FDG-PET/CT Brain FDG-PET is well established as a modality to localize an epileptogenic focus and can provide additional information regarding the functional status of the uninvolved brain. Reported sensitivities of PET in the assessment of TLE ranges from 87% to 90% and extra-TLE ranges from 38% to 55% [24-27]. FDG when combined with perfusion ictal-interictal SPECT and subtraction ictal SPECT co-registered to MRI demonstrated improved detection of the epileptogenic zone [28]. A major limitation of interictal FDG-PET is that it cannot precisely identify the surgical margin because the area of hypometabolism often extends beyond the epileptogenic zone [8]. FDG-PET allows for higher-resolution and better-quality images compared with SPECT [29]. In cases of unchanged seizure semiology yet are refractive to medical therapy, FDG-PET can identify lesions missed on CT or MRI [30]. MEG There is no relevant literature regarding the use of MEG in the evaluation of known seizure disorder with unchanged seizure semiology. MRI Functional (fMRI) Head There is no relevant literature regarding the use of fMRI in the evaluation of known seizure disorder with unchanged seizure semiology. MRI Head The excellent gray-white matter differentiation and multiplanar imaging capability of MRI are characteristics that contribute to greater sensitivity and accuracy of MRI compared with CT [8,17,31]. Low-grade gliomas have been identified on MRI in patients with a history of epilepsy for >20 years [17], and so there is use in assessment of seizures that are chronic and longstanding to assess for changes in structural abnormalities. Some authors suggest that priority for imaging with MRI should be given to patients who have focal findings on a neurologic examination [17]. Patients being evaluated for seizures with normal MRI scans on a 1.5T scanner may have findings identified on repeat MRI imaging on 3.0T scanners, even with unchanged seizure semiology [32,33].
Seizures and Epilepsy. FDG-PET/CT Brain FDG-PET is well established as a modality to localize an epileptogenic focus and can provide additional information regarding the functional status of the uninvolved brain. Reported sensitivities of PET in the assessment of TLE ranges from 87% to 90% and extra-TLE ranges from 38% to 55% [24-27]. FDG when combined with perfusion ictal-interictal SPECT and subtraction ictal SPECT co-registered to MRI demonstrated improved detection of the epileptogenic zone [28]. A major limitation of interictal FDG-PET is that it cannot precisely identify the surgical margin because the area of hypometabolism often extends beyond the epileptogenic zone [8]. FDG-PET allows for higher-resolution and better-quality images compared with SPECT [29]. In cases of unchanged seizure semiology yet are refractive to medical therapy, FDG-PET can identify lesions missed on CT or MRI [30]. MEG There is no relevant literature regarding the use of MEG in the evaluation of known seizure disorder with unchanged seizure semiology. MRI Functional (fMRI) Head There is no relevant literature regarding the use of fMRI in the evaluation of known seizure disorder with unchanged seizure semiology. MRI Head The excellent gray-white matter differentiation and multiplanar imaging capability of MRI are characteristics that contribute to greater sensitivity and accuracy of MRI compared with CT [8,17,31]. Low-grade gliomas have been identified on MRI in patients with a history of epilepsy for >20 years [17], and so there is use in assessment of seizures that are chronic and longstanding to assess for changes in structural abnormalities. Some authors suggest that priority for imaging with MRI should be given to patients who have focal findings on a neurologic examination [17]. Patients being evaluated for seizures with normal MRI scans on a 1.5T scanner may have findings identified on repeat MRI imaging on 3.0T scanners, even with unchanged seizure semiology [32,33].