Use of fluid-attenuated inversion recovery (FLAIR) images in brain check-up]

Fluid-attenuated inversion recovery (FLAIR) images are magnetic resonance (MR) images obtained with an inversion recovery sequence having a long inversion time (T 1) and a long echo time (TE). The purpose of this study was to evaluate the utility of FLAIR images in brain check-up. 320 healthy adults (229 males, 91 females) were examined with FLAIR sequences of several types having repetitive time (TR) of 7000 msec, inversion times of 1700 msec and echo times (TE) of 110 msec. All studies were performed on a SHIMAZU MAGNEX 100 HP 1.0 T imaging system. FLAIR images were useful in detecting cortical and subcortical lesions near the brain surface, which were unclear in the conventional T 2 weighted images. FLAIR images were useful in evaluation of periventricular hyperintensity area (PVH). Frequency and degree of PVH were increased in aging. FLAIR images were useful in the differential diagnosis of lacuna and perivascular space. In conclusion, FLAIR images were very sensitive for the detection of brain lesions in brain check-up.     

Yield of fluid-attenuated inversion recovery in drug-resistant focal epilepsy with noninformative conventional magnetic resonance imaging

PURPOSE: To determine the role in presurgical assessment and evaluate the yield of fast fluid-attenuated inversion recovery (FLAIR) sequences for patients with intractable partial epilepsy for whom conventional magnetic resonance imaging (MRI) was normal. MATERIAL AND METHODS: Forty patients were selected. Conventional MRI including spin echo T1-weighted sagittal images and fast spin echo T2-weighted axial images was normal in 33 patients and showed noninformative lesions in 7. Fast FLAIR and T2-weighted sequences were performed perpendicularly to the hippocampal long axis. RESULTS: Additional abnormalities were found in 40%. They were correlated with electroclinical data in 13 patients (32.5%) and not correlated or doubtful in 3 (7.5%). CONCLUSION: Fast FLAIR sequences brought congruent additional information in 32.5% cases and seemed useful in presurgical evaluation.     

Dynamic changes in magnetic resonance diffusion-weighted and fluid-attenuated images of cerebral fat embolism: a case report]

Cerebral fat embolism (CFE) is serious complication of a long-bone fracture. We reported magnetic resonance (MR) diffusion-weighted (DWI) and fluid attenuated inversion recovery (FLAIR) images in a patient suffered with CFE. A 26-year-old man with a right femoral bone fracture lapsed into a semicoma eight hours later. Eighteen hours after the depressed consciousness, DWI and FLAIR images on MR imaging showed multiple high-intensity spots in corona radiata, basal ganglia, thalamus, corpus callosum, brain stem and cerebellum. Thereby, he was diagnosed as CFE. These multiple lesions were more detectable on FLAIR images than DWI, particularly in posterior fossa. Eight days after the onset, follow-up DWI, FLAIR, and T 2-weighted MR image (T 2 WI) showed most of the lesions disappeared or shrunk. The resolution of the lesions suggests that most of the lesions were brain edema as a result of the unique pathophysiological condition of CFE. The remained lesions were diagnosed as cerebral infarctions. The consciousness of the patient improved alert. Three months later, follow-up MRI showed almost complete resolution of the abnormal intensities. Follow up DWI and FLAIR images observed in the patient indicated that many small lesions occurs throughout the whole brain without a preferential region, and many of the lesions can subside or attenuate in CFE.     

脑梗死患者磁共振液体反转恢复序列成像高信号血管征的意义

目的 探讨脑梗死患者磁共振液体反转恢复序列(FLAIR)成像高信号血管征(HVS)的意义.方法 对我院住院脑梗死患者共262例的磁共振FLAIR成像中的HVS进行识别与分析,并与磁共振血管成像(MRA)和数字减影血管造影(DWI)所见进行对比.结果 共发现HVS 119例(45.4%),其中发病<24 h者47例(47/56,83.9%),且显著高于发病1～7 d(61/151,40.4%)和7 d后(11/55,20.0%)者(χ2=49.371,均P<0.01).HVS位于大脑外侧裂74例(62.2%),皮质沟回11例(9.2%,11/119),后循环34例(28.6%,34/119).HVS分布与MRA和DWI对比表明,在血管病变和缺血性病灶有比较好的对应.结论 磁共振FLAIR成像的HVS有助于脑梗死患者血管病变的评估.     

Signal changes of superior cerebellar peduncle on fluid-attenuated inversion recovery in progressive supranuclear palsy

Pathological changes of the superior cerebellar peduncle (SCP) can occur in PSP. We assessed the clinical history and signal changes in the SCP on fluid-attenuated inversion recovery (FLAIR) images of 12 patients with clinically probable PSP. Three control groups were studied: Parkinson's disease (PD), multiple system atrophy with predominant parkinsonian features (MSA-P), and healthy controls. Three patients who had clinically probable PSP showed increased FLAIR signals within the SCP. No subject with PD or MSA-P showed any signal changes of the SCP. The signal changes in the SCP on FLAIR may be one indicator for differentiating PSP from other parkinsonian diseases.     

Identification of recent lacunar lesions in cases of multiple small infarctions by magnetic resonance imaging

In nine patients with recent lacunar stroke who revealed multiple small lesions in x-ray computed tomography (CT) and magnetic resonance imaging (MRI), CT and MRI enhancement studies were performed on the same day employing iodinated contrast medium and gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), respectively. In CT, the injection of contrast medium enhanced recent lesions in only four of the nine patients; furthermore, the effect was weak. In MRI, the injection of Gd-DTPA enhanced recent lesions in all patients except for one who was examined 4 weeks after ictus, and the effect was excellent. Recent infarcts could be identified only by Gd-DTPA-enhanced MRI in four of the nine patients. In patients with multiple small infarctions, identification of recent small infarcted lesions by CT or MRI is sometimes difficult; however, the use of Gd-DTPA in MRI makes it possible to distinguish recent infarcts from other lesions definitively.     

Interpretation of fluid-attenuated inversion recovery vascular hyperintensity in stroke

Fluid-attenuation inversion recovery (FLAIR) vascular hyperintensity (FVH) is a common presentation on brain magnetic resonance images of patients with acute ischemic stroke. This sign is known as a sluggish collateral flow. Although FVH represents the large ischemic penumbra and collateral circulation, the clinical significance of FVH has not been established. Varying protocols for FLAIR, treatment differences, and heterogeneity of endpoints across studies have complicated the interpretation of FVH in patients with acute stroke. In this review article, we describe the mechanism of FVH, as well as its association with functional outcome, perfusion-weighted images, and large artery stenosis. In addition, we review the technological variables that affect FVH and discuss the future perspectives.     

Preoperative imaging of superficially located glioma resection using short inversion-time inversion recovery images in high-field magnetic resonance imaging

OBJECTIVES: Short inversion-time inversion recovery (STIR) is the only magnetic resonance imaging (MRI) sequence able to produce high contrast images of both brain-CSF and gray matter-white matter in the central nervous system. The aim of the present study is to evaluate the effectiveness of STIR in imaging tumor involvement of the cortical surface and intra-axial structures, its usefulness in the resection of superficially located gliomas. PATIENTS AND METHODS: In this study, we perform conventional MRI (1.5 T) and STIR (3.0 T) before surgery in 10 patients with superficially located glioma. We estimate the spatial relationship between the tumor bulk, the adjacent cortical surface and intra-axial structures on T2WI (1.5 T) and STIR (3.0 T). STIR findings are applied to resection of the tumor in each case. RESULTS: For all patients, STIR provided more satisfactory images than T2WI of both the cortical surface structures and intra-axial structures surrounding the tumor. During surgery, the clear demonstration of cortical surface structures on preoperative STIR images assisted in determining tumor location and the sulci to be split for the trans-sulcal approach for patients whose cortex was normal in colour. Clear contrast on STIR between the tumor margin and peritumoral edema was useful for tumor resection. CONCLUSION: STIR is able to demonstrate anatomical details of the cortical surface and intra-axial structures of the brain and is therefore suitable for the preoperative evaluation of superficially located gliomas.     

Clinical classification for lacunar infarct. An investigation of 130 consecutive cases of lacunar infarctions]

A lacunar infarct is defined as the occlusion of a single perforating artery. Certain researchers have proposed that patients with lacunar infarcts can be classified into two clinically distinct entities: patients with a single, symptomatic lacunar infarct, and patients with multiple lacunar infarcts together with hypertension and leukoaraiosis. The present study attempted to delineate the characteristics of lacunar infarcts and evaluate the validity of the aforementioned hypothesis. A total of 130 consecutive patients with first-time symptomatic lacunar infarct were studied. All patients were dichotomized into two groups according to two different kinds of models as follows. Model-1: patients with a single lacune and patients with multiple lacunes; and Model-2: patients with large lacune and patients with small lacune. Associated factors for the multiple lacune group compared with the single lacune group as well as the large lacune group compared with the small lacune group, were analyzed by multivariate logistic regression analysis. Associated factors included age, sex, hypertension, diabetes mellitus, dyslipidemia, smoking, extracranial and intra-cranial vascular lesions, extent of lacunes and white matter lesions, progression status and blood pressure in the acute stage, and coagulation markers such as fibrinogen, thrombin-antithrombin complex, D-dimer, beta-thromboglobulin, platelet factor 4. Results for Model-1: hypertension (age-and sex-adjusted OR: 2.58, p = 0.017) and elevated systolic blood pressure (>160mmHg for the mean value during the first post-ictal week; OR: 2.55, p = 0.016) were significantly associated with the multiple lacune group. Large lacunes (>10mm in diameter) were negatively associated with the multiple lacune group (OR: 0.38, p = 0.017). Association between confluent white matter lesions and the multiple lacune group approached significance (OR: 2.16, p = 0.056). Results for Model-2: female sex (OR: 0.39, p = 0.021), mild stenosis of intracranial and extracranial arteries (<25%) (intracranial; OR: 5.42, p = 0.0042, extracranial; OR: 3.30, p = 0.016), progressing stroke (OR: 6.77, p<0.0001), and high levels of TAT (>3ng/ml) (OR: 2.80, p = 0.039) were significantly associated with the large lacune group. Multiple lacunes (OR: 0.38, p = 0.016) and confluent white matter lesions (OR: 0.28, p = 0.007) exhibited a significant negative association with the large lacune group. In conclusion, underlying vasculopathy in the presence of multiple lacunes may correspond to lipohyalinosis resulting from hypertension. Moreover, large lacune may correspond to microatheroma at the orifice of penetrating arteries.     

Predictive value of clinical lacunar syndromes for lacunar infarcts on magnetic resonance brain imaging

OBJECTIVE: We prospectively investigated the predictive value of clinical and CT-supported lacunar syndromes for lacunar infarcts on magnetic resonance (MR) brain imaging. PATIENTS AND METHODS: The 54 prospective, consecutive patients had clinical lacunar syndromes of acute onset and early computed tomography (CT; on admission day, i.e. < or =48 h after onset of symptoms) showing either a small deep infarct or no corresponding lesion. Taking MR (at day 2 to 4 after admission) as the gold standard, the positive predictive value of the CT-supported clinical syndrome for corresponding lacunar lesions was calculated. RESULTS: In 27 (50%) patients, early CT showed a lacunar infarct corresponding to the clinical syndrome, a further 27 (50%) patients had no fresh ischemic lesion. In 51 patients (94%), MR showed a recent lacunar infarct (hyperintense lacune in T2-weighted scans, no demarcation on T1-weighted scans and/or positive gadolinium-enhancement) corresponding to the clinical syndrome (positive predictive value 0.94, 95%, CI: 0.88 to 0.98). In 3 (6%) patients MR was normal. Aside from old unrelated ischemic (macro- and/or microangiopathic) lesions, MR revealed no acute non-lacunar infarct. CT and MR sites of lacunar lesions were matching. Compared to gold standard MR, the sensitivity of early CT for suspected lacunar lesions was 0.53 (95% CI: 0.38 to 0.67). CONCLUSION: Lacunar syndromes were highly predictive for small deep infarcts on MR. Magnetic resonance brain imaging may be redundant in the setting of a lacunar syndrome supported by a CT that excludes non-ischemic causes of stroke; it may therefore be abandoned in order to reduce costs in the health care system.     

MRI in neurofibromatosis type I: Using fluid-attenuated inversion recovery pulse sequences

Cranial magnetic resonance imaging results of 14 patients with neurofibromatosis type I were examined with T₂-weighted fluid-attenuated inversion recovery pulse sequences, as well as conventional T₂-weighted spin-echo sequences. Definition was better in 62 of 79 lesions or groups of lesions on fluid-attenuated inversion recovery images than on T₂-weighted spin-echo images. The lesions were demonstrated not only in the brainstem, cerebellum, globus pallidus, and cerebral white matter, but also in the hippocampus, pulvinar thalami, and splenium of the corpus callosum. The latter 3 lesions have not been demonstrated or emphasized in previous studies. It is concluded that fluid-attenuated inversion recovery imaging is more effective in detecting multiple lesions in patients with neurofibromatosis type I than conventional T₂-weighted spin-echo imaging.     

Serial T2 short inversion time inversion recovery images in a patient with medullary hemorrhage]

A 52-year-old man was admitted to our hospital because of hypesthesia on the right side of his body. He had no medical history. On admission, he exhibited hypesthesia and disturbance of the touch and the vibratory sense on the right side of his body excluding the face. A brain T2* -weighted image revealed the a dot like lesion surrounded by an iso-signal lesion in the medial medulla oblongata. Therefore a diagnosis of medullary hemorrhage was made. Although a vascular malformation was considered as the cause of the hemorrhage, cerebral angiography did not reveal any vascular malformations. After admission, he developed left hypoglossal nerve palsy on day 6, and intractable hiccups on day 11. A T2* -weighted image and a FLAIR image disclosed edema surrounding the hematoma in the medial medullary lesion. T2* weighted images are useful for diagnosing and evaluating serial changes of medullary hemorrhage.     

Progression of dementia associated with lacunar infarctions

BACKGROUND: Lacunar stroke (L) is the most common stroke subtype associated with vascular dementia (VaD-L). OBJECTIVE: To evaluate the cognitive and behavioral course in patients with probable VaD-L. METHODS: We longitudinally measured rates of change on MMSE, digit span, logical memory, Controlled Oral Word Association, CERAD battery and neuropsychiatric inventory (NPI) in 77 patients (age at entry 69 +/- 8.1 years) with probable VaD-L for 25.75 +/- 11 months. RESULTS: The mean number of follow-up visits was 2.6 +/- 0.67 (range 2-4). Time interval between any two consecutive visits was at least 5 months (range 5-41). MMSE deteriorated by 1.44+/- 1.8 points annually and NPI increased by 6.01 +/- 13.7 points annually (p < 0.0001). The rates of cognitive and behavioral decline were predominantly influenced by the cognitive state at entry into the study and the occurrence of new vascular episodes during follow-up [(-0.95 +/- 1.7) MMSE and (+2.02 +/- 14.1) NPI points annually without vascular episodes vs. (-2.09 +/- 1.6) and (+11.3 +/- 11.4) points following vascular episodes (p < 0.0001)]. Impaired cognition was associated with impaired behavior (p < 0.001). VaD-L patients without additional vascular episodes at follow-up have a progressively deteriorating course as well (p < 0.0001). CONCLUSION: VaD-L is characterized by cognitive and behavioral decline. The rate of decline is determined mainly by the severity of the cognitive and behavioral impairment at baseline and by the occurrence of new vascular episodes.     

Prognostic value of hyperintense vessel signals on fluid-attenuated inversion recovery sequences in acute cerebral ischemia

BACKGROUND: Fluid-attenuated inversion recovery (FLAIR) sequences may reveal hyperintense vessel signals (HVS) at the acute stage of cerebral ischemia. The aim of this study was to test the hypothesis that HVS are associated with a worse outcome. METHODS: We included 30 consecutive patients admitted within 12 h after onset of hemispheric cerebral ischemia. The outcome was assessed with the modified Rankin Scale at month 1. RESULTS: Proximal HVS were present in 9 patients and distal HVS in 16. All patients with proximal occlusions on time-of-flight sequences had distal HVS on FLAIR. Patients with poor outcome at month 1 (modified Rankin Scale 3-6) more frequently had had HVS on MRI (12/13 vs. 4/17; p< 0.001). CONCLUSION: Distal HVS found on FLAIR sequences within 12 h of acute cerebral ischemia are associated with a worse 1-month outcome.     

Fluid-attenuated inversion recovery magnetic resonance imaging detects cortical and juxtacortical multiple sclerosis lesions

BACKGROUND: Autopsy studies showed cortical and juxtacortical multiple sclerosis (MS) plaques. Fluid-attenuated inversion recovery (FLAIR) is an advanced magnetic resonance imaging sequence that reveals tissue T2 prolongation with cerebrospinal fluid suppression, allowing detection of superficial brain lesions. OBJECTIVES: To assess FLAIR, T1-weighted, and T2-weighted images for detecting lesions in or near the cerebral cortex in patients with MS and to explore the relation between cortical lesions and cortical atrophy. DESIGN, SETTING, AND PATIENTS: Cross-sectional study in a university MS clinic of 84 patients with MS and 66 age-matched healthy controls receiving 1.5-T fast FLAIR, T2-weighted, and T1-weighted images. MAIN OUTCOME MEASURES: Regional cortical atrophy was rated vs controls. Cortical and juxtacortical lesions were ovoid hyperintensities involving the cortex and/or gray-white junction. RESULTS: A total of 810 cortical and juxtacortical lesions were seen by FLAIR in patients (mean, 9.6 per patient), most commonly in the superior frontal lobe. Cortical and juxtacortical lesions were identified in 72 patients and 6 controls. Fourteen percent of cortical and juxtacortical lesions were seen on T1-weighted images and 26% were seen on T2-weighted images. More cortical and juxtacortical lesions were present in secondary progressive disease than relapsing-remitting disease. The total number of cortical and juxtacortical lesions correlated significantly with disease duration and the regional number correlated with the degree of regional atrophy. After taking into account noncortical (white matter) lesions, only the cortical and juxtacortical lesion count predicted atrophy in that region. CONCLUSIONS: FLAIR can detect many cortical and juxtacortical lesions in MS, which were appreciated previously in autopsy studies but usually missed by magnetic resonance imaging during life. Cortical and juxtacortical plaque formation may contribute to cortical atrophy in MS.     

Diffusion-weighted imaging and fluid-attenuated inversion recovery sequence in sporadic Creutzfeldt-Jakob disease One-case report

The diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) is extremely difficult.Diffusion-weighted imaging has been shown to be the most sensitive technique for the detection of signal alterations in sCJD patients.The present study analyzed the diagnostic value of diffusion-weighted imaging and fluid-attenuated inversion recovery sequence in the early stage of sCJD in one female patient and correlated the clinical symptoms during disease course and magnetic resonance manifestations.Thalamic and basal ganglia hyperintensities were observed on magnetic resonance images in a very early stage,i.e.,when the clinical typical manifestations of the disease were not present.With the progression of the disease,cortical and basal ganglia hyperintensities were observed on magnetic resonance images,showing an obvious cerebral atrophy.These findings suggest that diffusion-weighted imaging and fluid-attenuated inversion recovery sequence are helpful in diagnosing sCJD.     

Prospective study of lacunar infarction using magnetic resonance imaging

Using computed tomography and magnetic resonance imaging, we prospectively studied 100 patients hospitalized with a lacunar infarct. Our aim was to evaluate the capabilities of magnetic resonance imaging in the detection and delineation of lacunes in a project of clinicotopographic correlations. Seventy-nine patients had a classic lacunar syndrome; 35 had pure motor stroke, 26 had ataxic hemiparesis, seven had sensorimotor stroke, and 11 had pure sensory stroke. A miscellaneous group of 21 patients had less typical lacunar syndromes, primarily with brainstem signs and symptoms. Among a total of 153 lacunes, magnetic resonance imaging detected at least one lacune appropriate to the symptoms in 89 patients. In 16 patients at least two lesions correlated with the clinical features, and precise clinicotopographic correlations were possible in 68 patients. Magnetic resonance imaging was more effective when it was performed a few days after the stroke. Lesions causing different types of lacunar syndromes had significantly different volumes, suggesting that the size of the lesion may influence clinical features. Magnetic resonance imaging may be the imaging technique of choice in the study of lacunar syndromes.     

磁共振波谱分析与液体衰减反转恢复成像在诊断海马硬化中的作用分析

目的通过对23例颞叶癫痫病人的磁共振波谱分析(magnetic resonance spectroscopy,MRS)与液体衰减反转恢复(nuid attenuated inversion recovery,FLAIR)序列成像结果进行分析,探讨其在诊断海马硬化中的作用与意义。方法经手术治疗的23例颞叶癫痫病人,术中皮层电极及深部电极、术后病理检查结果证实为外侧型癫痫6例,海马硬化型17例,分析其术前磁共振T1、T2、FLAIR序列、MRS检查结果。结果6例颞叶外侧型癫痫海马区T1、T2、FLAIR序列、MRS检查均无异常,17例海马硬化型中6例T1、T2显示异常,7例FLAIR序列高信号,16例MRS显示氮-乙酰天冬氨酸(N—acetylaspantate,NAA)峰明显下降,其中1例显示双侧NAA峰下降。结论MRS可在MRI出现改变之前发现海马硬化,其诊断海马硬化灵敏且特异性高,FLAIR序列优于T2加权相,MRS与FLAIR序列是海马硬化术前诊断一个可靠的方法。     

磁共振液体反转恢复序列高信号血管征对急性大脑中动脉闭塞患者临床预后的评估

目的 探讨急性大脑中动脉闭塞患者MRI液体衰减反转恢复序列(FLAIR)高信号血管征( hyperintense vessel,HV)对于其预后的评估作用.方法 从南京卒中注册系统中提取2009年5月至2011年2月间表现为大脑中动脉区首次急性梗死的患者共74例,其中男性48例(64.9％);平均(60.7±15.3)岁,NIHSS评分12(1 ～25)分[采用中位数(范围)表示].所有患者均已行头颅MRI检查(包括DWI、FLAIR),并且经MRA或DSA提示大脑中动脉近端闭塞(MI段或M2段).根据FLAIR序列HV出现的部位和范围,将患者分为无HV组、近端HV组和远端HV组;比较各组间基线资料及神经功能评分,并以90d改良Rankin评分(mRS)为预后指标,行Logistic回归分析.结果 74例中无HV组25例(33.8％),近端HV组7例(9.5％),远端HV组42例(56.8％).远端HV组患者入院时NIHSS评分[11(1～22)分]、入院10 d NIHSS评分[14(4 ～25)分]、梗死体积[大面积梗死5例(6.8％)]及90 d mRS评分[3～6分者12例(16.2％)]明显低于无远端HV组[即近端HV组合并无HV组,分别为15(6 ～25)分,Z=-3.544;7(0～22)分,Z=-4.461;20例(27.0％),x2=20.916;27例(36.5％),x2=22.689;均P＜0.01];从早期神经功能恢复及短期预后改善程度上看,远端HV组均明显优于无远端HV组.Logistic回归分析发现,年龄(OR=1.111,95％ CI 1.036 ～1.191,P=0.003)、梗死体积(OR=3.679,95％ CI1.350～10.025,P=0.011)、远端HV(OR =0.131,95％ CI0.027 ～0.638,P=0.012)与90 d mRS评分显著相关.结论 远端HV是急性脑梗死预后的重要预测指标.