EPILEPSY IMAGING AND SURGERY
Epilepsy is a chronic disease characterized by the occurrence of seizures reflecting a sudden and transient disturbance in the electrical activity of the brain. In reality, there is not one but several epilepsies with a diversity of symptoms and evolution. In drug-resistant focal epilepsies*, detection of epileptogenic lesions is crucial to identify the best candidates for surgery. Focal cortical dysplasia (FCDs) are one of the most frequent lesions in children and adults. Surgical resection of dysplastic cortex yields good results, but FCDs can be difficult to identify in MRI imaging. 18F-FDG PET has been shown to be useful in cases of negative MRI and the added value of co-registration of PET and MRI has been demonstrated. Recently, a new hybrid PET/MRI imaging has been developed, allowing the simultaneous acquisition, on the same machine, of brain metabolism images provided by PET and morphological and functional images by MRI. However, the benefit of this new hybrid technique for surgical decision taking remains to be established.
CONTRIBUTION OF HYBRID PET/MRI IMAGING
In this study, the authors retrospectively compared 18F-FDG PET/MRI images (SHFJ hybrid PET/MRI machine) with anterior 18F-FDG PET co-registered with MRI (PET+MRI), in 25 patients with refractory focal epilepsy, included between 2017 and 2020. Visual analysis of image quality, localization of PET abnormalities, and presence of a structural lesion on MRI was performed in a double-blind fashion. The sensitivity of PET/MRI was found to be increased by 13% compared to PET+MRI. New structural lesions (mainly FCDs) were detected in 6 patients (24%). The decision for surgical intervention was reviewed in 10 patients, avoiding invasive explorations in 6 patients and modifying planning in 4 others. Seizure suppression (follow-up >1 year) was achieved in 12/14 patients who underwent cortical resection.
PET/MRI improves the detection of epileptogenic lesions, thus optimizing the pre-surgical workup and the results of surgical treatment, even in the most complex cases. It provides a higher degree of confidence for the physician interpreting the images, regardless of training and experience. Finally, the "single step" concept brought by PET/MRI, more comfortable for patients and convenient for clinicians, is an important issue in favor of this simultaneous imaging.
* Focal epilepsy (also called partial epilepsy) affects only a localized area of the brain, without involving the whole brain. The symptoms vary depending on where the seizure occurs.
Contact : Francine Chassoux francine.chassoux@aphp.fr