Direct comparison of visual cortex activation in human and non-human primates using functional magnetic resonance imaging

We report a technique for functional magnetic resonance imaging (fMRI) in an awake, co-operative, rhesus macaque (Macaca mulatta) in a conventional 1.5T clinical MR scanner, thus accomplishing the first direct comparison of activation in visual cortex between humans and non-human primates with fMRI. Activation was seen in multiple areas of striate and extra-striate visual cortex and in areas for motion, object and face recognition in the monkey and in homologous visual areas in a human volunteer. This article describes T1, T2 and T2* values for macaque cortex, suitable MR imaging sequences, a training schedule, stimulus delivery apparatus and restraining hardware for monkey fMRI using a conventional 19 cm knee coil. Much of our understanding of the functional organization of the primate brain comes from physiological studies in monkeys. Direct comparison between species using fMRI such as those described here will help us to relate the wealth of existing knowledge on the functional organization of the non-human primate brain to human fMRI.     

局灶性皮质发育不良所致难治性癫痫的微创神经外科治疗

目的应用神经导航结合术中皮质电极描记,微创治疗局灶性皮质发育不良(focal cortical dysplasia,FCD)所致的难治性癫痫。方法 26例局灶性皮质发育不良所致的难治性癫痫患者,术前常规使用CT、磁共振成像(magnetic resonanceimaging,MRI)、长程视频脑电图(digital video signal and electroencephalogram,VEEG)、磁共振波谱分析(MR Spectroscopy,MRS)等检查,如病灶位于功能区则行功能性磁共振成像(functional magnetic resonance imaging,fMRI)。术中通过神经导航确定的病灶与ECoG确定的致痫灶位置及范围进行对比,了解两者的吻合程度及差异,综合分析后精确并标记出癫痫波的起源位置和范围,将局灶性皮质发育不良病灶和周边的致痫皮质切除;如致痫灶位于功能区或附近,在保留功能区皮质的基础上,给予低功率皮质热灼。结果术后病理结果:26例患者病理标本符合FCD。术后患者无明显并发症出现。根据Engel术后效果分级进行评估,Ⅰ级23例,Ⅱ级2例,Ⅲ级1例。结论神经导航结合术中皮质电极描记在局灶性皮质发育不良所致的难治性癫痫手术中,具有定位准确、损伤少的优点,在切除致痫灶的同时能最大程度保护脑功能。     

移动磁体双室高场强术中磁共振成像系统在经蝶窦垂体腺瘤手术中的初步应用

目的 总结移动磁体双室高场强术中磁共振成像(iMRI)系统在经蝶窦垂体腺瘤手术中的初步经验.方法 共有28例垂体腺瘤患者行经蝶窦入路iMRI辅助下的手术.肿瘤大小1.60～7.27 cm,平均(3.37±0.65)cm.应用1.5T移动磁体双室设计的iMRI,其中14例联合使用神经导航系统,16例联合使用神经内镜.结果 27例经鼻蝶窦手术,1例经口鼻蝶安手术.28例经蝶窦垂体腺瘤手术中,13例iMRI发现肿瘤残留,其中3例巨大垂体腺瘤患者,由于肿瘤侵犯海绵窦包绕颈内动脉,虽经iMRI证实海绵窦内有肿瘤残留,但未勉强进一步切除.其余10例经iMRI证实垂体腺瘤均完全切除.未发生与iMRI相关的并发症或安全事故.结论 移动磁体双室高场强iMRI系统能够在术中获得高质量的影像,为术中实时判断垂体腺瘤切除程度提供了客观依据,提高了垂体腺瘤的全切率.     

Development of a functional magnetic resonance imaging protocol for intraoperative localization of critical temporoparietal language areas

The aim of this study was to evaluate the use of functional magnetic resonance imaging as an alternative to intraoperative electrocortical stimulation mapping for the localization of critical language areas in the temporoparietal region. We investigated several requirements that functional magnetic resonance imaging must fulfill for clinical implementation: high predictive power for the presence as well as the absence of critical language function in regions of the brain, user-independent statistical methodology, and high spatial accuracy. Thirteen patients with temporal lobe epilepsy performed four different functional magnetic resonance imaging language tasks (ie, verb generation, picture naming, verbal fluency, and sentence comprehension) before epilepsy surgery that included intraoperative electrocortical stimulation mapping. To assess the optimal statistical threshold for functional magnetic resonance imaging, images were analyzed with three different statistical thresholds. Functional magnetic resonance imaging information was read into a surgical guidance system for identification of cortical areas of interest. Intraoperative electrocortical stimulation mapping was recorded by video camera, and stimulation sites were digitized. Next, a computer algorithm indicated whether significant functional magnetic resonance imaging activation was present or absent within the immediate vicinity (<6.4mm) of intraoperative electrocortical stimulation mapping sites. In 2 patients, intraoperative electrocortical stimulation mapping failed during surgery. Intraoperative electrocortical stimulation mapping detected critical language areas in 8 of the remaining 11 patients. Correspondence between functional magnetic resonance imaging and intraoperative electrocortical stimulation mapping depended heavily on statistical threshold and varied between patients and tasks. In 7 of 8 patients, sensitivity of functional magnetic resonance imaging was 100% with a combination of 3 functional magnetic resonance imaging tasks (ie, functional magnetic resonance imaging correctly detected all critical language areas with high spatial accuracy). In 1 patient, sensitivity was 38%; in this patient, functional magnetic resonance imaging was included in a larger area found with intraoperative electrocortical stimulation mapping. Overall, specificity was 61%. Functional magnetic resonance imaging reliably predicted the absence of critical language areas within the region exposed during surgery, indicating that such areas can be safely resected without the need for intraoperative electrocortical stimulation mapping. The presence of functional magnetic resonance imaging activity at noncritical language sites limited the predictive value of functional magnetic resonance imaging for the presence of critical language areas to 51%. Although this precludes current replacement of intraoperative electrocortical stimulation mapping, functional magnetic resonance imaging can at present be used to speed up intraoperative electrocortical stimulation mapping procedures and to guide the extent of the craniotomy.     

功能区胶质瘤术中应用DTI-FT导航定位和保护锥体束(附13例报告)

目的研究功能区胶质瘤术中完善而有效的锥体束空间定位和功能保护方法。方法对13例功能区胶质瘤应用1.5T磁共振系统采集弥散张量成像(DTI)数据,在功能神经导航中进行纤维束示踪(FT),在导航中确定肿瘤与锥体束界面的标记点,应用自制导航穿刺针、着色明胶海绵对白质内锥体束走行进行空间定位。在空间定位锥体束基础上,应用皮质、皮质下直接电刺激或唤醒麻醉技术在肿瘤切除中对锥体束功能进行评估监测,保证其正常功能。结果本组锥体束与肿瘤交界区在神经导航中均得到确定,术中在DTI-FT导航下空间定位满意;锥体束功能判定明确者10例。均全切肿瘤,运动功能保持术前正常水平或得到改善。结论联合应用DTI-FT导航、神经电生理或唤醒麻醉技术可确保锥体束功能不出现手术损伤,同时为明确胶质瘤在脑白质内功能性边界提供有效方法。     

Functional cranial neuronavigation. Direct integration of fMRI and PET data

OBJECTIVE: We report our first experiences with the direct integration of fMRI data into cranial neuronavigation. Method: For navigation we used the MKM system and thin-sliced T1 contrast enhanced images. As a first step 21 patients had fMRI for localization of the precentral gyrus, 2 patients for Broca area detection. By anatomical correlation, these functional data were indirectly compared to the intraoperative findings using cortical SSEP (n=20) or cortical stimulation (n=3). Encouraged by these preliminary results, we started the direct integration of fMRI into neuronavigation in June 1999, followed by PET in January 2000, enabling us to compare functional images with intraoperative findings directly. fMRI and PET data were integrated by landmark matching referring on skin fiducials. Meanwhile, fMRI data of 8 patients (6 motorcortex, 2 Broca) and PET images of 1 patient were directly integrated into neuronavigation. Six out of 8 patients had additional cortical monitoring, 2/8 were exclusively operated on by functional neuronavigation. RESULTS: Using indirect comparison between fMRI and intraoperative findings we observed a good correlation in every case for the motorcortex, but only in 1/2 for the speech area. In all 6 direct integrated fMRI cases, these findings corresponded well to the conventional ones. Both patients with sole functional navigation did not have any postoperative neurological deficit. The inaccuracy of the fMRI ifT1 matching was 2. 7 mm (sigma=0.9 mm) and 1.3 mm (sigma=0.4 mm) of the subsequent referenciation of the navigation. The tumor delinement shown by 11C-methionine PET could be proven by intraoperative biopsy outside its indicated tumor margin. The inaccuracy of the PET matching was 0. 8 mm. CONCLUSION: Functional neuronavigation enables to visualize and preserve relevant brain areas. Other functional areas like short-term memory, which solely can be detected by fMRI might also be monitored in the future. The integration of PET data expect to gain a better differentiation of tumor and edema.     

Acoustic noise concerns in functional magnetic resonance imaging

Magnetic resonance (MR) acoustic scanner noise may negatively affect the performance of functional magnetic resonance imaging (fMRI), a problem that worsens at the higher field strengths proposed to enhance fMRI. We present an overview of the current knowledge on the effects of confounding acoustic MR noise in fMRI experiments. The principles and effectiveness of various methods to reduce acoustic noise in fMRI are discussed, practical considerations are addressed and recommendations are made.     

Intraoperative visualization for resection of gliomas: the role of functional neuronavigation and intraoperative 1.5 T MRI

OBJECTIVE: To investigate how functional neuronavigation and intraoperative high-field magnetic resonance imaging (MRI) influence glioma resection. METHODS: One hundred and thirty-seven patients [World Health Organization (WHO) grade I: 20; II: 19; III: 41; IV: 57] underwent resection for supratentorial gliomas in an operative suite equipped with intraoperative high-field MRI and microscope-based neuronavigation. Besides standard anatomical image data including T1- and T2-weighted sequences, various functional data from magnetoencephalography (n=37), functional MRI (n=65), positron emission tomography (n=8), MR spectroscopy (n=28) and diffusion tensor imaging (n=55) were integrated in the navigational setup. RESULTS: Intraoperative MRI showed primary complete resection in 27% of all patients (I: 50%; II: 53%; III: 2%; IV: 28%). In 41% of all patients (I: 40%; II: 26%; III: 66%; IV: 28%) the resection was extended owing to intraoperative MRI increasing the percentage of complete resections to 40% (I: 70%; II: 58%; III: 17%; IV: 40%). Integrated application of functional navigation resulted in low post-operative morbidity with a transient new neurological deficit in 10.2% (paresis: 8.8% and speech disturbance: 1.4%) decreasing to a permanent deficit in 2.9% (four of 137 patients with a new or increased paresis). CONCLUSIONS: The combination of intraoperative MRI and functional navigation allows safe extended resections in glioma surgery. However, despite extended resections, still in the majority of the grade III and IV gliomas no gross total resection could be achieved owing to the extension of the tumor into eloquent brain areas. Intraoperative MRI data can be used to localize the tumor remnants reliably and compensate for the effects of brain shift.     

The role of magnetoencephalography in pediatric epilepsy surgery

Introduction Magnetoencephalography (MEG) is a new diagnostic imaging and brain mapping device that has been recently used in the context of pediatric epilepsy, epilepsy surgery, and neuronavigation.Principles of magnetoencephalography MEG allows for the placement of magnetic spike sources on a conventional magnetic resonance imaging scan, the so-called magnetic source imaging, so that the localization of epileptiform activity in a child can be determined. Considerable effort is placed on analyzing the configuration and number of spike waves by MEG that relate to a primary epileptiform discharge. Such MEG spike clusters are corroborated now by intraoperative invasive subdural grid monitoring that show good correlation in the majority of cases. Another important role of MEG relates to the mapping of critical regions of brain function using known paradigms for speech, motor, sensory, visual, and auditory brain cortex.Future applications When linked to standard neuronavigation devices, MEG brain mapping can be extremely helpful to the neurosurgeon approaching nonlesional epilepsy cases or lesional cases where the safest and most direct route to the surgical disease can be selected. As paradigms for brain mapping improve and as MEG software upgrades become more sensitive to analyzing all types of spike sources, MEG will play an increasingly important role in pediatric neurosurgery, especially for the child with intractable epilepsy.     

The use of functional magnetic resonance imaging in reducing a risk of postoperative neurological deficits in the patients with brain tumour

Background and purposeThe purpose of the study was to compare the results of operative treatment of tumours located in the sensory-motor cortex guided with functional magnetic resonance imaging (fMRI) combined with the neuronavigation system to the results of classical operative treatment.Material and methodsThe studied group comprised 28 patients with a tumour located in the sensory-motor cortex area who underwent surgery guided with fMRI and the neuronavigation system. A control group comprised 30 patients with the same clinical diagnosis, operated on without functional neuronavigation.ResultsThe use of functional neuronavigation allowed for an 18% reduction in the intensity of neurological deficits after surgical treatment in patients from the studied group, compared to the subjects from the control group (p = 0.0001). In the patients with diagnosed high-grade glioma, improvement in the neurological condition in the studied group was 16% (p = 0.03). The initial neurological condition and the results of surgical treatment in patients with a tumour located less than 5 mm from the sensory-motor cortex, determined in fMRI examination, are worse than in patients with a tumour located more than 5 mm.ConclusionsIn patients with a diagnosed brain tumour in the sensory-motor cortex who have neurological deficits, fMRI provides valuable imaging data on active areas. Tumour location of more than 5 mm from the fMRI active area of the sensory-motor cortex is connected with a considerably lower risk of postoperative neurological deficits. Removing a tumour in the sensory-motor cortex region, guided with fMRI and the neuronavigation system, considerably lowers the risk of postoperative development or exacerbation of neurological deficits.     

Neuronavigation: concept,techniques and applications

Neuronavigation provides intraoperative orientation to the surgeon, helps in planning a precise surgical approach to the targetted lesion and defines the surrounding neurovascular structures. Incorporation of the functional data provided by functional MRI and magnetoencephalography (MEG) with neuronavigation helps to avoid the eloquent areas of the brain during surgery. An intraoperative MRI enables radical resection of the lesions, the possibility of immediate control for tumor remnants and updates of neuronavigation with intraoperative images to compensate for brain shift. In this study, the experience of 432 patients undergoing neuronavigation assisted neurosurgical interventions using either the pointer-based or microscope-based navigational systems at the University of Erlangen-Nuremberg, Germany is presented. The procedures included stereotactic biopsy (n=53), stereotactic cyst puncture/ventricular drainage (n=15), eloquent cortex/tumor localization to facilitate tumor resection, assessment of neurovascular structures in the vicinity of tumors of the sellar-suprasellar regions, skull base, posterior fossa and ventricular region (n=252), and, surgery for epilepsy (n=9). Functional brain mapping using fMRI and MEG and their integration with neuronavigation was carried out in 24 and 128 patients respectively. The simultaneous use of intraoperative MRI to look for the remaining tumor was done in 159 patients and the update of navigational data was carried out in 17 patients. The mean system accuracy obtained by using both the fiducial registration as well as anatomical landmark-surface fitting computer algorithm was 1.81 mm. This study reviews the relative merits and demerits of the pointer and microscope based navigational systems and also highlights the role of functional brain mapping and intraoperative MRI, when integrated with neuronavigation, in the surgical decision-making to offer the chances of more radical resections with minimal morbidity.     

EEG/MEG source imaging using fMRI informed time‐variant constraints

Multimodal functional neuroimaging by combining functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) or magnetoencephalography (MEG) is able to provide high spatiotemporal resolution mapping of brain activity. However, the accuracy of fMRI‐constrained EEG/MEG source imaging may be degraded by potential spatial mismatches between the locations of fMRI activation and electrical source activities. To address this problem, we propose a novel fMRI informed time‐variant constraint (FITC) method. The weights in FITC are determined by combining the fMRI activities and electrical source activities in a time‐variant manner to reduce the impact of the fMRI extra sources. The fMRI weights are modified using cross‐talk matrix and normalized partial area under the curve to reduce the impact of fMRI missing sources. Monte Carlo simulations were performed to compare the source estimates produced by L2‐minimum norm estimation (MNE), fMRI‐weighted minimum norm estimation (fMNE), FITC, and depth‐weighted FITC (wFITC) algorithms with various spatial mismatch conditions. Localization error and temporal correlation were calculated to compare the four algorithms under different conditions. The simulation results indicated that the FITC and wFITC methods were more robust than the MNE and fMNE algorithms. Moreover, FITC and wFITC were significantly better than fMNE under the fMRI missing sources condition. A human visual‐stimulus EEG, MEG, and fMRI test was performed, and the experimental data revealed that FITC and wFITC displayed more focal areas than fMNE and MNE. In conclusion, the proposed FITC method is able to better resolve the spatial mismatch problems encountered in fMRI‐constrained EEG/MEG source imaging.     

脑磁图功能定位在脑功能区肿瘤手术中的应用

目的 评价脑磁图(MEG)功能定位在脑功能区肿瘤手术的应用价值.方法 回顾性分析24例肿瘤位于功能区及其附近病人的临床资料.术前行MEG功能定位,术中结合神经导航系统实时定位肿瘤及功能区,指导肿瘤切除和功能保护.结果 肿瘤位于功能区6例,与功能区部分重叠6例,功能区边缘5例,功能区外1-2cm7例.肿瘤全切除20例,次全切除4例.术后出现一过性神经功能障碍加重6例,持久性功能障碍加重4例.结论 MEG功能定位是术前无创功能定位技术,能够明确肿瘤与功能区位置关系,应用于功能区及附近肿瘤手术,可减少神经功能障碍的发生,提高病人术后生活质量.     

Association between tissue hypoxia,perfusion restrictions,and microvascular architecture alterations with lesion-induced impairment of neurovascular coupling

Functional magnetic resonance imaging (fMRI) has been mainly utilized for the preoperative localization of eloquent cortical areas. However, lesion-induced impairment of neurovascular coupling (NVC) in the lesion border zone may lead to false-negative fMRI results. The purpose of this study was to determine physiological factors impacting the NVC. Twenty patients suffering from brain lesions were preoperatively examined using multimodal neuroimaging including fMRI, magnetoencephalography (MEG) during language or sensorimotor tasks (depending on lesion location), and a novel physiologic MRI approach for the combined quantification of oxygen metabolism, perfusion state, and microvascular architecture. Congruence of brain activity patterns between fMRI and MEG were found in 13 patients. In contrast, we observed missing fMRI activity in perilesional cortex that demonstrated MEG activity in seven patients, which was interpreted as lesion-induced impairment of NVC. In these brain regions with impaired NVC, physiologic MRI revealed significant brain tissue hypoxia, as well as significantly decreased macro- and microvascular perfusion and microvascular architecture. We demonstrated that perilesional hypoxia with reduced vascular perfusion and architecture is associated with lesion-induced impairment of NVC. Our physiologic MRI approach is a clinically applicable method for preoperative risk assessment for the presence of false-negative fMRI results and may prevent severe postoperative functional deficits.     

Visual activation in functional magnetic resonance imaging at very high field (4 Tesla).

OBJECTIVES: Functional magnetic resonance imaging (fMRI) at very high field strengths provides functional brain mapping with the enhanced signal to noise ratio and the larger blood oxygenation level-dependent (BOLD) effect. We report activated areas in the standard space detected by fMRI at 4 Tesla (T) during simple visual stimulation. MATERIALS AND METHODS: Twelve healthy young subjects were scanned using a 4 T scanner during binocular flashing visual stimulation. Functional images were realigned to the first scan and then spatially normalized. Individual and group data analyses were performed to identify areas of visual activation. RESULTS: Activation of the bilateral primary visual cortex (V1/V2) was observed along the entire calcarine fissure in all subjects. The activated area extended to the extrastriate cortex in all subjects. Activation of the bilateral lateral geniculate nucleus (LGN) was detected in all subjects. The group data showed activation of the bilateral primary visual cortex and the bilateral lateral geniculate nucleus. CONCLUSIONS: Robust activation of the vision-related areas was successfully obtained in all subjects using a 4 T magnetic resonance scanner. These results suggest that fMRI at very high field strengths may be effective in showing visual system physiology, and that it can be a promising method to assess visual function of human subjects.     

Anatomical and functional imaging of the auditory cortex in awake mustached bats using magnetic resonance technology

The auditory cortex of mustached bats, Pteronotus parnellii, has been studied extensively using neuroanatomical tract-tracing and electrophysiological techniques to elucidate the functional organization and neural mechanisms important for auditory processing. While these techniques have identified several cortical maps involved in processing auditory information, there has been no direct observation of the dynamics of simultaneous activation of several discrete areas. We applied magnetic resonance (MR) imaging techniques for visualizing brain structures in awake bats using a 7-Tesla magnet system; we also investigated functional MR imaging by measuring changes in stimulus-correlated blood oxygenation levels to detect cortical areas exhibiting evoked neural activity. High resolution (100 microm) anatomical images were successfully acquired without any motion artifacts. It was possible to reconstruct the whole brain image and analyze brain surface structures with three dimensional (3D) MR imaging data. These data provide detailed morphometric measurements that will allow localization of stimulus specific neural activity patterns using modified functional magnetic-resonance-imaging (fMRI) protocols. Motion artifacts is the primary disadvantage of using awake bats; our study shows that fMRI of a bat's brain is feasible and may prove to be an important advancement for a further understanding of auditory processing in this species.Themes: Sensory systems, Neural basis of behavior.     

A functional MRI protocol for localizing language comprehension in the human brain

We describe a functional magnetic resonance imaging (fMRI) protocol to separate activation of areas in the brain associated with language comprehension from sensory areas activated as a result of the presentation of the language stimulus, by comparing cortical activation patterns during the presentation of similar or the same language stimulus via two different sensory modalities (auditory and visual), and identifying the regions of activation that are common to both modalities. The protocol can be implemented on any MR scanner capable of functional imaging, and has proven valuable for the reliable identification of the lateralization and location of language centres in patients being considered for neurosurgical procedures. As well, the method has potential for the study of cortical processing of auditory speech and written language in healthy subjects and in subjects suffering from language disorders.     

Electroencephalogram-triggered functional magnetic resonance imaging in focal epilepsy

The high spatial resolution and cost performance of functional magnetic resonance imaging (fMRI) is useful for estimating focus localization in epilepsy, but this is difficult in the case of ictal fMRI because this is susceptible to motion artifacts. Electroencephalogram (EEG)-triggered fMRI, which is interictal, can be performed without marked movement and is thought to be useful, but requires further investigation in order to establish a methodology. The authors studied EEG-triggered fMRI in partial epileptic patients. Six patients were examined using a Nihon Kohden digital EEG recorder and Signa Horizon High Speed LX 1.5 T MRI scanner. Six electrodes were attached in the vicinity of the focus detected by scalp EEG. The fMRI scans were recorded after the discharges (activation) and scans without spikes (baseline). Equal numbers of activation and baseline scans were collected and analyzed using SPM99. In three of the six patients, an activated area was observed near the focus, but no activated areas were found in the other three subjects who tended to have a low number of spikes and low spike amplitude. Although various approaches focusing on improvement of the activation/non-activation ratio are required, EEG-triggered fMRI is a promising technique for detecting focal epileptic brain activity.     

Dissimilarity of functional connectivity uncovers the influence of participant's motion in functional magnetic resonance imaging studies

Head motion is a major confounding factor impairing the quality of functional magnetic resonance imaging (fMRI) data. In particular, head motion can reduce analytical efficiency, and its effects are still present even after preprocessing. To examine the validity of motion removal and to evaluate the remaining effects of motion on the quality of the preprocessed fMRI data, a new metric of group quality control (QC), dissimilarity of functional connectivity, is introduced. Here, we investigate the association between head motion, represented by mean framewise displacement, and dissimilarity of functional connectivity by applying four preprocessing methods in two independent resting‐state fMRI datasets: one consisting of healthy participants (N = 167) scanned in a 3T GE‐Discovery 750 with longer TR (2.5 s), and the other of chronic back pain patients (N = 143) in a 3T Siemens Magnetom Prisma scanner with shorter TR (0.555 s). We found that dissimilarity of functional connectivity uncovers the influence of participant''s motion, and this relationship is independent of population, scanner, and preprocessing method. The association between motion and dissimilarity of functional connectivity, and how the removal of high‐motion participants affects this association, is a new strategy for group‐level QC following preprocessing.     

Clinical application of functional MRI: a strategic tool for neurosurgery

The purpose was to incorporate preoperative functional imaging data into anatomic data of operative microscope for neurosurgical procedures of patients suffering from lesions contiguous to eloquent brain areas. The day before surgery, patients bearing scalp markers underwent fMRI, just before anatomical contrast-enhanced MR images. FMRI data analysis were realised using a t test (p<0.0001). The resulting functional-anatomical images were downloaded onto a surgical neuronavigation computer in order to outline tumoral target and functional areas. At surgery, cortical stimulation has been used to confirm functional data. Functional image-guided surgery of lesions abutting functional cortex can be safely performed.