EEG-triggered functional MRI in patients with pharmacoresistant epilepsy

Functional magnetic resonance imaging (fMRI) triggered by scalp electroence phalography (EEG) recordings has become a promising new tool for noninvasiv e epileptic focus localization. Studies to date have shown that it can be u sed safely and that highly localized information can be obtained. So far, n o reports using comprehensive clinical information and/or long-term follow- up after epilepsy surgery in a larger patient group have been given that wo uld allow a valuable judgment of the utility of this technique. Here, the r esults of I I patients with EEG-triggered fMRI exams who also underwent pre surgical evaluation of their epilepsy are given. In most patients we were a ble to record good quality EEG inside the magnet, allowing us to trigger fM RI acquisition by interictal discharges. The fMRI consisted of echoplanar m ultislice acquisition permitting a large anatomical coverage of the patient 's brain. In 8 of the 11 patients the exam confirmed clinical diagnosis, ei ther by the presence (n = 7) or absence (n = 1) of focal signal enhancement . In six patients, intracranial recordings were carried out, and in five of them, the epileptogenic zone as determined by fMRI was confirmed. Limitati ons were encountered a) when the focus was too close to air cavities; b) if an active epileptogenic focus was absent; and c) if only reduced cooperati on with respect to body movements was provided by the patient. We conclude that EEG-triggered fMRI is a safe and powerful noninvasive tool that improv es the diagnostic value of MRI by localizing the epileptic focus precisely. (C) 2000 Wiley-Liss, Inc.