MRI与PET对癫痫病的诊断价值

癫痫是常见病,以颞叶癫痫最常见,药物难治性癫痫的术前准确定侧和定位是手术成功的关键。MRI对部分癫痫有很重要的诊断价值,特别是结合脑电图和功能性磁共振成像。但是对于MRI诊断阴性的癫痫病人,PET整体定位系统能解决其定位诊断问题。     

视频脑电监测对癫痫术前定位的作用

目的　探讨视频脑电监测 (video -EEG)对癫痫术前定位的作用和意义。方法　对 4 2例难治性癫痫患者进行术前普通脑电图 (REEG)视频脑电图 (V -EEG)及术中皮质脑电图 (ECoG)进行比较研究。结果　长程视频脑电监测对癫痫诊断为 99 5 % ,癫痫灶的定位为 94 6 % ,显著高于常规脑电图 (P <0 .0 1)。结论　长程视频脑电监测对癫痫病人术前癫痫灶定位诊断有重要作用     

18F-FDGPET/CT脑显像在癫发作期及发作间期致灶定位中的应用价值

 目的探讨¹⁸F-FDGPET/CT脑3D显像在癫发作期和发作间期致灶定位中的应用价值。方法癫患者60例均行24h头皮脑电图、MRI、¹⁸F-FDGPET/CT脑显像。25例行皮质脑电图(ECoG)或深部脑电图(DEEG)。PET/CT图像经过目测和半定量的方法进行分析。结果(1)60例中,¹⁸F-FDGPET/CT脑显像阳性者57例,检出率95%,其中患者处于发作间期56例,PET/CT表现为低代谢灶者53例,发作期4例,PET/CT上均表现为高代谢灶。(2)PET/CT显示80%为单发灶(48/60),15%为2个以上病灶(9/60)。单发灶中,66.7%位于颞叶(32/48),另33.3%位于颞叶外皮质(顶叶6例,额叶10例)。(3)PET/CT与皮质脑电图(ECoG)或深部脑电图(DEEG)符合率为96%(24/25)。(4)32例颞叶癫行前颞叶切除术,术后随访结果EngelⅠ～Ⅱ级者30例。非颞叶癫16例,行致灶皮质切除术,12例达EngelⅠ～Ⅱ级。3例未检出致灶,9例DEEG定位双侧致灶未行手术治疗。结论对于颅内有病灶癫及明确的颞叶癫患者,PET/CT与EEG以及MRI检查结果具有高度一致性;对于没有病灶及非颞叶癫患者,PET/CT是一种无创、敏感、有效的定位癫源灶的方法。     

~(18)F-FDG PET-CT脑显像与EEG对颞叶癫痫灶术前定位价值的对比研究

目的对比18F-FDG PET-CT脑显像与EEG对颞叶癫痫灶术前定位的价值。方法回顾性分析经我院神经外科癫痫中心临床诊断为颞叶癫痫的患者152例,所有患者术前行18F-FDG PET-CT脑显像、长程/视频EEG检查,其中29例定位仍不确切者行颅内电极EEG检查,手术切除组织术后送病理检查,比较结果。结果 (1)本组152例患者PET-CT脑显像定位致痫灶的准确率为80.92%(123/152),长程或视频EEG定位致痫灶准确率为43.42%(66/152),两种检查方法定位致痫灶准确率差异有统计学意义(χ2=45.44,P<0.01);(2)本组29例患者颅内电极EEG定位致痫灶准确率为100%。结论发作间期18F-FDG PET-CT脑显像定位致痫灶灵敏、有效,其价值优于长程/视频EEG;18F-FDG PET-CT脑显像对颅内电极埋置有指导价值,两者联合使用,可以进一步提高致痫灶定位准确率。     

19. Correlation between FDG PET data and EEG dipole modeling

Purpose: FDG-PET images and EEG dipole modelling were used to localization of interictal epileptogenic foci. A multimodality approach with the analysis of FDG-PET images, EEG dipoles and anatomical images (MRI) were applied to patients with drug-resistant epilepsy.Methods: Source location was determined using Brain Electromagnetic Source Analysis (BESA) program. The dipole location provided by BESA was then transformed into PET co-ordinates using the patient's MRI previously registered with the PET image. As a difference with other methods, no external markers are necessary.Results: The study group includes ten drug-resistant epileptic patients. FDG hypometabolism was found in all patients. Abnormalities in glucose uptake were always ipsilateral to the EEG dipole. However, quantitative analysis of FDG-PET within hypometabolic areas showed no significant correlation between decrease glucose uptake and location of EEG-dipole source. The comparison of the results using both methods shows that the dipole location matches the FDG-PET hypometabolic area for all the patients. Combining the spatial localization on FDG-PET with the temporal accuracy of EEG dipole source aids in the exact localization of the epileptogenic focus.Conclusion: As a conclusion, the results show that projection of EEG dipole data onto FDG-PET may play a key role in the indication of surgery for the treatment of drug-resistant epileptic patients, provided it is simple and easy to perform.     

Functional MRI with simultaneous EEG recording: feasibility and application to motor and visual activation

The possibility of combining the high spatial resolution of functional magnetic resonance imaging (fMRI) with the high temporal resolution of electroencephalography (EEG) may provide a new tool in cognitive neurophysiology, as well as in clinical applications such as epilepsy. However, the simultaneous recording of EEG and fMRI raises important practical problems: 1) the patients' safety, in particular the risk of skin burns due to electrodes heating; 2) the impairment of the EEG recording by the static magnetic field, as well as by RF and magnetic field gradients used during MRI; and 3) the quality of MR images, which may be affected by the presence of conductors and electronic devices in the MRI bore. Here we present our experiences on 19 normal volunteers who underwent combined fMRI and 16-channel EEG examination. Consistent with previous reports, safety could be assured when performing EEG recordings during fMRI acquisition. Electrophysiological signals recorded with surface EEG were similar inside and outside the 1.5 T magnet. Furthermore, fMRI using motor or visual tasks revealed similar areas of activation when performed with and without 16-channel EEG recording. J. Magn. Reson. Imaging 2001;13:943-948.     

Video/EEG,SPECT和MRI对部分性癫痫定位诊断作用及临床意义探讨

目的：探讨录像脑电图检测（Ｖｉｄｅｏ／ＥＥＣ）,ＳＰＥＣＴ和ＭＲＩ３种方法对部分性癫痫的无创性定位和病因诊断的作用及临床意义。材料与方法：对５２例部分性癫痫患者分别进行Ｖｉｄｅｏ／ＥＥＧ,＾９９ｍＴｃ－ＨＭＰＡＯ－ＳＰＥＣＴ脑血流显像,＾１２３Ｉ－Ｉｏｍａｚｅｎｉｌ ＳＰＥＣＴ脑受体显像和全脑ＭＲＩ检查。根据Ｖｉｄｅｏ／ＥＥＧ记录的癫痫发作类型,ＳＰＥＣＴ显示的ｒＣＢＦ和ＢＺＤ的分布以及ＭＲＩ显示     

The evaluation of FDG-PET imaging for epileptogenic focus localization in patients with MRI positive and MRI negative temporal lobe epilepsy

Introduction

We studied the contribution of interictal FDG-PET ([18 F] fluorodeoxyglucose-positron emission tomography) in epileptic focus identification in temporal lobe epilepsy patients with positive, equivocal and negative magnetic resonance imaging (MRI).

Methods

Ninety-eight patients who underwent surgical treatment for drug resistant temporal lobe epilepsy after neuropsychological evaluation, scalp video EEG monitoring, FDG-PET, MRI and/or long-term intracranial EEG and with >12 months clinical follow-up were included in this study. FDG-PET findings were compared to MRI, histopathology, scalp video EEG and long-term intracranial EEG monitoring.

Results

FDG-PET lateralized the seizure focus in 95 % of MRI positive, 69 % of MRI equivocal and 84 % of MRI negative patients. There was no statistically significant difference between the surgical outcomes among the groups with Engel class I and II outcomes achieved in 86 %, 86 %, 84 % of MRI positive, equivocal and negative temporal lobe epilepsy patients, respectively. The patients with positive unilateral FDG-PET demonstrated excellent postsurgical outcomes, with 96 % Engel class I and II. Histopathology revealed focal lesions in 75 % of MRI equivocal, 84 % of MRI positive, and 23 % of MRI negative temporal lobe epilepsy cases.

Conclusion

FDG-PET is an accurate noninvasive method in lateralizing the epileptogenic focus in temporal lobe epilepsy, especially in patients with normal or equivocal MRIs, or non-lateralized EEG monitoring. Very subtle findings in MRI are often associated with histopathological lesions and should be described in MRI reports. The patients with negative or equivocal MRI temporal lobe epilepsy are good surgical candidates with comparable postsurgical outcomes to patients with MRI positive temporal lobe epilepsy.     

Klinischer Einsatz der funktionellen MRT bei chronischer Epilepsie

Functional magnetic resonance imaging (fMRI) is frequently used in the presurgical diagnostic procedure of epilepsy patients, in particular for lateralization of speech and memory and for localization of the primary motor cortex to delineate the epileptogenic lesion from eloquent brain areas. fMRI is one of the non-invasive procedures in the presurgical diagnostic process, together with medical history, seizure semiology, neurological examination, interictal and ictal EEG, structural MRI, video EEG monitoring and neuropsychology. This diagnostic sequence leads either to the decision for or against elective epilepsy surgery or to the decision to proceed with invasive diagnostic techniques (Wada test, intra-operative or extra-operative cortical stimulation). It is difficult to evaluate the contribution of the fMRI test in isolation to the validity of the entire diagnostic sequence. Complications such as memory loss and aphasia in temporal lobe resections or paresis after frontal lobe resections are rare and rarely of disastrous extent. This further complicates the evaluation of the clinical relevance of fMRI as a predictive tool. In this article studies which investigated the concordance between fMRI and other diagnostic gold standards will be presented as well as the association between presurgical fMRI and postsurgical morbidity.     

Preoperative assessment of language areas in epileptic patients using functional MR imaging

ObjectiveTo determine the role of functional magnetic resonance imaging (fMRI) in assessing hemispheric language dominance in patients with epilepsy who are candidates for surgical treatment.Patients and methodsThis study was conducted on (14) consecutively enrolled epileptic patients (12 males, 2 females; mean age, 21 years; range 16–58 years) who were prospectively examined by the neurologist. Eleven (78.6%) patients were dominantly right handed, three (21.4%) were dominantly left handed. All of them underwent language assessment with fMRI and the results were compared with the intraoperative direct electrical stimulation mapping recordings.ResultsIn all the 14 epilepsy cases, language mapping data was concordant between fMRI and intraoperative direct electrocortical stimulation recordings for language dominance. However, fMRI mapping allowed for discrete, focal localization of regions involved in language processes whereas electrical recordings only delineated hemispheric dominance.ConclusionfMRI is considered as a powerful pre-surgical planning tool that has the potential to replace invasive and costly conventional methods. FMRI maps can easily be uploaded and used intra-operatively during stereotactic neurosurgery for accurate localization of complex brain functions.     

99Tcm-HMPAO single photon emission computed tomography in partial epilepsy: a preliminary report

In the pre-operative assessment of patients being considered for temporal lobe surgery, accurate lateralization and localization of the epileptic focus is mandatory. Surface electroencephalography (EEG) can be misleading and confirmatory evidence, preferably non-invasive, of the site of the epileptic focus is valuable. Sixteen patients with partial epilepsy, six of whom were considered to be good surgical candidates, had technetium-99m hexamethylpropylene amine oxime (99Tcm-HMPAO) scanning. In those patients with poor epileptic control and a well localized EEG focus, there was a correlation between EEG and HMPAO scan abnormalities, whilst in all patients where no correlation existed, the HMPAO scan was normal. We conclude that 99Tcm-HMPAO single photon emission computed tomography may be a useful non-invasive, adjunctive investigation in the preoperative assessment of patients with partial epilepsy.     

Ictal SPECT in neocortical epilepsies: clinical usefulness and factors affecting the pattern of hyperperfusion

Introduction: The aims of this analysis were to: (1) determine the value of ictal SPECT in the localization of neocortical epileptogenic foci, (2) evaluate the relationships between the results of ictal SPECT and other potential affecting factors, and (3) compare traditional visual analysis and the subtraction method.Methods: We retrospectively analyzed 81 consecutive patients with neocortical epilepsy who underwent epilepsy surgery and achieved a favourable surgical outcome, including 36 patients with normal MRI. Side-by-side visual analysis and subtraction images were classified as correctly localizing,correctly lateralizing, or non-localizing/non-lateralizing images according to the resected lobe.Results: Side-by-side visual analysis and subtraction SPECT correctly localized the epileptogenic lobe in 58.9% and 63.0% of patients, respectively. The two methods were complementary and the diagnostic sensitivity of ictal SPECT using the two methods was 79.0%. Ictal SPECT using the visual method correctly localized the epileptogenic lobe more frequently in patients with a localizing pattern of ictal scalp EEG at the time of radioligand injection. When using subtraction images, an injection delay of less than 20 s after seizure onset was significantly correlated with correct localization. The subtraction method was superior to the visual method for localizing frontal lobe epilepsy (FLE) and parietal lobe epilepsy (PLE), and in patients with non-localizing/non-lateralizing EEG at onset.Conclusions: Ictal SPECT analyses using visual and subtraction methods are useful and complementary for the localization of the epileptogenic foci of neocortical epilepsy. Early radioligand injection and ictal EEG patterns are related to ictal SPECT localization. The subtraction method may be more useful in some epileptic syndromes.     

Sensitivity and specificity of quantitative difference SPECT analysis in seizure localization.

True ictal SPECT can accurately demonstrate perfusion increases in the epileptogenic area but often requires dedicated personnel waiting at the bedside to accomplish the injection. We investigated the value of perfusion changes as measured by ictal or immediate postictal SPECT in localizing the epileptogenic region in refractory partial epilepsy. METHODS: Quantitative perfusion difference images were calculated by registering, normalizing and subtracting ictal (or immediate postictal) from interictal SPECT for 53 patients with refractory epilepsy. Perfusion difference SPECT results were compared with visually interpreted SPECT, scalp electroencephalography (EEG), MRI, PET and intracranial EEG. RESULTS: In 43 patients (81%), discrete areas of increased perfusion (with ictal injections) or decreased perfusion (with postictal injections) were noted. Interictal scalp EEG was localizing in 28 patients (53%), ictal scalp EEG was localizing in 35 patients (66%) and intracranial EEG was localizing in 22 patients (85%) (of 26 patients who underwent invasive study). MRI was localizing in 34 patients (64%), PET was localizing in 32 of 45 patients (71%), interictal SPECT was localizing in 26 patients (49%) and peri-ictal SPECT (visual interpretation) was localizing in 30 patients (57%). By comparison with an intracranial EEG standard of localization, SPECT subtraction analysis had 86% sensitivity and 75% specificity. CONCLUSION: Our data provide evidence that SPECT perfusion difference analysis has higher sensitivity and specificity than any other noninvasive localizing criterion and can localize epileptogenic regions with accuracy comparable with that of intracranial EEG. To obtain these results, one must apply knowledge of the timing of the ictal injection relative to seizure occurrence.     

Combining EEG and fMRI: a multimodal tool for epilepsy research

Patients with epilepsy often present in their electroencephalogram (EEG) short electrical potentials (spikes or spike-wave bursts) that are not accompanied by clinical manifestations but are of important diagnostic significance. They result from a population of abnormally hyperactive and hypersynchronous neurons. It is not easy to determine the location of the cerebral generators and the other brain regions that may be involved as a result of this abnormal activity. The possibility to combine EEG recording with functional MRI (fMRI) scanning opens the opportunity to uncover the regions of the brain showing changes in the fMRI signal in response to epileptic spikes seen in the EEG. These regions are presumably involved in the abnormal neuronal activity at the origin of epileptic discharges. This paper reviews the methodology involved in performing such studies, particularly the challenge of recording a good quality EEG inside the MR scanner while scanning is taking place, and the methods required for the statistical analysis of the combined EEG and fMRI time series. We review the results obtained in patients with different types of epileptic disorders and discuss the difficult theoretical problems raised by the interpretation of an increase (activation) and decrease (deactivation) in blood oxygen level dependent (BOLD) signal, both frequently seen in response to spikes.     

Contribution of subtraction ictal SPECT coregistered to MRI to epilepsy surgery: a multicenter study

Objective  A multicenter prospective study was performed to assess the additional value of a subtraction ictal SPECT coregistered to MRI (SISCOM) technique to traditional side-by-side comparison of ictal- and interictal SPECT images in epilepsy surgery. Methods  One hundred and twenty-three patients with temporal and extratemporal lobe epilepsy who had undergone epilepsy surgery after evaluation of scalp ictal and interictal electroencephalogram (EEG), MRI, and ictal and interictal SPECT scans were followed up in terms of postsurgical outcome for a period of at least 1 year. Three reviewers localized the epileptogenic focus using ictal and interictal SPECT images first by side-by-side comparison and subsequently by SISCOM. Concordance of the localization of the epileptogenic focus by SPECT diagnosis with the surgical site and inter-observer agreement between reviewers was compared between side-by-side comparison and SISCOM. Logistic regression analysis was performed in predicting the surgical outcome with the dependent variable being the achievement of a good postsurgical outcome and the independent variables using the SISCOM, side-by-side comparison of ictal and interictal SPECT images, MRI, and scalp ictal EEG. Results  The SISCOM presented better concordance in extratemporal lobe epilepsy and less concordance in temporal lobe epilepsy than side-by-side comparison. Inter-observer concordance was higher in SISCOM than in side-by-side comparison. Much higher concordance of the epileptogenic focus by SPECT diagnosis with the surgical site was obtained in patients with good surgical outcome than in those with poor surgical outcome. These differences in concordance between good and poor surgical outcomes were greater in SISCOM than in side-by-side comparison. Logistic regression analysis showed the highest odds ratio of 12.391 (95% confidence interval; 3.319, 46.254) by SISCOM evaluation for concordance of the epileptogenic focus with the surgical site in predicting good surgical outcome. Conclusions  A SISCOM technique of ictal and interictal SPECT images provides higher predictive value of good surgical outcome and more reliability on the diagnosis of the epileptogenic focus than side-by-side comparison in medically intractable partial epilepsy.     

Functional magnetic resonance: new applications in epilepsy

Functional magnetic resonance imaging technique is a non-invasive tool that is capable to detect the subtle hemodynamic changes produced during regional brain activation. Functional MRI applications in epilepsy patients are language lateralization and mapping, memory function assessment and localization of ictal and interictal changes. Functional MRI for language lateralization is currently used in clinical practice and provides comparable results to the intracarotid amobarbital test. In functional MRI studies for memory function assessment, results show changes in epileptic patients, but further studies are required to validate this technique for individual cases. A new application is ictal or interictal functional MRI with EEG recording that provides more detailed information about simultaneous electrographic and hemodynamic changes during interictal discharges or EEG seizures. This technique seems to have encouraging results to localize the epileptogenic area and to study propagation patterns.     

Focal epileptiform activity in the brain: detection with spike-related functional MR imaging--preliminary results

The purpose of this study was to develop a spike-related functional magnetic resonance (MR) imaging method to detect epileptic brain activity. Correlations between simultaneous spike-related functional MR imaging and electroencephalographic (EEG) recordings were performed in 10 patients with focal epilepsy. Postprocessing techniques were implemented to eliminate contamination of the EEG recording from ballistocardiography and the echo-planar MR imaging sequence. A diagnostic EEG recording was achieved during functional MR imaging. Spike location correlated with the site of blood oxygen level-dependent signal increase. Spike-related functional MR imaging is a promising technique for detecting focal epileptic brain activity.     

手术治疗难治性癫痫52例MRI所见分析

目的 比较分析MRI检查与手术结果之间的相关性，探讨MRI对难治性癫痫的诊断和鉴别诊断价值。资料与方法选择52例经临床及脑电图诊断，并经手术或活检病理结果证实的癫痫患者，对其MRI图像进行回顾性分析。结果MRI对有结构改变组癫痫患者诊断价值确切，阳性检出率达84．6％(44／52)；对无明显结构改变组患者，诊断价值有限，应进行综合性定位检查。结论MRI对难治性癫痫的诊断、鉴别诊断和治疗前准确定位有重要意义，可帮助临床医生选择最佳手术适应证，提供有价值的影像学依据。     

Magnetoencephalographic mapping of interictal spike propagation: a technical and clinical report

Distinguishing propagated epileptic activity from primary epileptic foci is of critical importance in presurgical evaluation of patients with medically intractable focal epilepsy. We studied an 11-year-old patient with complex partial epilepsy by using simultaneous magnetoencephalography (MEG) and electroencephalography (EEG). In EEG, bilateral interictal discharges appeared synchronous, whereas MEG source analysis suggested propagation of spikes from the right to the left frontal lobe.     

Real-time display of artifact-free electroencephalography during functional magnetic resonance imaging and magnetic resonance spectroscopy in an animal model of epilepsy.

Simultaneous recording of electroencephalogram (EEG) and functional MRI (fMRI) or MR spectroscopy (MRS) can provide further insight into our understanding of the underlying mechanisms of neurologic disorders. Current technology for simultaneous EEG and MRI recording is limited by extensive postacquisition processing of the data. Real-time display of artifact-free EEG recording during fMRI/MRS studies is essential in studies that involve epilepsy to ensure that they address specific EEG features such as epileptic spikes or seizures. By optimizing the EEG recording equipment to maximize the common mode rejection ratio of its amplifiers, a unique EEG system was designed and tested that allowed real-time display of the artifact-free EEG during fMRI/MRS in an animal model of epilepsy. Spike recordings were optimized by suppression of the background EEG activity using fast-acting and easily controlled inhalational anesthesia. Artifact suppression efficiency of 70-100% was achieved following direct subtraction of referentially recorded filtered EEG tracings from active electrodes, which were located in close proximity to each other (over homologous occipital cortices) and a reference electrode. Two independent postacquisition processing tools, independent component analysis and direct subtraction of unfiltered digital EEG data in MATLAB, were used to verify the accuracy of real-time EEG display.