Neuroimaging MR assessment of epilepsy and seizures
- سال انتشار: 1397
- محل انتشار: پانزدهمین کنگره بین المللی صرع ایران
- کد COI اختصاصی: EPILEPSEMED15_125
- زبان مقاله: انگلیسی
- تعداد مشاهده: 420
نویسندگان
Medical Radiological Institute Zurich Switzerland
چکیده
Imaging evaluation of patients with epilepsy or following a seizure is based on high resolution MR imaging (MRI) preferentially at 3T field strenght with preferrntially 64 channel head coils to identify an epileptogenic morphologic substrate. A specifically designed protocol encompasses T2, 3D Flair, inversion recovery and contrast enhanced sequences to assess the hippocampus, cortical, white and deep grey matter microstructure; SWI sequences facilitate recognition of cavernomas,superficial siderosis, cortical vein thrombosis and calcifications.Computed tomography (CT) is usually applied in an emergency setting only in patients with new-onset seizures. Goals of Neuroimaging evaluation of a patient with epilepsy : Identify underlying brain structural abnormality: Categorize structural pathology : • hippocampal sclerosis isolated / amygdala involvement dual pathology • lesion focal /more generalized secondary changes pre-operative: locate function with respect to lesion: (data for image fusion): fMRI; SISCOM, PET-MR post-operative: identify potential cause for failure Distinguish 2ary changes eg following nonconvulsive status from 1 ary pathology Predictors of positive imaging findings are persistent neurologic findings, focal or multiple seizures, previous CNS disorder or systemic and CNS malignancy. The morphologic substrate of a location related/ partial epilepsy or a seizure is categorized into Hippocampal sclerosis / dual pathology Tumours Malformation of cortical development (MCD) Vascular lesions: cavernoma, cerebral amyloid angiopathy Encephalomalacia 2ary to trauma, ischemia infection, hemorrhage primary vs secondary seizure induced changes to trauma, infection or ischemia Supplementary techniques to morphologic MR imaging contribute to categorize lesions: These encompass diffusion weighted imaging, (DWI), perfusion MR, proton MR spectroscopy (MRS), diffusion tensor imaging (DTI) and functional MR imaging (f MRI). DWI provides information regarding restriction of water/proton mobility by cytotoxic edema,alteration of fiber structure and/or course and cell density eg in acute ischemia, and neoplasms. Vascularity and vessel permeability of neoplasms are assessed by perfusion MR and go parallel to a higher grade in gliomas and provide distinction between true progression and pseudoprogression in gliomas.MRS offers insight into the metabolism of lesions (cell proliferation, demyelination,lactate and 2HG accumulation) and is an additional means to grade glioamas and differentiate glioma recurrence from treatment induced changes. DTI delineates white matter tracts.By segmentation preoperative involvement of arcuate fasciculus, optic radiation and corticospinal tract by gliomas is evaluated. F-MRI localizes function in relation to a lesion in eloquent areas in particular in central location, lesions related Broca s or Wernickes area and optic tract of cortex.کلیدواژه ها
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