Chronological changes of lacunar infarctions on fluid-attenuated inversion recovery magnetic resonance images]

In 26 patients with lacunar syndromes, emergence of new lacunar infarctions were identified within 13 days from onset by diffusion-weighted magnetic resonance images. The identified lacunar infarctions were repeatedly imaged using fluid-attenuated inversion recovery (FLAIR) sequence up to 600 days from onset. On FLAIR images taken by 23 days from onset, lacunar infarctions showed homogeneous hyperintensity. On the later FLAIR images beyond 25 days from onset they were observed as heterogeneously hyperintense lesions in half of the patients. In the other patients, lacunar infarctions were observed as hypointense areas with a hyperintense rim beyond 41 days from onset, which indicates cystic transformation with surrounding gliosis. These FLAIR images of lacunar infarction differ from those of dilated perivascular space which is observed as an area of simple hypointensity.     

Fluid attenuation inversion recovery (FLAIR) images of dentatorubropallidoluysian atrophy: case report

The white matter lesions in a patient with late adult onsetdentatorubropallidoluysian atrophy (DRPLA) were studied in detail by MRI using the fluid attenuation inversion recovery (FLAIR) technique. The patient was a 60 year old woman with a family history ofDRPLA, in whom the number of CAG repeats in the DRPLA gene onchromosome 12 was expanded to 59 (normal allele 10). In addition toatrophy of the cerebral cortex, cerebellum, and pontomesencephalic tegmentum, the cerebral white matter and a part of the white matter tracts within the brainstem showed prominent high signal intensities onFLAIR images. These MR findings suggest that, in addition to thedegeneration of the dentatorubral and pallidoluysian systems, thepathological process extends to the white matter in DRPLA. This couldbe important for differentiating DRPLA from other clinically similar diseases such as Machado-Joseph disease or Huntington's disease.

     

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.     

Quantitative measurements of relative fluid-attenuated inversion recovery (FLAIR) signal intensities in acute stroke for the prediction of time from symptom onset

In acute stroke magnetic resonance imaging, a ‘mismatch'' between visibility of an ischemic lesion on diffusion-weighted imaging (DWI) and missing corresponding parenchymal hyperintensities on fluid-attenuated inversion recovery (FLAIR) data sets was shown to identify patients with time from symptom onset ≤4.5 hours with high specificity. However, moderate sensitivity and suboptimal interpreter agreement are limitations of a visual rating of FLAIR lesion visibility. We tested refined image analysis methods in patients included in the previously published PREFLAIR study using refined visual analysis and quantitative measurements of relative FLAIR signal intensity (rSI) from a three-dimensional, segmented stroke lesion volume. A total of 399 patients were included. The rSI of FLAIR lesions showed a moderate correlation with time from symptom onset (r=0.382, P<0.001). A FLAIR rSI threshold of <1.0721 predicted symptom onset ≤4.5 hours with slightly increased specificity (0.85 versus 0.78) but also slightly decreased sensitivity (0.47 versus 0.58) as compared with visual analysis. Refined visual analysis differentiating between ‘subtle'' and ‘obvious'' FLAIR hyperintensities and classification and regression tree algorithms combining information from visual and quantitative analysis also did not improve diagnostic accuracy. Our results raise doubts whether the prediction of stroke onset time by visual image judgment can be improved by quantitative rSI measurements.     

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.     

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.     

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.     

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.     

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.     

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.     

Magnetic resonance imaging in partial epilepsy: additional abnormalities shown with the fluid attenuated inversion recovery (FLAIR) pulse sequence.

Thirty six patients with a history of partial epilepsy had MRI of the brain performed with conventional T1 and T2 weighted pulse sequences as well as the fluid attenuated inversion recovery (FLAIR) sequence. Abnormalities were found in 20 cases (56%), in whom there were 25 lesions or groups of lesions. Twenty four of these lesions were more conspicuous with the FLAIR sequence than with any of the conventional sequences. In 11 of these 20 cases, lesions thought to be of aetiological importance were only seen with the FLAIR sequence. In eight this was a solitary lesion. In the other three, an additional and apparently significant lesion (or lesions) was only seen with the FLAIR sequence when another lesion had been identified with both conventional and FLAIR sequences. The 11 additional lesions or groups of lesions were seen in the hippocampus, amygdala, cortex, or subcortical and periventricular regions. No lesion was found with any pulse sequence in 16 (44%) of the original group of 36 patients. In the eight cases where a lesion was seen only with the FLAIR sequence, localisation was concordant with the electroclinical features. Two of the eight patients with solitary lesions seen only on the FLAIR sequence underwent surgery, after which there was pathological confirmation of the abnormality identified with imaging. In one patient with a congenital cavernoma, the primary lesion was best seen with a contrast enhanced T1 weighted spin echo sequence. In this selected series, the FLAIR sequence increased the yield of MRI examinations of the brain by 30%.     

T2-Fluid-attenuated inversion recovery (FLAIR) pseudoprogression in patients with anaplastic oligodendrogliomas treated with procarbazine,lomustine and vincristine (PCV) chemotherapy alone

Background

Pseudoprogression in gliomas has been extensively described after radiotherapy with or without chemotherapy, but not after chemotherapy alone. Here we describe the occurrence of pseudoprogression in patients with anaplastic oligodendrogliomas treated with postoperative procarbazine, lomustine and vincristine (PCV) chemotherapy alone.

Methods

We retrospectively reviewed the medical and radiological files of patients with 1p/19q codeleted, IDH-mutant anaplastic oligodendrogliomas treated with PCV chemotherapy alone who presented magnetic resonance imaging (MRI) modifications suggestive of tumour progression and in whom the final diagnosis was a pseudoprogression.

Results

We identified six patients. All patients underwent a surgical resection and were treated with PCV chemotherapy without radiotherapy. After a median of 11 months following the initiation of chemotherapy (range: 3–49 months), the patients developed asymptomatic white matter MRI modifications around the surgical cavity leading to the suspicion of a tumour progression. These modifications appeared as hyperintense on T2-fluid-attenuated inversion recovery (FLAIR) sequence, hypointense on T1 sequence, and lacked mass effect (0/6), contrast enhancement (0/6), restriction on diffusion-weighted imaging (0/4), relative cerebral blood volume (rCBV) increase on perfusion MRI (0/4), and hypermetabolism on ¹⁸F-fluoro-L-dopa positron emission tomography (¹⁸F-DOPA PET) scan (0/3). One patient underwent a surgical resection demonstrating no tumour recurrence; the five other patients were considered as having post-therapeutic modifications based on imaging characteristics. After a median follow-up of 4 years all patients were progression-free.

Conclusions

Anaplastic oligodendroglioma patients treated with postoperative PCV chemotherapy alone occasionally develop T2/FLAIR hyperintensities around the surgical cavity that can wrongly suggest tumour progression. Multimodal imaging and close follow-up should be considered in this situation.     

Multiple sclerosis: interobserver agreement in reporting active lesions on serial brain MRI using conventional spin echo, fast spin echo, fast fluid-attenuated inversion recovery and post-contrast T1-weighted images

Previous studies have addressed the question of the precision in assessing multiple sclerosis (MS) activity by counting enhancing lesions on gadolinium enhanced brain magnetic resonance imaging (MRI). However, counting the active lesions on serial unenhanced MRI obtained by various pulse sequences has not been yet considered. We compared the interobserver levels of agreement in reporting active MS lesions on serial enhanced and unenhanced MRI to assess whether the use of various unenhanced techniques may change the degree of interobserver measurement reproducibility. Dual-echo conventional spin echo (CSE), dual-echo fast spin echo (FSE), fast fluid-attenuated inversion recovery (FLAIR) and Gd-enhanced T1-weighted brain MRI were obtained from five MS patients at baseline and monthly for 2 months. Six experienced observers independently identified and counted active MS lesions on the two follow-up MRI scans. Active lesions were considered to be all the enhancing lesions and any new or enlarging lesion on enhanced and unenhanced scans. Interobserver levels of agreement were calculated by weighted κ values. Very good agreement was reached only for counting total and new Gd-enhancing lesions. Good agreement was achieved for counting new lesions on the three unenhanced techniques, whereas the agreement for counting enlarging lesions was poor with all the MRI techniques. The level of agreement was significantly heterogeneous for various MRI techniques but not for various lesion sites. These results confirm that counting enhancing lesions is the most reliable method for assessing MS activity, but the use of any of the available unenhanced MRI techniques did not result in different levels of interobserver agreement when reporting new and enlarging MS lesions on serial scans. Received: 10 December 1998 Received in revised form: 6 April 1999 Accepted: 26 April 1999     

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.