The evaluation of FDG-PET imaging for epileptogenic focus localization in patients with MRI positive and MRI negative temporal lobe epilepsy

Abstract

FDG-PET is an accurate noninvasive method in lateralizing the epileptogenic focus in temporal lobe epilepsy, especially in patients with normal or equivocal MRIs, or non-lateralized EEG monitoring. Very subtle findings in MRI are often associated with histopathological lesions and should be described in MRI reports. The patients with negative or equivocal MRI temporal lobe epilepsy are good surgical candidates with comparable postsurgical outcomes to patients with MRI positive temporal lobe epilepsy.

Potential Pediatric Applications of PET/MR

“…Both modalities were found to have a complementary role in the workup of children with intractable localization-related epilepsy, improving sensitivity and specificity. This finding is consistent with those of other studies (65,69) reporting the greatest benefit of 18 F-FDG PET in patients whose MR results were inconclusive or negative. Kim et al (67) determined the accuracy of imaging tools such as electroencephalography, MR, and 18 F-FDG PET in 42 pediatric patients who received epilepsy surgery (temporal lobectomies in 23/42 and extratemporal resection in 19/42).…”

“…The literature describes long-term seizure control, with a seizure-free outcome in 50%-80% of cases, after temporal lobe resection. The success of epilepsy surgery strongly depends on the precise presurgical identification of epileptogenic foci, for which MR is the most reliable tool (64)(65)(66)(67). Beyond electroencephalography, MR has been described as the primary imaging tool for TLE because of its high sensitivity and specificity (97% and 83%, respectively) for hippocampal sclerosis, the most common pathologic substrate of TLE.…”

“…Nevertheless, about 16%-55% of patients with TLE do not show any suspect lesion on MR scans (nonlesional epilepsy). Especially for this group of patients, other noninvasive functional imaging modalities-such as magnetoencephalography, 18 F-FDG PET, ictal SPECT or, more recently, subtraction ictal SPECT coregistered to MR-are of great value for preoperative assessment because patients with nonlesional epilepsy have a poorer surgical outcome than those with lesions that can be detected by MR (64)(65)(66)68).…”

Prognostic factors for seizure outcome in patients with MRI-negative temporal lobe epilepsy: A meta-analysis and systematic review

“…FDG-PET has demonstrated 100% concordance with MRI-identified focal lesions with respect to the lateralization of the epileptogenic zone [43]. For patients with MRInegative TLE [43], 84% were found to exhibit unilateral FDG-PET hypometabolism, and 90% of the patients exhibited concordance of the FDG-PET results with lateralized EEG findings. PET scans have been used to select a subgroup of TLE patients with normal MRI who exhibit better seizure control after surgery [45].…”

Current status and future role of brain PET/MRI in clinical and research settings

“…medial temporal sclerosis, focal cortical dysplasia and tuberous sclerosis complex) are numerous and have recently been reviewed by Lee and Salamon [91]. Briefly, they found that coregistration of [ 18 [94].…”