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Functional Magnetic Resonance Imaging in the Pre-Operative Original Articles FUNCTIONAL MAGNETIC RESONANCE IMAGING IN THE PRE-OPEraTIVE EVALUATION OF CEREBraL VASCULAR MALFORMATIONS RESONANCIA MAGNÉTIca CEREBraL FUNCIONAL EN LA EVALUacIÓN PREQUIRÚRGIca DE MALFORMacIONES VASCULARES Natalia Montes1 Diego Alberto Herrera2 Sergio Alberto Vargas2 KEY WORDS (MESH) SUMMARY Vascular malformations Objective: To describe our experience with pre-operative evaluation of intracranial Magnetic resonance imaging vascular malformations using functional magnetic resonance (fMRI). Method: Assessment Cerebral arteries of eight patients with cerebral vascular malformations (seven arteriovenous malformations [AVM] and one cavernous malformation) referred for pre-operative fMRI mapping of the PALABRAS CLAVE (DECS) eloquent cortex. An oxygen level-dependent technique (BOLD) was used to localize these Malformaciones areas in relation to the cerebral vascular malformation, applying different paradigms. vasculares Results: We found one AVM in the right mid-temporal lobe with distribution of the visual Imagen por resonancia and spatial memory to the contralateral hippocampus and parahippocampus; one posterior magnética left temporal AVM with activation of Wernicke’s area only; one left parietal AVM without Arterias cerebrales compromise of the sensory or motor cortex; a cavernous malformation at the left angular gyrus with hemispheric language dominance on that side; one right thalamic AVM with no compromise of the eloquent cortex; one left periventricular AVM with bilateral language dominance; one small left occipital AVM with normal activation of the primary visual cortex and decreased activation of the visual association cortex; and one temporo-occipital AVM with left language dominance and neurovascular uncoupling. Conclusion: fMRI can be used to delineate the anatomical relationship between the lesion and the eloquent cortex, providing useful information for pre-operative planning, and the estimated risk of the intervention. REsumEN 1 Radiologist. Neuro-radiology Fellow. Universidad de Antioquia. Medellín, Objetivo: Describir la experiencia en la evaluación prequirúrgica de pacientes con Colombia. 2 Neuro-radiologist, Centro Avanzado malformaciones vasculares con resonancia magnética cerebral funcional (RMf). Método: de Diagnóstico Médico (Cedimed) and Se evaluaron ocho pacientes con malformaciones vasculares cerebrales (siete malfor- Universidad de Antioquia. Medellín, Colombia. maciones arteriovenosas [MAV] y una malformación cavernosa) remitidos para mapeo Rev Colomb Radiol. 2010; 21:(4):1-11 1 prequirúrgico de la corteza elocuente con RMf. Se usó una técnica depen- diente de la concentración de oxígeno (BOLD) para localizar estas zonas en relación con la malformación vascular cerebral, aplicando diferentes paradigmas. Resultados: Se encontró una MAV en el lóbulo mesotemporal derecho, con representación de la memoria visuoespacial en el hipocampo y parahipocampo contralesionales; una MAV temporal posterior izquierda con activación contralateral exclusiva del área de Wernicke; una MAV parietal izquierda sin afectación de la corteza sensoriomotora; una malformación ca- vernosa en la circunvolución angular izquierda con dominancia hemisférica del lenguaje en ese lado; una MAV talámica derecha sin daño en la corteza elocuente; una MAV periventricular izquierda con patrón de equidominancia del lenguaje; una MAV pequeña occipital izquierda con activación normal en la corteza visual primaria y disminución en la activación de la corteza de asociación visual del lado izquierdo donde se encuentra la lesión, y una MAV temporo-occipital con dominancia hemisférica izquierda y desacople neu- rovascular. Conclusión: La RMf puede delinear anatómicamente la relación entre la lesión y la corteza elocuente y brindar información que facilita la planeación quirúrgica, incluida la estimación del riesgo de la intervención. Introduction A case series is presented in order to illustrate the usefulness Localization of the eloquent cortex is difficult even with the of this method. use of multiplanar magnetic resonance imaging (MRI). There Patients and methods may be distortion and displacement of this area with congenital We reviewed the clinical records of patients with a diagnosis lesions such as cerebral vascular malformations (1). Functional of cerebral vascular malformation referred for fMRI between magnetic resonance mapping (fMRI) using a blood level oxygen- March 2007 and December 2008 in order to assess the rela- dependent technique (BOLD) has gained popularity as part of the tionship between the lesion and cortical functional areas. Nine therapeutic planning process in patients who are candidates for patients (five women and four men) ranging from 17 to 50 years surgical, endovascular o radiosurgical treatment. This technique of age were included in the study (Table 1), and the retrospective is based on the local increase in oxyhemoglobin (molecule with paramagnetic properties) concentration in the cerebral vascu- review was approved by the Ethics Committee of the institution. lature, resulting from increased blood flow and volume in the The assessment included the localization, type and morphology cortex under stimulation (1,2). of the vascular malformation and its relationship (10) with the Mapping of cerebral function in the adjacent areas may be adjacent anatomical and functional structures. performed using intra- or pre-operative methods, including fMRI A 1.5 T Avanto (Siemens, Erlangen, Germany) magnetic as an alternative to positron emission tomography (3), magnetic resonance machine was used to acquire a T1 magnetization- encephalography (4,5), electrocorticography and the Wada test prepared rapid gradient echo (MP-RAGE) sequence in the (1,6,7), for example. Although these procedures, in particular sagittal plane in 20 healthy volunteers as follows: FOV = 240, fMRI, are very accurate for localizing the different cerebral matrix = 192x192, resolution = 1.3x1.3x1.3 mm, RT = 1,670 functions, they do not provide information about the time course ms, ET = 3.6 ms, flip angle = 8°, IT = 1,000 ms, averages = 2, of the activations and, consequently, about the organization of concatenations = 1, slices = 128, slice overmeasurement = 25%, the neural networks supporting each function (4,5). distance factor = 50%, bandwidth = 180 Hz/Px, duration, 4’39”. fMRI makes the therapeutic planning easier as it allows An echoplanar T2* gradient echo (RT = 3,000 ms, ET = 50 to define the relationship between the vascular lesion and the ms; matrix = 64x64; voxel size = 3x3x3 mm) sequence with functional cortex before proceeding to the surgical resection or continuous acquisition was used for the functional imaging endovascular exclusion, thus preventing a clinical deficit (8). (Table 2). Functional images were acquired following a block Language mapping is essential in these lesions because cerebral pattern, including alternating series every 30 s between basal and vascular malformations may be congenital and may give rise to active states. The paradigms (Table 3) consisted of alternating the reorganization of functional areas (6,9). closing and opening of the hand in order to activate the sensory- The purpose of this study is to describe our initial experience motor cortex, generation of verbs to assess language function, with the localization of the eloquent cortex using fMRI, in order modified Roland test to assess visual and spatial memory (11), to establish its relationship with cerebral vascular malforma- opening and closing of the eyes for visual activation, plus a tions and determine its importance in pre-operative planning. breath-holding paradigm. 2 Functional magnetic resonance imaging in The pre-operative evaluation of cerebral vascular malformations, Montes N; Herrera DA, Vargas SA Original Articles Table 1. Patients with cerebral vascular malformations assessed with fMRI before surgery (Medellin, Colombia, 2007-2008) Clinical Treatment No. Gender Laterality Malformation Paradigm fMRI interpretation Manifestation outcome Only left 18 year-old Right mid- hippocampal and Uncomplicated 1 Right Seizures Memory male temporal AVM parahippocampal embolization activation Mixed dominance Resection, mild Language 50 year-old Prior bleeding, Left temporal (left Broca’s post-surgical 2 Right (verb female headache AVM area and right dysphasia with generation) Wernicke’s area) full recovery Non-displaced activation in 39 year-old Motor (right left pre- and Uncomplicated 3 Right Headache Left parietal AVM male hand) post-central gyri embolization (sensorymotor cortex) Left temporal Language Left language 36 year-old 4 Right Seizures cavernous (verb dominance, lesion No intervention female malformation generation) in Wernicke’s area Non-displaced 17 year-old Bleeding, left Right thalamic Motor (left Uncomplicated 5 Right activation in right female hemiparesis AVM hand) embolization paracentral gyrus Bilateral language Corona radiata dominance, Bleeding, right Language 19 year-old and left semi- non-displaced Uncomplicated 6 Right hemiparesis, and right female oval white activation in embolization dysphasia hand motor matter AVM sensorymotor cortex Visual Partial seizures Reduced activation 38 year-old Left occipital (opening and Waiting for 7 Right with visual in left visual male AVM closing of embolization component association area eyes) Language (sentence Left hemisphere Intra- completion) 50% Left language 12 year-old parenchymal and breath- embolization 8 Right temporoccipital dominance and female hematoma. No holding and waiting
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