearing normal on CT showed high intensity on T-2 weighted images. Thirteen out of 24 aneurysms (54%) larger than 5 mm in diameter on angiography were detected on T-2 weighted images. Smaller aneurysms less than 4 mm were not visualized. MR imaging was able to indicate the ruptured one in cases of multiple aneurysms by showing hemorrhagic lesions more clearly than CT. We conclude that MR imaging is very helpful for diagnosing SAH, particularly when CT is normal, and in indicating aneurysm location as well as rupture site.     

低场MR FLAIR序列在脑白质疏松症诊断中的应用价值

目的：探讨低场MRI液体衰减反转恢复（fluid liquid attenuated inversion recovery,简称FLAIR） 序列在脑白质疏松症（LA）影像诊断中的应用价值。方法：采用0．3T低场MRI扫描仪对70例LA进行自旋回波（SE）序列和FLAIR序列成像，分析LA在SE及FLAIR序列中的影像表现，比较两种成像序列对LA病变的显示效果。结果：LA MRI表现为侧脑室周围和／或深部脑白质形态不规则、边缘模糊的斑点及点片状异常信号影，SE序列呈等T1或长T1、长T2信号改变，FLAIR呈略高或高信号改变；FLAIR序列成像与SE序列T2WI对LA病灶显示的满意程度及对病变的分级诊断均无明显差异。结论：在低场条件下采用FLAIR序列诊断LA，其成像效果并不比常规SE序列优越。     

MRI demonstration of subarachnoid neurocysticercosis simulating metastatic disease

We present a patient with neurocysticercosis with spinal subarachnoid spread who presented with lower back pain and progressive numbness and weakness of the left leg. MRI of the spine simulated metastasis. MRI of the brain demonstrated a “bunch of grapes” appearance in the basal cisterns, characteristic of cysticercosis. Received: 2 March 1998 Accepted: 7 March 1998     

Imaging of human brain activity at 0.15 T using fluid attenuated inversion recovery (FLAIR) pulse sequences

A 34% change in signal intensity correlated with visual stimulation was observed in the occipital lobes of three normal volunteers examined with MRI at 0.15 T using fluid attenuated inversion recovery pulse sequences. Similar results were observed at 1.0 T. A double difference technique in which difference images are themselves opposed provided an increase in sensitivity.